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

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-s(2) on a cubic lattice with characteristic dimensions of L-3 = 64(3)-200(3). Variations of the mean square displacement of the center of mass of the sheet (R-c(2)) and that of its center node (R-n(2)) 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 = root 8) of interaction nn = 1, -1. We find that sheets achieve their global diffusive motion, that is, R-c(2) proportional to t, in the long-time (asymptotic) regime while their C segmental dynamics exhibits a range of power-law behavior R-n(2) proportional to t(nu) with v = 1/4-1 from short to long-time regimes. The magnitude of the exponent nu 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 proportional to N-1/2 suggesting that sheets remain nearly flat with localized wrinkles and crumpling. (c) 2006 Wiley Periodicals, Inc.