Effect of solvent composition on transparency and surface hardness of poly(methyl methacrylate)-silica nanocomposites provided on polycarbonate

Poly(methyl methacrylate)-silica nanocomposites with 49 vol % of silica were prepared by blending poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) [content of 2-hydroxyethyl methacrylate: 15.1 mol %] with perhydropolysilazane in a ethylacetate/cyclohexane/xylene mixture, casting on polycarbonate (PC) substrates and drying for 24 h at room temperature. When the cyclohexane content in the solution was in a range from 21.7 to 32.3 vol %, composites were transparent in a wide range from 400 to 1000 nm of wavelength, the maximum surface hardness of composites on the substrate measured by nanoindentation was 1.07 GPa. Dynamic light scattering and viscometric analysis indicated that aggregates of poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) was formed in the mixture when the transparent composites were obtained on the PC substrates. (C) 2008 Wiley Periodicals, Inc.