Lactide Lactone Chain Shuttling Copolymerization Mediated by an Aminobisphenolate Supported Aluminum Complex and Al(OiPr)(3): Access to New Polylactide Based Block Copolymers

The chain shuttling ring-opening copolymerization of L-lactide with epsilon-caprolactone has been achieved using two aluminum catalysts presenting different selectivities and benzyl alcohol as chain transfer agent. A newly synthesized aminobisphenolate supported aluminum complex affords the synthesis of lactone rich poly(L-lactide-co-lactone) statistical copolymeric blocks, while Al(OiPr)(3) produces semicrystalline poly(L-lactide) rich blocks. Transalkoxylation is shown to operate efficiently. The crystalline ratios and glass transition temperatures of these new classes of polylactide based block copolymers can be tuned by adjusting the catalysts and the comonomers ratio.