Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (4,249)
  • 1988  (4,249)
  • Polymer and Materials Science  (3,199)
  • General Chemistry  (1,050)
  • 101
    Electronic Resource
    Electronic Resource
    Saponification kinetic study of mica-acrylonitrile graft copolymers (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 157 (1988), S. 177-187 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik der alkalischen Hydrolyse von Glimmer-Acrylnitril-Pfropfcopolymeren wurde untersucht. Die Abhängigkeit des Verseifungsgrades von der Alkalikonzentration und der Hydrolysezeit wurde bestimmt. Chemische und spektroskopische Techniken wurden zur Bestimmung des Hydrolysemechanismus herangezogen.
    Notes: Kinetics of alkaline hydrolysis of mica-acrylonitrile graft copolymers was studied. The dependence of alkali concentration and the time of hydrolysis on the degree of saponification was determined. Chemical and spectroscopical techniques were used to determine the mechanism of hydrolysis.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051570114
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 102
    Electronic Resource
    Electronic Resource
    A novel method for vinyl grafting onto cotton fabric using ceric-cellulose thiocarbonate redox system (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 157 (1988), S. 153-163 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Behandeln von Baumwollgewebe mit Schwefelkohlenstoff in Gegenwart von NaOH ergibt Cellulosethiocarbonat, welches mit Cerammoniumnitrat (CAN) einen Komplex bildt. Nach ausgiebigem Waschen war das CeIV-Cellulosethiocarbonat fähig, die vinylische Pfropfpolymerisation auf Baumwollgewebe ohne Homopolymerbildung zu initiieren. Die Pfropfausbeute wuchs im Falle von Methylmethacrylat mit wachsenden CAN-Gehalt (0 - 50 mmol/l) und steigender Temperatur (60 - 80°C). Bei pH 2 war die Pfropfung besonders begünstigt. Dagegen wurde die Pfropfung im alkalischen Bereich gestoppt. Die Zugabe von bis zu 7% Methanol, Ethanol oder Isopropanol zum wäßrigen Polymerisationsmedium erhöhte die Pfropfausbeute bedeutend; hierbei wurde mit Isopropanol die hdchste Steigerung erhalten. Hdhere Alkoholmengen dagegen erniedrigten die Ausbeute. Die Pfropfgeschwindigkeit ist anfangs hoch, spater wird die Pfropfungsreaktion langsamer. Unabhingig von den verwendeten Reaktionsbedingungen war eine Reaktionszeit von 60 Minuten ausreichend. Es wurde die Fahigkeit des Cdv-Cellulosethiocarbonats untersucht, die Pfropfung mit Methylmethacrylat, Acrylnitril und Acrylamid zu initiieren. Dabei ergab sich fur die Pfropfgeschwindigkeit folgende Reihenfolge: Methylmethacrylat 〉 Acrylnitril 〉 Acr ylamid.
    Notes: Treatment of cotton fabric with carbon disulphide in presence of NaOH resulted in cellulose thiocarbonate. The latter formed a complex when treated with ceric ammonium nitrate (CAN). After being thoroughly washed, the CeIV cellulose thiocarbonate was capable of initiating vinyl graft polymerization onto cotton fabric without homopolymer formation. The graft yield obtained with methyl methacrylate was found to increase by increasing CAN from zero to 50 mmol/l at temperatures from 60 to 80°C. Grafting was greatly favoured at pH 2; alkaline pH offset grafting. Incorporation of up to 7% of methanol, ethanol, or isopropanol in the aqueous polymerization medium enhanced grafting significantly with the certainty that the highest graft yield was obtained with isopropanol; using higher alcohol percentages decreased grafting. The rate of grafting showed an initial fast rate followed by a slower rate; 60 minutes reaction time proved appropriate for grafting irrespective of the condition used. In addition to methyl methacrylate the ability of CeIV-cellulose thiocarbonate to induce grafting of acrylonitrile and acrylamide was also examined. The rate of grafting followed the order methyl methacrylate 〉 acrylonitrile 〉 acrylamide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051570112
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 103
    Electronic Resource
    Electronic Resource
    Interface distribution functions of diluted polymer systems containing core fibrils (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 157 (1988), S. 165-176 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus der Röntgenkleinwinkelstreuung von aus der orientierten Schmelze kristallisierten Legierungen aus isotaktischem Polypropylen und Poly(1-buten) wurden Grenzflächenverteilungsfunktionen berechnet. Die Proben enthalten Nadelkristalle, die in Bezug auf ihre Abstandsverteilung ein „verdünntes System“ darstellen. Es wird gezeigt, daß die Berechnung von Grenzflächenverteilungsfunktionen aus jeweils nur zwei Grenzflächen möglich ist. Der Vergleich der erhaltenen Nadeldicken mit Ergebnissen aus anderen Auswertemethoden ergibt eine gute Übereinstimmung.
    Notes: Interface distribution functions have been evaluated from the equatorial small angle x-ray scattering of blends of isotactic polypropylene and poly(1-butene) crystallized in the shear field of the oriented melt. The samples contain core fibrils which represent a diluted system with respect to their distance statistics. It is shown, that interface distribution functions can be calculated from only two interfaces (diffuse phase boundaries between fibrils and amourphous phase). The calculated thicknesses agree well with values determined from other methods.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051570113
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 104
    Electronic Resource
    Electronic Resource
    Mitteilungen (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 157 (1988), S. 199-199 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No Abrstract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051570116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 105
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of inhibited oxidationPaper presented at the 18th Colloquium of Danubian countries for “Natural and artificial ageing of plastics” in Villach, Austria, June 24-26, 1987 (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 158 (1988), S. 15-69 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper accumulates the mechanism and kinetics of oxidation and the inhibition mechanism of oxidation processes using preventive antioxidants, chain-breaking antioxidants and deviations from the simple inhibition mechanism.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051580102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 106
    Electronic Resource
    Electronic Resource
    Reaction of some polymers containing carbonyl groups with phenol in the presence of mineral acids (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 160 (1988), S. 83-90 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktion von Poly(methylvinylketon) und acetyliertem Polystyrol mit Phenol in Gegenwart von HCl oder H2SO4 wurde untersucht, um Polymere mit Strukturen ähnlich dem Bisphenol A zu erhalten. Die Reaktion an Poly(methylvinylketon) führt zu intramolekularer Aldol-Kondensation, während acetyliertes Polystyrol die gewünschte Bisphenol A-Struktur liefert.
    Notes: The reaction of polymers containing carbonyl groups such as poly(methyl vinylketone), poly(methyl vinyl ketone-co-styrene) and acetylated polystyrene with phenol in the presence of HCI or H2SO4 has been studied in order to produce bisphenol A type structure on the polymer chain. Poly(methyl vinyl ketone) shows intramolecular aldol condensation and acetylated polystyrene results in bisphenol A type structure.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051600106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 107
    Electronic Resource
    Electronic Resource
    Viscoelastic properties of short fiber filled SBR composites (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 160 (1988), S. 29-39 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In der vorliegenden Arbeit wird der Einfluß der Verformungsamplitude, der Temperatur und der Frequenz auf die dynamischen Eigenschaften von SBR-Faserverbundstoffen untersucht. Der Einbau von Kurzfasern erhöht den Speichermodul bei beliebiger Verformungsamplitude. Je nach Fasertyp verringert sich die lineare Reaktionszone des Moduls auf die Verformung oder verschwindet vollkommen. Der Verlustfaktor tan δ ist größer bei Faserverbundstoffen, obwol die Signale größenmäßig sich nicht verändern, lediglich die entsprechende Verformung.Bei Temperaturanstieg verringert sich der Modulwert, jedoch ist dieser Abfall weniger stark ausgeprägt im Faser-SBR-Verbund. Die Relaxationsspektren zeigen eine maximale Dämpfung, die der Hauptrelaxation in der Elastomermatrix entspricht. Die Temperatur,bei der dieses Maximum auftritt, verlagert sich zu höheren Werten mitsteigender Anregungsfrequenz. Dadurch wird die Ermittlung der scheinbaren Relaxationsaktivierungsenergie möglich, die im Verbund Faser-Haftmittel-SBR höher ist (225-275 kJ/mol) als in dem faserfreien Stoff (194.6 kJ/mol) als Folge einer stärkeren Faser-Matrix-Wechselwirkung.
    Notes: This paper examines the effects of deformation amplitude, temperature and frequency on the dynamic properties of SBR-short fiber composites. The presence of the fiber increases the storage modulus at any deformation amplitude. Depending on the nature of the fiber, the linear response zone of the modulus versus deformation either diminishes or disappears. The loss factor tan δ is higher in fiber composites. Although the peaks do not vary in magnitude, they occur at different deformation amplitudes.Temperature increase causes the moduli to decrease, the gradient, however, being less pronounced for fiber composites. The relaxation spectra show a damping peak which correlates to the principal relaxation process in the elastomeric matrix. The temperature at which this peak appears is displaced towards higher values with increasing excitation frequency. This allows the determination of the apparent relaxation activation energy, which is higher in fiber plus adhesive composites (225 - 275 kJ/mol), as compared to the fiber-free composite (194 kJ/mol), as a consequence of stronger fiber-matrix interaction.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051600103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 108
    Electronic Resource
    Electronic Resource
    Preparation and properties of UV-curable polydimethylsiloxane urethane acrylate (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 160 (1988), S. 41-66 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde ein neuer Typ eines UV-härtbaren Polyurethanacrylatharzes synthetisiert, das auf hydroxyterminierten Polydimethylsiloxan (PDMS)-Weichsegmenten mit einem Molekulargewicht von 1800 und 2,4-Toluoldiisocyanat (TDI)/2-Hydroxyethylmethacrylat (HEMA) Hartsegmenten basiert. Die Reaktivität von 2,4-TDI mit den Hydroxygruppen von Silanol und HEMA wurde anhand von IR-Messungen diskutiert. Die charakteristischen Absorptionspeaks der NCO-Gruppen von 2,4-TDI in para- und ortho-Stellung sollten mit zunehmender Reaktionszeit abnehmen.Die Meßmethodik der wesentlichen physikalischen Eigenschaften dieser Art von UV-härtbaren Materialien wurde ebenso wie auch der Einfluß verschiedener reaktiver Verdünnungsmittel und einiger Pigmente untersucht. Dieses Harz mit guten optischen, elektrischisolierenden und Hafteigenschaften an verschiedenen Matrizes konnte in den chemischen Eigenschaften verbessert und die Viskosität reduziert werden, während die Beschichtungsverarbeitbarkeit durch Mischen mit verschiedenen reaktiven Verdünnern gefördert wurde. Die hervorragenden Hafteigenschaften auf Glasplatten wurden der ähnlichen Struktur zwischen den PDMS Weichsegmenten und Glas zugeschrieben, was eine breite Anwendung in der Beschichtungsindustrie erschließt.
    Notes: A new type of a UV-curable polyurethane acrylate resin based on hydroxyterminated polydimethylsiloxane (PDMS) soft segments with molecular weight 1800 and 2,4-toluene diisocyanate (TDI)/2-hydroxyethyl methacrylate (HEMA) hard segments were synthesized. The reactivity of 2,4-TDI with the hydroxy groups of silanol and HEMA was discussed by means of IR measurements. The characteristic absorption peaks of the  - NCO groups of 2,4-TDI in the para- and ortho-position should decline with increasing the reaction time. The measurements of fundamental physical properties of this type of UV-curable materials had been widely studied in addition to the effects of using various reactive diluents and some pigments. This kind of resin with good optical, electrical insulating, and adhesive properties on various matrices, could be improved in chemical properties and reduced in viscosity while promoting the coating processability by mixing with various reactive diluents. The excellent adhesive properties on glass plates can be attributed to the similar structure between the PDMS soft segments and glass which makes the application in the coating industry possible.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051600104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 109
    Electronic Resource
    Electronic Resource
    Photooxidative behaviour of polypropylene fire retarded with instumescent additiveResults presented at the “VIII Convegno Italiano di Scienza delle Macromolecole”, 18-22 October 1987, Milano, Italy. (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 160 (1988), S. 203-209 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A typical intumescent fire retardant additive for polypropylene, which is a mixture of ammonium polyphosphate and pentaerythritol, does not sensibly modify the photooxidative behaviour of unstabilized polypropylene whereas it modifies that of polypropylene stabilized with a substituted o-hydroxybenzophenone and a sterically hindered amine. The photostabilizing effectiveness of the amine is probably decreased owing to protonation by polyphosphoric acid. On the contrary, the photo-protection effectiveness of the o-hydroxybenzophenone is increased in the presence of the intumescent fire retardant. This might be due to a photoinhibition effect of pentaerythritol.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051600117
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 110
    Electronic Resource
    Electronic Resource
    Einfluß der chemischen Struktur auf die mechanischen Eigenschaften von modifizierten PolycarbonatenHerrn Prof. Dr. G. Kämpf zum 60. Geburtstag gewidmet (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 162 (1988), S. 109-121 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Beginning with the current theories concerning the solid state structure of bisphenol-A-polycarbonate, the effect of chemical substitution of the bisphenol upon the thermal, mechanical, and dynamic mechanical properties will be discussed in detail. The observed mechanical properties of the various polycarbonates is considerably influenced by their chemical structure. Among all of the polycarbonates, bisphenol-A-polycarbonate is unique, particularly with respect to its low temperature properties. The ductile-to-brittle transition as a function of temperature correlates to the high temperature region of Gamma relaxation (G′′). Any theoretical approach to completely characterize and describe the experimentally observed phenomena must take into consideration as a fundamental parameter the conformational flexibility of the polycarbonate chain.
