HIGHLY STEREOELECTIVE POLYMERIZATION OF RAC-(D,L)-LACTIDE WITH A CHIRAL SCHIFFS BASE ALUMINIUM ALKOXIDE INITIATOR/

A chiral Schiff's base/aluminium alkoxide initiator bearing a ligand d erived from R-(+)-1,1'-binaphthyl-2,2'-diamine was synthesized and use d for the stereoelective polymerization of rac-(D,L)-lactide. Rather h igh stereoelectivity is observed: a polymer with 88% enantiomeric enri chment in D units is obtained at 19% conversion. At high conversions a stereocomplex between D- and L-enriched stereocopolymers is formed. T he polymerization reaction shows living type features, and narrow mole cular weight distributions ((M) over bar(w)/(M) over bar(n) = 1,05-1,3 0) are obtained up to very high conversions. This indicates that trans esterification reactions do not occur significantly with this sterical ly hindered initiator.