STATICS AND DYNAMICS OF ADSORBED POLYMER-CHAINS - A MONTE-CARLO SIMULATION

Monodispersed polymer chains under good solvent condition adsorbed on a short-range attractive impenetrable wall (xy-plane) is investigated by dynamic Monte Carlo simulation using the bond-fluctuation model. Ch ain conformation, segment orientation, fraction of segment adsorbed, s urface coverage, chain dimensions and volume fraction profiles are mea sured for systems with a different number of chains over a wide range of temperatures. An adsorbed layer begins to form at the same adsorpti on transition temperature T-a of a single chain. However, the second-o rder phase transition at T-a in the single chain adsorption is suppres sed in the multi-chain system as is indicated in the disappearance of the peak at T-a in the specific heat. Volume fraction profiles near th e adsorption regimes are found to be in agreement with previous theore tical results. For the dynamics, the time auto-correlation function, r elaxation time, and mean square displacements are measured. The auto-c orrelation function can be described by a stretched exponential form a nd the relaxation time extracted from it starts to increase dramatical ly with a Vogel-Fulcher behavior at a temperature T-2 which is much lo wer than T-a. The diffusion coefficients parallel and perpendicular to the z-axis are measured and analyzed for the dilute and multi-chain s emi-dilute systems. Both the static and dynamic results indicate a gla ss transition occurs at T-2 below which the system shows a glassy beha vior. The low temperature transport properties and glassy behavior are analyzed and discussed in term of appropriate physical pictures. (C) 1995 American Institute of Physics.