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

Abstract

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.

Synthesis of chitin–bentonite clay based polyurethane bio-nanocomposites

“…For traditional polymer solution systems, the phase separation mechanism is similar to that of polymer blends, i.e., nucleation and growth mechanism and spinodal decomposition mechanism [26,27]. Generally, the component with higher content is apt to form the continuous phase and the other the dispersed phase.…”

Influence of the silica content in SPEEK–silica membranes prepared from the sol–gel process of polyethoxysiloxane: Morphology and proton mobility

“…According to the conclusions drawn by other research groups [38,39], DMAc is an amphiphilic solvent that, when used in the preparation of nanocomposite materials from organic polymers and alkoxysilanes, helps suppressing particles aggregation [38] and reducing the organic-inorganic phase separation thanks to the formation of hydrogen bonds with the silanol moieties of the hydrolyzed alkoxysilanes and its high compatibility with the organic polymers [39]. As mentioned in the experimental part, our working hypothesis is that the conversion of polyethoxysiloxane into silica is catalyzed by the sulfonic acid groups of SPEEK.…”

Organic-inorganic hybrid materials. V. Dynamics and degradation of poly(methyl methacrylate) silica hybrids

“…Two main procedures are used to prepare poly(methyl methacrylate)–silica hybrid materials (PMMA–SiO 2 ). The first uses a mixture of a tetrafunctional silicon alkoxide and PMMA to produce composite materials 5–11. The extensive hydrogen bonding between PMMA and the silicate network can inhibit macroscopic phase separation.…”