Synthesis And Properties Of Energetic Materials Based On 2,5-Bis（Tetrazole） Terephthalic Acid

Four novel coordination polymers based on 2,5-bis-（2H-tetrazol-5-yl）terephthalic acid（H₄dtztp）ligands,namely[Mg（dtztp）_0.5（DMF）（H₂O）₂]·H₂O（1）,[Ba-（dtztp）_0.5（H₂O）₂]（2）,[Ca₄（dtztp）₂（H₂O）₁₀]·H₂O（3）and[Mn₂（dtztp）（H₂O）₆]·H₂O（4）,were synthesized by solvothermal and hydrothermal method.The structures of the complexes were characterized by elemental analysis,infrared spectroscopy and X-ray powder diffraction.In addition,their crystal structures were studied by X-ray single crystal diffraction.Four complexes belong to the triclinic system and P-1 space group.The thermal behaviors of four energetic complexes were investigated by differential scanning calorimetry（DSC）,their initial decomposition temperatures were 344°C,351°C,359°C and 361°C,respectively.The temperatures at which the main frame began to collapse were 260°C,380°C,204°C,and 310°C,respectively.The results showed that complex 2 had better thermal stability.Combined with the DSC test data at the four heating rates,the non-isothermal reaction kinetic parameters and the corresponding thermal decomposition reaction mechanism equations of the four energetic complexes were calculated by Kissinger’s and Ozawa’s methods.The thermal ignition temperature(T_TIT)and critical temperature（T_b）of the four complexes were calculated by the thermal decomposition initial temperature and decomposition peak temperature.Their thermal ignition temperature and critical temperature value were:336.75°C,413.05°C,189.04°C,375.21°C;355.88°C,427.16°C,238.56°C,382.17°C.Using thermal decomposition kinetic parameters,the activation entropy（ΔS^≠）,activation enthalpy（ΔH^≠）and activation free energy（ΔG^≠）of their thermal decomposition process were obtained by calculation,theΔG values of the four complexes were all greater than zero,which were non-spontaneous reactions,and none of them will spontaneously decompose spontaneously.It showed that these four energetic complexes had good thermal stability.The constant volume combustion heat of complexes 1-2 were measured by oxygen bomb calorimeter,and its standard formation enthalpy were calculated by Hess’s law.