Living and ’Immortal’ Polymerizations of Epoxide with Metalloporphyrin Catalyst

Abstract

By using aluminum porphyrin as catalyst for the polymerization of epoxide, the synthesis of polyether with well-defined molecular weight can be accomplished. Successive polymerization of two or more epoxides results in the formation of block copolymer with polyether chains of controlled lengths. By taking advantage of the spectroscopic characteristics of porphyrin, the structure of the growing species of the polymerization can be investigated in detail. The polymer with narrow molecular weight distribution can be obtained even in the presence of protic compound such as hydrogen chloride, carboxylic acid, alcohol, and water. The number of the molecules of polymer can be increased with the amount of protic compound added, retaining the narrow molecular weight distribution of polymer. These behaviors are much different from ‘living’ polymerization, and a new concept of ‘immortal’ polymerization is presented. Unusual reactivity of the aluminum-axial group bond of aluminum porphyrin is the origin of “immortality” of the polymerization.