Synthesis,Structure And Properties Of Triazole Energetic Coordination Polymers Modulated By No₃^- Ions

In order to reconcile the contradiction between high energy and insensitivity of energetic coordination polymers（ECPs）,and obtain ECPs with excellent detonation performance and stronger stability,in this paper,there are eight new ECPs were constructed by introducing the energetic NO₃^-anion,neutral nitrogen-rich 1,3,5-tris（triazol-1-yl）benzene ligand and Co（Ⅱ）,Zn（Ⅱ）,Ni（Ⅱ）,Cu（II）,Fe（II）and Mn（II）ions:{[Co（TTB）（NO₃）₂]·CH₃CN}_n（1）,{[Zn（TTB）（NO₃）₂]·CH₃CN}_n（2）,{[Ni（TTB）（NO₃）₂]·DMF}_n（3）,{[Cu₆（TTB）₂（CN）₆]·CH₃CN}_n（5）,{[Fe₃（TTB）₄（NO₃）₂]·4NO₃}_n（7）,{[Ni（TTB）₂（H₂O）₂]·2NO₃}_n（4）,{[Cu（TTB）（NO₃）₂]·CH₃CN}_n（6）,{[Mn（TTB）（NO₃）₂]·CH₃CN}_n（8）.Their structures and properties were discussed as follows:（1）The spatial structures and compositions of eight ECPs were determined by means of X-ray single crystal diffraction,elemental analysis and infrared spectroscopy.Their structures and preparation processes were analyzed.Eight ECPs showed different coordination characteristics and spatial configurations.Seven ECPs were regulated by NO₃^-,while one ECP was regulated by CN^-generated via the decomposition of acetonitrile during the synthesis.ECPs 1-6 and 8were two-dimensional layered structures.In the contrast,ECP 7 was a three-dimensional network structure.The three triazole rings of the ligand TTB were involved to constructed energetic coordination polymers with multidimensional space structure with various degrees of torsion occur in the coordination process.From the analysis of the experimental conditions in the preparation process of the ECPs,it can be seen that the ECPs are more easily obtained by using acetonitrile as the solvent under solvothermal conditions.Different solvent systems can change the structure of the ECPs.（2）The thermal decomposition behavior of eight ECPs were tested by thermogravimetric analyzer and differential scanning calorimeter.From the analysis of TG-DSC curves,it can be seen that the thermal decomposition temperature of ECPs 1-8 were higher than 200℃,and their thermal stability is great.Except for ECP 7,the TG curves of other ECPs showed a rapid weight loss process,indicating that the decomposition process of the ECPs experienced a strong exothermic stage,and the energy was released in a concentrated manner.The kinetics of thermal decomposition process of ECPs were studied by Kissinger and Ozawa-Doyle equations.The apparent activation energies,pre-exponential factors and the corresponding Arrhenius equations of ECPs thermal decomposition process were obtained.（3）Density functional theory was used to estimate the explosion heat of ECPs.Meanwhile,the detonation velocity and pressure of the ECPs were obtained by combining the Kamlet-Jacobs equation.The results showed that ECP 1 has excellent overall detonation properties,and the theoretical explosion heat value can reach up to 6.2771 kcal g^-1.The impact sensitivity and friction sensitivity test showed that ECPs 1-8 have insensitive properties.（4）The effects of eight ECPs on the combustion and decomposition process of AP and RDX were studied by DSC technology.It was found that ECPs 1-8 promoted the combustion and decomposition of AP.Among them,ECP 7 had the best promotion effect.ECP 6 had the best effect for improving the combustion performance of RDX.In addition,the non-model isoconversion method was used to further confirm that the combustion-promoting effect of ECP6 on AP was better than that of ECP 5.Furthermore,the kinetic equations of the low temperature decomposition stage of 5+AP and 6+AP were obtained.