Synthesis of new homopolyester and copolyesters by anionic ring-opening polymerization of α,α′,β-trisubstituted β-lactones

Novel polyester and copolyesters have been prepared by anionic ring-opening polymerization of racemic 4-alkyloxycarbonyl-3,3-dimethyl-2-oxetanones that had been synthesized in five steps from diethyl oxalpropionate used as chemical precursor. The anionic polymerizations, realized in bulk or in solution with tetraethylammonium benzoate as initiator, led to a homopolymer and copolymers with high molecular weights and polydispersity indices close to unity. These features can be explained by the presence of two methyl groups on the same carbon atom in the lactone, preventing transfer reactions to the monomer. Preparation of seeds and re-initiation by addition of fresh monomer confirmed a living process. The hydrolysis of poly[(R,S)-3,3-dimethylmalic acid] under physiological condition yielded (R,S)-3,3-dimethylmalic acid. A terpolymer was also prepared for biological studies related to its use as biodegradable materials for tissue regeneration.