Ring opening polymerization of cyclic organosilicon compounds: Recent progress

A novel initiator, i.e. trimethylsilylmethyllithium has been successfully used for the ring opening polymerization of cyclosiloxanes in toluene, in the presence of the cryptand [211]. Suitable conditions have been found in which monomodal distributions of molecular weights of polysiloxanes are observed by GPC, even in the case of D 4 and 1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinyl cyclotetra siloxane (D 4 Vi) polymerizations. Moreover, kinetics of propagation and of formation of cyclosiloxanes can be followed by 29 Si or 13 C NMR spectroscopy on living polymer solutions. The rate of propagation of hexaethylcyclotrisiloxane is 120 times lower than that of the corresponding dimethylated analog D 3 , under the same conditions.