STATISTICAL THERMODYNAMICS OF BLOCK COPOLYMER ADSORPTION .1. FORMULATION OF THE MODEL AND RESULTS FOR THE ADSORBED LAYER STRUCTURE

A generalization of the self-consistent-field theory of Scheutjens and Fleer for adsorption of homopolymer from a binary solution toward a theory for adsorption of block copolymers from a multicom-ponent mixture is presented. No a priori assumptions about the conformations of the adsorbed molecules are made. Equations for the conformation probabilities, the segment density profiles, and the free energy are derived. Results on the segment density distribution in adsorbed layers of diblock and triblock copolymers are given. We find that diblock copolymers tend to adsorb with the adsorbing block rather flat on the surface and the less adsorbing or nonadsorbing block in one dangling tail protruding far into the solution. We compare these predictions with those for terminally anchored chains and find overall agreement but also typical differences. The effect of the surface affinity and the solvent quality on the structure of adsorbed diblock copolymers is discussed. © 1990, American Chemical Society. All rights reserved.