The structure of amorphous polymers near surfaces: athermal systems

The Wall PRISM theory of Yethiraj and Hall for calculating the distribution of a polymer liquid near a hard wall is generalised to the case of polymers with complex monomeric architectures, consisting of multiple sites. Results are shown for freely jointed chains, alkanes, isotactic polypropylene, polyisobutylene, and polydimethyl siloxane. It is found that the side chain groups in the substituted polymers are preferentially present near the wall, and tend to shield the atoms on the chain backbone from the surface. Wall PRISM is found to give accurate results for the polymer density distribution beyond about 2 A from the wall. In the immediate vicinity of the wall, the theory satisfactorily predicts the distribution for a melt of hard chains, but is not rich enough to account for the subtle effect of intermolecular interactions on the local distribution in the immediate vicinity of the surface. (C) 1998 Elsevier Science Ltd. All rights reserved.