Biomass-derived dynamic covalent epoxy thermoset with robust mechanical properties and facile malleability

摘要

Biomass-derived dynamic covalent thermoset has been considered as a promising solution to the high dependence on fossil resources and the difficulty in recyclability after curing of conventional bisphenol A epoxy resins.However,the design and preparation of a dynamic covalent biobased epoxy thermoset with both comparable thermal and mechanical performances to bisphenol A epoxy resins and reprocessibility remains a significant challenge.Herein,based on imine chemistry,a novel Schiff base-containing dynamic covalent epoxy thermoset was facilely fabricated from biobased protocatechualdehyde and synthetic siloxane diamine.Due to the more reactive epoxides in the epoxy monomer than in bisphenol A epoxy oligomer,the thermoset exhibited a high cross-linking density,resulting in high thermal stability and glass transition temperature.The rigid aromatic Schiff base moieties endowed the thermoset with excellent mechanical properties:Thanks to the plasticization of the flexible siloxane,the thermoset displayed high impact strength.Meanwhile,owing to the high segmental mobility,the fast exchange of imine bonds was guaranteed;and the thermoset was able to be recycled through reprocessing.Taking these features,this work provided great potential for designing and preparing sustainable substitutes for bisphenol A epoxy resins in the high-performance applications.