Excellent Comprehensive Performance Epoxy Resin with Ultra-high Toughness Enabled by Heteroatom-Containing Hyperbranched Polyester

The inherent brittleness and flammability of epoxy resin restrict its applications in aerospace and electronic packaging fields, and simultaneously improving its toughness and flame retardancy remains a major challenge. In this work, a hyperbranched polymer (HBPE) was synthesized via a “one-pot” polycondensation method. The abundant hydroxyl and carboxyl in HBPE can undergo covalent cross-linking reactions with epoxy resin, ensuring favorable compatibility and processability. Meanwhile, the modified resin shows improvements in mechanical properties, flame retardancy, and thermal stability, with significantly enhanced comprehensive performance. Unexpectedly, compared with pure epoxy resin, HBPE can significantly improve the toughness of the resulting epoxy resin, increasing its impact strength by 231.3%, from 16.79 kJ/m 2 to 55.63 kJ/m 2, owing to its unique hyperbranched structure and the dynamic hydrogen-bond network. These excellent properties exhibited by the modified resin highlight the great potential of the hyperbranched polyester (HBPE) developed in this study for epoxy resin applications.