ACS applied materials & interfaces | 2019
Litchi-like Core-Shell HMX@HPW@PDA Microparticles for Polymer-Bonded Energetic Composites with Low Sensitivity and High Mechanical Properties.
Abstract
The reduction of interfacial interaction and the deterioration of mechanical properties by the introduction of the indispensable paraffin wax is a long-standing problem. To address it, a novel litchi-like core-shell 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX)@paraffin wax@polydopamine (PDA) structure was constructed with a new high melting point paraffin wax (HPW, 101.9 °C) as the inner shell and the bio-inspired strong adhesive PDA as the exterior shell. The evolution of element states on the surface of energetic microcapsules conducted by X-ray photoelectron spectroscopy (XPS) indicated that the successful introduction of paraffin wax and PDA to form the core@double shell structure. Compared with the core@double shell particles based on the conventional low melting point paraffin wax (LPW, 69.8 °C), the HMX@HPW@PDA particles demonstrated a 120% increase of impact energy EBAM from 5 J (raw HMX) to 11 J by Bundesanstalt für Materialprüfung (BAM) method. Attributed to the stronger interfacial interaction, the litchi-like core-shell HMX@paraffin wax@PDA based energetic composites also exhibited much superior mechanical properties than that of the corresponding HMX@paraffin wax based ones and could be equaled to or even higher than that of the raw HMX based ones. In addition, the β-δ phase transition temperature of HMX in HMX@HPW@PDA crystals was improved by 11.3 °C than that of raw HMX. The simplicity and scalability of the described approach provided a creative opportunity for design and fabrication of energetic composites with high safety performance and mechanical properties.