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  • 1
    Electronic Resource
    Electronic Resource
    Polyelectrolyte-induced vesicle formation in lamellar liquid-crystalline model systems (2000)
    Springer
    Colloid & polymer science 278 (2000), S. 164-168 
    Details
    ISSN: 1435-1536
    Keywords: Key words Polyelectrolytes ; Lamellar liquid crystals ; Vesicle formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The object of the research was to investigate the influence of a semiflexible polyanion (carboxymethylcellulose) in the absence and presence of a more flexible cationic polyelectrolyte [poly(diallyldimethyl-ammonium chloride)] on structure formation in liquid-crystalline model systems consisting of sodium dodecyl sulfate (SDS)/ decanol/water. Small-angle X-ray measurements in combination with electron microscopic investigations show the adsorption of the polycation on the SDS head groups. These polymer-modified lamellae form multilamellar vesicles. The semiflexible polyanion was embedded into the liquid crystal without macroscopic phase separation and multivesicular vesicles were formed on the supramolecular level. In combination the oppositely charged polyelectrolytes induce the formation of multivesicular structures where two lamellar structures coexist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050027
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  • 2
    Electronic Resource
    Electronic Resource
    Interactions between poly(diallyldimethylammonium chloride) and poly(acrylic acid) in dependence on polymer concentration (1994)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 865-871 
    Details
    ISSN: 0392-6737
    Keywords: Disperse systems ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The phase diagram of the ternary system,i.e. poly(diallyldimethylammonium chloride), poly(acrylic acid, sodium salt), and water was investigated by varying the molecular weight of the components. In general, a range of phase separation is surrounded by a one-phase system. The range of phase separation can be subdivided into a region of flocculation and/or coacervation in contrast to stable symplex dispersions. By increasing the molecular weight of the components the range of phase separation is increased and phenomena of flocculation followed by coacervation were observed predominantly. Above a molecular weight of 10 000 g/mol the transition to concentrated macroscopic homogeneous one-phase systems was observed at a constant ionic strength of 2 mol/l coinciding with the «critical ionic strength» for Coulombic interactions in this system. That means the transition to concentrated one-phase systems can be understood by the disappearance of Coulombic forces above a system-specific ionic strength resulting in a quite additive behaviour of the mixtures with regard to the components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456736
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  • 3
    Electronic Resource
    Electronic Resource
    Amphoteric character of polyelectrolyte complex particles as revealed by isotachophoresis and viscometry (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 906-912 
    Details
    ISSN: 1435-1536
    Keywords: Polyelectrolyte complexes ; ampholytes ; surface charge ; electrophoresis ; viscometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Isotachophoresis and viscometric measurements were performed on aqueous dispersions of non-stoichiometric polyelectrolyte complexes in order to elucidate the surface charge situation of the complex particles in dependence on component charge density, ratio of cationic to anionic groups in the complex, and pH and ionic strengths of the ambient medium. Components for complex formation were acryl-based anionic and cationic polyelectrolytes of the pendent type. From our results, an amphoteric character of the polyelectrolyte complex particles can be concluded, with an isoelectric point characterized by zero mobility and a minimum in reduced viscosityη spec/c of the particle dispersion, and with the sign of net surface charge depending on ambient pH and component charge density. The influence of ionic strength on theη spec/c vs pH plots can be interpreted by assuming a competition between salting-out and electrostatic shielding effects. No correlation could be established between the overall molar ratio of cationic to anionic groups and the isoelectric point of the complex particles, which obviously indicates a different composition of “surface” and “bulk” of the polyelectrolyte complex particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410845
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  • 4
    Electronic Resource
    Electronic Resource
    Investigations on synthesis and characterization of carboxy-groups containing cellulose sulfates (1991)
    Springer
    Polymer bulletin 27 (1991), S. 147-153 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Carboxymethyl cellulose and C-6-carboxy cellulose were treated with SO3 and HSO3CL in DMF yielding the corresponding watersoluble sulfate half-esters. A preferred sulfation of primary hydroxyl groups was found by 13C-n. m.r. spectroscopy. The potentiometric titration of the polyelectrolytes showed significant differences in the titration behaviour which can be explained by the different acidity of the carboxy groups in the two cellulose derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296024
