Lewis Acid-Catalyzed Tacticity Control during Radical Polymerization of (Meth)acrylamides

摘要

The tacticity control during the radical polymerization of (meth)acrylamides was achieved in the presence of a catalytic amount of Lewis acids such as Y(OTf)_3 and Yb(OTf)_3. The conventional polymerization of N-isopropylacrylamide without Lewis acids produced an atactic polymer (meso diad = 42 - 46%), whereas the polymer prepared using the Lewis acids in methanol had the meso diad of more than 90%. An analogous effect of the Lewis acids was observed during the polymerization of other (meth)acrylamides, including acrylamide, N,N-dimethylacrylamide, methacrylamide, N-methylmethacrylamide, N-isopropylmethacrylamide, N-phenylmethacrylamide, and (R)-N-[(methoxycarboxyl)-phenylmethyl]methacrylamide.