Study of ligand substituent effects on the rate and stereoselectivity of lactide polymerization using aluminum salen-type initiators.

ABSTRACT: A series of aluminum salen-type complexes [where salen is N,N'-bis(salicylaldimine)-1,2-ethylenediamine] bearing ligands that differ in their steric and electronic properties have been synthesized and investigated for the polymerization of rac-lactide. X-ray crystal structures on key precatalysts reveal metal coordination geometries intermediate between trigonal bipyramidal and square-based pyramidal. Both the phenoxy substituents and the backbone linker have a significant influence over the polymerization. Electron-withdrawing groups attached to the phenoxy donor generally gave an increased polymerization rate, whereas large ortho substituents generally slowed down the polymerization. The vast majority of the initiators afforded polylactide with an isotactic bias; only one exhibited a bia

SUBMITTER: Hormnirun P 

PROVIDER: S-EPMC1622826 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature