Strengthening and toughening energetic polymer composites via assembly of metal-phenolic network

Abstract

Polymer bonded explosive (PBX) regarded as classic representative of energetic polymer composites confronts inferior mechanical properties due to weak interfacial interaction. Herein, a green, simple, and versatile method was proposed to decorate 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) with metal-phenolic network (MPN) via one-step coordination assembly of tannic acid and iron ions. The resultant HMX with homogeneous MPN coating presented a rough surface relative to pristine HMX. The existence of MPN layer imparted ample hydroxy groups on the modified HMX without altering inner crystal structure. Compared with pristine HMX, MPN-decorated HMX improved the β → δ phase transition temperature by 19.3 °C. By intermingling with fluoropolymer to acquire PBX, superior mechanical properties emerged for MPN-decorated PBX instead of pure PBX. The optimal condition enhanced tensile strength and fracture energy by 63.5% and 78.7%, respectively. Such an amelioration in strength and toughness of PBX rooted in intensive interfacial interaction attributed to mechanical interlocking and interfacial hydrogen bonds. The recommended approach provides an alternative route to garner high-performance energetic polymer composites.