VISIBLE-LIGHT-MEDIATED LIVING AND IMMORTAL POLYMERIZATIONS OF EPOXIDES INITIATED WITH ZINC-COMPLEXES OF N-SUBSTITUTED PORPHYRINS

The novel, visible-light-mediated living polymerization of epoxides was developed by using as initiators zinc N-methylated tetraphenylporphyrin complexes ((NMTPP)ZnX; X = SCH2CH2CH3 (lb), OCH(CHa)2 (lc)) in benzene at room temperature. The NMR studies demonstrated that the polymerization is initiated by the attack of the axial group of the initiator onto the monomer, affording a (N-meth-yltetraphenylporphinato)zinc alkoxide as the growing species. The polymerization of 1,2-epoxypropane with lb proceeded with immortal character in the presence of a protic compound such as 1-propanethiol or methanol to give the polymer of narrow molecular weight distribution with the number of the molecules corresponding to the sum of those of lb and the protic compound. The polymerization of an episulfide, followed by an epoxide under visible light irradiation, afforded a block copolymer consisting of polythioether and polyether blocks of uniform block lengths. © 1990, American Chemical Society. All rights reserved.