Designing a Novel Modified Curing Agent to Alleviate the Conflict Between Toughness and Strength in Epoxy Resins

The high brittleness of epoxy resins (ERs) restricts their high‐performance applications, while traditional toughening methods typically face a conflict between toughness and strength. To address this issue, existing studies have alleviated the conflict between toughness and strength by introducing rigid‐flexible structures or non‐covalent sacrificial bonds into the cross‐linked polymer networks. However, these methods often involve complex synthesis processes, and the atom utilization efficiency remains to be improved. Therefore, this study proposes a simple and cost‐effective strategy by synthesizing a novel modified curing agent (BA‐ZT) through the Aza‐Michael addition reaction between trimethylolpropane tri‐polypropylene glycol ether (amine‐terminated, ZT‐143) and n ‐butyl acrylate (BA). Benefiting from the three‐terminal amino structure of ZT‐143, this curing agent induces the formation of dense plastic zones in the cross‐linked polymer networks while preserving a good cross‐linking density. Experimental results demonstrate that the modified curing agent increases the elongation at break of the ER to 77.0%, nearly 490.09% higher than that of the unmodified ER, while retaining good tensile strength (27.97 MPa). However, the thermal decomposition temperature and glass transition temperature ( T g ) are reduced. This study provides a simple and cost‐effective strategy for mitigating the conflict between toughness and strength in ERs.