Enhancement of mechanical properties of TATB-based polymer bonded explosive by surface grafting polymer brushes

Improving the interfacial interaction between explosive crystals and the polymeric binder was essential for enhancing the mechanical properties of polymer bonded explosives (PBXs). In this study, the surface of the 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystal was initially coated with a polydopamine (PDA) layer, which served as an active platform for anchoring the 2-bromoisobutyryl bromide as an ATRP initiator; then, the co-polymer chains composed of Acrylonitrile(AN), 2-Hydroxyethyl methacrylate (HEMA) and 2-(Dimethylamino)ethyl methacrylate (DMAEMA) were grown through surface-initiated atom transfer radical polymerization (SI-ATRP) from the surface of TATB modified with ATRP initiator. The formation of the PDA, ATRP initiator and polymer brush coating layer on the surface of TATB was confirmed through SEM, TEM, XPS and contact angle tests. After incorporating a rigid-flexible gradient interface structure composed of PDA and polymer brush layer, the PBXs exhibited enhanced mechanical strength and creep resistance. Compared with the pristine TATB-based PBXs, the static mechanical properties, including tensile and compressive strength, of TATB@PDA@PAN-co-PHEMA-co-PDMAEMA based PBXs were increased by 36.7% and 23.9%, respectively. The maximum creep strain decreased by 39.4% at 30 °C and 14.6% at 75 °C. Additionally, the coefficient of thermal expansion decreased by 8.37%. This study presents an universal method for enhancing the mechanical properties of PBX by integrating PDA chemistry with SI-ATRP.