Production of micron-sized polystyrene particles containing PEG near the particles surface

Polystyrene (PS) particles in the size range of 1-7 mum, containing poly(ethylene glycol) or PEG on the particles surface, were prepared by multi-step seeded polymerizations. Micron-sized PS particles were first prepared by dispersion polymerization using 2,2'-azobisisobutyronitrile as initiator and polyvinyl pyrrolidone as stabilizer. Conventional swelling method was then used to increase the size of the PS particles with a large amount of styrene in presence of oil soluble initiator, benzoyl peroxide. In the final step, the PS particles have been used to carry out seeded polymerization with small amount of styrene in presence of poly(ethylene glycol)-azo or PEGA initiator with average molecular weights of the PEG chains of 200 and 3000 g mol(-1), respectively. The average size, size distribution, and surface morphology indicate that seeded polymerization in the final step with small amount of styrene in presence of PEGA is the best way to produce monodisperse polystyrene particles containing PEG near the particles surface.