三维纳米结构FOX-7的构筑与热分解性能

以具有三维纳米网格结构且可降解的聚缩醛胺气凝胶(PHA)作模板,采用蒸发结晶法,原位诱导1,1-二氨基-2,2-二硝基乙烯(FOX-7)结晶析出,得到FOX-7/PHA复合物,然后利用硫酸的稀溶液(10%)降解去掉模板,即可得到具有三维纳米结构的FOX-7(nano-FOX-7)。高效液相色谱(HPLC)测定nano-FOX-7的纯度为99%,说明模板基本去除完全。对样品的形貌、物相、结构和热分解性能进行了表征测试。结果表明,去模板后的nano-FOX-7较为完整地保留了模板PHA的三维纳米网络结构,其中FOX-7的平均晶粒尺寸为83.68 nm。与raw-FOX-7相比,特殊的纳米多孔结构使FOX-7的转晶峰和低温分解峰分别延后11.3℃和21.3℃,放热几乎集中在高温分解峰291.0℃处,分解焓从原料的1309 J·g-1增加到1421 J·g-1,表观活化能提高了128.62 kJ·mol^-1,增幅达31.46%,能量释放效率和热稳定性大幅提高。

Construction and Thermal Decomposition Properties of Three-dimensional Nanostructure FOX-7

The three-dimensional nanostructured and degradable polyhemiaminal aerogel (PHA) was used as template to induce the in situ crystallization of 1,1-diamino-2,2-dinitroethylene (FOX-7) by evaporation crystallization method. The FOX-7 with three-dimensional nanostructure (nano-FOX-7) was prepared after the degradation of the PHA in dilute sulfuric acid (10%). The purity of nano-FOX-7 was determined to be 99% by high performance liquid chromatography (HPLC), indicating that the template was almost completely removed. The morphology, phase, structure and thermal properties of the samples were characterized. Detemplated nano-FOX-7 preserved three-dimensional nano structure of PHA. The average size of nano-FOX-7 crystal particle was 83.68 nm. Owing to the special micro-nano structure, the peak temperature of phase transition and first thermal decomposition temperature for nano-FOX-7 was delayed by 11.3 °C and 21.3 °C, respectively. Compared with raw FOX-7, the thermal decomposition of nano-FOX-7 almost completely took at exothermal profile with peak of 291.0 °C. The enthalpy of the thermal decomposition increased from 1309 J·g^-1 (raw FOX-7) to 1421 J·g^-1 (nano-FOX-7), together with 31.6% increase of the apparent activation energy (from 408.80 kJ·mol^-1 to 537.42 kJ·mol^-1), which explained the remarkable improvement of the energy release efficiency and thermal stability for the nanostructure FOX-7.