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  • 5
    Electronic Resource
    Electronic Resource
    Neutron activation analysis of the rare earth elements in rocks from the earth's upper mantle and deep crust (1987)
    Springer
    Journal of radioanalytical and nuclear chemistry 112 (1987), S. 545-553 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Three techniques for analyzing rare earth elements (REE) in geological materials are described, i.e. instrumental neutron activation analysis (INAA), neutron activation analysis with pre-irradiation chemical REE separation (PCS-NAA) and radiochemical neutron activation analysis (RNAA). The knowledge of REE concentrations in eclogites, peridotites and minerals from the earth's lower crust and upper mantle is very useful in constraining their petrogenetic history.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02132385
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  • 6
    Electronic Resource
    Electronic Resource
    Zur Bildung wasserlöslicher Polysalze. 4. Mitt.: Untersuchungen zum Übergang vom löslichen Symplex zur Polysalzfällung3. Mitt.: siehe [7] (1986)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 37 (1986), S. 108-114 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The transition range between macroscopic soluble polycation-polyanion-complexes (symplexes) and polysalt precipitates was investigated by combining potentiometry, conductometry and tubidimetry. As starting materials mainly poly(ethylene imine) and cellulose sulphate as well as cationically and anionically modified poly(acrylamide)s were used. Under the conditions applied, only in a few systems the formation of stoichiometric 1: 1-symplexes is indicated by the electrochemical or the turbidimetric endpoint. The course of phase separation depends principally on the structure of the polyelectrolytes, but it is also strongly affected by the choice of the excess component and the contact of the low-molecular electrolyte (NaCl).
    Notes: Der Übergang von makroskopisch löslichen Polyanion-Polykation-Komplex (Symplex) zur Polysalzfällung wird mittels Kombination von Potentiometrie, Konduktometrie und Turbidimetrie untersucht. Als Ausgangsmaterialien dienen vor allem Cellulosesulfat und Polyethylenimin sowie anionisch und kationisch modifizierte Polyacrylamide. Unter den angewandten Bedingungen wurden bei elektrochemischer bzw. bei turbidimetrischer Endpunktanzeige nur in wenigen Fällen 1: 1-Symplexe erhalten. Die Endpunkte und der Verlauf der Trübungskurve hängen von der chemischen Struktur der Komponenten, aber in erheblichem Maße auch vom Salzgehalt (NaCl) und von der Wahl der Überschußkomponente ab.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1986.010370211
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  • 7
    Electronic Resource
    Electronic Resource
    Synthese, Charakterisierung und Symplexbildung von Polyampholyten aus ungesättigten Dicarbonsäure- und Allylaminderivaten. 4. Mitt.: Spektroskopische Untersuchungen zur Symplexbildung zwischen Poly(dimethyldiallylammoniumchlorid) und einem ampholytischen Copolymer aus Maleinsäure und Methyldiallylamin3. Mitteilung: siehe [1] (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 405-407 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: By means of IR and 13C-NMR spectroscopy the symplex formation of an alternating copolymer of maleic acid and methyldiallylamine with dimethyldiallylammonium chloride has been investigated. It was show that a zwitter-ionic bond originally existing in the polyampholyte at the isoelectric point, is cleaved in symplex formation and subsequently replaced by an ammonium group.
    Notes: Mittels IR- und 13C-NMR-Spektroskopie wurde die Symplexbildung des alternierenden Copolymers aus Maleinsäure und Methyldiallylamin mit Poly(dimethyldiallyl-ammoniumchlorid) untersucht. Es wurde gezeigt, daß eine im isoelektrischen Punkt des Polyampholyts vorliegende zwitterionische Bindung bei der Symplexbildung gespalten wird und an ihre Stelle eine elektrostatische Bindung zwischen Carboxylatgruppe und quaternärer Ammoniumgruppe tritt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400610
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  • 8
    Electronic Resource
    Electronic Resource
    Zum Polyelektrolytverhalten einer C-6-substituierten Carboxycellulose im Vergleich zu Carboxymethylcellulose (1990)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 333-338 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Comparing a C-6-substituted carboxy cellulose and carboxy methyl cellulose samples differing in substituent distribution, the acidity of the COOH-group and the symplex formation of these polymers are investigated. The acidity of the COOH-group is inversely correlated to the average distance between the anionic charge centre and the anhydroglucose ring. Obviously, no significant effect of the regioselectivity of substitution on symplex formation exists.
