Monodisperse micron-sized crosslinked polystyrene particles. IV. Effect of network structure on polymerization procedure

Monodisperse micron-sized polystyrene particles crosslinked using urethane acrylate were produced by dispersion polymerization in ethanol solution and the effect of the crosslinked network structure on the polymerization procedure was studied. The influences of the concentrations of the initiator and urethane acrylate on the particle diameter (D _n), the particle number density (N _p), and the polymerization rate (R _p) were found to obey the approximate relationships D _n ∝ initiator]^0.43 urethane acrylate]^0.05, N _p ∝ initiator]^−1.30 urethane acrylate]^0.19, and R _p ∝ initiator]^{0.24 ± 0.02}. The power-law dependence of D _n and N _p on the initiator concentration showed a similar trend to that of linear polystyrene reported in the literature. Especially, it was found that urethane acrylate does not have a serious effect on D _n and N _p of the particles produced. The dependence of R _p on the initiator concentration was observed to be higher than that of linear polystyrene, suggesting that there is still competition between heterogeneous polymerization and solution polymerization because of the crosslinked network structure of the primary particle. Received: 1 April 1999 Accepted in revised form: 29 June 1999