Zy. Zhong et al., A novel and versatile calcium-based initiator system for the ring-opening polymerization of cyclic esters, MACROMOLEC, 34(12), 2001, pp. 3863-3868
A novel and efficient calcium alkoxide initiating system, generated in situ
from bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide] and an alco
hol, for the ring-opening polymerization of cyclic esters has been develope
d. The solution polymerization in THF using mild conditions is living, yiel
ding polyesters of controlled molecular weight and tailored macromolecular
architecture. The polymerizations initiated with the 2-propanol-Ca[N(SiMe3)
(2)](2)(THF)(2) system are first-order in monomer with no induction period.
At high 2-propanol/Ca[N(SiMe3)(2)](2)(THF)(2) ratios, complete conversion
of a-propanol occurs due to fast and reversible transfer between dormant an
d active species.