Phase-separated structure and optical properties of simultaneously polymerized polymethacrylate/polyurethane blends

Abstract Simultaneous polymerization of methacrylate monomers and urethane prepolymers enables diverse structures to form within the polymer blend, resulting in a tough polymer blend. In this study, a polymer blend with a salami structure with dimensions of several tens of microns was obtained by simultaneously polymerizing polymethacrylate and polyurethane containing polytetramethylene glycol (PTMG). In addition, the methacrylate component of the polymer blend was co-polymerized with hydroxyethyl methacrylate (HEMA), which contains a hydroxyl group that can then react with the urethane component. The effects of HEMA copolymerization on the structure and composition of each area, as well as on the viscoelastic and optical properties, were investigated. The HEMA copolymerization increased the compatibility between the polyurethane and polymethacrylate regions. Consequently, the hard areas within the spherical domains decreased in size, accompanied by a decrease in the differences in composition and refractive index between regions. A copolymerized polymer blend containing 5.42 mol% HEMA exhibited the same transparency (total transmittance and haze) as poly(methyl methacrylate) (PMMA).