ANIONIC DISPERSION POLYMERIZATION OF STYRENE .1. 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 ran ge of 1.41-6.16 mu m, and having narrow molecular weight distributions M(w)/M(n) of 1.02-1.28. sec-Butyllithium was used as the initiator. P olystyrene-block-polybutadiene diblock copolymer containing 23% polyst yrene 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 s tabilizer for the preparation of micron-size polystyrene particles wit h narrow size distribution. Tetrahydrofuran (THF) was used as a promot er for obtaining narrow molecular weight distributions. However, this study revealed that the addition of small amounts of THF as promoter b roadened the particle size distribution. High solids content polystyre ne dispersions were also prepared without using any promoter by both b atch and/or multi-addition monomer processes. (C) 1996 John Wiley & So ns, Inc.