Host–guest energetic materials: a promising strategy of incorporating small insensitive molecule into the lattice cavities of 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane to enhance the safety on the premise of maintaining the excellent energy density

Abstract

Crystal density is one of the crucial properties that should be pursued in developing novel high energy density materials (HEDMs) since it can obviously affect the detonation performance of energetic materials. However, the dense packing of sensitive HEDM molecules can seriously increase the unpleasant mechanical sensitivity. Here, the host–guest intermolecular explosives showed a promising potential to resolve this inherent contradiction of famous high explosive 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW) by self-assembly with insensitive methanoic acid (MA) under environmental conditions. Based on the perfect space matching between MA and lattice cavities of HNIW, the crystallographic density of HNIW-MA has exceeded the gold standard regarding the density of HEDMs and was determined to be 2.003 g cm⁻³ at 296 K. More importantly, the safety performance of HNIW-MA was improved while maintaining high crystal density due to the regulation by a small amount of insensitive guest molecules. Experimental results have shown the H₅₀ of HNIW-MA was 20.8 cm, which is significantly higher than that of α-HNIW of 14.8 cm and ε-HNIW of <14.1 cm.