Study On Two-Dimensional Confined Self-Assembly Construction And Formation Mechanism Of Energetic Materials

The crystal morphology of the energy material has a significant effect on its safety,mechanical and detonation properties.it is difficult to directionally adjust the crystal morphology of the energy material by conventional crystallization method.Therefore,the development of the new directional adjustment method of crystal morphology is important,which by altering the morphology,particle size and crystal orientation to adjust the properties of explosive crystal and used to prepare the explosive grains with different purposes.The morphological directional regulation method of explosives crystals was studied by experimental and theoretical method in this paper,including physically confined solvent recrystallization method,additive-induce recrystallization method,and recrystallization from thermal sublimation deposition.The explosive crystals with controllable morphology are prepared and its growth mechanism is explored.The main research contents are as follows:(1)Plate-like ?-HMX crystals are grown on the hydroxylated substrate using a crystallization technique combining physical limiting and solvent-antisolvent method.The obtained crystals have been investigated by X-ray diffraction(XRD),Raman spectroscopy,and atomic force microscopy(AFM).The experimental results indicate that the most morphological important face of the plate-like ?-HMX crystal is the(Oil)face adopting a layer-by-layer growth mode.Meanwhile,molecular dynamics(MD)simulations were performed to study the morphology of HMX crystal growth on the hydroxylated substrate based on modified attachment energy(MAE)model.The calculated results show that the major face is the(011)face and the interaction energies between the crystal face and the hydroxylated substrate are in the order of(011)>(110)>(020),which agree well with experimental results above.(2)HMX crystals are recrystallized using an additive-induce recrystallization method.The effects of additives cetyltrimethylammonium bromide(CTAB),sorbitan oleate(SP-80),and polyethyleneimine(PEI)on the morphology of HMX crystals in acetone(AC)solvent were studied.The experimental results show that the additive CTAB has a significant effect on the crystal morphology of HMX.Meanwhile,the MAE model is used to predict the crystal morphology of HMX under the action of different additives.The calculated results indicate that the aspect ratio of the HMX crystal morphology under the action of the additives CTAB is smaller than that of the other two additives.It is theoretically explained that the additive CTAB has a significant effect on the morphology of HMX crystal.(3)Recrystallization of Plate-like a-RDX crystals on the substrate by thermal sublimation deposition.The effect of the substrate on the crystal morphology of RDX is studied.The obtained crystals have been investigated by Single crystal X-ray diffraction,Raman spectroscopy,and Atomic force microscopy(AFM).The experimental results show that quadrilateral plate-like a-RDX crystals can be obtained on the surface of MgO(110)substrate,and the most morphological important face of the plate-like a-RDX crystal is the(100)face adopting a layer-by-layer growth mode.Meanwhile,the force field method were performed to study the morphology of RDX crystals growth on the MgO(110)substrate.The calculated results show that the favorable attachment surface of the RDX crystals on the MgO(110)substrate is(100)face based on the energy change(?E),which agree well with experimental results above.