    Notes: Ausgehend von den bisher erarbeiteten Vorstellungen über die Festkörperstruktur des Bisphenol-A-Polycarbonats wird die Auswirkung einer chemischen Substitution des Bisphenols auf die thermischen, mechanischen und mechanisch-dynamischen Eigenschaften diskutiert. Innerhalb der Substanzklasse der Polycarbonate zeigt sich dabei hinsichtlich der beobachteten mechanischen Phänomene ein erheblicher Einfluß der chemischen Struktur. Vor allen Polycarbonaten ist das Bisphenol-A-Polycarbonat besonders hinsichtlich seiner Tieftemperatur-Eigenschaften ausgezeichnet. Der Spröd/Zäh-Übergang als Funktion der Temperatur korreliert mit der Hochtemperaturflanke des mechanischen Nebenrelaxationsgebietes. Eine die experimentell beobachteten Phänomene vollständig charakterisierende Theorie muß als wesentlichen Parameter die konformative Beweglichkeit der Polycarbonat-Ketten berücksichtigen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051620107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 111
    Electronic Resource
    Electronic Resource
    Effect of vulcanization temperature on the cure characteristics and vulcanizate properties of natural rubber and styrene-butadiene rubberPresented at the International Symposium on Polymer Materials, Aug. 31 - Sep. 4, 1987, San Sebastian, Spain. (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 162 (1988), S. 123-134 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mischungen von Elastomeren wie Naturkautschuk und Styrol-Butadien-Kautschuk werden bei verschiedenen Temperaturen vulkanisiert und die Behandlungscharakteristika und Vulkanisateigenschaften verglichen. Die optimale Behandlungszeit bei einer bestimmten Vulkanisationstemperatur konnte empirisch durch eine Exponentialbeziehung dieser Temperatur ausgedrückt werden. Die Vernetzungsdichte der Vulkanisate nimmt mit steigender Vulkanisationstemperatur ab. Für eine vorgegebene Mischung gibt es eine bestimmte Vulkanisationstemperatur, bei der die Materialien die besten Eigenschaften für spezifische Anwendungen besitzen.
    Notes: Gum compounds of natural rubber (NR) and styrene-butadiene rubber (SBR) are vulcanized at different temperatures and the cure characteristics and vulcanizate properties are compared. The optimum cure time at a particular vulcanization temperature could be expressed empirically in terms of that temperature using an exponential relation. The crosslink density of the vulcanizates is found to decrease with an increase in the vulcanization temperature. For a given compound there is a particular vulcanization temperature which gives the best compromise of properties for specific applications.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051620108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 112
    Electronic Resource
    Electronic Resource
    GPC estimation of molecular mass distribution of addition polymers from bisphenol-a-diglycidyl ether and amines (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 162 (1988), S. 149-162 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Thermisch polymerisierte Proben von linearen Additionspolymeren des Bisphenol-A-Diglycidylethers (DGEBA) mit den drei unterschiedlichen Aminen, (A) Benzylamin (BA), p-Chloranilin (PCA) und Cyclohexylamin (CHA), wurden mittels Gelpermeationschromatographie (GPC) unter Verwendung von THF als Elutionsmittel untersucht.Bei der Eichung des Systems und der Interpretation der Chromatogramme wurde der Solvatationseffekt der Hydroxylgruppen durch THF berücksichtigt. Der Vergleich der Chromatogramme weist darauf hin, daß das Polymere mit CHA schon im Bereich kleiner Molmassen (einschließlich der Dimeren) und in einem frühen Reaktionsstadium cyclisiert. Der Vergleich der mittleren Molmassen der Proben, die nach zwei unabhiingigen Methoden  -  Dampfdruckosmometrie (VPO) und GPC  -  gemessen wurden, zeigt, daß die Cyclisierung der Polymeren mit BA und PCA in einem geringeren Umfang stattfindet. Die beiden letztgenannten Polymeren neigen also weniger zur Cyclisierung.
    Notes: Thermally polymerized samples of linear addition polymers of bisphenol-A-diglycidyl ether (DGEBA) and the following three different amines (A): benzylamine (BA), p-chloroaniline (PCA), and cyclohexylamine (CHA) were chromatographed by gelpermeation chromatography (GPC) using THF as eluent. The solvation effect of hydroxyl groups by THF has been taken into consideration when calibrating the system and interpreting the chromatograms. The comparison of the chromatograms suggests that the polymer with CHA is cyclized already in the range of small molecular masses (including dimers) and in an early stage of reaction. The comparison of average molecular masses of the samples as measured with independent methods - vapour pressure osmometry (VPO) and GPC - shows that the cyclization of the polymers with BA and PCA takes place to a lower extent, the latter polymer being less capable of cyclization.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051620110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 113
    Electronic Resource
    Electronic Resource
    Synthèse de Copolymères Greffés Poly(ethylène-g-Méthacrylate de méthyle) et leur Influence sur les Propriétés Mécaniques des Alliages de Polyéthylène avec le Polychlorure de Vinyle (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 162 (1988), S. 175-191 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Graft copolymers P(E-g-MMA) were prepared by ozonisation of low density polyethylene (LDPE) and grafting of methyl methacrylate (MMA) in bulk onto the peroxides and hydroperoxides thus obtained (Mn graft PMMA = 7700 and 21400). The emulsifying effect of P(E-g-MMA) copolymers on PE-PVC mixtures was examined. With added quantities of 5.0% copolymers the braking strength value σB for the mixture PE-PVC 50-50 is varying between 0.60 to 1.10 kg/mm2; the variation of the elongation at break point εB is more difficult to explain. The alloy fractographs were also examined under the scanning electron microscope. We observed PE modules of 20 to 30 in average diameter, without copolymer, and 1 to 2 after adding 5% of copolymers. This underlines the emulsifying role played by the copolymer. These results are compared with those of other teams. The P(E-g-MMA) that we prepared, can be considered as a suitable emulsifier for LDPE-PVC mixtures and presents the advantage of being more accessible for industrial synthesis of new alloys PE-PVC.
    Notes: Les copolymères greffés P(E-g-MMA) sont préparés par réaction du méthacrylate de méthyle (MMA) en masse sur le polyéthylène basse densité ozonisé. La masse moyenne des greffons de PMMA variable suivant la température et le temps de réaction est de 7700 et 21400. Ces copolymères sont testés comme émulsifiants de mélanges de PE et de PVC dont les propriétés mécaniques, la contrainte à la rupture σR, l'allongement à la rupture εR% et le module d'élasticité E sont mesurées avant et après l'addition de 5% en poids de copolymère. Pour le mélange PE-PVC 50-50 σR passe de 0,60 à 1,10 kg/mm2, la variation de εR est plus complexe. La visualisation, au microscope électronique à balayage, des fractographies de ces divers mélanges, montre une diminution d'au moins un facteur 10 de la taille des phases après addition de copolymère et confirme bien le rôle d'émulsifiant d'émulsifiant de ceux-ci permettant d'obtenir ainsi de nouveaux alliages PE-PVC dont les propriétés sont comparées avec celles d'alliages préparés par d'autres auteurs avec d'autres émulsifiants.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051620112
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 114
    Electronic Resource
    Electronic Resource
    Estimation of polymer fractionation efficiency by comparison of theoretical models and experimental molecular mass distribution (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 162 (1988), S. 163-173 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In dieser Arbeit wird die Effizienz einer neuen modifizierten Säulenfraktionierungsmethode durch Vergleich von theoretischen Modellen und experimentell erhaltenen Molmassenverteilungen vorgestellt. Fünf theoretische Funktionen wurden zur Anpassung der experimentellen Daten benutzt: die Log-normal-, Tung-, Schulz-, Polynomial- und Flory-Verteilungsfunktion. Die Kurvenanpassung wurde durch die mittlere quadratische Abweichung abgeschätzt. Die mittlere quadratische Abweichung war in allen theoretischen Modellen von der gleichen Größenordnung. Mit der Polynomial- und Flory-Funktion wurden die kleinsten Werte für die mittlere quadratische Abweichung und somit die beste Anpassung der aus der Gelpermeationschromatographie erhaltenen Verteilungskurven erreicht. Diese Kurven geben die wahre Verteilung der benutzten Polymeren wieder. Diese theoretischen Modelle dienten auch als Referenzverteilungsfunktionen. Die experimentell mit zwei verschiedenen LCIsungsmittelpaaren bestimmten Fraktionswerte wurden dann den ausgewlhlten Referenzmodellen angepdt. Die Fraktionswerte der beiden benutzten Lösungsmittelpaare stimmten gut mit dem Polynomial- und Flory-Modell überein. Dies bestätigt die hohe Effizienz der vorgeschlagenen Fraktionierungsmethode.
    Notes: In this paper the efficiency of a new modified column fractionation method was presented through the comparison of theoretical models and experimentally obtained molecular mass distribution. Five theoretical functions were used for fitting the experimental data: log-normal, Tung, Schulz, polynomial, and Flory distribution function. The curve fittings were estimated by the mean square deviation. The mean square deviations in all the theoretical models were of the same order. The least values of mean square deviation and consequentely the best fitting of the gel permeation chromatography (GPC) distribution curve, which deals as a true distribution of the applied polymer sample, were achieved with polynomial and Flory model. These theoretical models were further chosen as a reference distribution function. The experimental fractionation data in two quite different solvent pairs were afterwards fitted to the chosen referent models. Fractionation data of the both applied solvent pairs have been in close agreement with Flory and polynomial model. This confirms the high efficiency of the proposed fractionation method.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051620111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 115
    Electronic Resource
    Electronic Resource
    Thermal chlorination of atactic polypropylene (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 163 (1988), S. 23-35 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Chlorierung von ataktischem Polypropylen (APP) wurde thermisch gestartet und in Tetrachlorkohlenstoff durchgeführt. Es wurde gefunden, daß mit zunehmender Verdünnung der Chlorierungsgrad steigt, was in % Gewichtszunahme gemessen wurde. Grund für dieses Verhalten ist eine größere Aufweitung und Beweglichkeit der APP-Ketten, wodurch die durch Chlor zu ersetzenden Stellen besser zugänglich werden. Die Reaktionsordnung in Abhängigkeit von der APP-Konzentration beträgt 0,84 und die Aktivierungsenergie (Er) 5,29 kcal/mol. Die Erhöhung der Strömungsrate führt zu einem höheren Chlorierungsgrad. Dieser steigt bis zu einer Strömungsrate von 1 l/h linear an, um dann ein konstantes Nivoau anzustreben. IR-Spektroskopie und 13C-NMR-Untersuchungen weisen darauf hin, daß die Chlorierung an allen drei ersetzbaren H-Atomtypen vorkommt. Der Startschritt des Mechanismus ist wahrscheinlich die Substitution des tertiären H-Atoms durch freie Chlorradikale und nachfolgendem Austausch der sekundären und primären H-Atome durch entweder fortschreitende Substitution oder den Eliminierungs-Additions-Mechanismus.
