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. Chain conformation, segment orientation, fraction of segment adsorbed, surface coverage, chain dimensions and volume fraction profiles are measured for systems with a different number of chains over a wide range of temperatures. An adsorbed layer begins to form at the same adsorption transition temperature Ta of a single chain. However, the second-order phase transition at Ta in the single chain adsorption is suppressed in the multi-chain system as is indicated in the disappearance of the peak at Ta in the specific heat. Volume fraction profiles near the adsorption regimes are found to be in agreement with previous theoretical results. For the dynamics, the time auto-correlation function, relaxation time, and mean square displacements are measured. The auto-correlation function can be described by a stretched exponential form and the relaxation time extracted from it starts to increase dramatically with a Vogel–Fulcher behavior at a temperature T2 which is much lower than Ta. The diffusion coefficients parallel and perpendicular to the z-axis are measured and analyzed for the dilute and multi-chain semi-dilute systems. Both the static and dynamic results indicate a glass transition occurs at T2 below which the system shows a glassy behavior. The low temperature transport properties and glassy behavior are analyzed and discussed in term of appropriate physical pictures.