聚多巴胺仿生改性HMX降感和界面增强的双重效应及其作用机制

The development of advanced weapon requires the PBXs (polymer bonded explosives) based on HMX with both high energy and safety. Because of their great values and applications in weapon systems and national defense, there is a growing research interests in the PBXs with high safety. Desensitization for energetic material HMX and interfacial enhancement between HMX and modifying agents as well as between HMX and binder are the key effective approaches to improve the safety of PBXs. In this project, the bioinspired coating method will be introduced to energetic materials to modify HMX. The surface of HMX will be coated with the nano-scale polydopamine film, which could be thin, integrity, compact, robust and riched in active groups. The HMX with polydopamine coating could be less defects and more anchors for further reaction on the surfaces. In the stable output energe condition, the modified HMX will show synergistic effects for double-action of desensitization and interfacial enhancement. By accurate regulation of the polydopamine characteristics, the relaltions were established between the polydopamine characteristics and sensitivities of HMX as well as mechanical properties of the PBXs. Moreover, the mechanism for the double-action will be studied on the microstructures and molecular interactions of the twofold interfaces for HMX-polydopamine film and modified HMX-binder by the measurements, simulations and experiments, which will include the changes of the surface defects and heat dissipation performances for the modified HMX, chemical bonds between the modified HMX and binder, and the way of energy dissipation by the interfaces. The revealing mechamism will direct the designation and fabrication of the PBXs based on HMX with high safety. The study in this project has important significance for basic research and practical application values to optimize the performances of the PBXs.

先进武器系统的发展对高能HMX基PBX的综合安全性能提出了更高要求。通过HMX高效降感和增强HMX与改性剂及粘结剂的界面结合强度，从本质上提高其PBX综合安全性能显得至关重要。本项目将聚多巴胺仿生改性方法引入含能材料HMX的改性中，利用原位聚合包覆HMX的纳米级聚多巴胺膜的轻薄均匀、完整牢固及丰富活性基团等特点，保证高能量水平输出的前提下，实现HMX高效降感和界面增强双重效应的协同。本项目通过控制聚合反应条件精准调控改性HMX表面聚多巴胺膜的特性，在建立膜特性对HMX机械感度和PBX力学性能影响规律的基础上，结合聚多巴胺膜改性HMX基PBX体系中界面微观结构和分子间相互作用的测试表征、模拟计算和实验研究，分析界面对能量的耗散和传导行为，深入揭示聚多巴胺膜改性HMX实现高效降感和界面增强双重效应的作用机制，科学指导HMX基PBX的安全性能优化设计和制备，具有重要基础研究意义和实际应用价值。

通过对HMX表界面及HMX与粘结剂界面相互作用进行改性，可以实现HMX高效降感和提升PBX界面力学性能，对获得综合安全性更好的PBX、发展新一代高能安全弹药具有重要意义。.本项目利用聚多巴胺的粘附性、成膜性以及表面丰富的活性基团，对HMX进行了表面改性，研究了聚多巴胺膜特性对HMX降感和界面力学增强的影响规律，获得了其降感和界面增强的作用机制。首先，对聚多巴胺反应条件进行单项分解，获得了控制成膜特性的关键条件、成膜质量对机械感度的影响规律。进一步地，针对多巴胺聚合反应较慢效率较低的问题，开发了氧化剂催化快速制备聚多巴胺包覆HMX的方法，获得的HMX@PDA颗粒表面能有所提高，摩擦感度降为40 %，特性落高提升至64 cm，具备了公斤级的制备能力。通过对PDA与HMX间的相互作用进行模拟计算，发现HMX与PDA之间存在较强的界面作用，可以减弱改性颗粒的硬度和刚性，提高其延展性和塑性。通过对晶体撞击过程进行高速摄影，发现PDA包覆可以降低样品点火后反应的剧烈程度，阻碍反应传播，揭示了PDA对HMX晶体降感的作用机制。其次，通过对HMX@PDA样品对树脂的浸润性、药浆流变性、PBX药柱力学性能、药柱拉伸及切削断裂界面进行分析，发现聚多巴胺改性后HMX样品对树脂浸润性更好，药浆流变性更好，药柱力学性能有所提高，应力增大约12%，破坏功提高约32%，主要是由于PDA与粘结剂之间形成了非共价键，从而提高了炸药与粘结剂之间的相互作用。最后，利用聚多巴胺表面丰富的活性基团，将TiO2纳米催化剂均匀键合在HMX表面，提高了催化剂与HMX颗粒的接触面积和催化活性位点，达到高效催化其分解的目的，分解温度降低60℃，分解峰温度降低了35℃。.通过本项目的研究，明确了PDA成膜特性及其对HMX降感和界面增强作用的影响规律和作用机制，提供了快速、大规模制备表面改性炸药晶体的方法，为安全弹药用不敏感炸药提供更钝感的单质晶体及改性方法。