Clay-polystyrene nanocomposite from pickering emulsion polymerization stabilized by vinylsilane-functionalized montmorillonite platelets

Abstract Controlling the chemical nature and functionality of a Pickering stabilizer in surfactant-free emulsion polymerization plays a salient role in the nucleation and growth of latex particles. Silane-functionalization of montmorillonite (Mt) platelets is expected to tune the partition behavior of the clay platelets toward a monomer phase and enhance their stabilizing ability in oil-in-water (o/w) system. Such fabrication should result in prompted heterogeneous coagulative nucleation of latex particles, and therefore, drive a fabrication of clay-hydrophobic polymer latex nanocomposites. In this paper, Pickering emulsion polymerizations of styrene and n-butyl acrylate, stabilized by Mt. platelets onto which various silane agents were chemically grafted, were formulated. Along with characterizations of silane-functionalization on Mt. platelets, a kinetic study on the clay-polymer latexes was performed via a dynamic light scattering method and morphological observations. Polystyrene latex particles stabilized by the silane-functionalized Mt. platelets showed faster heterocoagulative nucleation even at the early stage of particle formation, owing to their attractive interaction with the monomer. The secondary participation of vinyl moieties on the Mt. platelets in radical reactions was followed, and it reinforced the adsorption behavior via covalent linkages. This is the first report that presented kinetic evidence of an attractive interaction between hydrophobic monomers and silane-functionalized Mt. platelets which led to the formation of a clay-latex clustered structure.