Isospecific polymerization of styrene with modified ziegler-type catalysts

Effects of various kinds of additives as well as aging of the catalyst on the polymerization of styrene catalyzed by TiCl4/MgCl2–AlEt3 system have been 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 additive, the catalyst system gives high activity and isotacticity. The use of a mixture of AlEt3/H2O (1:1 mole ratio) as a cocatalyst is also efficient. The catalyst [TiCl4–PCl3/MgCl2–AlEt3/H2O] displays high activity and product isotacticity (94%) with an average molecular weight up to 2×10−6. When Co(acac)3 is added to [TiCl4/MgCl2–AlEt3] catalyst after it was aged, the isotacticity can be up to 97%.