A biocatalytic approach towards sustainable furanic-aliphatic polyesters

An eco-friendly approach towards furanic-aliphatic polyesters as sustainable alternatives to aromatic-aliphatic polyesters is presented. In this approach, biobased dimethyl 2,5-furandicarboxylate (DMFDCA) is polymerized with various (potentially) renewable aliphatic diols via Candida antarctica Lipase B (CALB)-catalyzed polymerization using a two-stage method in diphenyl ether. A series of furanic-aliphatic polyesters and oligoesters is successfully produced via enzymatic polymerization. Some products reach very high (M-w) over bar (weight average molecular weight) values of around 100 000 g mol(-1). Studies on the effect of the diol structure on the enzymatic polymerization indicate that CALB prefers long-chain alkane-alpha,omega-aliphatic linear diols containing more than 3 carbons. We also found that the molecular weights of the obtained furanic-aliphatic polyesters increase steadily with the increase of reaction temperature from 80 to 140 degrees C. MALDI-ToF MS analysis reveals that five polyester species may be present in the final products. They were terminated with the ester/-OH, ester/ester, -OH/-OH, no end groups (cyclic), and ester/aldehyde groups, respectively. Furthermore, the structure-property relationships were studied by comparing the crystalline/thermal properties of a series of relevant furanic-aliphatic polyesters.