Sustainable and mechanically robust epoxy resins derived from chitosan and tung oil with proton conductivity

The development of sustainable and functional epoxy resins from renewable biomass is gaining increasing attention. Herein, renewable and mechanically strong epoxy resins from chitosan and tung oil that possess proton conduction properties are developed. Firstly, tung oil-based epoxy monomers and chitosan based chain transfer agent were prepared. Then, a "grafting from " reversible addition-fragmentation chain transfer (RAFT) polymerization was carried out on chitosan using epoxy monomers toward elastic graft copolymer, which combined rigid backbone and flexible side chains in one macromolecule. After being cured with citric acid (catalyst-free), a biomass-based epoxy resins with dual network structure can be obtained. The thermal and mechanical properties of these epoxy resins could be tuned through controlling the content of cross-linkers. Moreover, the chitosan bearing abundant amino groups not only enhanced strength of the epoxy resins, but also endowed them with proton conductivity. Overall, the epoxy resins exhibited high tensile strength and comparable proton conduction, which provides a new paradigm to design green functional materials for potential applications.