High-performance fully bio-based dynamic covalent supramolecular epoxy resin: synthesis and properties†

Abstract

Bio-based dynamic covalent thermosets have attracted widespread attention due to their potential to reduce dependence on fossil resources and address recycling issues after disposal. However, a longstanding challenge has been reconciling the use of bio-based raw materials with high-performance properties. To address this issue, we designed a method for preparing a fully bio-based dynamic covalent supramolecular epoxy resin, utilizing the reactive carbonyl and carboxyl groups of levulinic acid. Even with a relatively low crosslinking density (3152 mol m⁻³), the resin exhibits a glass transition temperature (T_g) of 164 °C, tensile strength of 111 MPa, and tensile modulus of 1864 MPa. In comparison, a resin cured with the commercial hardener DDM, which has a crosslinking density of 8855 mol m⁻³, displays a T_g of 167 °C, tensile strength of 86 MPa, and tensile modulus of 1278 MPa. Furthermore, the resin demonstrates reprocessability without the need for a catalyst. Benefiting from the dynamic effects of ester bonds within the network, the closed-loop chemical recovery of resin was confirmed. Additionally, the resin can be degraded in an alkaline environment, allowing for the recovery of the starting monomer, furandimethyl acid. This high-performance bio-based material is easy to synthesize and can be closed-loop recycled, providing a new strategy for the green development of high-performance thermosets.