Investigation of a Ziegler–Natta catalyst system derived from a mixture of lithium tetraalkylaluminate, aluminum chloride, and titanium tetrachloride and its usefulness in polymerizations involving styrene

Vinyl ethers, 1-olefins, and styrene were homo- and copolymerized by the use of catalyst derived from a mixture of lithium tetraalkylaluminate (LiAlR4), aluminum chloride (AlCl3), and titanium tetrachloride (TiCl4), in order to determine the nature of the active components present.It is postulated that the active catalyst in the stereospecific polymerization of vinyl ethers is ether-coordinated TiCl3•LiCl, while in the polymerization of 1-olefins and styrene, it is the alkylated derivatives of TiCl3•LiCl.For homo- and copolymerization of styrene, AlR3 seems to be the preferred alkylating agent. About 3 to 4 equivalents of AlR3 are needed for complete alkylation of TiCl3•LiCl, probably due to heterogeneity of the system.Highly isotactic polystyrene and copolymers of styrene with 1-olefins can be prepared in good yields by the use of this catalyst.