THEORY OF ADSORBED BLOCK COPOLYMERS

We present a study of adsorbed diblock copolymers, which is based on the mean-field selfconsistent theory of incompressible polymer/solvent blends. We assume that one of the blocks is tightly adsorbed and model the remaining block using the formalism recently developed for crystallizable/ amorphous block copolymer blends. Restricting attention primarily to near-θ conditions, we present series of calculations describing adsorption at a single surface and adsorption on two parallel surfaces a finite distance apart. For the second case, we calculate the long-range forces acting on the two surfaces. We make quantitative comparisons with experiment for conditions corresponding to slightly good, θ, and slightly poor solvents. We determine the thickness and shape of the polymer density profiles, obtain approximate scaling relations and the ranges of their applicability, study finite molecular weight effects, as well as the extent of the interdigitation of layers adsorbed on opposite surfaces, and show how these quantities vary as the surface separation changes. In addition, we show how the scaling of the apparent range of the measured long-range force can differ from the scaling of the thickness of a single adsorbed layer. © 1990, American Chemical Society. All rights reserved.