INTERACTIONS BETWEEN POLYMER-COATED SURFACES IN POOR SOLVENTS .1. SURFACES GRAFTED WITH A-HOMOPOLYMER AND B-HOMOPOLYMER

Using a two-dimensional self-consistent field theory, we investigate t he interaction between two planar surfaces where (1) each surface is g rafted with both A and B homopolymers and (2) one surface is coated wi th end-grafted A's and the other is coated with end-grafted B's. The c hains 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 int eraction 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 i nteraction 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 fi ndings indicate that fine control over the pair interaction function o f coated colloidal particles can be gained through grafting mixtures o f homopolymers.