Isospecific polymerization of styrene with modified ziegler-type catalysts

Effects of various kinds of additives as well as aging of the catalyst on t he polymerization of styrene catalyzed by TiCl4/MgCl2-AlEt3 system have bee n studied. Experiments show that in toluene the isotacticity of polystyrene can be up to 83% for aged catalyst, whereas when the catalyst is not aged. non-stereospecific polymer is the main product. When PCl3 is used as an ad ditive, the catalyst system gives high activity and isotacticity. The use o f a mixture of AlEt3/H2O (1: 1 mole ratio) as a cocatalyst is also efficien t. The catalyst [TiCl4-PCl3/MgCl2-AlEt3/H2O] displays high activity and pro duct isotacticity (94%) with an average molecular weight up to 2 X 10(-6). When Co(acac)(3) is added to to [TiCl4/MgCl2-AlEt3] catalyst after it was a ged, the isotacticity can be up to 97%. (C) 2001 Elsevier Science Ltd. All rights reserved.