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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 4042-4046 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate the effect of polymer concentration on the diffusion and localization (entropic trapping) of linear polymer chains in a two-dimensional model system of small obstacles and large pores. Three distinct regimes are identified: the entropic trapping regime, a reptation regime where the larger pores are polymer saturated and the untrapped polymers reptate, and finally a crowding regime where intermolecular interactions dominate. In this model system, the entropic trapping, reptation, and crowding mechanisms compete and lead to a characteristic maximum in the diffusion coefficient for intermediate polymer concentrations. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 3310-3312 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using Monte Carlo simulations, we test the prediction [Sommer and Blumen, Phys. Rev. Lett. 79, 439 (1997)] that the radius-of-gyration of a polymer chain moving in a periodic array of obstacles should be a minimum when a few defects are present. Our results agree qualitatively with this prediction, but the excluded volume interactions greatly reduce the effect. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1022-1344
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When the stress applied to a Rouse-like polymer chain is large enough, one must use anharmonic entropic spring forces in order to keep the chain contour length from increasing to unphysical values. Although one can derive “exact” equations relating the spring extension to the entropic force produced by a finitely extensible non-linear elastic (FENE) random-walk polymer, such expressions are usually of little interest because their complexity would entail large evaluation times in numerical studies by computer. Moreover, these expressions can rarely be used directly in analytical studies. In this article, we describe a systematic method to construct analytically simple yet numerically accurate expressions to relate the entropic force to the extension of an entropic spring for a random-walk polymer chain in arbitrary dimension d ≥ 2. These expressions are modified Pade approximants which yield the correct asymptotic behaviours in both the small and large extension limits. It is shown that the well-known Warner empirical approximation is but a limiting case (for infinite dimensions).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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