    Notes: Chlorination of atactic polypropylene (APP) was thermally initiated and carried out in carbon tetrachloride (CCl4) solution. It was found that with the increase in dilution, there is an increase in the extent of chlorination, as measured in terms of % weight-gain. The reason for this behaviour has been ascribed to a greater degree of opening up and mobility of APP chains thus increasing the accessibility of the replaceable sites to chlorine. The order of the reaction with respect to APP concentration was found to be 0.84, the overall activation energy (Er) being 5.29 kcal/mol. Increase in flow rate leads to an increase in the extent of chlorination and was found to be increasing linearly with a flow rate up to 1 l/h beyond which it levels off. IR spectroscopy and 13C-NMR studies indicate the chlorination occurring in all the three types of replaceable H-atoms in APP. The mechanism appears to be initial substitution of tertiary H-atom by free chlorine radical followed subsequently by replacement of secondary and primary H-atoms via either progressive substitution or elimination-addition mechanism.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051630103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 116
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 117
    Electronic Resource
    Electronic Resource
    Translational friction of a particle inside a vesicle studied by an extended shell method (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 97-111 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The translational friction of a particle inside a rigid hollow sphere is determined in this work. This should be important in model studies of solute diffusion in cells or vesicles. An extended shell algorithm is developed and used in which the cell or vesicle is modeled as a large number of beads. In the extended algorithm, the shell is divided into groups of beads and the assumption is made that the force exerted by each bead on the solvent is constant within a group. The algorithm is tested by using it to determine the translational friction constants of spheres and prolate ellipsoids modeled as shells of beads.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 118
    Electronic Resource
    Electronic Resource
    An analysis of the 225-230-nm CD band of elapid toxins (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 113-122 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectroscopic measurements of three representative elapid toxins are presented. An analysis of the data leads to the conclusion that the 228-nm CD band in this class of proteins originates largely in the disulfide chromophore. The intensity of this CD band is sensitive to conformational change associated with the disulfide group.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 119
    Electronic Resource
    Electronic Resource
    A synthetic model of collagen: An experimental investigation of the triple-helix stability (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 157-163 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Variations I-XVIII of a trimerlike cross-linked collagen model peptide were synthesized and used to investigate the cooperation of different neighboring Gly-X-Y tripeptides. The carboxy-terminal decapentapeptide of the tripe-helical part of collagen type I was chosen as the starting point of sequentially modified elongations. The transition temperatures determined by CD measurements show that the incorporation of the imino acid free tripeptides Gly-Ala-Ala and Gly-Ile-Ala results in a weakening of the triple-helical structure. It is demonstrated that the desired thermal stability of the collagen triple helix requires the “clustered” arrangement of helix-promoting tripeptides, especially of Gly-Pro-Hyp.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270112
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 120
    Electronic Resource
    Electronic Resource
    Anion effects on equilibria and kinetics of the disorder-order transition of κ-carrageenan (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 139-155 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of a number of tetramethylammonium salts on the equilibria and kinetics of the disorder to order transition in the polysaccharide κ-carrageenan have been investigated. Data from the temperature dependence of optical rotation show that anion stabilization of the ordered form follows the lyotropic series I- 〉 Br- 〉 NO-3 〉 Cl- 〉 F-. Stopped-flow polarimetry was used to study the kinetics of conformational ordering following a rapid increase in salt concentration. The transition to the new equilibrium position was shown to be biphasic for all of the tetramethylammonium salts studied. The rate equation for the fast phase and the temperature dependence of the observed forward rate constant accord with a cooperative dimerization process. Activation parameters for helix nucleation, ΔH* and ΔS*, vary with both salt concentration and (at constant ionic strength) the anion type, increasing through the lyotropic series from I- to F-. The slow phase shows second-order kinetics, and is interpreted as further stabilization of the ordered form either through limited aggregation or annealing. The rate constant for the slow phase also follows the lyotropic series. Thus we have shown that both the growth and nucleation processes are anion dependent.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 121
    Electronic Resource
    Electronic Resource
    Effect of discrete distribution of ions on B- and Z-DNA: A theoretical investigation (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 187-200 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using an iterative approach, we have placed monovalent (“solvated”) and divalent (both solvated and “unsolvated”) ions around a 20 base pair sequence, (dC-dG)10, in standard B and ZI conformations. The molecule with its attendant ions in the various conformations is subjected to to energy minimization using the program AMBER. In the presence of solvated cations (both monovalent as well as divalent) the B form is more stable than the Z form. However, direct binding with the unsolvated divalent cations makes the Z form more stable. Groove-binding provides some insight into the facility with which the B to Z transition occurs with higher charged cations. In the presence of unsolvated divalent cations, the Z form binds more charges at the groove through more ligands, compared to the B form. The orientation around the CpG phosphates in the minor groove of the Z form is found ideal for ion binding. Detailed molecular models for the ion binding have been developed. In general, phosphate groups dominate the ion binding. Large perturbations are seen mostly in the angles that control the phosphate orientation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 122
    Electronic Resource
    Electronic Resource
    Determination of thermodynamic functions from scanning calorimetry data. II. For the system that includes self-dissociation / association process (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 271-297 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The basic relations between the molar fractions and the scanning calorimetry data for the system that includes self-dissociation/association process such as \documentclass{article}\pagestyle{empty}\begin{document}$$ m_0 {\rm A}_{\rm 0} \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} m_1 {\rm A}_{\rm 1} \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} m_2 {\rm A}_{\rm 2} \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} ... \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} m_n {\rm A}_n $$\end{document} are presented, where mi is the stoichiometric coefficient of the ith state Ai. The relations are described for each state j as \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{d}{{dT}}\left[{- m_j \log f_j (T) + \sum\limits_i {m_i f_i (T)}} \right] = \Delta H_j (T)/RT^2 $$\end{document} where fj(T) is the molar fraction function of state j and ΔHj(T) is the difference enthalpy function of the system referred to the state j, which can be obtained by scanning calorimetry; R is the gas constant; and T is the absolute temperature. By these relations, scanning calorimetry data can be deconvoluted in order to determine the thermodynamic functions by means of single and double deconvolution. The concentration dependence of the data is analyzed by a method presented in this paper. The nonlinear least squares fitting method for the determination of the functions is discussed. For an example of the application of this method to the actual scanning calorimetry data, thermodynamic data of multistate thermal transition of Vibrio parahaemolyticus hemolysin are analyzed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 123
    Electronic Resource
    Electronic Resource
    The role of hydroxyproline in collagen folding: Conformational energy calculations on oligopeptides containing proline and hydroxyproline (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 299-312 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have observed that the rate of folding of the enzymatically hydroxylated form of poly(Gly-Pro-Pro) into the triple-helical conformation is considerably higher than that of the unhydroxylated polypeptide [R. K. Chopra and V. S. Ananthanarayanan (1982) Proc. Natl. Acad. Sci. USA 79, 7180-7184]. In this study, we examine a plausible kinetic pathway for triple-helix formation by selecting peptide models for the unhydroxylated collagen molecule, and computing their conformational energies before and after proline hydroxylation. Starting with the available data on the preferred conformations of proline- and hydroxyproline-containing peptide sequences, energy minimization was carried out on the following pairs of peptides: Gly-Ala-Pro-Gly-Ala and Gly-Ala-Hyp-Gly-Ala; Gly-Pro-Pro-Gly-Ala and Gly-Pro-Hyp-Gly-Ala; Gly-Ala-Pro-Gly-Ala-Pro and Gly-Ala-Hyp-Gly-Ala-Hyp. It was found that, with each pair of peptides, the energetically most favorable conformation (I) has an extended structure at the Gly-Ala or Gly-Pro segment and a β-bend at the Pro-Gly or Hyp-Gly segment. In the Hyp-containing peptides, this conformation is further stabilized by a (Hypi + 2)OH…OC(Glyi) hydrogen bond. Conformation I is lower in energy by about 6-13 kcal/mol of the peptide than the fully extended conformations that resemble the single collagen polypeptide chain and contain no intramolecular hydrogen bond. In contrast to the proline counterpart, the hydroxyproline-containing peptides are found capable of adopting a partially extended conformation that does not contain the β-bend but retains the (Hyp)OH…OC(Gly) hydrogen bond. The energy of this conformation is intermediate between conformation I and the fully extended conformation. The continuation of the β-bend along the chain is restricted by stereochemical constraints that are more severe in the latter two pairs of peptides than in the first pair. Such a restriction may be considered to trigger the “unbending” of the minimum energy conformation leading to its straightening into the fully extended conformation; the latter, in turn, would lead to triple-helix formation through favorable interchain interactions. We propose that the partially extended conformation in the Hyp-containing peptides could serve as a kinetic intermediate on the way to forming the fully extended conformation. Because of the (Hypi + 2)OH…OC(Glyi) hydrogen bond, this conformation would also serve to lock the trans geometry at the Gly-Ala(Pro) and Ala(Pro)-Hyp peptide bonds, thereby enhancing the rate of their helix formation. A scheme for collagen folding in proposed on the basis of these results.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270209
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 124
    Electronic Resource
    Electronic Resource
    Salt-induced isomerization of a synthetic RNA poly[r(A-U)] (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 351-354 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270214
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 125
    Electronic Resource
    Electronic Resource
    Structural versatility of peptides from Cα,α-dialkylated glycines. II. An IR absorption and 1H-nmr study of homo-oligopeptides from Cα,α-diethylglycine (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 373-379 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational preferences of the N-trifluoroacetylated homo-peptides of Cα,α-diethylglycine from monomer to pentamer in chloroform solution were determined by using ir absorption and 1H-nmr. Intramolecular hydrogen bonding was found to be the dominant factor for all NH groups. The likely absence of a conformational transition upon increasing main-chain length, and the remarkable stability to dilution, heating, and addition of perturbing agents, are additional relevant findings of this study. These results are in agreement with those of the fully extended, C5-conformation-forming homo-peptides from the higher homolog Cα,α-di-n-propylglycine, but contrast dramatically to those of the homo-peptides from the lower homolog Cα,α-dimethylglycine, which have been shown to adopt the 310-helical structure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270303
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 126
    Electronic Resource
    Electronic Resource
    Helical formation of a 13-residue C-peptide analogue of ribonuclease a in sodium dodecyl sulfate solution (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 423-430 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformation of a 13-residue C-peptide analogue of ribonuclease A -  - in surfactant solutions was studied by CD. The CD spectrum of the peptide in excess NaDodSO4 solution was typical for a helical conformation; the spectrum appeared to be virtually independent of pH (2.5-6) and temperature (3-25°C). Analysis of the CD data indicated a helicity of about 65-70% with no α-sheet and β-turn; this corresponded to 8 or 9 residues in the helical form or slightly more than two turns of α-helix. This compares with an average of about one turn of α-helix for the C-peptide analogue in water at pH 4.7 and 7°C. The conformation of the peptide in cationic surfactant, dodecyl ammonium chloride, and nonionic surfactant, dodecyl heptaoxyethylene ether, solution resembled that in water. We concluded that the C-peptide analogue can develop a maximum helicity close to the corresponding segment in ribonuclease A in hydrophobic environment provided by the clustering of NaDodSO4 molecules to the cationic side groups of the peptide, except that the end effects may destabilize two or three residues each at both ends of the helix. Thus, in the interior of a protein molecule this hydrophobic effect may overshadow the charged-group effect than can be explained by the helix dipole model for the helical segments on the exterior of the protein molecule.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270306
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 127
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270401
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 128
    Electronic Resource
    Electronic Resource
    Base sequence effects in double-helical DNA. II. Configurational statistics of rodlike chains (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 561-584 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Matrix generator techniques have been adapted to account for precise structural features of the nucleotide repeating unit and to translate the primary sequence of DNA base pairs into three-dimensional structures. Chains have been constructed to reflect the local sequence-dependent differences of bending and twisting of adjacent residues and various overall chain properties, including the average unperturbed moments of the end-to-end vector r and the mean angular orientation (〈γ〉 between base pair normals, 〈φ1〉 between long axes, and 〈φ2〉 between short axes) of terminal chain residues, have been computed. The chain backbone is treated implicitly in terms of the spatial fluctuations of successive base pairs. Motions are limited to low-energy perturbations of the standard B-DNA helix. Approximate potential energy schemes are used to represent the rules governing the patterns of local base-base morphology and flexibility. Theoretical predictions are compared with experimental observations at both the local and the macro-molecular level. Initial applications are limited to the rodlike poly(dA) · poly(dT) and poly(dG) · poly(dC) helices. The former duplex is found to be more compressed and the latter more extended than random-sequence DNA of the same chain length. The flexibility of the duplexes as a whole is described in terms of the average higher moments of the displacement vector ρ = r - 〈r〉 and the likelihood of chain cyclization is estimated from the three-dimensional Hermite series expansions of the displacement tensors. Emphasis is placed on theoretical methodology and the practical relevance of the calculated chain moments to observed physical properties.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 129
    Electronic Resource
    Electronic Resource
    Base sequence effects in double-helical DNA. III. Average properties of curved dna (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 585-603 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The matrix-generator methods set forth in the preceding paper for treating rodlike DNA are adapted here to the calculation of average chain extension, macroscopic flexibility, and terminal residue orientation in curved duplexes. The different characteristics of curved vs rodlike chains are illustrated with the hypothetical poly[d(A5G5)] · poly[d(T5C5)] duplex. The curved helix is both more compact and macroscopically stiffer than either the poly(dA) · poly(dT) or the poly(dG) · poly(dC) chain. The calculations have also been extended to simple repetitive DNA sequences generated by synthetic ligation studies and the computed average chain properties compared with observed gel mobilities. The predicted chain extension is also checked against the measured persistence lengths of the rodlike poly[d(GC)] and poly[d(AT)] alternating copolymers, and the known cyclization tendencies of selected repeating sequences. Chains are generated from local potential energy maps describing the morphology and flexibility of adjacent base pairs. The energy maps, while approximate, are more accurate descriptors of local structure than many of the intuitive models of DNA curvature offered to date. According to the energy surfaces, the intrinsic bending of curved DNA can be traced to asymmetry in the bending of the Gs and Cs that join half-helical turn stretches of adenines in these chains. The oligo A stretches are analogous to residues of a perfectly elastic DNA that bend with equal likelihood in opposing directions. In other models of DNA curvature, the (G · C) base pairs are presumed to adopt the classical B-DNA structure, while the (A · T) base pairs are thought to be in some perturbed conformation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 130
