Efficient Diphenyl Phosphate-Mediated Hydrolysis of Epoxy Thermosets with Reutilized Products for High-Performance Adhesive

Abstract

The dense and hydrophobic three-dimensional cross-linked network of epoxy thermosets severely limits efficient hydrolytic recycling. Current hydrolysis strategies often lack systematic understanding of catalyst structure–function relationships and high-value utilization of degradation products. Herein, we report an efficient diphenyl phosphate (DPP)-mediated hydrolysis strategy integrating epoxy network deconstruction with direct functional upcycling. Epoxy thermosets are efficiently hydrolyzed within 1 h at 150 °C, whereas structurally related phosphate compounds exhibit substantially lower hydrolysis performance. The enhanced performance of DPP arises from the synergistic contributions of phosphate hydroxyl functionality, the phosphoryl group, and aromatic structural features, which facilitate ester-bond activation and interactions with the epoxy matrix. DPP also serves a dual function by promoting hydrolytic cleavage while providing phosphorus-containing functionality for downstream material reconstruction. The recovered degradation products are directly converted into high-performance adhesives without extensive separation and purification. The strategy is further applicable to carbon fiber reinforced polymers and selected thermosets and thermoplastics containing hydrolyzable linkages, enabling effective polymer deconstruction and carbon-fiber recovery. Overall, this strategy couples efficient thermoset hydrolysis with direct functional upcycling.