Facile fabrication of flower-like nanocomposite microparticles via seeded miniemulsion polymerization
Seed polymer/silica particles are synthesized by double in situ miniemulsion polymerization of methyl methacrylate (MMA) and hydrolysis–condensation of tetraethoxysilane (TEOS) under basic conditions simultaneously. Nanocomposite microparticles with a controlled morphology are fabricated from seed polymer/silica particles by the further miniemulsion polymerization of styrene. We have demonstrated that the seed PMMA/silica particles are cross-linked by nanosilica particles, which are dispersed homogeneously in the polymer matrix. The in situ formed silica nanoparticles acting as the cross-linking agent favor the formation of nonspherical nanocomposite microparticles with a flower-like structure. Furthermore composite microparticles of spherical morphology are obtained without γ-(trimethoxysilyl)propyl methacrylate (MPS). The addition of divinylbenzene (DVB) leads to a higher degree of cross-linking of the seed polymer particles, which favors the formation of peanut-like microparticles.