Monodisperse micron-sized crosslinked polystyrene particles. IV. Effect ofnetwork 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 proc edure was studied. The influences of the concentrations of the initiator an d urethane acrylate on the particle diameter (D-n), the particle number den sity (N-p), and the polymerization rate (R-p) were found to obey the approx imate relationships D-n proportional to [initiator](0.43) [urethane acrylat e](0.05), N-p proportional to [initiator](0.43) [urethane acrylate](0.19), and R-p proportional to [initiator](0.24 +/- 0.02). The power-law dependenc e of D-n and N-p on the initiator concentration showed a similar trend to t hat of linear polystyrene reported in the literature. Especially, it was fo und 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 concentrati on was observed to be higher than that of linear polystyrene, suggesting th at there is still competition between heterogeneous polymerization and solu tion polymerization because of the crosslinked network structure of the pri mary particle.