Mechanism of stereospecific polymerization of propylene with titanium trichloride–aluminum alkyl catalysts

The effect of various aluminum alkyls at varying concentrations on the rate and stereospecificity of propylene polymerizations with titanium trichloride was examined. It was concluded that dialkylaluminum halides were merely chemisorbed on the surface of the titanium trichloride while the trialkylaluminums reacted more extensively with the surface. In the case of diethylaluminum chloride standard chemisorption kinetics were observed. The rate of polymerization was also found to be a function of solvent, with certain aromatic solvents causing significant rate increases. With diethylaluminum chloride essentially no termination occurs; the polymers are “living polymers.”