The effect of Surface Neutrality on ODT of PS-b-PMMA films

The film transitions, the order-to-disorder transition (ODT), has been investigated in a symmetric polystyrene- b-poly(methyl methacrylate) (PS-b-PMMA) on a random copolymer (P(S-r-MMA)) grafted substrate where the interfacial interactions are balanced. With decreasing film thickness less than 25L0, the ODT significantly decreases, 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 for films thicker than 25L0 was observed above the bulk value. 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.