Characterization of porous microspheres prepared via γ-ray irradiation

Abstract

To study the mechanism and formation of gamma ray–irradiated porous polymeric microspheres, a polymerization reaction was seeded with particles and pores of various sizes. The porous particles were formed via phase separation derived from the modification of an un-grafted polystyrene (PS). The morphology of the porous sulfonated polystyrene/poly(methyl methacrylate) (SPS/PMMA) microspheres was controlled by varying the degree of swelling and the duration of sulfonation. The procedure was initiated by swelling SPS microspheres with MMA, which possessed similar solubility parameters to PS. Water permeated the SPS microspheres via osmosis and produced a sizeable water phase, which formed pores after drying. A sufficient swelling period was required to stabilize the permeated MMA and water. Furthermore, hydrophilic groups within the particles contributed to the degree of water and monomer that was absorbed by the particles. As a result, various micro-sized porous particles were fabricated and pore sizes could be controlled by adjusting the sulfonyl groups.