Multiscale Dynamics of an Interacting Sheet By a Bond-Fluctuating Monte Carlo Simulation

Document Type

Article

Publication Date

9-15-2006

Department

Physics and Astronomy

School

Mathematics and Natural Sciences

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 L s = 16–64, N = L on a cubic lattice with characteristic dimensions of L 3 = 643–2003. Variations of the mean square displacement of the center of mass of the sheet (R ) and that of its center node (R ) and radius of gyration (R g) 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, R ∝ t , in the long‐time (asymptotic) regime while their segmental dynamics exhibits a range of power‐law behavior R ∝ t ν 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 R g depends on N, L s, and T . Data for the equilibrium value of the gyration radius scale with its size R g ∝ N 1/2 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

Publication Title

Journal of Polymer Science Part B-Polymer Physics

Volume

44

Issue

18

First Page

2512

Last Page

2523

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