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  • 1
    Electronic Resource
    Electronic Resource
    Monte Carlo simulation of the conformational entropy of polymer chains (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 1672-1674 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A Monte Carlo method, namely, the "statistical counting method'' (SCM) has been proposed for simulating the conformational entropy of a single free or confined linear self-avoiding random walk chains on the simple cubic lattice. For a free linear chain with length 1081, it is found from the calculated results of 100 groups of 104 samplings that the maximum and the minimum values of the conformational entropy are 1670.2 and 1660.3, respectively, the deviations from the average value 1663.8 are only +0.39% and −0.2%. In the range of chain length 8–20 the calculated entropy data are found to be in agreement with their precise values obtained by M. F. Sykes, et al. [J. Phys. A 5, 653 (1972)] with deviation less than 0.05%. In the range of chain lengths up to 27 confined in a cube of side length 2, the entropy data are also consistent with their precise values obtained from the direct counting of conformation number with the deviations less than 0.6%. For a long chain with lengths up to 2101, the calculated entropy data have confirmed the prediction by the renormalization group theory very well and the deviation is less than 0.8%. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470753
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  • 2
    Electronic Resource
    Electronic Resource
    Infinite Dilution Diffusion Coefficients of Several Aromatic Hydrocarbons in Octane and 2,2,4-Trimethylpentane (1995)
    s.l. : American Chemical Society
    Journal of chemical & engineering data 40 (1995), S. 1053-1055 
    Details
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/je00021a004
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  • 3
    Electronic Resource
    Electronic Resource
    Single-chain polystyrene glasses (1993)
    s.l. : American Chemical Society
    Macromolecules 26 (1993), S. 2950-2953 
    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/ma00063a046
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of Pauci-Chain Polystyrene Microlatex Particles Prepared by Chemical Initiator (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 1592-1597 
    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/ma00109a035
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  • 5
    Electronic Resource
    Electronic Resource
    Infrared spectroscopic studies of melting behavior of poly(ethylene 2, 6-naphthalenedicarboxylate) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1385-1389 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The FTIR method was used to study the melting behavior of poly(ethylene 2, 6-naphthalene-dicarboxylate) (PEN) samples of different thermal history of crystallization. With subtraction of the spectra of PEN samples of different crystallinities and amorphous PEN, the spectra of crystalline trans conformers, amorphous trans conformers, and amorphous gauche conformers were obtained. By following the changes in intensity of various gauche and crystalline bands during heating, the phenomenon of multiple melting endothermic peaks was shown to be due to the melting of imperfect crystalline conformation formed during crystallization. For two-step annealed samples, the crystalline conformational defects change into a more perfect one during annealing at higher temperatures. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    The role of H+ ions in the electrochemical polymerization of pyrrole (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1263-1273 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Pyrrole was found to polymerize electrochemically in a smooth and facile way when the immediate vincinity of the anode is at a pH of 3 ([H+] = 10-3 mol/dm3). The polymerization is inhibited by the presence of a H+ scavenger, di-tert-butylpyridine. Polymerization of pyrrole in a buffered solution of pH 4 gives a polypyrrole (PPy) film of slightly different chemical structure from that obtained in a buffered solution of pH 3, as shown by their IR spectra. No polymerization takes place in the buffered solution at pH 〉 7. These facts show the important role of H+ ions played in the electrochemical polymerization of pyrrole. Pyrrole might go through a protonated structure before it transfers an electron to the electrode, to form a cation radical which starts the polymerization. A new mechanism of polymerization is proposed in conformity with observed facts about the structure of PPy.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920604
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  • 7
    Electronic Resource
    Electronic Resource
