Feasible self-healing CL-20 based PBX: Employing a novel polyurethane-urea containing disulfide bonds as polymer binder

Damages generated in functional materials can deteriorate their performance and shorten their lifetime, endowing the materials with self-healing ability is expected to resolve this problem. In this work, a novel energetic composite refers to CL-20 based PBX, which can self-heal its mechanical damage under a mild condition, was designed and prepared via incorporating disulfide bonds into the polymeric binder. The highly efficient self-healing polyurethane-urea containing disulfide bonds (DSPU) was synthesized by using the prepolymer of poly(caprolactone) diol (PCL-diol) with isophorone diisocyanate (IPDI) as the main-chain to achieve good mechanical toughness, then cross-linking with bis(4-aminophenyl) disulfide (APD) to gain the superior reversibility. The CL-20 based PBX using this DSPU as binder can evidently self-heal its inner damage, i.e. micro-crack, after heating at 60 °C for several hours, and the strength of the damaged sample after Brazilian test can also be recovered to more than 70% of the pristine value.