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270601
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 131
    Electronic Resource
    Electronic Resource
    Conformational studies of N-acetyl-N′-methylamide derivatives of α-aminobutyric acid, norvaline, and valine. I. Preferred conformations in solution as studied by 1H-nmr spectroscopy (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 969-984 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H-nmr studies were extensively carried out to elucidate preferred conformations of dipeptides CH3C*O - X - NHCH3, with X = Abu, nVal, and Val in various solvents. The vicinal 1H - 1H coupling constants for the NH - CαH moiety and those around the Cα - Cβ bond in the articulated side chain provided the information regarding the average conformation of these molecules. The results indicate that transformation of skeletal conformations takes place in solution among conformers having similar dihedral angles, θHN - CαH, in the Karplus expression.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270607
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 132
    Electronic Resource
    Electronic Resource
    1H-nmr studies of the 20-31 fragment of calmodulin and of its cyclic analogue (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 789-803 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-resolution 1H-nmr spectroscopy at 500 MHz has been used to study the Ca2+ binding domain I of bovine brain calmodulin in aqueous solution. All the resonances of the linear dodecapeptide Asp-Lys-Asp-Gly-Asn-Gly-Thr-Ile-Thr-Thr-Lys-Glu and of its cyclic analogue, synthesized by classical solution methods, have been completely assigned using a combination of several one- and two-dimensional nmr experiments, including the zero quantum correlation. Chemical shift values and 3JCHNH coupling constants indicate that, on the nmr time scale, both peptides are flexible and assume multiple conformations in rapid equilibrium, with no relevant contribution of structured features. Addition of Ca2+ causes only minor spectral changes in aqueous solution of both peptides, while larger effects are observed in more hydrophobic mixtures such as water/trifluoroethanol. The linear analogue shows nonspecific interactions, while only Asp3 and Asn5 are significantly perturbed in the cyclic peptide. This evidence, together with identical findings in La3+ titration studies of the cyclic analogue in pure water, suggest that loop I of calmodulin is endowed with an intrinsic binding ability.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270507
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 133
    Electronic Resource
    Electronic Resource
    On the interaction of chromomycin A3 with calf thymus DNA in the presence of metal cations at different pH values (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 831-842 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interactions of the antitumor antibiotics, chromomycin A3, with a variety of metal cations in the pH range of 3.0-8.5 were systematically studied by CD, absorption, and 1H-nmr spectroscopies. Results were compared with those obtained in the presence of increasing amounts of calf thymus DNA. The negatively charged chromomycin A3, pKa 6.3, forms aggregates that become ordered and smaller in size, in the presence of variety of metal cations. Spectrophotometric titrations have shown that binding of the neutral drug to DNA at pH 4.5 does not require divalent cations, although the strength of the binding is greatly enhanced in their presence. At higher pH values (〉 7.0) and low DNA/drug ratio ( 〉 20), the metal cations are necessary to induce the binding between chromomycin A3 and DNA. At higher DNA/drug ratios (〉 100: 1), an appreciable proportion of the drug is bound even in the absence of divalent cations. Its binding affinity to the DNA is enhanced in the presence of these cations and at low pH values. Therefore, we conclude that chromomycin A3 binds in two related modes, in the presence and in the absence of divalent cations. The spectral data accumulated indicate the metal cation is involved in the binding of the drug to the DNA by forming a drug-metal-DNA ternary complex.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270510
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 134
    Electronic Resource
    Electronic Resource
    Vibrational spectroscopy of L-valyl-glycyl-glycine, a parallel-chain β-structureThis is paper number 38 in a series on “Vibrational Analysis of Peptides, Polypeptides, and Proteins,” of which paper number 37 is Ref. 27. (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 885-908 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bands in the ir and Raman spectra of L-valyl-glycyl-glycine (VGG) and VGG-ND have been assigned on the basis of a normal mode analysis of the known parallel-chain β-structure of this tripeptide. Amide I, II, III, and V mode shifts are obtained by the interactions of dipole derivatives in symmetry coordinates, referred to as dipole derivative coupling. These derivatives, obtained from ab initio studies, are also used to calculate ir intensities of amide I, II, and V modes. The agreement between predicted and observed frequencies and intensities is very good, providing confidence in the application of our force fields to the calculation of the vibrational modes of the general parallel-chain β-sheet structure (following paper).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270602
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 135
    Electronic Resource
    Electronic Resource
    Interaction of the fibrinogen-binding tetrapeptide gly-pro-arg-pro with fine clots and oligomers of α-fibrin; comparison with αβ-fibrin (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 775-788 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetrapeptide Gly-Pro-Arg-Pro(GPRP) was introduced by diffusion into fine unligated clots formed from human fibrinogen at pH 8.5 and ionic strength 0.45 by batroxobin (αβ-fibrin) and by thrombin (α-fibrin). The α-fibrin clots were essentially liquefied at GPRP concentrations above 1 mM and αβ-fibrin clots above 15 mM, and the degree of polymerization of the resulting oligomers decreased progressively with increasing GPRP concentration as shown by γ-γ ligation with factor XIIIa and subsequent gel electrophoresis. Much smaller concentrations of GPRP, when introduced into unligated clots by diffusion, were sufficient to modify their mechanical properties profoundly. The shear modulus of elasticity G25 measured 25 s after imposition of stress fell, for example, by a factor of 0.4 at 0.1 mM GPRP in α-fibrin and at 1.1 mM in αβ-fibrin. The rate of shear creep under constant stress and the proportion of irrecoverable deformation also increased enormously. This behavior, and the corresponding decrease in steady flow viscosity, may be interpreted in terms of competition of GPRP with A sites on the E domains of fibrin monomers for bidning to “a” sites on the D domains, resulting in a moderate increase with increasing GPRP concentration of the average proportion of severed network strands and an enormous increase in the rate at which all strands dissociate and reassociate. Reassociation of severed strands in new configurations is a necessary corollary since the differential modulus or compliance remains constant during creep and creep recovery. The greater susceptibility of α-fibrin clots to interaction with GPRP is attributed to stabilization of contacts between monomer units by Bb associations in αβ-fibrin. Ligated clots, with or without GPRP, exhibited essentially no time-dependent creep and no irrecoverable deformation, corresponding to an absence of any severance of network strands.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 136
    Electronic Resource
    Electronic Resource
    Vasopressin conformational fluctuations: A molecular dynamics study (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 939-956 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular dynamics simulations have been used to study the conformational fluctuations of the oligopeptide hormone vasopressin. Starting coordinates for these simulations were built upon the crystal structure of pressinoic acid, the cyclic ring moiety of vasopressin, recently determined by x-ray diffraction. Coordinates for the additional tripeptide “tail” of vasopressin were selected by arbitrary positioning of this segment using interactive computer graphics. Two such starting configurations were minimized to relax strains, and long dynamics simulations (20 and 40 ps) in vacuo were then conducted following extensive heating and equilibration sequences (36 ps). In these studies, vasopressin was found to undergo few substantial conformational changes at 300 K on the time scale simulated, in contrast to the results of a shorter previous simulation, but comparable structural transitions were observed during the equilibration periods. The pressinoic acid structure was found to be a reasonably stable possible conformation for vasopressin in vacuum on this time scale.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270605
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 137
    Electronic Resource
    Electronic Resource
    Equilibrium dialysis study of binding of hexammine cobalt(III) to DNA (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1045-1051 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270611
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 138
    Electronic Resource
    Electronic Resource
    On the multiple-minima problem in the conformational analysis of polypeptides. II. An electrostatically driven Monte Carlo method - tests on poly(L-alanine) (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1283-1303 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new approach to the multiple-minima problem in protein folding is presented. It is assumed that the molecule is driven toward the native structure by three types of mechanism. The first one involves an optimization of the electrostatic interactions, whereby the molecule evolves toward conformations in which the charge distribution becomes energetically more favorable. The second mechanism involves a Monte Carlo-energy minimization approach, and the third one is a backtrack mechanism that acts in the opposite direction, increasing the energy - the third type of movement provides a means to perturb the molecule when it is trapped in a stable but energetically unfavorable local energy minimum. This paper describes the implementation of a model based on these mechanisms, and illustrates its effectiveness by computations on different arbitrary starting conformations of a terminally blocked 19-residue chain of poly(L-alanine) for which the global minimum apparently corresponds to the right-handed α-helix. In all cases, the global minimum was attained, even when the starting conformation was a left-handed α-helix. In the latter case, the trajectory of conformations passed through partially melted forms of the left-handed α-helix (because of electrostatic defects at the ends), and then through the formation of structures leading to the more stable right-handed α-helix.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270808
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 139
    Electronic Resource
    Electronic Resource
    Order-Disorder conformation change of xanthan in 0.01M aqueous sodium chloride: Dimensional behavior (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1641-1654 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Weight-average molecular weights Mw, second virial coefficients, and z-average radii of gyration 〈S2〉1/2z were determined by light scattering as a function of temperature T for four sodium salt samples of xanthan in 0.01M aqueous NaCl, in which the polysaccharide undergoes an order-disorder conformation change with increasing T. The data for 〈S2〉1/2z and Mw at 25 and 80°C, the lowest and highest temperatures studied, confirmed the previous conclusion that the predominant conformation at the former T, i.e., in the ordered state, is a double helix, while that at the latter T, i.e., in the disordered state, is a dimerized coil expanded by electrostatic repulsions between charged groups of the polymer. As T was increased from 25 to 80°C, 〈S2〉1/2z sigmoidally decreased or increased depending on the dimer's molecular weight. This temperature dependence of 〈S2〉1/2z and that determined elsewhere for a high molecular weight sample were found to be described almost quantitatively by a simple dimer model in which the double helix melts from both ends, when the double-helical fraction in the dimer at a given T estimated previously from optical rotation data was used.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271009
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 140
    Electronic Resource
    Electronic Resource
    Reversal of the Mg++-induced B-to-Z transition of poly[d(G-C)] with hydrostatic pressure (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1687-1690 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271012
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 141
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 142
    Electronic Resource
    Electronic Resource
    Binding of nogalamycin to model tetranucleotides (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1491-1517 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intercalated complexes of the antitumor antibiotic nogalamycin (NGM) with the double-stranded oligonucleotides d(GCGC)2, d(ATAT)2, and d(ACAC) · d(GTGT) are investigated with the theoretical method SIBFA. The amino sugar part of the drug locates preferentially in the minor groove. An intrinsic preference for the d(ATAT)2 sequence over the d(ACAC) · d(GTGT) and d(GCGC)2 sequences is obtained, corresponding to relative energies 0, 11, and 15 kcal/mole, respectively. A mixed sugar-puckering pattern is preferred in the d(ATAT)2 complex while a uniform sugar-puckering pattern is preferred for the other sequences. No direct specific interaction involves the N+ - H part of protonated NGM. The location of the amino sugar as well as the sequence selectivity is due to the global electrostatic interaction of the dimethylammonium group with the given groove. The two hydroxyl groups of the amino sugar and the carbonyl of the carbomethoxy group encounter partners for hydrogen bonding at the intercalation site, but these interactions do not appear to govern the base sequence selectivity. The nogalose part is not found to be directly involved in the binding or in the selectivity. The conformations of isolated and intercalated NGM are discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270913
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 143
    Electronic Resource
    Electronic Resource
    Chromatography and electron microscopy of cross-linked fibrin polymers - a new model describing the cross-linking at the DD-trans contact of the fibrin moleculesa part of this work was presented at the xth international congress of thrombosis and haemostasis, san diego, usa, july 14-19, 1985, and was published in abstract form (1985) [thromb. haemostas. 54, 937]. (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1733-1748 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of fibrin molecules results in the formation of a double-stranded protofibril. Although convincing data have not been presented, it is classically believed that γ-chain cross-linking of fibrin molecules occurs between the longitudinal end-to-end contacts (DD-long contacts) of the molecules within each of the two strands of a protofibril (intrastrand cross-linking). In this investigation the question addressed was whether γ-chain cross-linking takes place across the two strands (interstrand cross-linking) between the transversal half-staggered contacts of the molecules. Demonstration of double-stranded protofibrils in the presence of urea would indicate an interstrand cross-linking, whereas in the case of intrastrand cross-linking, the chaotropic agent urea would dissociate the double-stranded structure to form single-stranded fibrils. Protofibrils were obtained by generating soluble cross-linked fibrin polymers (sXLFbP): After incubation of souble fibrin polymers with Factor XIIIa at 37°C, the polymerization and cross-linking reaction was stopped by the addition of 6M urea and EDTA. Gel filtration of the reaction mixture in the presence of 3M urea was effect in separating sXLFbP from monomeric molecules. The sXLFbP-containing fractions were adsorbed onto mica in the presence of different concentrations of urea and investigated by electron microscopy after rotary shadowing. In the presence of 3M urea the sXLFbP appeared as double-stranded protofibrils. In the presence of 4M urea some parts of the double-stranded structure were found to be unfolded whereas in the presence of 6M urea multiple-bended single-stranded fibrils were observed. SDS-polyacrylamide gel electrophoresis of the sXLFbP demonstrated no γ-chain cross-linking within the protofibrils. Ultracentrifugation of the sXLFbP showed that in the presence of 3M urea noncross-linked fibrin polymers dissociated to monomeric molecules. When sXLFbP was centrifuged into 6M urea on sucrose density gradients, no reduction of the polymer size could be observed. The data indicate that γ-chain cross-linking occurs between the transversal contacts of the fibrin molecules within a protofibril, thus generating interstrand cross-linking. A model of the cross-linking of polymerized fibrin molecules is developed and the term DD-trans contact is proposed for this specific alignment of the D-domains.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 144
