One-Pot Synthesis of α,ω-Chain End Functional, Stereoregular, Star-Shaped Poly(lactide)

The synthesis of stereoregular alpha,omega-chain end functional linear, telechelic, and star-shaped polymers and copolymers is reported using a one-pot chain end functionalization methodology. Aluminum methyl complexes are applied in combination with functional and multifunctional initiating species to synthesize stereoregular poly(lactide)s by the stereospecific ring-opening polymerization of rac-lactide. The quenching of the reactions with an excess of acid chloride functional molecules has enabled the in situ quantitative modification of the omega-chain ends of the polymers such that primary and secondary alkyl and aryl groups can be incorporated. This methodology has been extended to the synthesis of linear, telechelic, and star-shaped polymers with "click" functional handles for both copper-catalyzed Huisgen 1,3-dipolar cycloaddition and thiol-ene Michael additions and block copolymers through the application of a trithiocarbonate, suitable for mediating RAFT polymerization. This tolerant and mild method is used in the synthesis of star-shaped block copolymers with a biodegradable poly(lactide) core and results in poly(lactide)s that display increased resistance to degradation.