Poly(isobutylene) nanoparticles via cationic polymerization in nonaqueous emulsions

The preparation of poly(isobutylene) (PIB) nanoparticles via cationic emulsion polymerization is presented. As a requirement, an oil-in-perfluoroalkane nonaqueous emulsion is developed, which is inert under the carbocationic polymerization conditions. To stabilize the dichloromethane/hexane droplets in the fluorinated, continuous phase, an amphiphilic block copolymer emulsifier is prepared containing PIB and 1H,1H-perfluoroalkylated poly(pentafluorostyrene) blocks. This system allows for the polymerization of isobutylene with number-average molecular weights (Mn) up to 27,000 g mol(-1). The particle morphologies are characterized via dynamic light scattering and electron microscopy. For Mn > 20,000 g mol(-1), the particles exhibit shape-persistence at room temperature and are ≈100 nm in diameter.