The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced ...The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.展开更多
Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity.The emergence of co-crystal explosives is a new opportunity to change this situa...Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity.The emergence of co-crystal explosives is a new opportunity to change this situation.If the co-crystal explosive is coated into spherical particles with uniform particle size distribution,this contradiction can be further reduced.Therefore,binder-coated hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene(CL-20/TNT)co-crystal microspheres were prepared by droplet microfluidic technology in this work.The coating effects of different binder formulations of nitrocellulose(NC)and NC/fluorine rubber(F2604)on the co-crystal spheres were studied.The scanning electron microscopy(SEM)results showed that the use of droplet microfluidic technology with the above binders can provide co-crystal microspheres with regular spherical morphology,uniform particle size distribution and good dispersion.X-ray diffraction(XRD),fourier-transform infrared(FT-IR),differential scanning calorimetry(DSC)and thermo-gravimetric(TG)methods were employed to compare the properties of the co-crystal microspheres,raw material and pure co-crystal.The formation of CL-20/TNT co-crystal in the microspheres was confirmed,and the co-crystal microspheres exhibited better thermal stability than the raw material and pure co-crystal.In addition,the mechanical sensitivity and combustion performance of the co-crystal microspheres were further studied.The results showed that the co-crystal microspheres were more insensitive than CL-20 and pure co-crystal,and displayed excellent self-sustained combustion performance and theoretical detonation performance.This study provides a new method for the fast,simple and one-step preparation of CL-20/TNT co-crystal microspheres,with binder coating,uniform particle size distribution,and excellent performance level.展开更多
To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitro...To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.展开更多
利用溶液挥发法首次合成1个全新的木犀草素-4,4'-联吡啶药物共晶,并通过红外光谱、核磁共振、X射线粉末衍射及差示扫描热量分析等对其表征。选择不同物质量比的木犀草素与4,4'-联吡啶及不同反应溶剂为主要影响因素,探索并确定...利用溶液挥发法首次合成1个全新的木犀草素-4,4'-联吡啶药物共晶,并通过红外光谱、核磁共振、X射线粉末衍射及差示扫描热量分析等对其表征。选择不同物质量比的木犀草素与4,4'-联吡啶及不同反应溶剂为主要影响因素,探索并确定相应合成条件:木犀草素和4,4'-联吡啶以13的物质量比混合后溶于7.0 m L丙酮溶剂,25℃下搅拌3 h后,于室温下挥发,5 d后得到黄褐色粉末状晶体。结果表明,在极性相对较小的溶剂体系中,反应物分子间形成数目合适且方向饱和的氢键连接,可有效促进药物共晶生成。展开更多
基金Defense Research&Development Organization(DRDO),India for financial support towards this study。
文摘The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.
基金National Natural Science Foundation of China(Grant No.22005275)to provide fund for conducting experiments。
文摘Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity.The emergence of co-crystal explosives is a new opportunity to change this situation.If the co-crystal explosive is coated into spherical particles with uniform particle size distribution,this contradiction can be further reduced.Therefore,binder-coated hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene(CL-20/TNT)co-crystal microspheres were prepared by droplet microfluidic technology in this work.The coating effects of different binder formulations of nitrocellulose(NC)and NC/fluorine rubber(F2604)on the co-crystal spheres were studied.The scanning electron microscopy(SEM)results showed that the use of droplet microfluidic technology with the above binders can provide co-crystal microspheres with regular spherical morphology,uniform particle size distribution and good dispersion.X-ray diffraction(XRD),fourier-transform infrared(FT-IR),differential scanning calorimetry(DSC)and thermo-gravimetric(TG)methods were employed to compare the properties of the co-crystal microspheres,raw material and pure co-crystal.The formation of CL-20/TNT co-crystal in the microspheres was confirmed,and the co-crystal microspheres exhibited better thermal stability than the raw material and pure co-crystal.In addition,the mechanical sensitivity and combustion performance of the co-crystal microspheres were further studied.The results showed that the co-crystal microspheres were more insensitive than CL-20 and pure co-crystal,and displayed excellent self-sustained combustion performance and theoretical detonation performance.This study provides a new method for the fast,simple and one-step preparation of CL-20/TNT co-crystal microspheres,with binder coating,uniform particle size distribution,and excellent performance level.
基金supported by the National Natural Science Foundation of China (22275018)the Project of State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology)(Grant No.QNKT20-04)。
文摘To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.
文摘利用溶液挥发法首次合成1个全新的木犀草素-4,4'-联吡啶药物共晶,并通过红外光谱、核磁共振、X射线粉末衍射及差示扫描热量分析等对其表征。选择不同物质量比的木犀草素与4,4'-联吡啶及不同反应溶剂为主要影响因素,探索并确定相应合成条件:木犀草素和4,4'-联吡啶以13的物质量比混合后溶于7.0 m L丙酮溶剂,25℃下搅拌3 h后,于室温下挥发,5 d后得到黄褐色粉末状晶体。结果表明,在极性相对较小的溶剂体系中,反应物分子间形成数目合适且方向饱和的氢键连接,可有效促进药物共晶生成。
