Stereoregularity of polystyrene derivatives, 3. Poly(methylstyrene)s Obtained by Anionic Catalysts

The stereoregularity of the polymers of ortho-, meta-, and para-methylstyrenes prepared with various anionic catalysts was determined by means of ¹³C NMR spectroscopy. The substituent effect on the stereoregularity was discussed comparing with that of polystyrenes obtained under the same polymerization conditions. Syndiotactic-rich poly(methylstyrene)s were prepared with butyllithium in toluene and the syndiotacticity increased in the order of para-, meta-, and ortho-derivatives. Although the structure of the polymers prepared with sodium-naphthalene (Na-naph.) in THF did not change with the position of the substituent, in toluene, however, the methyl group at ortho-position influences the stereoregularity. The trend of the stereoregularity of the polymers produced by potassium-naphthalene was almost the same as that of poly(methylstyrene)s prepared by Na-naph. Nearly random polymers were obtained with the cesium ion as catalyst.