Supramolecular Nanoclusters Enable High-Performance and Recyclable Epoxy Resins.

Abstract

Epoxy resins are essential matrix materials for high-performance composites, yet achieving both superior mechanical properties and recyclability remains a significant challenge. In this study, we report a supramolecular nanocluster (SNs) strategy to simultaneously address these dual demands. The SNs, synthesized via cationic polymerization of an epoxy monomer initiated by a Zn² ⁺-based liquid coordination complex, incorporate metal-coordination and hydrogen-bonding interactions along with flexible polyether chains. When integrated into a highly cross-linked epoxy network, these nanoclusters form localized reinforcement domains, where rigid supramolecular regions enhance stiffness while flexible segments mitigate stress concentration. The optimized epoxy resin achieves a tensile strength of 134 MPa, a modulus of 4.9 GPa, and a 49% improvement in fracture toughness. Using this resin as a matrix for carbon fiber-reinforced composites, a notable enhancement is observed in tensile and flexural performance. Furthermore, the embedded Zn² ⁺ sites act as built-in catalysts, enabling complete resin hydrolysis via ester bond cleavage within 6 h at 170°C in water. The resulting oligomeric products are directly repurposed as a water-soluble sizing agent for carbon fibers, establishing a recyclable pathway. This work offers a viable strategy to reconcile the trade-off between high performance and sustainability in epoxy thermosets.