    Electronic Resource
    Electronic Resource
    Diffusion coefficients of segmentally flexible macromolecules with two subunits: A study of broken rods (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1771-1786 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general treatment for the solution dynamics of segmentally flexible macromolecules having two subunits is presented. Bead modeling allows for a complete inclusion of hydrodynamic interactions in this treatment. The finite size of the beads is also considered, so that it is therefore possible to account properly for torsional motions of the subunits. Expressions for the components of the resistance matrix are derived. From them, the translational and rotational diffusion coefficients can be calculated. Distinction is made between hinged macromolecules, whose only internal motion is bending, and swivel-jointed macromolecules, for which torsions of the subunits are also allowed. Numerical results are presented for broken rods with the two types of flexibility. The effects of hydrodynamic interaction between arms of broken rods are about 25% for translation and under 10% for rotation. These findings give support to the treatments of Harvey, Wegener, and co-workers in which interactions were neglected. The rotational dynamics of hinged and swivel-jointed rods are compared. Although there are differences in the short-time behavior, the longest relaxation time is the same for the two cases. Finally, the validity of Wegener's rotational diffusion constants is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 145
    Electronic Resource
    Electronic Resource
    Cluster analysis of protein fourier transform infrared spectra (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1831-1838 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cluster analysis techniques were used to examine a set of Fourier transform infrared (FT-IR) spectra of bovine serum albumin (BSA) in the adsorbed and nonadsorbed states. The region from 1480 to 1600 cm-1, comprising the amide II band, was used. Spectra were preprocessed to compensate for linear baseline variation, and the single linkage method of cluster analysis was applied. As expected, the spectra of adsorbed and nonadsorbed BSA fell into two distinct clusters. However, no further clustering was observed among the adsorbed BSA spectra on the basis of surface type, suggesting that surface specificity of the spectral changes induced in BSA by adsorption is not detectable above experimental variation. This work illustrates the value of using cluster analysis in the FT-IR study of proteins as a complement to other data analysis methods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 146
    Electronic Resource
    Electronic Resource
    Fourier transform ir spectroscopy of collagen and gelatin solutions: Deconvolution of the amide I band for conformational studies (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1749-1760 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ir spectra of lathyritic rat skin collagen and calf skin gelatin solutions at a variety of temperatures were obtained using Fourier transform ir spectroscopy and a 9-reflection, 2-pass ZnSe prism sample cell. The spectra were then deconvolved (based on Kauppinnen's method) and the behavior of the amide I band at ∼ 1650 cm-1 observed in detail. Throughout the temperature range studied (4-50°C), three component absorption peaks within the amide I band (at 1633, 1643, and 1660 cm-1) are common to the spectra irrespective of the degree of triple helix content of the sample. Changes in the relative intensities of these component peaks are, however, conformationally dependent. During denaturation of the triple helix, the dominant 1660-cm-1 component in the native collagen spectrum diminishes and the 1633-cm-1 peak becomes relatively intensified. The inherently strong basicity of the carbonyl group of the proline residues together with the frequent occurrence of this imino acid in the X position of the Gly-X-Y triplet of collagen largely accounts for the -30-cm-1 shift of the amide I band during denaturation. Temperature and conformationally dependent changes in the fine structure of the amide I band from dilute solutions of collagen can be monitored in a reproducible and quantitative fashion.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 147
    Electronic Resource
    Electronic Resource
    Dielectric relaxation studies on bovine ligamentum nuchae (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1787-1793 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dielectric relaxation studies of bovine ligamentum nuchae are reported over the frequency range of 1 MHz to 1 GHz and over the temperature range of 23-48°C. A temperature-dependent relaxation process was observed at low megahertz-frequency with the correlation time of around 40 ns. The result is quite similar to that of a synthetic polypentapeptide (VPGVG) and of α-elastin. The relaxation is proposed to arise in part from the peptide libration within the polypentapeptide of bovine ligamentum nuchae.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 148
    Electronic Resource
    Electronic Resource
    Study of furanose ring flexibility in polynucleotide chains using raman spectra analysis (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1817-1829 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bands within the range of 800-850 cm-1 of Raman spectra of polynucleotides sensitive to the change in conformation of sugar-phosphate backbone are analyzed theoretically. The bands are interpreted as the appearance of a quasi-local deoxyribose vibrational mode whose frequency is dependent on the ring puckering. The localization region of the vibrational mode is pointed out. The theory establishes a relationship between the observed spectral intensity and the population of deoxyribose conformational states described in the framework of the pseudorotation concept. The approach developed allowed one to describe the band shapes and their temperature behavior, and to determine the pseudorotation potential of deoxyribose in the helix B-form of A · T containing polynucleotides. Using the analysis of Raman spectra of DNA fibers in water-ethanol mixture the deoxyribose flexibility during the B-A transition is investigated in terms of the population of conformers and effective potential. It is shown that N- and S-type deoxyribose conformers are populated in the DNA B-form (those of the S-type are preferable), whereas N-type conformers are primarily populated in the DNA A-form.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 149
    Electronic Resource
    Electronic Resource
    Masthead (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271201
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 150
    Electronic Resource
    Electronic Resource
    Molecular structure of L-lysyl-L-alanyl-L-alanine: A tripeptide found in histone H1 (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1887-1896 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of L-lysyl-L-alanyl-L-alanine hydrochloride has been determined by x-ray diffraction. The peptide is in zwitterionic form with the carboxylic group deprotonated, and with positive charges both in the amino terminal and ∊-amino groups of lysine. Crystals are monoclinic, space group P21 and Z = 4, with two peptide molecules in the asymmetric unit, which show different conformations. While one molecule has torsional angles for the Lys-Ala peptide bond (ϕ2, ϕ2) in the β-pleated sheet region, the values for the other molecule are close to those for the α-helix. This molecular flexibility is of interest for the study of H1 histone, which contains this sequence repeated several times. The two lysine residues show fully extended side chains. Two methanol molecules and two acetonitrile molecules are also present in the unit cell. An extensive network of hydrogen bonds and ionic interactions stabilize the crystal structure.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360271203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 151
    Electronic Resource
    Electronic Resource
    Polymerization of lactams, 79.Part 78: cf. 17 Preparation of the cyclic dimer of 2-pyrrolidone (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1-7 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An alternative method for the preparation of the cyclic dimer 3 of 2-pyrrolidone is presented, which is based on hydrolysis of 1-(1-pyrrolin-2-yl)-2-pyrrolidone (4, x = y = 3), and some physicochemical properties of 4 and its hydrolytical products are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 152
    Electronic Resource
    Electronic Resource
    Poly(epichlorohydrin)s obtained by means of a new calcium complex as catalyst (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 45-51 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new catalytic complex was developed by reacting 1,1-diphenylethylene with metallic calcium and submitting the resulting derivative [designated as (Ar)2Ca] to chemical modifications with 1-chloro-2,3-epoxypropane (epichlorohydrin; ECh). From these reactions a series of (Ar)2Ca · x ECh catalysts resulted differing by the mole ratio ECh/Ca. A value of 0,7 was found to be the optimal one with regard to the catalytic efficiency of polymerizing epichlorohydrin. The poly(epichlorohydrin)s (PECh), obtained with yields of 46, 5 to 82, 4%, are distinguished by their chlorine content and cover a range of molar masses from 0,35 · 105 to 2,23 · 105 g/mol. The catalysts were characterized by elemental analyses and thermogravimetry. According to X-ray patterns, PECh obtained by means of (Ar)2Ca · 0,7 ECh as catalyst displayes no crystallinity like PECh prepared in the presence of appropriate aluminium systems.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 153
    Electronic Resource
    Electronic Resource
    Terpolymerization of maleic anhydride, styrene and electron-acceptor monomers (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 53-65 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The free-radical terpolymerization of maleic anhydride, styrene, and acrylic monomers such as acrylonitrile, methyl acrylate and methyl methacrylate was studied. The alternating copolymerization of maleic anhydride with styrene was found to be favored in those systems. Contrary to theoretical predictions, maleic anhydride is more reactive than styrene in ternary systems. The relative reactivity of the acrylic monomers studied was found to decrease in the order: methyl methacrylate ≥ methyl acrylate 〉 acrylonitrile. In the presence of a Lewis acid, such as ZnCl2 or C2H5AlCl2, the relative reactivity of acrylic monomers increases and at the respective complexing agent concentration the copropagation of the acrylic monomer with styrene can dominate. On the basis of the results obtained, some aspects of the mechanism of alternating propagation in systems comprising an electron-donor monomer and two electron-acceptor monomers are discussed.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 154
    Electronic Resource
    Electronic Resource
    Bioactive polymers, 51.Part 50: J. Bioactive and Compatible Polymers, in press. Synthesis and characterization of a macromolecular prodrug of ampicillin (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 103-110 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The coupling reaction of ampicillin with the polysaccharide xanthane in DMSO, using dicyclohexylcarbodiimide as activator, was studied. To find the conditions for maximum yield a regression equation was established, describing the dependence of the yield of coupling product on the reaction parameters (drug/support mole ratio, activator/support mole ratio and duration), starting from an experimental, centrated rotable complex, second order program. The coupling product was spectroscopically characterized and the in vitro release rate of ampicillin in a weakly basic medium was established along with the determination of its antimicrobiological activity.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 155
    Electronic Resource
    Electronic Resource
    Polyadditions of diisocyanatodiketenes, 3-(ω-isocyanatoalkyl)-4-(ω-isocyanatoalkyliden)-2-oxetanones, and polymeranalogous reactions with the resulting polymersDedicated to Dir. Dr. Kuno Wagner, Leverkusen on the accasion of his 65th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 129-143 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactions of diisocyanatodiketenes, 3-(ω-isocyanatoalkyl)-4-(ω-isocyanatoalkylidene)-2-oxetanones (3a-c), with oligomeric diols (4 or 5) as well as 1,4-butanediol afforded linear polyurethanes containing reactive diketene moieties. From these poly(diketene-urethane)s polymeranalogues products were prepared by reaction with ethanol, ammonia, water or acetic acid. The resulting polyurethanes containing ß-ketoester, ß-ketoamide or keton moieties were characterized by IR spectroscopy, viscosimetry, differential scanning calorimetry and size exclusion chromatography. The properties of the products based on diols 4 or 5 are mainly determined by the oligomeric diols, whereas the (modified) diisocyanate part has a great influence e.g. on the thermal behaviour of the polyurethanes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890113
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 156
    Electronic Resource
    Electronic Resource
    Synthesis and reactivity of 1,4-disubstituted butadienes in the solide statePart of the Thesis of M. A., University of Mainz, Mainz 1987.Herrn Prof. Dr. H. Dörfel zum 60. Geburtstag gewidmet (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 163-184 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel synthetic route to (2E,4E)-6-amino-2,4-hexadienoic acid (1) and related ω-aminodiene compounds is reported. These substances form layer perovskites, CdCl4(NH3 - R)2, that furnish stereoregular 1,4-polybutadienes upon γ-irradiation in a topochemical solid state reaction. The synthesis of a chiral derivative is also described, that can be crystallized in a perovskite structure and polymerized by γ-rays. An ambivalent solid state reactivity is observed for the hydrochloride of 1: γ-rays induce a chain reaction leading to a polymer of identical chemical structure and stereochemistry as reported for the perovskite, but with higher molecular weight. Upon UV-irradiation, however, the hydrochloride undergoes a stereoselective (2+2)-cycloaddition to a cyclobutanoic dimer as main product and oligomers after prolonged irradiation. In the case of γ-irradiation at 273 or 300K significant contributions from postpolymerization are found both for the hydrochloride and the perovskite of 1.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 157
    Electronic Resource
    Electronic Resource
    Temperature dependence of the pitch of the cholesteric helix of poly(γ-benzyl-L-glutamate) in N,N-dimethylformamide and N-methyl-2-pyrrolidone (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 201-205 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Temperature depenences of the pitch of cholesteric helix in solutions of poly(y-benzyl-L-glutamate) in N,N-dimethylformamide and N-methyl-2-pyrrolidone were measured for various molar masses of poly(γ-benzyl-L-glutamate). It was found that in N-methyl-2-pyrrolidone inversion of the cholesteric helix takes place, i. e., that the right-handed helix changes to the lefthanded one. By using an equation derived by Kimura, the temperatures at which the system has a nematic order were determined. The results obtained allow the statement that an important role in the inversion of the cholesteric helix in poly(γ-benzyl-L-glutamate) solutions is played by conformational changes in side chains of the polypeptide molecule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890119
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 158
    Electronic Resource
    Electronic Resource
    Interference effects from liquid-crystalline block copolymers: Matrix method and analytical approachDedicated to Prof. R. Hosemann on his 75th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 227-236 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to calculate the interference effects from liquid-crystalline block copolymers, Biswas and Blackwell have presented an elegant matrix method. For the cases where an analogous, analytical approach can be made, we show that the matrix method leads to the same result as the analytical method. In addition to the conventional reciprocal lattice with reciprocal lattice points at h2π/〈c〉, where 〈c〉 is the average periodicity, one has to consider three further reciprocal lattices with reciprocal lattice points h′2π/cA, h″2π/cB, and h″′2π/(cB + cB). cB and cB are the lengths of the comonomer units. This method will be illustrated by model calculations for p-benzoate/biphenyl-4,4′-diylisophthalate copolyestersPoly[(isophthalic acid-alt-biphenyl-4,4′-diol)-co-4-hydroxybenzoic acid].. Further, interesting possibilities of the matrix method will not be treated here.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890122
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 159
    Electronic Resource
    Electronic Resource
    Siloxane networks swollen in chloroform/diethyl ether. Divergent preferential adsorption (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 251-261 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Total solvent sorption and preferential adsorption by networks of poly(methylphenylsiloxane) (PMPS) and of poly(dimethylsiloxane) (PDMS) were determined in the mixture chloroform/diethyl ether. This liquid mixture has a negative GE. The swelling degree of the networks was found to vary linearly with mixed solvent composition (Cl3CH volume fraction φ), contrary to what is expected in view of GE 〈 0. The preferential adsorption by PDMS shows an inversion which is of the divergent type (preferential adsorption of the liquid in major proportion in the mixture). With PMPS no inversion was observed, Cl3CH is always preferentially adsorbed, but the trend is also divergent (with the inversion point displaced to φCl3CH = 0). The unexpected behaviour of the swelling degree and the displacement of the inversion in preferential adsorption are attributed to strong attractive interactions of the siloxane backbone with the two solvents, and of phenyl groups (in PMPS) with Cl3CH. The intrinsic viscosity of linear PMPS at infinite dilution was determined in the same mixed solvent, in order to check the possible influence of the polymer concentration. Comparison with network swelling shows a similar behaviour.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890201