    Notes: Es wird über vergleichende Untersuchungen zur Acidität der Carboxygruppe und zur Symplexbildung bei einer C-6-substituierten Carboxycellulose einerseits, Carboxymethylcellulosen mit unterschiedlicher Substituentenverteilung andererseits berichtet. Die Acidität der Carboxygruppe korreliert invers zum mittleren Abstand zwischen anionischem Ladungszentrum und Anhydroglucosering. Ein signifikanter Einfluß der Regioselektivität der Substitution auf die Symplexbildung besteht offensichtlich nicht.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1990.010410605
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  • 9
    Electronic Resource
    Electronic Resource
    Synthese, Charakterisierung und Symplexbildung von Polyampholyten aus ungesättigten Discarbonsäure- und Allylaminderivaten. 1. Mitteilung: Synthese und Charakterisierung von Copolymeren aus Maleinsäre und Allylaminderivaten (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 36-43 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Alternating ampholytic copolymers of maleic acid with allylamine, diallylamine, methyldiallylamine and dimethyldiallylammonium were synthetized by free radical polymerization and characterized by viscometry, potentiometry, and turbidimetry in dependence of pH and ionic strength of the aqueous solutions of the polymers. The influence of the chemical structure of the cationic units on solution properties of the polyampholyte is predominantly discussed from the aspect of zwitterion formation. The isoelectric points of the four polymers differ only slightly, but they depend considerably on the ionic strength of the system.
    Notes: Alternierende ampholytische Copolymere von Maleinsäure mit Allylamin, Diallylamin, Methyldiallylamin und Dimethyldiallylammonium wurden durch radikalische Polymerisation synthetisiert und mittels Viskosimetrie, Potentiomtrie und Turbidimetrie in Abhängigkeit vom pH-Wert und der Ionenstärke wäßriger Lösungender Polymere charakterisiert. Der Einfluß der chemischen Struktur der kationischen Einheiten auf das Verhalten der Polyampholyte in wäßriger Lösung wird vor allem unter dem Gesichtspunkt der Zwitterionenbildung diskutiert. Der isoelektrische Punkt unterscheidet sich für die vier Polymere nur wenig, hängt jedoch erheblich von der Ionenstärke des Systems ab.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400108
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  • 10
    Electronic Resource
    Electronic Resource
    Zur Interpretation einer vom Verhältnis 1:1 abweichenden Symplex-Stöchiometrie (1989)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 40 (1989), S. 110-112 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In symplex titration between anionic and cationic polyelectrolytes rather frequently deviations from a 1:1 endpoint stoichiometry with regard to ionic groups are observed. An interpretation of this phenomenon based on the law of mass action is proposed, which assumes a different degree of dissociation between polyions and low molecular counterions of the polyelectrolyte components in question. Applicability and limitation of this approach for an interpolatory calculation of the endpoint stoichiometry are shown.
    Notes: Für die bei Polyanion-Polykation-Titrationen (Symplex-Titrationen) oft von einem Verhältnis 1: 1 der anionischen zu kationischen Gruppen abweichende Endpunkt-Stöchiometrie wird eine Interpretationsmöglichkeit auf Basis des Massenwirkungsgesetzes dargelegt. Hierbei wird von einem unterschiedlichen Dissoziationsgrad der beteiligten Polyelektrolyte hinsichtlich Dissoziation der niedermolekularen Gegenionen vom Polyion ausgegangen. Möglichkeiten und Grenzen einer interpolatorischen Berechnung der Endpunkt-Stöchiometrie werden aufgezeigt.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1989.010400208
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