Stereoregular Polymers. I. Polymerization of Styrene by Triethylaluminum-Titanium Tetrachloride Catalysts

Styrene was polymerized by the heterogeneous catalysts of Ziegler’s type which were prepared under various conditions. The important factor which have pronounced effects on the stereospecificity and the catalytic activity of the mixture are concluded to be the existence of the remaining titanium tetrachloride,ethylaluminium chlorides and some soluble aluminium-titanium complex compounds, and the crystalline nature of the solid catalytic mass.The first three are considered to be responsible for the atactic polymerization of styrene and can be removed by washing with n-heptane. The crystallinity of the solid catalysts seems to be necessary for its high tereospecificity and catalytic activity. The solid catalyst was examined by X-ray. It was found that the crystalline component of the catalyst did not correspond to TiCl3 or TiCl2, and thus it was suggested that some crystalline complex compounds containing Al and Ti or some other modification of TiCl3 (or TiCl2) would be responsible for the effective catalytic component of Ziegler catalyst. The authors also suggested that the fact might be one of the important differences between the heterogeneous catalysts of Ziegler’s type and Natta’s type.