Development of robust and rapid self-healing polymers for the repair of microcracks in energetic composite materials

Abstract

Adhesives with superior toughness and self-healing properties are critical for the practical application of energetic composite materials (ECMs). However, most self-healing polymers exhibit low creep resistance and toughness, which makes simultaneous optimization a challenge. To overcome this, we introduced asymmetric alicyclic and bent biphenyl ring structures into the hard domain units of soft polymers, which resulted in adhesives with robust mechanical properties. The synergistic effect of dynamic disulfide and hydrogen bonding in the adhesive allows for excellent self-healing efficiency. We then conducted a comprehensive investigation into the structure, thermal stability, self-healing, mechanical properties, rheology, and adhesion properties of the synthesized disulfide bond-containing self-healing polyurethanes (PUDS). Our study demonstrates that PUDS films can achieve a toughness of 20.93 MJ m− 3, and when cut in half and reassembled, they recover to more than 90% of their original toughness within 20 minutes, showcasing impressive mechanical properties and self-healing efficiency. Our experimental measurements and molecular dynamics simulations reveal that the interfacial interaction with 1,3,5-trinitro-2,4,6-triaminobenzene (TATB) is stronger when the hard segment content of the adhesive is higher. Furthermore, even after accidental mechanical damage, cracked ECMs can be effectively healed within 24 hours at 60℃. Self-healing and highly resilient adhesives offer promising avenues for enhancing the safety and longevity of energy-containing composites, with potential military and civil applications.