Sugar-derived, erythritan and threitan monomers for the synthesis of bio-based polyesters and polycarbonates

Competitive, sustainable plastic materials which are both bio-based and degradable are desperately needed to replace the world’s ever-growing use of environmentally persistent, fossil fuel-based commodity plastics. Erythritol, a fermentation product of glucose, has been used to form the inexpensive, yet useful, heterocyclic monomer, erythritan, which can be polymerized with comonomers to create promising, new bio-based polyesters. This presentation reports the synthesis of various polyerythritan esters which have been characterized by TGA, DSC, and HFIP-GPC and considered as potential replacements to PBS or PET for applications including packaging materials. Additionally, erythritan’s diastereomer, threitan, has been investigated as an alternative monomer for the synthesis of polycarbonates because of its geometric preference for polymerization over cyclization. Polyerythritan esters synthesized using aliphatic diacids showed promising thermal stabilities (T₉₅ values from 315-373 °C) and good molecular weight values (M_n up to 28,300 Da). Although these polyerythritan esters had higher T_g values (up to 47 °C) than those of comparable fossil fuel-based analogues or commercial, bio-based PBS, they either had nonexistent or very low T_m values when compared to competitors. To address this issue, erythritan was also polymerized with sustainable aromatic diesters, bio-based dimethyl uvitonate and PET’s chemical recycling product bis(hydroxyethyl)terephthalate (BHET). The resulting 100% sustainable, semi-aromatic polyerythritans had substantially higher T_g values (130 and 101 °C) than that of PET. Ongoing work towards threitan based polymers is presented as well.