Tacticity effects on the miscibility behavior of poly(methyl methacrylate)/poly(ethylene oxide-b-dimethylsiloxane-b-ethylene oxide) blends

Abstract

The miscibility of a triblock copolymer poly(ethylene oxide)-poly(dimethylsiloxane)-poly(ethylene oxide) with syndiotactic and isotactic poly(methylmethacrylate) wasstudied. Although isotactic poly(methyl methacrylate) (PMMA) was miscible with poly(ethylene oxide) (PEO) in the pure state, it was immiscible with the PEO end blocks in the copolymer. In comparison, the syndiotactic poly(methyl methacrylate) (sPMMA) was miscible with the PEO blocks as indicated by melting point depression, decrease in crystallinity, and slower rate of spherulite growth of PEO. When blends of the triblock copolymer were cooled to low temperatures, the poly(dimethylsiloxane) (PDMS) middle block which resided in the interlamellar region of PEO spherulites also crystallized; the development of PDMS crystals was clearly suppressed at high sPMMA contents.