Transition behavior of PS-b-PMMA films on the balanced interfacial interactions

The thickness dependence of the order-to-disorder transition (ODT), measured by in situ grazing-incidence small-angle X-ray scattering (GISAXS), has been investigated in thin films of a symmetric polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) on a random copolymer (P(S-r-MMA)) grafted to the substrate where the interfacial interactions are balanced. With decreasing film thickness less than 25L(0), the ODT significantly decreases to 193 degrees C for film of 10L(0) in thickness, because the interfacial interactions by a random copolymer grafted to the substrate provide a surface-induced compatibilization toward two block components. However, a plateau of the ODT at similar to 213 degrees C for films thicker than 25L(0) was observed above the bulk value of 200 degrees C. The elevation of this ODT indicates a suppression of compositional fluctuations normal to the film surface, more than likely because the dominant orientation of the lamellar microdomains was found to be parallel to the film surface. (C) 2010 Elsevier Ltd. All rights reserved.