MORPHOLOGICAL INVESTIGATIONS OF CROSS-LINKED POLYSTYRENE MICROSPHERESBY SEEDED POLYMERIZATION

Crosslinked polystyrene microspheres with novel surface and inner morp hologies were synthesized by seeded polymerization following a seed-sw elling method, using uncrosslinked polystyrene microspheres as seeds a nd a mixture of toluene, styrene (St), and divinylbenzene (DVB) as the swelling agent. With the increasing toluene/(St + DVB) ratio, the cro sslinked particles changed from smooth-surfaced spheres to deformed sp heres with dimples or heavy dents at the surface. A single hole inside the spherical particles was produced at low St/DVB ratio, while highe r St/DVB ratios gave irregular dented or dimpled particles. Ultrathin cross-section observation by TEM revealed a non-uniformly crosslinked inner structure.