G. Richard et al., INFLUENCE OF RARE-EARTH COMPOUNDS ON THE ANIONIC RING-OPENING POLYMERIZATION OF CYCLOSILOXANES, Polymer bulletin, 39(5), 1997, pp. 581-588
The influence of rare earth compounds on the polymerization of cyclosi
loxanes has been studied for hexamethylcyclotrisiloxane (D-3) and octa
methylcyclotetrasiloxane (D-4). In both cases, it has been shown that
rare earth compounds alone do not lead to well defined polymers : yiel
ds are never quantitative and the formation of cyclic side-products is
always observed. The influence of these compounds has also been studi
ed in the anionic polymerization of the same cyclosiloxanes initiated
by organolithium reagents or fluorides. In the case of D-3, it has bee
n shown that back-biting reactions can be slowed down in the presence
of rare earth compounds whereas for D-4, both polymerization and back-
biting reactions get slower.