Triethylaluminum—titanium tetrachloride catalysts for preparation of crystalline polystyrene

The reaction between Et3Al and TiCl4 is discussed, with emphasis on the effect of temperature, concentration, stoichiometry, and order of component addition on the ability of products to catalyze the isotactic polymerization of styrene. A well‐defined peak in relative catalyst activity becomes apparent when the interaction of these variables is followed by measuring the average oxidation state of titanium. Experimentally, the polymerization is first‐order with respect to styrene and titanium, although efficiency of Ti use is small. The mode of polymerization is characterized by a lower activation energy for active site generation and a higher activation energy for termination than is typical of free‐radical polymerization. A convenient procedure for laboratory preparation of isotactic polystyrene employing the Et3Al/TiCl4 catalyst is given.