Versatile Copolymerization of Glycolide and rac-Lactide by Dimethyl(salicylaldiminato)aluminum Compounds

The dimethylaluminum compounds Al(CH3)2[(O-2-{(C6F5)NCH}-4,6-R2C6H2)], R = H (1) or cumyl (2), weresynthesized and tested as initiators in the homo- andcopolymerization of rac-lactide and glycolide. These complexesresulted active for the production of PLGA copolymers withvariable microstructure. All the copolymers were fully characterizedby NMR, GPC, and DSC analysis. The copolymerizationreactions were performed in bulk and in solution, by varyingcomonomers ratio, monomer/catalyst feed ratio, temperature,reaction time, and solvent. Interestingly, by changing the reaction conditions, copolymers from random, to blocky, to diblockwere obtained, demonstrating the effectiveness and versatility of such systems in modulating the copolymers microstructure andthe related thermal properties.■ INTRODUCTION