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Multiscale dynamics of an interacting sheet by a bond-fluctuating Monte Carlo simulation

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Abstract

The conformation and dynamics of sheets with attractive and repulsive node–node interactions (nn) are examined in an effective solvent medium using Monte Carlo simulations. A bond-fluctuating coarse grained description is used to model the sheet by a set of nodes (N) tethered together by flexible bonds in a planar structure with linear scale Ls = 16–64, N = Lmath image on a cubic lattice with characteristic dimensions of L3 = 643–2003. Variations of the mean square displacement of the center of mass of the sheet (Rmath image) and that of its center node (Rmath image) and radius of gyration (Rg) of the sheet with the time step (t) are analyzed to characterize the nature of its global motion, segmental dynamics, and conformational relaxation at a low (T = 2) and a high (T = 10) temperature with the range (r = √8) of interaction nn = 1, –1. We find that sheets achieve their global diffusive motion, that is, Rmath imaget, in the long-time (asymptotic) regime while their segmental dynamics exhibits a range of power-law behavior Rmath imagetν with ν = 1/4−1 from short to long-time regimes. The magnitude of the exponent ν and their crossover (and relaxation) from one power-law to the next depend on temperature, interaction, and molecular weight N of the sheet. The radius of gyration of the sheet relaxes well to its equilibrium with its distinct patterns of expansion (swelling with relatively stiffer bonds (nn = 1)) and contraction (crumpling with nn = −1). Both the relaxation time and the rate of change of Rg depends on N, Ls, and T. Data for the equilibrium value of the gyration radius scale with its size RgN1/2 suggesting that sheets remain nearly flat with localized wrinkles and crumpling.© 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2512–2523, 2006

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