Theoretical calculations of solvent effects on the adsorption of linear molecules using the multilayer lattice model

Abstract

Ash, Everett, and Findenegg's model for multilayer polymer adsorption was modified to handle solvent effects upon adsorption behavior. Some of the assumptions of the model are: (1) the segments of the polymer and the solvent monomer are approximately the same size, (2) the segments of the polymer and the solvent monomer occupy only the lattice points of a given geometrical array (close-packed hexagonal) ; (3) the energies of interaction between nonbonded segments are angularly independent, are additive in nature, and extend no further than the nearest neighbors; and (4) the surface has a homogeneous interaction energy for each segment type.The specific polymers examined were the asymmetric dimer (A-B) and the asymmetric tetramer (A-B-B-B) in a solvent (C).Parameters required for computer calculations were the nearest neighbor energies of interaction between all combinations of nonbonded segment pairs (A, A; B, B; C, C; A, B; A, C; and B, C) and interaction energies between the surface and each segment type in each layer near the surface. Analyses were made for the effects of each of these parameters on the surface excess, and on the energy, entropy, and number of each molecular configuration in each layer near the surface.