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

The ternary catalyst system neodymium phosphate/di-n-butyl magnesium triethyl aluminum complex/hexamethyl phosphoramide (Nd(P204)3/MgBu2·AlEt3/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(P204)3 with MgBu2·AlEt3 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.