A novel latent initiator for cationic polymerizations of epoxides: Composite catalysts containing aluminum complexes phase-separated in epoxides

A novel latent initiator for cat-ionic polymerizations of epoxides heterogeneous aluminum complex/phenol initiator (HAP) is reported. Phase transitions are newly employed for realizing the latent property. The initiator consists of 4,4'-dihydroxydiphenylsulfone and aluminum tris(alkyl acetoacetate), with the alkyl group containing more than 18 carbons. The composite initiator is phase-separated and dispersed uniformly in epoxy resins at room temperature. When the mixture is heated to a temperature greater than 70 degreesC, the composite initiator makes clear mixtures with epoxy resins because of the phase change in the aluminum complexes. Homogeneous epoxy resins containing these composite initiators are ready for various types of processing, including impregnation and injection. Gelation occurs rapidly at temperatures greater than 100 degreesC. The phase change in the initiator makes it possible for the epoxy compounds to have a long storage stability at room temperature and a high curing speed at greater than 100 degreesC. (C) 2002 John Wiley & Sons, Inc.