A sustainable aqueous interfacial strategy for producing epoxidized Eucommia ulmoides gum as a high-performance bio-based epoxy resin

The development of sustainable bio-based substitutes for fossil-fuel-derived epoxy resins is vital for reducing the environmental impact of polymer coatings. In this work, a sustainable aqueous interfacial strategy was developed to produce epoxidized Eucommia ulmoides gum (EEUG) as a high-performance bio-based epoxy coating material. Unlike conventional solution-based epoxidation methods, this approach uses water as the reaction medium and enables efficient epoxidation via an in situ hydrogen peroxide/acetic acid oxidation system, thereby avoiding large quantities of organic solvents. The extent of epoxidation was governed by tuning the reaction parameters, yielding a maximum epoxy content of 0.120 mol per 100 g of resin. Structural characterization confirmed the successful conversion of C C bonds into epoxy groups while preserving the trans-polyisoprene backbone of Eucommia ulmoides gum. The resulting EEUG-based coating exhibited thermal stability and chemical resistance comparable to those of conventional E51 epoxy coatings, along with enhanced flexibility, damping capability, and hydrothermal adhesion retention. Electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) tests demonstrated excellent anti-corrosion performance, with the impedance modulus of coating (|Z| 0.01 Hz ) maintaining approximately 10⁸ Ω·cm² after 30 days of immersion in a simulated seawater solution. This work demonstrates a green and scalable pathway for converting renewable biomass into functional epoxy materials for sustainable protective coatings.