Organocatalytic living ring-opening polymerization of cyclic carbosiloxanes.
[reaction: see text] 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 pK(b) 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.
Lohmeijer
Bas G G
BG
IBM Almaden Research Center, 650 Harry Road, San Jose California 95123, USA.
Dubois
Geraud
G
Leibfarth
Frank
F
Pratt
Russell C
RC
Nederberg
Fredrik
F
Nelson
Alshakim
A
Waymouth
Robert M
RM
Wade
Charles
C
Hedrick
James L
JL