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