Title

Lactide Cyclopolymerization Kinetics, X-ray Structure, and Solution Dynamics of (tBu-SalAmEE)Al and a Cautionary Tale Of Polymetalate Formation

Document Type

Article

Publication Date

2013

Abstract

The complex (tBu-SalAmEE)Al (tBu-SalAmEEH3 = N,N-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-2-(2-aminoethoxy)ethanol, 1) catalyzes the ring-expansion polymerization of lactide to form cyclic poly(lactide) (cPLA). The X-ray structure of 1 was determined, its polymerization kinetics were examined and its interactions with Lewis bases were observed. The data from these experiments are consistent with a coordination–insertion mechanism whose rate-determining step is catalyst rearrangement by loss of a hemilabile, datively bound, bridging ligand ether. cPLA was examined by thermogravimetric analysis and found more stable than its linear counterpart. In the course of these studies, we unexpectedly observed the formation of polymetalate (AlMe(tBu-SalAmEE)AlMe2)2 (6), which was characterized (X-ray, EA, and 1H and 13C NMR).

Journal

Macromolecules

Volume

46

Issue

9

First Page

3273

Last Page

3279