Monte Carlo Simulation of Polymers Confined Between Two Surfaces in the Presence of Diluent

Structure and surface properties of polymers confined between two surfaces are studied in the presence of diluent by using an off-lattice Monte Carlo method. When the diluent–chain interaction is weak, the density of diluent beads near the surface increases sharply with increasing the diluent–surface interaction while the chain bead density near the surface decreases gradually. The total bead density near the surface increases with increasing the diluent–surface interaction until it exceeds the total bulk density. This is mainly due to a large increase in the diluent bead density near the surface. Because of the increase of diluent at the surface, chains near the surface change their conformation, i.e., long tails become abundant while short trains and loops are relatively depleted. On the other hand, when the diluent–chain interaction becomes strong, the total bead density near the surface increases slightly, but it exceeds the total bulk density only when the diluent–surface interaction is strong enough, because the diluents approaching the surface induce chain beads to move to the surface due to strong interaction between the chain and diluent.