Phase Separation Behavior of Silicate Phases Grown in Poly(methyl methacrylate) by a Sol−Gel Process

The diffusion and growth of an inorganic phase, namely, silica (obtained by reacting tetraethyl orthosilicate) in poly(methyl methacrylate) (PMMA), has been studied using small-angle X-ray scattering as well as electron microscopy. Previous workers have documented some of the structural features as well as the mechanical properties of such a composite system. In this work an emphasis has been placed on the fractal characteristics of the microscopic particles observed utilizing small-angle X-ray scattering. Fractal characteristics of the silica particles have been studied while varying the tetraethyl orthosilicate content with respect to PMMA. The growth of these particles in PMMA was also studied as a function of the reaction media. Typically, the silica forms mass fractals when reacted in a solvent media of tetrahydrofuran. When a small amount of dimethylformamide is added to the reaction, the fractal dimension varies from surface to mass fractal depending upon metal alkoxide content.