    On the origin of the fluorescence emission of poly(ethylene terephthalate) by excitation at 340 nm (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1399-1408 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fluorescence emission of amorphous poly(ethylene terephthalate) films at wavelengths larger than that of the excimer emission was investigated. A film thickness dependence of the excitation spectra for 360 nm emission was observed. For thick films (e.g., 280 μm), their excitation spectra for 380-460 nm emission showed excitation peaks in the region of 320-360 nm, and the intensity ratio of the 370 nm emission (excited by 290 nm radiation) to the 390 nm emission (excited by 340 nm radiation) decreased with increasing thickness of the film. Apparently, the 370 nm emission (excimer) and the 380-460 nm emission originate from different species of the excited state. From the studies of model systems, dilute solutions of dimethyl terephthalate in CHCl3-acetone and dimethyl terephthalate-PMMA in CHCl3, it was found that the excitation at 340 nm is related to a \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \pi \limits^* $\end{document} ← n transition. Fluorescence emission from the S1 (n-\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \pi \limits^* $\end{document}) state and the interaction between the C=O group and the phenylene π-electrons results in the fluorescence in the 380-460 nm region.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920616
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  • 8
    Electronic Resource
    Electronic Resource
    Chemical oxidation of a neutral electrochemically prepared polythiophene film (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 1093-1100 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Neutral polythiophene films obtained by NH4OH compensation of electrochemically polymerized samples were re-oxidized chemically to the metallic state by a wide range of oxidants. The electrochemically and chemically oxidized polythiophene films were found to be quite stable in air. Results of IR, SEM and WAXS studies are described and discussed. The feasibility of chemical re-oxidation of neutral electrochemically prepared polythiophene films offers a convenient means to produce flexible highly conductive polythiophene films.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860519
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  • 9
    Electronic Resource
    Electronic Resource
    Studies on electrochemically prepared oxidized polypyrrole salt films (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 1101-1108 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It was found that oxidized polypyrrole (PPy) film, electrochemically polymerized from aqueous H2SO4 solutions, shows correct stoichiometry in the mole ratio C : H : N, although still containing a large amount of oxygen. The apparent density of the film obtained was close to its flotation density of 1,514 g/cm3. Morphology studies by SEM showed an aggregation of ca. 1 μm properties into hollow bowls of 30 μm diameter in the case of PPy-BF4, PPy-PF6 and PPy-CIO4 films, electrochemically prepared from CH3CN (1% H2O) solutions, while a PPy-HSO4 film from aqueous solution gave a much smoother film surface and no hollow bowls. Interesting morphology was observed for the growth of electrochemically oxidized PPy in CH3CN solution on a wire net anode of 27 × 27 μm2 holes. The nucleation of the oxidized PPy growth was found to be always initiated at the mid-points of the four sides of the square holes so that regular arrays of hollow bowls resulted. In aqueous H2SO4 solution the oxidized PPy grew on the surface of the net wires. Besides particles of ca. 0,3 μm diameter numerous solid blocks of 5 μm size with sharp edges were observed. The metallic temperature dependence of the conductivity of various oxidized PPy films was demonstrated by voltage shorted compaction (VSC) measurements, while a partially electrochemically reduced PPy-BF4 film showed a broad maximum in VSC conductivity around 100 K.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860520
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  • 10
    Electronic Resource
    Electronic Resource
    Fourier transform infra-red spectroscopy of atactic polystyrene in the glass transition region (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 2563-2570 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fourier transform infra-red (IR) studies on samples of atactic polystyrene with different thermal history, i.e. quenched from the melt (QM), quenched from the rubbery state (QR), slowly cooled (SC), and sub-glass-transition (sub-Tg) annealed (AN), were carried out in the absorption region from 500 to 600 cm-1 with gradually increasing temperatures through the glass transition region at 100°C. The heights of the positive peak (532 cm-1) and the negative peak (566 cm-1) appearing in the temperature difference spectra, T-60°C, are considered to be a measure of the amount of frequency shifts for the 540 cm-1 and 557 cm-1 bands in the conformationally sensitive spectral range of atactic polystyrene. These bands show a continuously increasing low-frequency shift with increasing temperature, except for sample QM, the 557 cm-1 band of which shows an inappreciable frequency shift in the range 60 〈 T/°C 〈 100. The different temperature behaviour of these shifts for samples QM, QR, SC and AN is due to changes in their intermolecular interactions. Sub-Tg annealing of the sample QM is shown to shift the frozen high-temperature state of the quenched sample to the temperature-defined equilibrium. For all samples of different thermal history the difference in their IR spectra vanish at temperatures above Tg.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021901021
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