不对称修饰氟化石墨烯原位增强聚酰亚胺减摩抗磨行为研究

Polyimide (PI) has excellent film forming characteristic and thermal stability, while pure PI cannot be applied directly as anti-wear material due to its high friction coefficient, strong wear rate and insufficient compression strength. Fluorinated graphene (FG) with high mechanical properties, low surface energy and good self-lubricity can be applied in PI matrix, however, the adhesion between the FG and the PI matrix is weak. It is urgent to find the way of keeping the low surface energy of the FG and enhancing the adhesion between the FG and the PI matrix simultaneously, which can effectively improve the tribological properties of the PI. In this project, it is proposed to cap the FG on the water-soluble polyacrylamide microspheres by self-assembling method, then modify the capped FG to obtain the asymmetric modified FG (AFG), and use AFG to enhance the anti-wear and friction-reducing performance of the PI. Meanwhile, we plan to explore the decentralized drive mechanism and interface interaction between the AFG and the PI matrix, elucidate the tribological enhancement effect and structure-active relationship of the AFG/PI composites, establish the corresponding physical model, and guide the investigation on friction behavior and mechanism of the FG enhanced PI composites.

聚酰亚胺（PI）具有良好的成膜性和热稳定性，但摩擦系数高、磨损率大、抗压强度不足；氟化石墨烯（FG）机械强度高、表面能低、自润滑性能好，但其与PI基体间的界面相互作用弱。如何确保FG拥有低表面能的同时，增强其与PI基体间的界面相互作用，从而将FG的自润滑性能和其对PI基体的增强作用相统一而改善PI的摩擦学性能是亟待解决的问题。本项目拟通过自组装法将FG包覆在水溶性聚丙烯酰胺微球表面，并化学修饰得到不对称修饰FG；而后利用不对称修饰FG原位增强PI的减摩抗磨性能，着重研究不对称修饰FG在PI基体中的分散驱动机制及二者之间的界面相互作用关系，阐明不对称修饰FG对PI摩擦学性能的增强机制及其构效关系，建立相应的物理模型，为FG增强PI摩擦学行为和机理方面的研究提供指导。

聚酰亚胺（PI）是指分子主链上含有酰亚胺环的一类聚合物，其优异的力学和热稳定等性能使其成为应用范围最广的一种聚合物。但是，随着航空和航天工业对高比模量、比强度、耐温和抗磨材料的需求，单一组分的PI已经很难满足新型器件对材料的要求，各种PI复合材料应运而生。该项目着重研究了氟化石墨烯等纳米材料的摩擦学性能及其增强的聚酰亚胺复合材料的摩擦学性能，其主要研究内容如下：1）项目成功合成了聚丙烯酰胺微球和氟化石墨烯纳米片，但是二者之间的吸附力较弱，难以在搅拌和超声下维持吸附状态，因此未能实现“先包覆后修饰”的修饰策略，即未能通过先将氟化石墨烯包覆在聚丙烯酰胺微球表面，而后化学修饰氟化石墨烯得到单面修饰的氟化石墨烯；2）选取了硫代乙酰胺和尿素等化学试剂作为修饰试剂直接与氟化石墨烯表面的C-F键发生化学反应，成功得到了硫化氟化石墨烯和氨基化氟化石墨烯；将氟化石墨烯、硫化氟化石墨烯和氨基化氟化石墨烯分别作为填料增强了聚酰亚胺的机械和摩擦学性能，并揭示了相关力学变化规律和摩擦磨损机理；3）使用酸、碱和多种有机试剂成功修饰了氟化石墨烯，得到了可分别在水中和润滑油中的均匀分散的功能化氟化石墨烯，研究了其摩擦学性能，并揭示了相关摩擦学机理；4）本项目还研究了聚丙烯酰胺微球、碳纳米管、聚氨酯等物质的摩擦学性能和减摩抗磨机理。