Interactions between Polymer-Coated Surfaces in Poor Solvents. 1. Surfaces Grafted with A and B Homopolymers

Using a two-dimensional self-consistent field theory, we investigate the interaction between two planar surfaces where (1) each surface is grafted with both A and B homopolymers and (2) one surface is coated with end-grafted A's and the other is coated with end-grafted B's. The chains are grafted at low densities and the B polymers are chosen to be solvophobic. We vary the solvent affinity of the A chains and the interaction between the A and B monomers. We determine the morphology of the layers and the energy of interaction as the layers are compressed. The energy of interaction versus distance profiles show a wide region of attraction as the surfaces are brought together. This attractive interaction is due to the self-assembled structures that appear at low grafting densities in poor solvents. The properties of the attraction can be tailored, as we demonstrate in a simple scaling picture. Our findings indicate that fine control over the pair interaction function of coated colloidal particles can be gained through grafting mixtures of homopolymers.