Enzymatic polymerization of furan-based polymers in biobased solvents†

Abstract

The demand for biobased polymers is on the rise, driven by increasing environmental awareness and the imperative for sustainability. Biobased materials, which offer renewability, have emerged as a solution to the depletion of petroleum-based resources. Among biobased raw materials, 2,5-furandicarboxylic acid (2,5-FDCA) has gained prominence as an extensively studied monomer in the last decade. Polyesters based on 2,5-FDCA have shown compatibility and potential as biobased alternatives to polyethylene terephthalate (PET) for packaging applications. Besides FDCA, 2,5-bis(hydroxymethyl)furan (2,5-BHMF), a furan hetero-aromatic diol derivable from carbohydrates, has been identified as a versatile building block, presenting interesting properties for polymeric materials. In adherence to sustainability principles, the choice of catalyst for biobased polymer production is crucial. Biocatalysts, such as enzymes, not only provide renewability but also offer advantages such as mild reaction conditions, aligning with sustainable practices. However, many enzymatic polymerizations are reported in organic solvents, that are not environmentally friendly and/or non-renewable. To address this issue, this study explored the use of biobased solvents—namely, p-cymene, pinacolone, and D-limonene—for the enzymatic polymerization of dimethyl 2,5-furan dicarboxylate (2,5-FDCA-based) polyesters and copolyesters with 2,5-BHMF. By employing Candida antarctica lipase B (CALB), the enzymatic polymerization of this enzyme, particularly with p-cymene, has demonstrated high performance, resulting in high-molecular-weight polyester and copolyester products up to 7000 and 12 800 g mol⁻¹, respectively. This study examined the thermal properties and crystallinity of the obtained products by analyzing their structure–property relationships. This research contributes to the advancement of sustainable polymer synthesis by considering biobased raw materials, environmentally friendly catalysts, and biobased solvents.