Enhancing the mechanical properties of TATB-based PBXs through strong hydrogen bonding interactions

Interfacial strength is a key factor affecting the mechanical properties of materials. This study aims to enhance the mechanical properties of energetic polymer bonded explosives (PBXs) by modifying 1,3,5-triamino-2,4,6-trintrobenzene (TATB) crystals—a typical energetic material—using 2-ureido-4[1H]-6-methyl-pyrimidinone (UPy) derivatives with strong hydrogen-bonding interactions. Specifically, strongly adhesive polydopamine (PDA) was employed to graft UPy-functionalized molecules with isocyanate groups (-NCO) and hydroxyl groups (-OH). Scanning electron microscopy (SEM) images indicate that TATB crystals became rougher after being coated with PDA, while the introduction of UPy did not affect the surface morphology. The presence of urethane bond peaks in the samples indicates that UPy-NCO was successfully grafted onto the PDA. UPy is essentially nonpolar and is prone to bind with binders, having the potential to improve the creep resistance of PBXs. Due to the strong interfacial enhancement by UPy and PDA, the tensile strength and compressive strength of the sample grafted with 1 wt.% UPy significantly increased by 35.6% and 26.5%, respectively. Theoretical calculations indicate interfacial enhancement by UPy introduction, where the strong hydrogen bonding may produce a positive impact. The successful introduction of UPy modified the nature of TATB and improved its interfacial strength, finally enhancing the mechanical properties of the PBXs. The conditions for the grafting reaction in this study are mild and universal and thus can be applied to other compositions.