Preparation and Slow Release Behavior of Porous Hydroquinone-carrying Poly (styrene-divinylbenzene) Microspheres

Poly (styrene-divinylbenzene) (PSt-DVB) porous microspheres in the size range of 2.4～9μm were prepared by modified two-step seed swelling polymerization method. Uniform polystyrene (PS) particles were synthesized by dispersion polymerization and used as the seed particles. Effects of polymerization conditions such as seed type, dispersion time, dibutyl phthalate (DBP)/seed particle ratio, and the DVB/seed particle ratio on particle size distribution and pore structure of the PSt-DVB microspheres were investigated in detail. It was found that particle size distribution became narrower and swel-ling time was shortened from more than 24h to 10h with the introduction of ultrasonic dispersion. The results indicate that the average size of the final beads increase with the increase of seed diameter, DBP/PS seed particle and DVB/PS seed particle ratios. The surface area increases and the pore diameter decreases with the increase of DBP/PS seed particle and DVB/PS seed particle ratios. The produced porous microspheres were applied as a carrier to study the slow release behaviors of hydroquinone as a model active, used in cosmetics and pharmaceuticals as skin color lightening agent. The results show that the porous microspheres have a promising application in slow release process.