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  • 1
    Electronic Resource
    Electronic Resource
    Structural reorganization of phosphatidylcholine vesicle membranes by poly(2-ethylacrylic acid): influence of the molecular weight of the polymer (1989)
    s.l. : American Chemical Society
    Macromolecules 22 (1989), S. 765-769 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00192a042
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  • 2
    Electronic Resource
    Electronic Resource
    Makromolekulare schalter für doppelschichtmembranen (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 166 (1989), S. 257-272 
    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: Controlled polyelectrolyte adsorption can be used to render phospholipid bilayer membranes sensitive to physical and chemical signals. We describe in this paper the design and construction of macromolecular switches for bilayer membranes, which can be used to create lipid vesicles that release their contents rapidly and quantitatively in response to changes in pH, temperature, light intensity or glucose concentration. The kinetics and mechanisms of the molecular switching processes observed in such systems are also discussed.
    Notes: Kontrollierte Adsorption von Polyelektrolyten kann ein wirksames Werkzeug im Design von dünnen molekularen Filmen sein. Man kann erwarten, daß die Adsorption von Polyelektrolytketten das empfindliche Kräftegleichgewicht erheblich beeinflußt, das die strukturellen und funktionellen Eigenschaften von geordneten Strukturen wie Einzel-, Doppel- und Mehrfachschichten bestimmt. Andererseits ist die Adsorption von Polyelektrolyten außerordentlich sensitiv auf Umgebungsparameter, z.B. pH, Temperatur oder lonenstärke. Kontrollierte Adsorption kann daher zu Sensitivität auf bestimmte chemische oder physikalische Stimuli führen, sodaß auf diese Weise ein molekularer Schaltmechanismus entworfen werden kann. Durch Umsetzen dieser ldee in reale Systeme gelang es uns, molekulares Schalten in Mischungen von Poly(2-ethylacrylsäre) mit natürlichen oder synthetischen Phosphatidylcholinen zu bewirken. Insbesondere haben wir Phosphatidylcholinvesikel hergestellt, die ihren lnhalt nach einer Änderung von pH, Temperatur, Glukosekonzentration oder nach Bestrahlung mit Licht schnell und quantitativ freisetzen. Die Entwicklung und die Herstellung von Doppelschichtmembranen, die auf solche Änderungen reagieren, sowie die Kinetik und der Mechanismus des damit verbundenen molekularen Schaltprozesses werden im vorliegenden Artikel diskutiert.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051660118
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  • 3
    Electronic Resource
    Electronic Resource
    On the kinetics and mechanism of thermal degradation of polystyrene (1982)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 1207-1218 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal degradation of polydisperse polystyrene samples with mol. wts. (M̄n) between 60000 and 22000 has been investigated at different temperatures under oxygen free conditions. Product analysis has been carried out by GPC. The experimental degradation could be simulated by a model consisting of scission and depolymerization. The dynamical behaviour of this model is expressed in a matrix from. The ratio of scission and depolymerization is constant for all polymers and different temperatures during degradation. Therefore, a master curve could be evaluated, which gives a general relation between the decrease of mol. wt. and the mass of volatiles. Finally a radical chain mechanism has been proposed in a lumped form which is consistent with the kinetic model and the experimental results.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1982.021830514
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  • 4
    Electronic Resource
    Electronic Resource
    On the kinetics and mechanism of thermal degradation of poly(p-methylstyrene) (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 561-582 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal behavior of polydisperse poly(p-methylstyrene) (PPMS) samples with M̄w's of 99200 and 356000 g/mol was investigated under oxygen-free conditions at temperatures between 220 and 345°C. The reaction products were analysed by gel permeation chromatography (GPC), gas chromatography (GC) and swelling measurements. In the initial stage of the reaction crosslinking occurs; at higher temperatures the gel decomposes to polymers with a low degree of polymerization and to volatile products with molecular weights in the range up to trimers. A radical chain mechanism is proposed for degradation which explains the experimental results. On this basis a model is evaluated for gel formation, which is discussed in detail. The results of the present investigation are compared with the thermal degradation of polystyrene (PS) which is chemically similar but does not crosslink.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880309
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  • 5
    Electronic Resource
    Electronic Resource
    On the kinetics and mechanism of thermal degradation of polystyrene, 2.Part 1: cf.1. Formation of volatile compounds (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 991-1001 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal degradation of polystyrene (PS) was carried out in the absence of oxygen between 292 and 336°C. The formed volatile products were analysed qualitatively and quantitatively by means of gas charomatography. It was found that the composition of the volatile fraction is a function of conversion and independent of temperature for most of the products. A radical chain mechanism is proposed to explain these experimental results.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850513
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  • 6
    Electronic Resource
    Electronic Resource
    Advanced computerized evaluation of gel permeation chromatography results: Calibration and correction for peak broadening (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1415-1423 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An advanced method for evaluating gel permeation chromatography (GPC) results is described. Based on a modified broad-molecular-weight standard calibration method the calibration curve for poly(p-methylstyrene) (PPMS) is constructed with several narrow-molecularweight polystyrene (PS) standards and 4 broad-molecular-weight PPMS samples (weight-average molecular weight M̄w = 14000 to 450000). The molecular weight range is covered from that of the monomer up to several hundredthousands. A computer code is developed to correct the elution curves for axial dispersion by a personal computer (PC) in relatively short calculation times.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880617
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal crosslinking of styrene/p-methylstyrene copolymers (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2775-2787 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal crosslinking of polydisperse styrene/p-methylstyrene copolymers with compositions of between 0 and 100 mol-% of styrene and weight-average molecular weights of about 300000 was investigated under oxygen-free conditions at 260°C and 275°C. At these temperatures the formation of oligomers was negligible. The reaction products were analysed by gel permeation chromatography and by swelling experiments. Two competing reactions  -  degradation and crosslinking  -  were found which occur to an extent proportional to copolymer composition. By comparing the properties of the treated copolymer samples - molecular weights, amount and characteristics of the gel - with the properties of pure poly(p-methylstyrene) samples degraded at 275°C it can be concluded that samples with 83 mol-% and 79 mol-% of styrene treated at 275°C and 260°C, respectively, should remain unchanged with respect to molecular weight and composition, because degradation and crosslinking compensate each other. In the samples containing less styrene crosslinking predominates. The ratio of the reaction rates determined experimentally agrees well with the value calculated from the reaction rates of the homopolymers given in the literature. A simple radical-chain mechanism is proposed that explains the experimental results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021881128
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  • 8
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    Structural reorganization of phosphatidylcholine vesicle membranes by poly(2-ethylacrylic acid): influence of the molecular weight of the polymer (1989)
    American Chemical Society
    Details
    Publication Date: 1989-03-01
    Print ISSN: 0024-9297
    Electronic ISSN: 1520-5835
    Topics: Chemistry and Pharmacology , Physics
    Published by American Chemical Society
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