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%.

中文翻译：

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用于结合热可逆 DA 作用和形状记忆效应的能量复合材料的实用自修复聚氨酯粘合剂

通过呋喃官能化聚己内酯 (PCL) 预聚物和双马来酰亚胺化合物之间的狄尔斯-阿尔德 (DA) 环加成反应，设计并制备了一种用于含能复合材料的新型热修复聚氨酯粘合剂。合成的 PCL-DA-PU 的结构和性能通过质子核磁共振进行了充分表征 ( ¹H-NMR) 和傅里叶变换红外光谱 (FT-IR)、凝胶渗透色谱 (GPC)、热重分析 (TGA) 和差示扫描量热法 (DSC) 测量。所制备的材料通过将有利于划痕闭合的 PCL 链段的形状恢复效果与裂解的 DA 键的重新交联相结合，显示出良好的划痕自愈能力，光学显微镜和拉伸分析证明了这一点。通过拉伸试验确定的划痕愈合效率达到了约 89%。此外，由于PCL-DA-PU粘合剂中DA键的贡献，TATB基含能复合材料的微裂纹和其他损伤几乎得到修复，机械强度可恢复78%以上。