Practicable self‐healing polyurethane binder for energetic composites combining thermo‐reversible DA action and shape‐memory effect

A novel thermally mendable polyurethane binder for energetic composites was designed and prepared via the Diels‐Alder (DA) cycloaddition reaction between a furan functionalized polycaprolactone (PCL) prepolymer and a bismaleimide compound. The structures and properties of synthesized PCL‐DA‐PU were fully characterized via Proton Nuclear Magnetic Resonance (1H‐NMR) and Fourier Transform Infrared spectroscopy (FT‐IR), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC) measurements. As‐prepared material showed good self‐healing ability of scratches by virtue of combining the shape recovery effect of PCL segments favoring scratch closure with the re‐crosslinking of the cleaved DA bonds, which was evidenced by optical microscopy and tensile analysis. A scratch healing efficiency determined by tensile tests of about 89% was achieved. Moreover, with the contribution of DA bonds in PCL‐DA‐PU binder, the microcracks and other damages in the TATB based energetic composites were almost mended and the mechanical strength can recovery above 78%.