Polymers from Sugars and Cyclic Anhydrides: Ring-Opening Copolymerization of a D-Xylose Anhydrosugar Oxetane

A D-xylose 3,5-anhydrosugar derivative has been used as an oxetane co-monomer in the ring-opening copolymerization (ROCOP) with cyclic anhydrides, to form a family of seven novel sugar-derived polyesters, with up to 100% renewable content. ROCOP proceeds with high alternating selectivity to form AB-type copolymers that are thermally robust (T-d,T-onset > 212 degrees C) and exhibit a broad range of glass-transition temperatures (T-g 60-145 degrees C). These polyesters are amenable to further postpolymerization functionalization. The hydroxy group of the sugar moiety can be unveiled, then functionalized further, e.g., phosphorylated. The internal alkene of some of the anhydride moieties can also be subject to thiol-ene reactions. Combining those orthogonal strategies affords AB copolyesters with alternating functional substituents. By exploiting the living character of the ROCOP process, block copolymers have also been synthesized through sequential co-monomer addition experiments.