Anionic dispersion polymerization of styrene. I. Investigation of parameters for preparation of uniform micron-size polystyrene particles with narrow molecular weight distribution

Anionic dispersion polymerization in a hexane medium has been applied to the synthesis of monodisperse polystyrene particles in the size range of 1.41–6.16 μm, and having narrow molecular weight distributions M_w/M_n of 1.02–1.28. sec-Butyllithium was used as the initiator. Polystyrene-block-polybutadiene diblock copolymer containing 23% polystyrene block, (i.e., Stereon 730A) with a molecular weight of 147,000 g/mol and a polydispersity of 1.05, was found to be a suitable steric stabilizer for the preparation of micron-size polystyrene particles with narrow size distribution. Tetrahydrofuran (THF) was used as a promoter for obtaining narrow molecular weight distributions. However, this study revealed that the addition of small amounts of THF as promoter broadened the particle size distribution. High solids content polystyrene dispersions were also prepared without using any promoter by both batch and/or multi-addition monomer processes. © 1996 John Wiley & Sons, Inc.