Effect of reaction parameters on the particle size in the dispersion polymerization of 2-hydroxyethyl methacrylate

Poly(2-hydroxyethyl methacrylate) particles in the micron size range were o btained by the dispersion polymerization. Cellulose acetate butyrate and di benzoyl peroxide were used as steric stabilizer and initiator, respectively . The ultimate particle size could be adjusted by the selection of a suitab le polymerization medium consisting of an alcohol added to toluene and by v arying their relative amounts. The particle size increased with increasing solubility parameter of the mixture, i.e., by decreasing the toluene/2-meth ylpropan-1-ol, toluene/butan-2-ol, and toluene/3-methylbutan-1-ol ratio. Th e particle size decreased with increasing concentration of the stabilizer a nd/or initiator. At the same time, the particle size distribution became na rrower. Particles prepared from polymerization mixtures purged with nitroge n before the start of polymerization were smaller, and of narrower distribu tion, than those prepared from nitrogen-non-purged mixtures. Equilibrium sw elling of particles in toluene decreased with the decreasing content of tol uene in the polymerization mixture. (C) 1999 John Wiley & Sons, Inc.