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 160
    Electronic Resource
    Electronic Resource
    Polylactones, 15Part 14: R. Dunsing, H. R. Kricheldorf, Eur. Polym. J. 24, 145 (1988).. Reactions of δ-valerolactone and ∊-caprolactone with acidic metal bromides (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 317-331 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: δ Valerolactone and ∊-caprolactone were reacted with BBr3, AIBr3, TiBr4, SnBr4 or Bu2SnBr2 in dichloromethane or chloroform in a 1 : 1 mole ratio. When these exothermic reactions were conducted with cooling, complexation of the lactones at the exocyclic oxygen was detectable by means of IR and 1H NMR spectroscopy as the first reaction step. However, heating to 60°C causes in all cases ring cleavage, and after hydrolytic removal of the metal bromides ω-bromocarboxylic acids or oligomers with ω-bromoalkanoyl end groups were obtained. SnBr4, Bu2SnBr2 and ZnBr2 proved to be good initiators of the polymerization of both lactones. At low monomer/initiator (M/I)-ratios (high initiator concentrations) most of the initiator remained unchanged, and the average degrees of polymerization of the resulting polylactones largely exceeded the value expected for the M/I-ratio. By means of viscosity and GPC measurements weight-average molecular weights up to 70 000 were found. All polylactones obtained by initiation with these three metal bromides contain ∊-bromoalkanoyl end groups. Furthermore, high-molecular-weight poly(∊-caprolactone) could be prepared at polymerization temperatures up to 150°C. The results do not indicate a cationic polymerization mechanism, but an insertion mechanism involving the metal-O bond formed after the first cleavage of the lactone rings.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 161
    Electronic Resource
    Electronic Resource
    Emulsion copolymerization of acrylonitrile and butyl acrylate, 7Part 6: cf.9. Effect of concentration and type of emulsifier on polymerization kinetics (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 341-350 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The emulsion copolymerization of acrylonitrile and butyl acrylate initiated by potassium peroxodisulfate (K2S2O8) in the presence of an anionic, cationic, or nonionic emulsifier has been kinetically investigated at 60°C under batch conditions by gas chromatography (GLC) and gravimetric methods. It is found convenient to define three stages of emulsion polymerization. In the range of low conversion (interval 1) are generated particles and the rate of polymerization increases with increasing polymer particle concentration. In interval 2 (ca. from 15 to 70% conversion) the number of polymer particles and the rate of polymerization (maximum) are constant. At very high conversion (above ca. 70% conversion) the monomer concentration within polymer particles decreases abruptly and the polymerization rate slows down (interval 3). The rate of polymerization in interval 2 was found to be proportional to the 0,41, 0,48, and -0,42 power of the emulsifier concentration for the anionic, nonionic, and cationic emulsifier, respectively. The dependence of the final particle number on the emulsifier concentration deviates from simple micellar theory predictions. The exponent of the emulsifier concentration decreases with increasing emulsifier concentration (for the anionic and nonionic emulsifiers). These results were explained by a coagulative nucleation mechanism. The unexpected polymerization behaviour in the presence of the cationic emulsifier was explained by the formation of a product (due to interaction of the initiator with the emulsifier).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890209
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 162
    Electronic Resource
    Electronic Resource
    Cationic transannular polymerization of 1,5-cyclooctadiene (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 733-742 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cationic transannular oligomerization of cis-cis-1,5-cyclooctadiene (1), initiated by AlEtCl2 and Al2Et3Cl3, was studied. Several cationic catalysts were examined, and the order of activities of these catalysts was found to be the following one: BF3 · OEt2 〈 AlCl3 〈 AlEtCl2 〈 Al2Et3Cl3. The number-average molecular weights of the resultant polymers are ≈ 1000 - 2000, and the softening temperature ranges 130 - 160°C. By means of NMR, IR and PC-MS spectral analyses, the structure of poly(1,5-cyclooctadiene), proposed earlier by Marvel et al., could be corroborated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 163
    Electronic Resource
    Electronic Resource
    Synthesis and polymerization of a macromonomer derived from phosphatidylcholine (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 755-760 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A lecithin-type macromonomer 1 was synthesized from natural egg phosphatidylcholine (lecithin). The macromonomer has an olefinic polymerizable group at the hydrophilic site, and is characterized by its chemical structure resembling lecithin. It could be polymerized in a liposome system by UV irradiation, giving polymers with a maximum molecular weight of 98 000. Polymers with molecular weights above 48 000 form thin and flexible membranes with a few 10 μm in thickness. The polymers can also be redispersed in water and the liposomes can be reconstituted.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890405
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 164
    Electronic Resource
    Electronic Resource
    Preparation of metal-free polyphthalocyanine thin films by an evaporation-polymerization method (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 761-764 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A thin film (thickness: 200 nm) of metal-free polyphthalocyanine, which is insoluble in organic solvents, was prepared by an evaporation-polymerization process under mild conditions developed by us. The thin film is not only though, but it also resists chemicals and heat. Its conductivity is 1,1 · 10-4 S · cm-1, and it increases to 0,15 S · cm-1 on I2-doping.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 165
    Electronic Resource
    Electronic Resource
    Crosslinkable liquid-crystalline combined main-chain/side-group polymers with low glass transition temperatures (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 791-796 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crosslinkable and crosslinked liquid-crystalline polymers with elastic properties were prepared from main-chain and combined main-chain/side-group polymers. These polymers exhibit nematic, smectic A, and smectic C phases. Polymers of these types with azoxybenzene as mesogen do not crystallize upon cooling. As a consequence, the liquid-crystalline phases are frozen in glassy around room temperature.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890410
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 166
    Electronic Resource
    Electronic Resource
    Combined liquid-crystalline polymers with chiral phases, 1 2-octanol as chiral end of the mesogens (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 797-804 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Combined liquid-crystalline polymers containing azobenzene and azoxybenzene as the mesogenic groups and 2-octanol as the chiral end-group were synthesized and characterized. These polymers exhibit cholesteric, smectic A, and chiral smectic C* phases with monolayer and doublelayer structures. The polymers with azoxy groups do not crystallize upon cooling. Therefore, some of the liquid-crystalline phases can be frozen in in the glassy state.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890411
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 167
    Electronic Resource
    Electronic Resource
    Poly(vinylsaccharide)s, 4.Part 3: cf.28. Synthesis and polymerization of 6-o-methylallylgalactose derivatives (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 805-813 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Methylallyl ethers of 1,2:3,4-di-O-isopropylidene-D-galactopyranose and 1,2:3,4-di-O-cyclohexylidene-D-galactopyranose were synthesized as new monomers containing saccharide moieties and copolymerized with maleic anhydride. The hitherto unknown 6-O-(2-alkoxycarbonylallyl)-1,2:3,4-di-O-isopropylidene-D-galactopyranoses (8a and 8b; alkyl: methyl and ethyl, respectively) were prepared and polymerized under free radical conditions. The substances were characterized by 13C NMR, elemental analyses and molecular weight determinations. Water solubility of these polymers was obtained by removing the isopropylidene protecting groups. The inherent viscosities of these polymers, measured in 0,1 M Na2SO4 aqueous solution, were of the same order of magnitude as those of polyacrylamides of the corresponding degrees of polymerization.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890412
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 168
    Electronic Resource
    Electronic Resource
    Ring-chain competition in kinetically-controlled condensation polymerization (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 823-832 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Gordon and Temple's scheme of rate equations for ring-chain competition reactions in condensation polymerization has been solved analytically (for very small rates of ring formation) and numerically over a wide range of conditions. The numerical method was computationally efficient. Except in extreme cases, the distribution of ring sizes was found to be practically the same as that predicted for equilibrium conditions by Jacobson and Stockmayer, viz. that the number concentration of rings with a degree of polymerization i is proportional to i-5/2 at the end of the reaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890414
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 169
    Electronic Resource
    Electronic Resource
    Physical behaviour of stereoblock-isotactic polypropylene (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 815-821 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Preliminary results regarding the physical behaviour of a stereoblock-isotactic polypropylene are reported. The polymer was obtained using a soluble Ziegler-Natta catalyst and films were prepared by pressure molding. The particular steric configuration is responsible of low crystallinity and small crystal size; the bulk structure can be represented by a fringed micellar model in which small crystallites act as physical crosslinks. The observed behaviour being typical of a thermoplastic elastomer well agrees with the suggested model.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890413
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 170
    Electronic Resource
    Electronic Resource
    Characterization of cellulose nitrate with gel permeation chromatography - low angle laser light scattering (GPC-LALLS), GPC-infrared, and membrane osmometry (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 833-843 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cellulose nitrates with nitrogen contents in the range 11,2 to 13,3 mol-% are characterized with gel permeation chromatography (GPC) using various detectors, membrane osmometry, static low angle laser light scattering (LALLS) and solution viscosity measurements. The molecular weight data from GPC-LALLS are generally in good agreement with those obtained by static LALLS and membrane osmometry. GPC-infrared is used to analyze the nitrogen content. These techniques are also used to characterize cellulose nitrate in propellants. A comparison between two different column packings in GPC-LALLS analysis is integrated into this study.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890415
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 171
    Electronic Resource
    Electronic Resource
    Melting, crystallization, and solution behavior of chain molecules with hydrocarbon and fluorocarbon segments (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 911-925 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Melting, crystallization, and solution behavior of n-alkanes with fluorocarbon segments of twelve carbon atoms on one end, F(CF2)12(CH2)nH, or on both ends, F(CF2)12(CH2)n(CF2)12F were investigated by DSC, MAS 13C NMR, light scattering, and birefringence studies. Both triblock F(CF2)m(CH2)n(CF2)mF and diblock F(CF2)12(CH2)nH compounds with 4 ≦ n ≦ 14 melt by a two-step process. In the first step, the alkyl segment conformations gain nearly liquid like trans/ gauche ratios, while the perfluorinated segments remain ordered. “Gels” which incorporate the entire solvent are formed by crystallization from even dilute solutions of hydrocarbon and fluorocarbon solvents. The gels are built up of extremely long, interdigitated needles of the pure solute. Due to the bilayer structures and different degrees of ordering of the hydrocarbon and the fluorocarbon segments, the crystals grow preferentially in the direction parallel to the lamellar surface. Light scattering experiments in octane demonstrated the formation of micelle type associates.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890422
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 172
    Electronic Resource
    Electronic Resource
    Electro-optical properties and molecular flexibility of polyelectrolytes in dilute solutions (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 927-937 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of the electric birefringence of aqueous polyelectrolyte solutions in the very dilute regime ( ≈ 10-5 g · mL-1) reveal that the macroions are fully extended. However, this rod-like conformation is easily altered towards a more coiled conformation when a strong static electric field is applied, particularly in the case of very high molar-mass polymers. With the application of rectangular dc pulses, as ordinarily used in Kerr-effect measurements, the change of molecular shape interferes with the transient rise and decay of the birefringence signal, because the rotational mobility as well as the optical anisotropy of the macroions become time-dependent. As a result, the mean relaxation time for the rise curve is considerably smaller than that of the field-free decay, and the steady-state birefringence is much lower than expected for the unperturbed macroions. The change of the molecular shape can be avoided if the orientation of the macroions is induced by high-frequency ac pulses. This experimental technique is therefore suitable to obtain the unperturbed shape and size of the macroions. A molecular interpretation for the dependence of the birefringence function on the pattern of the electric field is proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890423
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 173
    Electronic Resource
    Electronic Resource
    Synthesis of monomers and polymers by the Heck reactionDedicated to Prof. Dr. H. Dörfel on the occasion of his 60th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 119-127 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Heck reaction allows the synthesis of monomers in a one-step reaction. Catalyzed by Pd, bromoarenes are reacted with ethylene to form substituted styrenes and symmetrical stilbenes. Unsymmetrical stilbenes are obtained from substituted bromoarenes and styrenes. Substituted hydroquinones and terephthalic acids are also available in high yields. Poly(1,4-phenylenevinylene) is obtained starting from 4-bromostyrene.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890112
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 174
    Electronic Resource
    Electronic Resource
    Conformational analysis of ß(1→4)-linked polysaccharides in aprotic solvent solutions (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 153-162 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The 1H NMR parameters (chemical shift and coupling constant) of ß(1→4)-linked polysaccharides xylan, cellulose, and chitin are compared in solutions of aprotic solvents. The following NMR parameters are analyzed: (1) Chemical shifts of labile protons, (2) their variation with temperature, (3) coupling constants through the H—C—O—H moiety  -  for monomers, dimers, and the corresponding polymers. It is observed that the OH-3 hydroxyl group for cellulose and chitin oligomers and polymers present a particular behaviour, which is in agreement with the existence of an intramolecular hydrogen bond between this hydroxyl of one monomeric unit, and the heterocyclic oxygen atom of the adjacent monomeric unit. This kind of intramolecular hydrogen bond is not observed in case of the xylan series. It can be concluded that substitution of an equatorial hydrogen atom at the C-5 position of the sugar ring by a CH2OH group  -  when passing from xylan to cellulose and chitin  -  induces a rotation restriction around the glycosidic bond. This places the OH-3 hydroxyl group in a favourable position to be hydrogen-bonded. The consequent implication on the respective conformations of the chains in solution is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890115
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 175
    Electronic Resource
    Electronic Resource
    Evaluation of the viscometric constants for chitosan (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 195-200 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Viscosity-average relative molecular masses have been determined for a series of chitosans having the same relative molecular mass and relative molecular mass distribution but differing extents of N-acetylation. The results obtained show that the same viscometric constants in the Mark-Houwink equation [η] = Km ·Ma are applicable to chitosans over the range between 0 and 40% N-acetylation Comparison of literature values for number- and weight-avepge rela-tive molecular masses Mn, and Mw, with the viscosity-average relative molecular mass M, values calculated using the related viscosity data and each of the three sets of viscometric constants that have been proposed for chitosan, confirms that the most accurate values currently available are km = 1,81 · cm-3 · 10-1 and a = 0,93, using 0,l M acetic acid/0,2M NaCl as solvent.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890118
