Sustainable Synthesis of Terpolyesters Based on a Levoglucosenone-Derived Cyclic Acetal Diol.

Biobased polyesters are gaining increasing interest as sustainable replacements for traditional fossil-based polymers. The compound (1R,2S,5R)-6,8-dioxabicyclo[3.2.1]octane-2,4-diol (HO-LGOL) is a cellulose-derived monomer that can be used to synthesize polyesters with properties similar to those obtained with classical reagents. In this work, several HO-LGOL-based copolymers were sustainably synthesized in the green solvent dioxolane Cygnet (0.0) (referred to as "Cygnet 2") utilizing Candida antarctica Lipase B (CaLB) as a biocatalyst. HO-LGOL was reacted with dimethyl adipate and aliphatic diols of various lengths. Different ratios of reactants were also investigated, and an equimolar amount of HO-LGOL and aliphatic diol was found to yield copolymers with the highest level of HO-LGOL incorporation. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF) confirmed the structure of end groups and the presence of HO-LGOL in longer polymer chains. The incorporation of HO-LGOL resulted in terpolymers with an HO-LGOL content of up to 49% (relative to the aliphatic diol), which exhibited lower crystallinity and higher thermal stability compared to the corresponding aliphatic homopolymers.