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 (H-1-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%.