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

The ternary catalyst system neodymium phosphate/di-n-butyl magnesium trieth yl aluminum complex/hexamethyl phosphoramide (Nd(P-204)(3)/MgBu2 . AlEt3/HM PA) for the polymerization of styrene was examined. The effects of the addi tion order of each component, the aging time and temperature and the presen ce of a small amount of styrene during the preparation of the catalyst syst em on the activity of the catalyst system and the molecular weight of the r esultant polymers were investigated. A stable and homogeneous catalyst syst em which produces polystyrene with narrow molecular weight distributions ca n be prepared by an alkylation reaction of Nd(P-204)(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 furt her improve their stability. (C) 2001 Elsevier Science Ltd. All rights rese rved.