Pickering乳液法构筑石墨烯薄膜及其对二硝酰胺铵吸湿性抑制机制研究

Ammonium Dinitramide (ADN) has been identified as an ideal novel oxidizer to be used for the development of the highly energetic propellants featured environmentally friendly and low signature. However, a critical challenge associated with the use of ADN lies in its high hygroscopicity, which leads to a significantly compromise in both the energy level and the storage life of the propellants. In this proposal, spherical ADN particles with excellent moisture resistance will be achieved through an encapsulation of impermeable graphene nanoplatelets on them in the Pickering emulsion. The effects of the edge crosslinking as well as the hydrophobic modification of graphene nanosheets on the hygroscopicity of ADN will be studied. Molecular dynamic simulation (MD) will be performed to explore the interfacial interactions between graphene coating layers and water molecules, which allows to correlate the water barrier performances and structural characteristics of graphene in molecular scale. Moreover, the influences of graphene multilayers on the thermal decomposition as well as the safety characteristics of spherical ADN will be evaluated, and the compatibility between the components of solid propellants and the graphene encapsulated ADN composites will also be studied, allowing for establishing experimental basis for their practical applications. The results of this project would provide both theoretical and technical supports for design and synthesis of ADN with excellent moisture resistance, and reveal great significance for developing high energetic, low signature and environmentally friendly propellant.

二硝酰胺铵（ADN）是研制绿色环保型、低特征信号推进剂理想的新型高能氧化剂。然而，ADN极强的吸湿性通常导致推进剂能量水平下降，贮存寿命缩短，这也是制约ADN在推进剂中应用的瓶颈问题。为了降低ADN的吸湿性，本项目拟通过Pickering乳液界面相互作用在球形ADN表面包覆超阻隔材料石墨烯纳米片，获得抗吸湿性能优异的ADN复合粒子；研究石墨烯边缘交联结构的构筑及表面疏水改性对ADN吸湿性的影响规律，并采用分子动力学模拟研究石墨烯包覆层与水分子的界面作用特性，从分子水平揭示材料的结构与性能关系；研究石墨烯对于ADN热分解性能、安全性能的影响，以及石墨烯包覆的球形ADN复合体系与推进剂组分相容性，为ADN复合材料的应用奠定基础。本项目的研究将为抗吸湿ADN复合材料的设计和合成提供理论和技术支撑，对发展绿色环保、低特征信号高能推进剂具有重要意义。

石墨烯超高的强度、韧性和阻隔性能等优点使其成为高能氧化剂二硝酰胺铵（ADN）理想的包覆材料，在降低ADN吸湿率的同时，能够有效改善推进剂的综合性能。如何将石墨烯薄膜包覆到球形ADN表面实现石墨烯的有效阻水，掌握石墨烯包覆层对ADN热分解性能、安全性能影响规律，阐明石墨烯包覆的ADN复合粒子与推进剂组分相容性是实现ADN复合材料在固体推进剂中该应用的重要挑战。.本项目采用反相Pickering乳液技术完成了多种石墨烯包覆ADN复合材料的制备及结构性能表征研究；掌握了氧化石墨烯表面双亲性调控方法，获得了可作为Pickering乳液界面稳定剂的双亲性氧化石墨烯，揭示了Pickering乳液多相质界面相互作用机制，明确了初始溶剂体积比、石墨烯稳定剂浓度、ADN溶质质量对与乳液类型、微观形态之间的关系；分别采用高温真空干燥和真空冷冻干燥两种方法驱除乳液溶剂，获得了石墨烯包覆的ADN复合粉体和石墨烯包覆的ADN气凝胶微球，开展了两种复合材料动态吸湿性能、热分解性能、激光点火性能、机械感度以及与推进剂常规组分相容性研究，发现通过石墨烯包覆，ADN吸湿率显著降低、机械感度降低、热分解温度降低、能量释放率提高、激光点火性能改善、与推进剂常规组分相容性良好。以上结果证明，基于反相Pickering乳液技术制备的石墨烯包覆ADN复合材料在固体推进剂中具备重要的应用前景。