Ultrasonically initiated miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles

Ultrasonically initiated miniemulsion polymerization of styrene was conducted in the presence of Fe3O4 nanoparticles. Stable polystyrene (PS)/Fe3O4 nanocomposite emulsions were prepared and magnetic PS/Fe3O4 composite particles were obtained through magnetic separation. The whole procedure comprised two steps. First, Fe3O4 nanoparticles were dispersed in the monomer phase with the aid of stabilizer Span‐80. Second, miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles was carried out under an ultrasonic field in the absence of a chemical initiator. The affecting factors, including stabilizer concentration, surfactant concentration, hexadecane concentration and the amount of Fe3O4, were systematically studied. Stabilizer concentration, surfactant concentration and hexadecane concentration strongly affected the formation of the coagulation. The least amount of coagulation was formed at 2.5 wt% Span‐80 concentration. The addition of Fe3O4 nanoparticles drastically increased the polymerization rate owing to the fact that Fe3O4 nanoparticles increased the acoustic intensity and Fe2+ reacted with H2O2 to produce hydroxyl radicals and increase the number of radicals. The increase in cosurfactant concentration and power output also increased the polymerization rate. Copyright © 2005 Society of Chemical Industry