In situ emulsion copolymerization of methyl methacrylate and butyl acrylate in the presence of SiO2 with various surface coupling densities

Poly(methyl methacrylate- co -butyl acrylate) (poly(MMA- co -BA))/SiO 2 nanocomposite particles with various morphologies were prepared through in situ emulsion copolymerization of methyl methacrylate and butyl acrylate using surface 3-(methacryloyloxy) propyl trimethoxysilane (MPS)-modified SiO 2 nanoparticles as nanofillers. The surface MPS-coupling density of SiO 2 nanoparticles could influence the hydrophilic–lipophilic properties of SiO 2 nanoparticles and subsequently influence the particle morphology of poly(MMA- co -BA)/SiO 2 nanocomposite particles. With the increase of the surface MPS-coupling density of SiO 2 nanoparticles, the morphology of nanocomposite particles changed from a raspberry-like one to a guava-like one. A formation mechanism of nanocomposite particles with various morphologies was proposed on the basis of the results of polymerization kinetics, particle size evolution in the process of polymerization, and particle size and morphology of the final nanocomposite particles.