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 176
    Electronic Resource
    Electronic Resource
    Association of three-block copolymers polycaprolactam-block-polystyrene-block-polycaprolactam (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 221-226 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Colloidal particles of three-block copolymers polycaprolactam-block-polystyrene-block-polycaprolactam, formed in a solvent mixture toluene/2,2,3,3-tetrafluoropropanol as a good solvent of polycaprolactam, were studied by static and dynamic light scattering and transmission electron microscopy. Two kinds of spherical multimolecular particles differing in size were found in the solution. The smaller particles containing tens of copolymer molecules were interpreted as regular copolymer micelles, and the larger particles formed from thousands of copolymer molecules were interpreted as associates of these micelles.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890121
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 177
    Electronic Resource
    Electronic Resource
    Dielectric and viscometric behaviour of poly(dibenzyl itaconate) as a function of temperature (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 145-151 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric and viscometric behaviour of poly(dibenzyl itaconate) (1) in 1,4-dioxane is studied as a function of temperature. The dipole moments at 25°C and at 33°C are determined by measuring the dielectric constant as a function of polymer concentration at fixed temperature. Also, the variation of the dielectric constant for a fixed concentration is determined at several temperatures in the temperature range between 15 and 39°C. The dipole moment is by 10% higher at 33°C than at 25°C, and the variation of the dielectric constant with temperature shows a stepwise increase between 25°C and 30°C. Viscosity measurements demonstrate an anomalous behaviour of 1 in 1, 4-dioxane at approximately the same range of temperatures. At ca. 25°C the value of the Huggins constant drops to practically zero. By measuring samples with different molecular weights the unperturbed dimensions, interaction parameter, and Mark-Houwink-Kuhn-Sakurada exponent are obtained. All of these parameters exhibit a discontinuity at ca. 25°C. The variations in the dielectric and viscometric behaviour with temperature are attributed to a conformational change of the macromolecules of 1 in 1, 4-dioxane.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890114
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 178
    Electronic Resource
    Electronic Resource
    Transformation of polyester chains into dicationically living ones and synthesis of telechelic co-oligomers thereof (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 293-298 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Unliving chains of aliphatic polyester were transformed into dicationically living poly(THF)-block-polyester-block-poly(THF) chains, and four different telechelic triblock co-oligomers with primary, secondary, tertiary amine, and hydroxyl end-groups were synthesized. A novel approach to the exchange of hydroxyl or carbonyl ends of polyester for amino end-groups is described. The primary amine-terminated telechelic triblock was used to modify an epoxy resin to give a toughened product with high strength.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890205
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 179
    Electronic Resource
    Electronic Resource
    Preparation and characterization of unsymmetrical “liposomes in a net” (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 299-315 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Negatively charged lipid molecules were converted into polymerizable lipids by introduction of polymerizable mono- or bifunctional counterions. As an attempt to mimic the cytoskeleton of biomembranes, unsymmetrical polymeric vesicles were prepared, where the polyelectrolyte is attached either only to the inner or to the outer bilayer surfaces. Polymerizable cations were introduced to the outer surface of preformed small unilamellar vesicles via ion-exchange. The outer counterions of vesicles bearing polymerizable counterions at both sides of the membrane were replaced by Na+. Polymerization of these systems leads to unsymmetrical vesicles. The introduction, separation and polymerization of the organic counterions was monitored by UV-spectroscopy. Due to polymerization of the counterions, the phase transition temperature of the membranes is shifted remarkably to higher temperatures. For a comparison of ionically attached and covalently bound polymers, two cationic lipids were synthesized, which have a bifunctional polymerizable headgroup. In contrast to the lipids with “ionic” spacers, the polymerization of the covalently bound methacrylic units resulted in a decrease of the phase transition temperature. Thus, by application of ionically bound polymerizable units, unsymmetrical polymerized vesicle membranes are readily available. These systems may serve as models for mimicking the cytoskeleton of living cells.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890206
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 180
    Electronic Resource
    Electronic Resource
    Infrared spectroscopic studies on polyethylene, 7Part 6: cf.: W. F. Maddams, J. Woolmington, Makromol. Chem. 186, 1665 (1985).. The use of the methyl deformation band for branch characterisation (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 333-339 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The factors relating to measuring the position of the methyl deformation mode at about 1378 cm-1 with sufficient precision to permit its use for the identification of the different branches present in the various types of “linear” low density polyethylene(as manufactured by the copolymerization of ethylene and a 1-alkene) have been examined systematically. With a data density of eight points per wavenumber, and the well established subtraction procedure with polymethylene or with a near-linear polyethylene to remove the overlapping methylene deformation band, it is possible to achieve a precision of ±0,15 cm-1. This is ample to distinguish between methyl, ethyl, and butyl or hexyl branches, but not to characterise uniquely these last two. The use of Fourier self-deconvolution to separate the methyl band has also proved very effective. The precision obtainable when these methods are applied to spectra measured with one data point per wavenumber is somewhat lower, but is still adequate for characterisational purposes. The results for a series of polymers containing ethyl branches at various concentrations suggest a small difference for the peak position for branches present in crystalline and amorphous regions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 181
    Electronic Resource
    Electronic Resource
    Intrinsic viscosity of intramolecularly crosslinked polyelectrolyte: Poly(vinyl alcohol)/borax systems (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 351-360 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The intrisic viscosity [η] of poly(vinyl alcohol) (PVA) was determined in aqueous solutions with various concentrations cb of borax (Na2B4O7) as functions of molecular weight M and concentration cs of NaCl as an added salt. Polyelectrolyte viscosity behaviour was observed for the systems containing both borax and NaCl, due to the complexation with negatively charged borate ions B(OH)-4 · [η] changes depending on the ionic strength I. It was found that the Stock-mayer-Fixman treatment for the molecular-weight dependence of [η] is valid in the lower molecular-weight range (M 〈 105), even though the present PVA chain contains some intrachain crosslinks. Theta conditions can be attained at an appropriate concentration cs Θ of NaCl. The value of cs Θ is dependent on cb, but the conformational parameter from the Stockmayer-Fixman treatment K0 is almost independent of cb. The effect of intrachain crosslinks becomes evident only as a considerably large negative value for the excluded volume parameter B at infinite ionic strength. In addition, the electrostatic part of the expansion factor α3e was found to be linearly correlated to a reduced parameter (M/I)1/2 for all cb systems, from the slope of which the charge density was estimated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890210
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 182
    Electronic Resource
    Electronic Resource
    Terpolymérisation acrylonitrile-styrène-acrylate de méthyle, 4Partie 3: cf. J. Guillot, L. Rios Guerrero, Makromol. Chem. 183, 1979 (1982). Copolymérisation en emulsion styrène-acrylate de méthyle en réacteur fermé (batch) en présence de persulfate de potassium (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 361-377 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To improve the knowledge of emulsion copolymerization of monomers both swelling their copolymers, but which are of quite different polarity (water solubility), a series of styrene (S)/methyl acrylate (MeA) copolymerizations was carried out in batch at 50°C with potassium persulfate as initiator. The overall rates of copolymerization increase with the amount of MeA in the monomer feed. Copolymer composition follows the usual copolymerization equation if bulk/solution reactivity ratios (rij) and monomer partition between aqueous and organic phase are taken into account (simulation). However, accurate kinetic data at low conversion (gas chromatography) put in evidence an enhanced polymerization of the more hydrophilic monomer (MeA), which can be attributed to polymerization in the water phase. Particle sizes increase with conversion and tend to a limiting value, the higher the MeA content is. Particle number (Np), which is practically constant with conversion of S homopolymerization, tends to increase with MeA content as polymerization proceeds. This trend is enhanced if the emulsifier (sodium dodecanesulfonate, SDS) concentration is increased. Overall propagation rate constants were estimated as function of the experimental conditions and monomer concentration within the particles. From kinetic data (rate of polymerization) and Np, it was found that the average number of radicals per particle, ñ, remains close to 0,5. It was then possible considering S(kp = 125 1 · mol-1 · s-1) as a standard monomer, to estimate the polymerization rate constant for MeA (335 1 · mol-1 · s-1). Since adsorption of emulsifier was shown to be closely related to particle surface composition, the specific area As of SDS was measured on latices at various conversions and initial monomer feeds. As conversions increases, the particle surface appears to be richer and richer in MeA, which corresponds to a particle structuration. Strong and weak acid group titration is also in quite good agreement with the colloidal behaviour.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890211
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 183
    Electronic Resource
    Electronic Resource
    Terpolymérisation acrylonitrile-styrène-acrylate de méthyle, 5Partie 4: cf.1. Copolymérisation en emulsion styrène-acrylate de méthyle en réacteur fermé en présence du styrène amorceur redox persulfate the potassium/hydrogénodisulfite de sodium (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 379-397 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of emulsion copolymerizations of styrene (S) with methyl acrylate (MeA) initiated by the redox system potassium persulfate (KPS)/sodium hydrogen disulfite (SBS) was carried out at 50°C. The monomer feed composition and the monomer/water (M/W) ratios were widely varied. The polymerization rate was found to be higher than in the case when only KPS was applied. Initial (influence of polymerization in water phase) and final copolymer molecules (accumulation of MeA in the feed due to a lower reactivity) are richer in the more hydrophilic monomer (MeA). It could be shown that a high water solubility makes the emulsion reactivity ratios to be “apparent” kinetic parameters, which result in a higher number of azeotropic compositions, compared to bulk or solution, according to the M/W ratio. Particle sizes are smaller and the size distribution is larger than in polymerizations in the presence of KPS alone. Particle number (Np) tends to increase with conversion for monomer mixtures rich in MeA, contrary to S homopolymerizations in which Np remains constant. Comparison of Np and kinetic data suggests that only part of the particles in actually active in polymerization (N*p). N*p can be estimated assuming that the average number of radical per particle, ñ remains close to 0,5 - as found in a previous study - which gives also an estimate of very tiny particles generated at low conversion and undetectable by the usual QELS and MET techniques. The experimental data, to some extent, allow to quantify the competition between micellar and homogeneous nucleation mechanisms.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890212
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 184
    Electronic Resource
    Electronic Resource
    Group transfer polymerization of methyl methacrylate in acetonitrile, 1. Initiation by [(1-methoxy-2-methyl)-1-propenyloxy]-trimethylsilane (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 429-435 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The group transfer polymerization (GTP) of methyl methacrylate in acetonitrile with [(1-methoxy-2-methyl)-1-propenyloxy]trimethylsilane as initiator and tetraethylammonium cyanide as catalyst is accompanied by a severe termination reaction of both the initiator and the active chains with the solvent leading to trimethylsilylacetonitrile and methyl isobutyrate or inactive polymer. Therefore, in order to work under reaction conditions characteristic for a living system acetonitrile as solvent has to be avoided.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890216
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 185
    Electronic Resource
    Electronic Resource
    Thermodynamic properties in the liquid state of high melting polymers containing phenylene and naphthylene groupsThis work was partially done in the Dept. of Chemistry at Rensselaer Polytechnic Institute. (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1579-1594 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High melting polymers of three different types of crystallization behavior were analyzed as to their thermal properties. The heat capacity at constant pressure of liquid poly(butylene terephthalate) (PBT) from 490 to 540 K was measured by scanning calorimetry. Combining with prior measured liquid heat capacity data of poly(oxy-1,4-phenylene) (PO) (358 - 620 K), poly-(thio-1,4-phenylene) (PPS) (540 - 600 K), poly(ethylene 2,6-naphthalenedicarboxylate) (PEN) (400 - 450 K, 530 - 600 K), an addition scheme for liquid heat capacities was constructed. In addition, the thermodynamic functions H and S have been calculated for those five polymers. The absolute, molar, residual entropy for the glassy state at zero kelvin is estimated to be 6,6,15,2, 7,48, 5,70, and 19,9 J/(K · mol) for PPS, PEN, PPO, PO, and PBT, respectively. Another two polymers with similar structure, poly(1,4-oxybenzoic acid) (POB) and poly(2,6-oxynaphthoic acid) (PON), were also studied in their high temperature mesophase states. A test of the addition scheme has been made to predict their heat capacities.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890713
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 186
    Electronic Resource
    Electronic Resource
    Longitudinal volume viscosity of isotactic polypropylene (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 573-585 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The volume flow of isotactic polypropylene (i-PP) with number-average molecular weight M̄n = 103 200, melting temperature Tm = 426 K and glass transition temperature Tg = 238 K, has been measured. The elastic modulus of the longitudinal wave, longitudinal volume viscosity, initial longitudinal volume viscosity, and retardation times, are described for compression rates between ca. 1,0·10-5 and 200,0·10-5 s-1, and at temperatures between 443 K and 473 K as well as pressures up to 150 MPa at which no sign of crystallization was detected. The longitudinal volume viscosity decreases with increasing compression rate and with decreasing volume deformation, the behaviour being in all cases a typical non-equilibrium one. The longitudinal volume viscosity increases with increasing temperature, the volume flow activation energy being about 78,08 kJ/mol.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890311
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 187
    Electronic Resource
    Electronic Resource
    Effects of ionenes on structure and catalytic activity of cobaltphthalocyanine, 3.Part 2: cf.2. Interaction of 2,4-ionene with cobaltphthalocyanine and model compounds (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 587-596 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to obtain detailed information about the interaction between the constituents of the cobaltphthalocyanine-tetrasodium sulfonate/ionene system, a catalyst used in thiol autoxidation, 2,4-ionene was studied in combination with Fe(CN)4-6, Fe(CN)3-6, congo red, and several metal(II)phthalocyanines. In all cases, stoichiometric complexation was observed, at a ratio where the positive charges on the polymer were just matching those of the anionic species. The hexacyanoferrate complexes were found to be less stable than the dye complexes, due to the formation of dye aggregates in the latter systems. These aggregates appear to enhance the electrostatic interaction with the polymer to such an extent that even irreversible ionomeric “crosslinking” may occur. The results are discussed in relation to the catalytic activity of the polymeric catalyst.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890312
