01668nas a2200169   4500008004100000022001400041245009800055210006900153260008300222300002300305490000700328520097000335100002401305700002101329700002301350856012501373       2006                        eng d  a1539-375500aFlexible ring polymers in an obstacle environment: Molecular theory of linear viscoelasticity0 aFlexible ring polymers in an obstacle environment Molecular theo  aONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USAbAMERICAN PHYSICAL SOCcAUG  aArticle No. 0218050 v743 a<p>We formulate a coarse-grained mean-field approach to study the dynamics of the flexible ring polymer in any given obstacle (gel or melt) environment. The similarity of the static structure of the ring polymer with that of the ideal randomly branched polymer is exploited in formulating the dynamical model using aspects of the pom-pom model for branched polymers. The topological constraints are handled via the tube model framework. Based on our formulation we obtain expressions for diffusion coefficient D, relaxation times tau, and dynamic structure factor g(k,t). Further, based on the framework we develop a molecular theory of linear viscoelasticity for ring polymers in a given obstacle environment and derive the expression for the relaxation modulus G(t). The predictions of the theoretical model are in agreement with previously proposed scaling arguments and in qualitative agreement with the available experimental results for the melt of rings.</p>1 aIyer, Balaji, V. S.1 aLele, Ashish, K.1 aJuvekar, Vinay, A.  uhttps://library.ncl.res.in/content/flexible-ring-polymers-obstacle-environment-molecular-theory-linear-viscoelasticity-102025nas a2200265   4500008004100000020002200041022001400063245007900077210006900156260008300225300001200308490000900320520111100329653002901440653002701469653002601496100002101522700002401543700002301567700001101590700001701601700001801618700002101636856010201657       2008                        eng d  a978-0-7354-0549-3  a0094-243X00aBlob-spring model for the dynamics of ring polymer in obstacle environment0 aBlobspring model for the dynamics of ring polymer in obstacle en  a2 Huntington Quadrangle, STE 1no1, Melville, NY 11747-4501 USAbSoc RheolcAUG  a445-4470 v10273 a<p>The dynamical behavior of cyclic macromolecules in a fixed obstacle (FO) environment is very different than the behavior of linear chains in the same topological environment; while the latter relax by a snake-like reptational motion from their chain ends(1) the former can relax only by contour length fluctuations since they are endless.(2) Duke, Obukhov and Rubinstein proposed a scaling model (the DOR model) to interpret the dynamical scaling exponents shown by Monte Carlo simulations of rings in a FO environment.(2) We present a model (blob-spring model) to describe the dynamics of flexible and non-concatenated ring polymer in FO environment based on a theoretical formulation developed for the dynamics of an unentangled fractal polymer.(3) We argue that the perpetual evolution of ring perimeter by the motion of contour segments results in an extra frictional load. Our model predicts self-similar dynamics with scaling exponents for the molecular weight dependence of diffusion coefficient and relaxation times that are in agreement with the scaling model proposed by Obukhov et al.(2).</p>10afractal polymer dynamics10alinear viscoelasticity10aring polymer dynamics1 aLele, Ashish, K.1 aIyer, Balaji, V. S.1 aJuvekar, Vinay, A.1 aCo, A.1 aLeal, L., G.1 aColby, R., H.1 aGiacomin, A., J.  uhttps://library.ncl.res.in/content/blob-spring-model-dynamics-ring-polymer-obstacle-environment-002288nas a2200181   4500008004100000022001400041245011900055210006900174260007100243300001400314490000700328520154400335100002401879700002101903700002301924700003201947856012701979       2009                        eng d  a0888-588500aSelf-similar dynamics of a flexible ring polymer in a fixed obstacle environment: a coarse-grained molecular model0 aSelfsimilar dynamics of a flexible ring polymer in a fixed obsta  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV  a9514-95220 v483 a<p>In this contribution we concern ourselves with an interesting problem, namely, the dynamics of ideal flexible ring polymers constrained in tin array of fixed obstacles. The fundamental issue in this problem is to understand how a topologically constrained polymer chain is able to relax its conformation in the absence of chain ends. The key physics was provided in tin elegant scaling theory by Rubinstein and co-workers (Obukhov, S. P; Rubinstein, M.; Duke, T. Dynamics of a Ring Polymer in a Gel. Phys. Rev. Lett. 1994, 73, 1263-1267). In this work we develop a coarse-grained mean-field model based oil the physical arguments of the scaling theory and derive constitutive relations for rings in fixed obstacle and melt environments. The model is composed of three distinct steps. In the first step the dynamics of an arbitrary section of a ring chain is worked out based oil fractal Blob-Spring (BS) dynamics, and the center of mass diffusion and the relaxation spectrum of this section are determined. In the second step the center of mass diffusion obtained using the BS dynamics is used to model the one-dimensional diffusion of the section in a topologically constrained environment. In the final step we invoke the idea of dynamic self-similarity and argue that the dynamics described in the first and the second step, for any arbitrary section of the chain, applies to all sections of the chain. The constitutive relation is obtained consequently as the superposition of dynamic response of all sections of the ring chain.</p>1 aIyer, Balaji, V. S.1 aLele, Ashish, K.1 aJuvekar, Vinay, A.1 aMashelkar, Raghunath, Anant  uhttps://library.ncl.res.in/content/self-similar-dynamics-flexible-ring-polymer-fixed-obstacle-environment-coarse-grained-0