NEUTRON REFLECTIVITY STUDIES OF ORDERED COPOLYMER FILMS

In a thin film geometry symmetric block copolymers self-assemble to form well-oriented multilayered structures, ideally suited for study by reflectivity techniques. Neutron reflectivity was performed on selectively deuterated poly(styrene-b-methyl methacrylate) copolymers to determine quantitatively the spatial distribution of monomer segments within the lamellar microdomains. The reflectivity curves are shown to be highly sensitive to gradients in the scattering length density normal to the film surface. The scattering length density profiles which best model the experimental data yield segment density profiles in ordered copolymers with unprecedented detail. The approach is extended to analyze chain distributions in multicomponent systems, including mixtures of symmetric copolymers with different molecular weights and mixtures of copolymers and homopolymers.