Design Of Insensitive High-energy Cocrystal Energetic Materials Based On Nitroguanidine

Cocrystallization has attracted considerable interest in energetic material field recently due to the anxious demand of insensitivity high-energy explosives. CL-20 and HMX are two high energy explosives, whereas they have failed to see widespread implementation due to the high mechanical sensitivity. In order to improve their safety, two cocrystals of CL-20/NQ and HMX/NQ are designed successively with insensitivity component explosive NQ based on the formation rule of supramolecular and cocrystal in this paper. Density functional theory and molecular dynamics method are employed to investigate their structure, performance, molecular ratio and polymorph. These studies will provide the new method and idea for the design of insensitivity high-energy cocrystal energetic materials. Follows are the main works in this paper.(1) Optimization complex structures of CL-20/NQ and HMX/NQ are designed based on the formation rule of supramolecular. The analyses of electron density topological, reduced density gradient, electric charge transfer and natural bond orbital are used to investigate the energy and intermolecular interaction. Results suggest that the two cocrystals are formed by a series hydrogen bonds of N–H···O, C–H···O, or C–H···N and a few vd Ws of O···O or N···O. And the result has been confirmed by several former analyses. Moreover, comparing the results of energy and reduced density gradient, it can be found that the intermolecular interaction in HMX/NQ cocrystal is larger than that in CL-20/NQ cocrystal, that is, the former in the structure is much easier to form cocrystallization.(2) The analyses of trigger bond and molecular electrostatic potential are employed to predict the sensitivity and detonation velocity. Result indicates that the sensitivity of CL-20/NQ cocrystal is lower than isolated CL-20 component. The detonation velocity is larger than the isolated HMX component. Additionally, the sensitivity of HMX/NQ cocrystal is lower than isolated HMX component. The detonation velocity is much larger than the isolated NQ component.(3) Different molecular ratios of CL-20/NQ and HMX/NQ cocrystal model are designed based on the cocrystal rule. And their binding energy, radial distribution function and mechanical property are investigated. Results show that the cocrystal has the lager binding energy and more interaction in the ratios of 5:7 and 1:1(CL-20: NQ). However, the ratio of 5:7 in the mechanical property presents not well, which has the uncertainty for sensitivity. Moreover, result also shows that HMX/NQ cocrystal in the 1:1 can have lager binding energy, hydrogen bond interaction and better mechanical properties.(4) Considering the better composite structure and molecular ratio of two kind cocryatl explosives, the crystal structure is predicted by Polymorph Predictor method. Results suggest that the most possible crystal form of CL-20/NQ cocrystal is monoclinic(P21/c space group), a = 1.398 nm, b = 1.409 nm, c = 0.952 nm, α = γ = 90.00°, β = 93.85°, V = 1.871nm3, Z = 4. The most possible crystal form of HMX/NQ cocrystal is monoclinic(P21 space group), a = 2.264 nm, b = 0.420 nm, c = 0.798 nm, α = γ = 90.00°, β = 103.00°, V = 0.739nm3, Z = 2.