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 188
    Electronic Resource
    Electronic Resource
    Etude cinétique de la polymérisation en émulsion du styrène en présence d'éamulsifiants amphiioniques de type sulfobétaïne (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 619-636 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Emulsion polymerization of styrene was carried out at 70°C with sodium persulfate as initiator in the presence of 3 different sulfobetaïne-type amphoteric surfactants. Their micellar properties were well-characterized as function of temperature, ionic strength and pH. The kinetic behavior, based on the analysis of monomer consumption, particle size and molecular weight, was found to depend on the emulsifier type and concentration. The results were compared with those obtained in the presence of sodium dodecyl sulfate (1) and under emulsifierfree conditions. With dodecyldimethylammoniopropanesulfonate (2), the kinetic behavior was similar to what is observed in 1-emulsified polymerization, whereas with dimethyloctadecylammoniopropanesulfonate (3) and 3-N-acetyl-N-(dodecyldimethylammoniomethyl)aminopropanesulfonate (4), exhibiting lower critical micell concentration, the particle formation mechanism was also controlled by homogeneous nucleation associated with a limited flocculation period. The pH was found to affect the polymerization kinetics, however, the effect was more likely attributed to the initiator decomposition.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890315
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 189
    Electronic Resource
    Electronic Resource
    2H NMR study of correlated spin-lattice relaxation in solid polyelectrolyte complexes of poly(dimethyliminioalkylenes) (α,ω-ionenes) and polystyrenesulfonate (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 663-670 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spin-lattice relaxation rates (1/T1) have been used to study the correlation between the molecular motions in the polyion components of polyelectrolyte complexes from poly(dimethyliminioalkylenes) (α,ω-ionenes) and polystyrenesulfonate. The length of the alkyl chains in the α,ω-ionenes has been varied studying the complexes with 3,3-ionene, 6,6-ionene, and 10,10-ionene, respectively. In the latter, three different positions in the alkylene chains were deuterated selectively. The relaxation rate curves show that the more rigid polystyrenesulfonate component of the complexes is relaxed through the rapid large-angle motions in the alkylene chains of the α,ω-ionenes. In the complex with 10,10-ionene coupling is stronger with the mobility of the CH2 groups adjacent to the quaternary ammonium ion.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890318
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 190
    Electronic Resource
    Electronic Resource
    Influence of chemical structure on glass transition temperatures of poly(propylene terephthalate) and poly(propylene isophthalate) (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 691-699 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(propylene terephthalate)Systematic IUPAC name: poly(oxypropyleneoxyterephthaloyl). (PPTP) and poly(propylene isophthalate)Systematic IUPAC name: poly(oxypropyleneoxyisophthaloyl). (PPIP) were prepared by melt polycondensation. Different fractions with number-average molar masses in the range 5 000 - 20 000 g·mol-1 were obtained and their respective glass transition temperatures (Tg) determined by calorimetry. The solubility parameters of the polymers were obtained by viscosity measurements in different solvents and were found to be 9,4 and 9,5 cal1/2·cm-3/2 (19,2·103 and 19,4·103 J1/2·m-3/2) for PPIP and PPTP, respectively. The glass transition temperatures were compared with those reported for analogous polyesters and it was shown that intramolecular interactions highly influence the Tg of these polyesters, whereas the effect of intermolecular interactions seems to be less important.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890321
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 191
    Electronic Resource
    Electronic Resource
    Contribution to the study of acrylamide polymerization, 1. Polymerization in the presence of an inhibitor (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 701-707 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The average rate of initiation, Ri, is determined for the polymerization of acrylamide (AAM) in water in the presence of the water-soluble initiator ammonium peroxodisulfate (APS) and the inhibitor 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (HTPO). The inhibitor and products from its interaction with the initiator to some extent participate also in other reactions: some lead to partial regeneration of inhibitor and some may be considered to be transfer reactions to the inhibitor. The determined ratio of the rate constant of termination and the square of the rate constant of propagation kt/k2p which does not significantly differ from the value listed for the AAM polymerization in water without admixtures, shows that participation of HTPO in propagation and termination reactions is not important.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890322
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 192
    Electronic Resource
    Electronic Resource
    Polyuréthannes à propriétés émulsifiantes et électrolytiques, 1. Cinétique de condensation des alkylimino-2,2′ diéthanols et de leurs dérivés sulfobétaïniques avec divers monoisocyanatesA la demande de l'auteur, la publication a été retenue. (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1693-1717 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This work deals with model reactions allowing the synthesis of low-molecular-weight polyurethanes with electrolytic and emulsifier properties. The kinetics of addition reactions of 2,2′-alkyliminodiethanols (3a - c) and their ammonium sulfonate derivatives 5 and 6 with propyl (8a) and cyclohexyl isocyanate (8b) were studied in DMSO and in the bulk. The tertiary amino groups of 3 exhibit catalytic effects, whereas the ammonium sulfonate internal salts inhibit the reaction. 8a is 2 - 3 times more reactive than 8b and the addition rates decrease with increasing R. Autoassociations (OH ··· OH) should mainly be intramolecular because of the proximity of the alcohol groups. In bulk the 8a + 3 additions apparently follow second order kinetics. On the other hand, the third order law must be taken into account with 8b. In contrast, in DMSO, due to the strong (solvent, —OH and/or —NCO) complexations, the kinetics do neither follow the simple second order, nor the third order law. By the use of two successive second order kinetics, diols were found more reactive than their monoalcohol-monocarbamate derivatives. However, the difference in reactivity decreases with increasing reaction temperatures. Sulfobetaine units may be inserted into the polyurethane chains if diols with ammonium sulfonate groups are used as comonomer, but their weak reactivity must be taken into account.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890724
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 193
    Electronic Resource
    Electronic Resource
    Polyuréthannes à propriétés emulsifiantes et électrolytiques, 2Partie 1: cf.1. Cinétique de polycondensation en solution des alkylimino-2,2′ diéthanols avec le diisocyanate d'isophorone. Etude par 1H et 13C NMR (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1719-1737 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 13C NMR analysis of carbamates and substituted ureas as model compounds, derived from 5-isocyanato-1,3,3-trimethylcyclohexylmethyl isocyanate (isophorone diisocyanate) (3), allowed the quantitative determination of global conversions of hydroxyl and NCO groups. The individual conversions of the two NCO groups, as observed in the polycondensations of 2,2′-methylimino- and 2,2′-dodecyliminodiethanol (1a and 1b) with 3 in toluene, were examined. The primary NCO group of 3 was found to be two times more reactive than the secondary one. The global kinetics of the polycondensations followed the 2nd and 3rd order for conversions lower than 50%. Beyond 50% of conversion, zero order kinetics were observed because of the decrease of the rate due to the steric hindrance of both cyclohexyl and alkyl residues. Alkyl radical length in 1 and hydroxyl auto-association equilibria were found to have the same effect on polycondensation as on condensation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890725
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 194
    Electronic Resource
    Electronic Resource
    Electrochemical preparation of poly(di(2-thienyl)benzene)s and poly(4,4′-di(2-thienyl)biphenyl) (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1755-1763 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1,3-Di(2-thienyl)benzene (T13B), 4,4′-di(2-thienyl)biphenyl (TBP), and 3,5-di(2-thienyl)-pyridine (T35P) were prepared. Films were deposited on the electrode in the anodic oxidative polymerization of T13B, 1,4-di(2-thienyl)benzene (T14B) and TBP, but the oxidation product of T35P did not cover the entire surface of the electrode. The infrared spectra of the films indicated oxidative coupling to occur at the 5 and 5′ positions of the thiophene rings. While the cyclic voltammograms of poly-T14B were well-defined, those of poly-T13B and poly-TBP had complex shapes with two or three anodic peaks. When the absorption spectra were measured during electrochemical oxidation, new peaks appeared at 2,0 and 1,9 eV for poly-T13B and poly-TBP, respectively. The films looked green in the oxidized state and faintly yellow in the neutral state. The green colour was retained without applied voltage in the cell and in the dry state. It was concluded that conjugation along the main chain is insufficient in these polymers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890802
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 195
    Electronic Resource
    Electronic Resource
    Combined liquid-crystalline polymers with chiral phases, 2Part 1: S. Bualek, R. Zentel, Makromol. Chem. 189, 797 (1988). Lateral substituentspresented in part at the Conference “Liquid Crystal Polymers” in Bordeaux 20 - 24, Juli 1987, ref.20. (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1793-1807 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chiral combined liquid-crystalline polymers (i. e. polymers with the mesogenic groups in the main chain as well as in the side groups) with dipole moments perpendicular to the mesogenic groups were synthesized and characterized. These dipole moments were introduced by lateral substituents, which were located at different parts of the mesogen or directly at the chiral centre. The polymers, thus prepared, show crystalline or glassy phases at room temperature and smectic A, chiral smectic C* or cholesteric phases at higher temperatures. Since the lateral substituents decrease the melting temperature more strongly than the clearing temperature, the liquid-crystalline phases are broadened compared to the unsubstituted polymers. Often glassy liquid-crystalline phases are obtained. The dipole moments perpendicular to the mesogenic groups or at the chiral centre may help to obtain a high spontaneous polarisation in the chiral smectic C* phase (ferroelectricity).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890805
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 196
    Electronic Resource
    Electronic Resource
    Poly(propylene sulfoxide)  -  a first approach to a dipolar aprotic, water-soluble and reactive polymerDedicated to Dr. P. Rempp on the occasion of his 60th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2017-2028 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The oxidation of atactic poly(2-methylthiirane) (PPS, M̄w ≈ 1 - 2 · 105) to its corresponding sulfoxide (PPSO) is studied under a variety of experimental conditions: m-chloroperbenzoic acid in homogeneous chloroform solution ( - 7°C) and hydrogen peroxide or bromine in an interfacial chloroform-water system (20°C) lead to selective and quantitative oxidation under stoichiometric conditions with simultaneous chain degradation (M̄w (PPSO) ≈ 0,5 - 3 · 104). The high density of sulfoxide functions affords to the PPSO chain a number of specific properties such as: (a) solubility in dipolar protic (CH3OH, CHCHl3 …) and aprotic (DMF, DMSO) solvents, the polymer coils being, however, strongly associated in aqueous solution, (b) strong polarity of the bulk polymer, as shown by an “apparent local dipole moment” of about 4,1 D, (c) poor thermal stability, degradation starting at about 130°C under nitrogen, with a weight loss of 50% at 160°C (apparent activation energy Ea = 100 kJ · mol-1).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890905
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 197
    Electronic Resource
    Electronic Resource
    Mobility and 29Si NMR relaxation in some cyclic siloxanesDedicated to Prof. Dr. Hans-Joachim Cantow on his 65th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2077-2084 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 29Si NMR spin-lattice relaxation time (T1) measurements were performed with asymmetrically substituted oligomeric cyclosiloxanes (MeRSiO2/2)n (with R = phenyl, n = 3 and R = H, n = 4 - 6). Temperature- and field-dependend measurements allow separation into different relaxation mechanisms. Based on these results, molecular correlation times τc were calculated. The methyl-H cycles were found to be more mobile than the methyl-phenyl ones.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890910
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 198
    Electronic Resource
    Electronic Resource
    Approach to the composition dependence of the glass transition temperature of compatible polymer blends, 2Part 1: cf.1. The effect of local chain orientationDedicated to Paul Rempp on the occasion of his 60th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2085-2097 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In a previous publication a new concept has been presented for the composition dependence of the glass transition in compatible polymer blends. The concept starts with the idea that besides conformational energy barriers, contacts due to interaction are responsible for both conformation and “free” volume distribution. In accordance with the Flory-Huggins lattice theory, the contact probability has been related to the volume fraction of the components, corrected for the different volume expansion coefficients. The concept accounts for both chainspecific and interaction-specific contributions. It is concluded that local chain orientation due to the increased hetero-contact interaction may explain the observed molecular weight influences on the composition dependence of Tg of polymer blends. Using experimental data for poly(vinyl methyl ether)-polystyrene (PVME-PS) blends it is shown that this local chain orientation due to hetero-interaction is extremely strong in blends of the low molecular weight PS with high MW PVME. Thus, apparently, the stiffer component is dominating the Tg behaviour of compatible polymer blends.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890911
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 199
    Electronic Resource
    Electronic Resource
    An easy calculation of the expected n-ad sequence proportions in polymers obeying first-order markov statistics and being prepared by ring-opening polymerization of chiral heterocyclic monomers (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2107-2116 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An easy and fast calculation method of the normalized n-ad sequence proportions in optically active polymers which derive from heterocyclic monomers and which obey first-order Markov statistics is developed. The proposed method does not require any computer calculation and provides very accurate values up to high conversions in polymer. It can be applied over a wide range of enantiomeric excess of the initial monomer, and of copolymerization reactivity ratios. This is useful for testing whether a polymer fits the first-order Markov propagation model.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890913
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 200
    Electronic Resource
    Electronic Resource
    Transient electric birefringence of poly(sodium p-styrenesulfonate) solutions at very low field strengthsDedicated to Professor H. -J. Cantow on the occasion of his 65th birthday (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2125-2134 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of the electric birefringence were performed on dilute, aqueous solutions of a poly(sodium p-styrenesulfonate). The concentrations were chosen to be somewhat below and above the critical concentration (c*) where, on grounds of theoretical considerations, the rod-to-coil transition is expected to occur. The measurements were conducted at very low field strengths E, viz. in the order of E = 104 V · m-1, using d. c. pulses as well as 30 kHz a. c. pulses. When an a. c. field is applied, birefringence is always negative and shows a monotonous rise and decay. The same holds true for a d. c. field provided the concentration of the polymer is below c*. However, when a d. c. pulse of very low field strength is applied to a solution the concentration of which is above the critical concentration, some strange features occur: At the beginning of the pulse the birefringence is negative, but then it reverses its sign and approaches a positive steady-state value. After cessation of the pulse the birefringence passes through a maximum before decaying to zero. The whole birefringence curve looks like a superposition of two signals with opposite signs. These features disappear at higher field strengths. On the basis of an analysis of the field-strength dependence, it is tentatively concluded that other mechanisms besides the rotational orientation of the molecules contribute to birefringence. One such process could be migration of the macroions giving rise to flow birefringence.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890915
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...