University of Connecticut |
Polymer Program SeminarOrganocatalysis: Strategies for Controlled Polymerization Process Friday, December 1, 2006 11:00 am , IMS Room 20 We have developed a family of organocatalysts for the controlled polymerization of lactones to well-defined polyesters of novel architectures and macromolecular topologies. N-heterocyclic carbenes, thio-ureas, and guanidines are potent catalysts for the ring-opening polymerization of lactones. These organocatalysts are both selective and highly active, exhibiting characteristics of living polymerization with turnover frequencies as high as 18 per second with turnover numbers up to 1000. In the presence of alcohols, N-heterocyclic carbenes are potent catalysts for the ring-opening polymerization of lactide to generate linear polylactides. In the absence of alcohols, N-heterocyclic carbenes mediate the polymerization of lactide to cyclic polylactides of high molecular weight and narrow molecular weight distribution.
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