Silica nanoparticles as surfactants and fillers for latexes made by miniemulsion polymerization

Polymer dispersions made of a variety of monomers, including styrene, butyl acrylate, and methyl methacrylate, were generated by the miniemulsion proc ess in the presence of a coupling comonomer, a hydrophobe, and silica nanop articles. Depending on the reaction conditions and the surfactants employed , different hybrid morphologies were obtained, comprising a "hedgehog" stru cture where the silica surrounds the latex droplet and provides stabilizati on even without any low molecular weight surfactant. In other parts of the composition diagram noncoupled structures as well as "raspberry" hybrids wh ere whole clusters of silica nanoparticles are completely embedded in the p olymer particle can be made. The resulting structures are promising for a n umber of applications, e.g. the increase of scratch resistance in water-bas ed coatings.