A Self-Healing Adhesive Exploiting Hydrogen-Bonding Interactions and Aromatic Disulfide Units in Energetic Composites

Energetic composites with high solid content are prone to microcracking and interfacial debonding, which can compromise mechanical integrity and service reliability. To address these long-standing durability challenges, herein, a self-healing polyurethane with hydrogen bonds and disulfide bonds (PUHD) was designed by integrating hydrogen-bond reorganization with dynamic disulfide-bond exchange. PUHD was synthesized using polytetramethylene ether glycol (PTMEG) as the soft segment and isophorone diisocyanate (IPDI) and 4,4′-dihydroxydiphenyl disulfide (DHDPS) as hard-segment components. FT-IR, Raman, XRD, GPC, and DSC analyses confirmed the successful construction of a predominantly amorphous dual dynamic network with suitable chain mobility and thermal stability for energetic-composite applications. The neat PUHD exhibited a hardness of 0.94 MPa and a storage modulus of 3.15 MPa at 20 °C and 5 Hz; surface cracks disappeared within 24 h at ambient temperature, and the storage-modulus recovery reached approximately 97%. In sample filler-containing composites, increasing solid content enhanced hardness and modulus but restricted polymer-chain mobility, thereby slowing crack repair and reducing healing recovery. In nitrocellulose/nitroglycerin (NC/NG)-containing composites, the visible crack closure could be achieved within 24 h, while maintaining useful mechanical properties after self-healing. Notably, JQ-e showed the highest initial hardness of 2.69 MPa and retained 2.19 MPa after healing. These findings collectively demonstrate that the synergistic dynamic network not only enables efficient room-temperature crack repair but also preserves adequate mechanical reinforcement, thus offering a viable pathway toward more reliable energetic-composite formulations.