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  • 1
    Digitale Medien
    Digitale Medien
    Stereoselective polymerization of butadiene by a new dicationic nickel complex (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 33-41 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Der neuartige dikationische Komplex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-Bis(diphenylphosphin)ferrocen) zeigte in Anwesenheit von Diethylaluminiumchlorid (AIEt2CI) hohe Aktivität für die Polymerisation von 1,3-Butadien. Reaktionsdauer, Temperatur und das Aluminium/Nickel-Verhältnis wurden auf maximale Aktivität und Selektivität optimiert. Umsätze über 90% konnten erreicht werden. Im Vergleich zu Polybutadienen, die mit anderen Nickel-Phosphin-Systemen hergestellt wurden, zeigten die synthetisierten Polybutadiene höhere cis-1,4-Anteile (〈80%) und eine geringe Bildung von 1,2-Einheiten (2%). Alle Polymeren hatten niedrige mittlere Molekulargewichte (Mw 〉 11 800).
    Notizen: The new dicationic nickel complex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-bis(diphenylphosphino)ferrocene) in the presence of diethylaluminium chloride (AIEt2CI) exhibited high activity on the 1,3-butadiene polymerization. Reaction time, temperature and aluminium/nickel molar ratio were optimized in order to achieve maximum activity and selectivity. Conversions higher than 90% were obtained in contrast to other nickel-based systems using phosphine ligands, the resulting polybutadiene showed high cis-1,4 (〈80%) content and only small amount of 1,2-units (2%). All polymers presented low molecular weights (Mw 〉 11 800).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1996.052390104
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  • 2
    Digitale Medien
    Digitale Medien
    Application of thin film dialysis to the determination of equilibrium constants (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 837-842 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A theoretical basis for thin-film dialysis involving binding between a ligand and nondialyzing species is presented. A general differential equation that applies to the case of equivalent, noninteracting sites is derived relating [A]F, [A]T, [P]T, and K. Numerical solutions to this equation are used to develop a series of escape curves corresponding to specific values of the parameters [P]T, [A]i, K, and k0. A general method for determining an equilibrium binding constant from thin-film dialysis data is given. A comparison of thin-film dialysis results predicted by this theory with literature data shows essential agreement.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1978.360170403
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  • 3
    Digitale Medien
    Digitale Medien
    Complexity of the hydrolytic degradation of aliphatic polyesters (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 239-253 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Aliphatic polyesters are more or less hydrolytically degradable, depending on their chemical, configurational and morphological structures. Hydrolysis can be either homogeneous or heterogeneous, depending on many structural and environmental factors. The present understanding of this hydrolytic degradation is recalled. The importance of diffusion-reaction phenomena is discussed on the basis of the behaviors of polyesters derived from α-hydroxy acids, namely lactic and glycolic acids and attempts are made to extend the understanding to other members of the aliphatic polyester family. The main results of some recent investigations of the effects on poly(lactic acid) polymers of basic additives and of initiators such as stannous octoate and zinc metal, which are now industrially used, are presented.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1997.052470116
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  • 4
    Digitale Medien
    Digitale Medien
    Binding of alcohols to the peptide CO-group of poly-L-proline in the I and II conformation. I. Demonstration of the binding by infrared spectroscopy and optical rotatory dispersion (1969)
    New York : Wiley-Blackwell
    Biopolymers 8 (1969), S. 237-246 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The binding of n-butanol, benzyl alcohol, and trifluoroethanol to polyproline I (all peptide bonds in cis configuration) and II (all peptide bonds in trans configuration) has been demonstrated. It was found by infrared spectroscopy that hydrogen bonds are formed between the CO groups of the polymer and the OH groups of the alcohols. Their strength increases from n-butanol via benzyl alcohol to trifluoroethanol. The binding of benzyl alcohol could also be followed by optical rotatory dispersion due to the fact that the electronic transitions of the benzyl ring are rendered optically active by the binding to the polymer.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1969.360080209
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  • 5
    Digitale Medien
    Digitale Medien
    A cooperative transition between two helical conformations in a linear system: poly-L-proline I ⇌ II. II. Kinetic studies (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 721-737 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The conformational transition between the two helical forms I and II of poly-L-proline serves as an experimental model for the study of the kinetic, behavior of cooperative systems. The slow I ⇌ II conversion after a sudden perturbation of the solvent composition was followed polarimetrically. The dependence of the mean relaxation times on chain length and the degree of conversion was compared with Schwarz's theory. In addition, a description of the entire relaxation curves was possible in three special cases: all-or-nothing, small perturbations of the I ⇌ II equilibrium in long chains, and conversions which start off with molecules completely in one or the other conformational state. The mathematical model on which the theory is based contains only one more adjustable parameter than the equilibrium model, but it adapts to the experimental results surprisingly well. The present kinetic results and equilibrium measurements on this system are described by the same values of those parameters which are common to both models. The found value of the rate constant of the propagation step, i.e. the cis ⇌ trans isomerization of a peptide bond at an existing I-II junction, agrees with the rate of isomerization in N,N-dimethylacetamide reported in the literature. The rate of nucleation is up to 105 times smaller than the rate of propagation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.360100410
