EFFECT OF SWELLING PROCESS ON MONODISPERSITY OF POROUS POLYSTYRENE-DIVINYLBENZENE MICROSPHERES PREPARED BY TWO-STEP SWELLING POLYMERIZATION METHODS

摘要

Porous polystyrene-divinylbenzene(PS-DVB) microspheres of narrow size distribution in the size range of 3.9-4.4 micrometres were prepared by two-step swelling polymerisation methods. The effects of swelling conditions such as swelling activator, temperature, the dispersion method and dibutyl phthalate(DBP)/seed particle ratio on particle size distribution of the PS-DVB microspheres were investigated in detail. Optimal swelling conditions for the preparation of uniformly sized PS particles were shown to be use of DBP as swelling activation agent, swelling temperature 35 deg C, dispersion by ultrasonic-assisted magnetic dispersion, and DBP/seed particle ratio 1-1.5 ml.g^-^1. It was found that particle size distribution became narrower and swelling time was shortened from more than 24 h to 10 h with the introduction of ultrasonic dispersion, which was attributed to the cavitation effect of ultrasonics and the significant magnetic field action arising therefrom, speeding up the equilibrium of swelling process. Swelling temperature also had a significant effect on the monodispersity and particles with the best uniformity could be achieved with the temperature at 35 deg C. The possible reason was that the process of seed particles absorbing swelling agent through water phase was an equilibrium course of thermodynamics and kinetics. 20 refs.