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 (M¯n) up to 27 000 g mol−1. The particle morphologies are characterized via dynamic light scattering and electron microscopy. For M¯n > 20 000 g mol−1, the particles exhibit shape‐persistence at room temperature and are ≈100 nm in diameter. Poly(isobutylene) (PIB) nanoparticles are prepared in nonaqueous fluorinated emulsions. The required inert emulsifier for the oil‐in‐perfluoroalkane system is synthesized. The emulsifier is applied for the heterogeneous cationic polymerization of isobutylene yielding PIB number‐average molecular weights (M¯n) of 27 000 g mol−1. For M¯n > 20 000 g mol−1, the particles are shape‐persistent at room temperature and ≈100 nm in diameter.