Simultaneous Configuration of High Room-Temperature Self-Healing Efficiencies and Tough Mechanical Properties of Energetic Adhesives for Energetic Composites

Abstract

Room-temperature self-healing adhesives require more flexible polymer chains and weaker interactions, which are not conducive to good mechanical properties. Therefore, an energetic self-healing adhesive containing asymmetric alicyclic structures and multiple urea groups was designed. The asymmetric alicyclic structures could form loosely packed hard domains, and the irregular arrangement of multiple continuous urea groups could strengthen the physical cross-linking and improve the strengths of the hard domains. As a result, adhesives with improved mechanical properties (tensile strength and toughness) were obtained, and their dynamic adaptabilities and responsiveness required for self-healing at room temperature were maintained. The glycidyl azide polymer-based polyurethane (GPU) adhesive (GPU-3.0) exhibited excellent comprehensive performance in terms of toughness, healing efficiency, adhesion strength, and energy level. The maximum tensile strength and toughness of the energetic composite material (ECM, GPU/Al) prepared using GPU-3.0 and Al were 2.52 MPa and 2.45 MJ m–3, respectively. After 72 h at room temperature, the scratches on the GPU/Al surface were no longer observed and the mechanical properties were completely recovered. Therefore, the designed adhesive, which displays a high-efficiency room-temperature self-healing capacity and good mechanical properties, is applicable in self-healing ECM systems. This strategy should provide insights for use in improving the stabilities and safety of ECMs.