ASYMMETRIC POLYMERIZATION OF AROMATIC ISOCYANATES WITH OPTICALLY-ACTIVE ANIONIC INITIATORS

The asymmetric anionic polymerization of o-, m-, and p-methylphenyl isocyanates, p-methoxyphenyl isocyanate, p-chlorophenyl isocyanate, 2,6- and 3,4-dimethylphenyl isocyanates, and 1-naphthyl isocyanate was carried out using chiral anionic initiators such as the lithium salts of (-)-menthol, (-)-( 2-methoxymethyl) pyrrolidine, and (+)-1-(2-pyrrolidinylmethyl) pyrrolidine. Although o-methylphenyl isocyanate gave an insoluble polymer and 2,6-dimethylphenyl isocyanate afforded no polymer, the other monomers gave soluble polymers, which showed optical activity due to the prevailing helicity of the polymer chain induced by chiral initiator residues attached to the a-end of the polymer chain. The molecular mechanics conformational calculation for a tetramer of m-methylphenyl isocyanate sup ported the helical conformation of the main chain. The optical rotation of the polymers depended significantly on temperature. (C) 1994 John Wiley & Sons, Inc.