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  • 6
    Digitale Medien
    Digitale Medien
    Untersuchungen zur kinetik der polykondensation von sebacoylchlorid mit α,ω-alkandiolenHerrn Professor Dr. Georg Manecke zum 60. Geburtstag. (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 2257-2260 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The kinetics of polycondensation of sebacoyl chloride with α,ω-alkane dioles HO - (CH2)n - OH (5≤n≤10) in dioxane can be described by a second order law related to the functional groups. The rate constants at a given temperature have all the same value within the accuracy of the measurements. The mean values of the rate constants are k=0,63·10-3mol-1ls-1 (T=299,9 K),k=1,19·10-3mol-1ls-1 (T=312,9 K), and k=2,98·10-3mol-1l s-1 (T=331,8 K). Thus, these polycondensation reactions are independent of the chain length of the α,ω-dioles. The mean activation energy is EA=41 kJ mol-1 and the pre-exponential factor is A=8,5·10×3 mol-1ls-1.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1977.021780812
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  • 7
    Digitale Medien
    Digitale Medien
    Untersuchungen zur radikalischen copolymerisation von 2-isopropenylnaphthalin mit maleinsäreanhydrid (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2987-2989 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1979.021801221
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  • 8
    Digitale Medien
    Digitale Medien
    Beiträge zur polymerisation von 2-isopropenylnaphthalin, 32. Mitt.: cf.3.. Anionische homopolymerisation von 2-isopropenylnaphthalinTeil der Dissertation von D. Engel, Mainz. (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 3279-3289 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The anionic homopolymerization of 2-isoprenylnaphthalene with butyllithium in tetrahydrofuran at -78°C is described. The refractive index increment amounts to dn/dc = 0,2084 ml/g for these polymers in toluene at 25°C and wavelength λ = 436 nm. Determination of the molecular weights by light scattering yielded values between 13 000 and 270 000. The second virial coefficients also determined by light scattering measurements are comparable with the corresponding data of poly(α-methylstyrene). A calibration curve is given for gel permeation chromatography of the poly(2-isoprenylnaphthalene)s, whose polymolecularity indexes Mw/Mn lie between 1,06 and 1,2. Their intrinsic viscosity/molecular weight relationship is [η] = 1,43·10-2 M0,663. From 1H NMR of the α-methyl group fractions of isotactic triads between 30 and 55% are evaluated. The glass transition temperature extrapolated to infinite molecular weight is Tg∞ = 221°C. Above 300°C fast degradation by monomer formation is observed.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1981.021821132
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  • 9
    Digitale Medien
    Digitale Medien
    Untersuchungen zur kationischen polymerisation von 2-isopropenylnaphthalin (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2991-2993 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1979.021801222
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  • 10
    Digitale Medien
    Digitale Medien
    Zur kinetik der radikalischen fällungspolymerisation von methyacrylonitril in substanz unter anfangsbedingungen (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 166 (1973), S. 199-207 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The AIBN initiated bulk polymerization of methacrylonitrile was carried out at 50 to 75°C. With regard to the initiator concentration the reaction order is 1/2. The overall activation energy was found to be 22,9 kcal. mole-1. The parameter k2w/ka (kw = propagation constant, ka = termination constant) was calculated from the number average of the degree of polymerization (P̄n) and the overall reaction rate at the time t = 0 (vbr,o), taking into account only the low molecular weight fraction of polymers with a distribution of bimodal character. At a temperature of 60°C and with respect to initial state k2w/ka = 1,75 .10-5 dm3 mol-1.s-1 and the efficiency of initiation f = 0,58 was obtained. The kinetic constants do not differ from those of solution polymerization.
    Notizen: Die durch AIBN initiierte Polymerisation von Methacrylonitril wurde bei 50-75°C in Substanz untersucht. Die Reaktionsordnung ist in bezug auf die Initiatorkonzentration 1/2. Die Bruttoaktivierungsenergie beträgt 22,9 kcal . mol-1. Wird K2w/ka (Kw = Wachstumskonstante, ka = Abbruchskonstante) aus dem Zahlenmittel des Polymerisationsgradaes (P̄n) und der Bruttogeschwindigkeit zur Zeit t = 0 (vbr,0) bestimmt, darf bei Polymeren mit bimodaler Molekulargewichtsverteilung nur der kurzkettige Anteil berücksichtigt werden. Für 60°C wird unter Anfangsbedingungen k2w/ka = 1,75.10-5 dm3.mol-1. s-1 und der Radikalausbeutefaktor f = 0,58 gefunden. Die kinetischen Konstanten unterscheiden sich nicht von denen der Lösungspolymerisation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1973.021660117
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