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Organocatalytic Living Ring-Opening Polymerization of Cyclic Carbosiloxanes

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journal contribution
posted on 12.10.2006, 00:00 by Bas G. G. Lohmeijer, Geraud Dubois, Frank Leibfarth, Russell C. Pratt, Fredrik Nederberg, Alshakim Nelson, Robert M. Waymouth, Charles Wade, James L. Hedrick
An organocatalytic route to narrowly dispersed poly(carbosiloxanes) of predictable molecular weight and end group fidelity is described. N-Heterocyclic carbenes (NHC) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) catalyze the ring opening of cyclic carbosiloxanes. The pKb of the catalyst is important in preventing adverse transetherification reactions and obtaining well-defined polymers. Mechanistic studies indicate that hydrogen bonding to TBD or the NHC activates alcohols or silanols for ring-opening reactions.