Styrene polymerization with ternary neodymium-based catalyst system: effects of catalyst preparation procedures

Abstract

The ternary catalyst system neodymium phosphate/di- n-butyl magnesium triethyl aluminum complex/hexamethyl phosphoramide (Nd(P 204) 3/MgBu 2·AlEt 3/HMPA) for the polymerization of styrene was examined. The effects of the addition order of each component, the aging time and temperature and the presence of a small amount of styrene during the preparation of the catalyst system on the activity of the catalyst system and the molecular weight of the resultant polymers were investigated. A stable and homogeneous catalyst system which produces polystyrene with narrow molecular weight distributions can be prepared by an alkylation reaction of Nd(P 204) 3 with MgBu 2·AlEt 3 at ambient temperature followed by the addition of HMPA. An introduction of a small amount of styrene during the preparation of the catalysts can further improve their stability.