Zhang Lin, Ren Yilong, Peng Shiguang, Guo Dan, Wen Shizhu, Luo Jianbin, Xie Guoxin
State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
Nanoscale. 2019 Apr 25;11(17):8237-8246. doi: 10.1039/c9nr00767a.
Core-shell nanospheres have been widely used in catalysis, batteries, medicine, etc. owing to their unique structural characteristics, which exhibit optimal performance and integrated functions of both the core and shell materials. To simultaneously achieve outstanding mechanical properties and remarkable lubrication properties in desirable polymer composites, core-shell nanospheres with polytetrafluoroethylene (PTFE) as the core and poly methyl methacrylate (PMMA) as the shell have been adopted as structural units to form bulk nanocomposites. We demonstrated that the mechanical and lubrication properties of the nanocomposites prepared using core-shell nanospheres as the continuous matrix were dramatically improved. Specifically, when compared with that of pure PTFE, the compressive strength of the PTFE@PMMA nanocomposite obviously increased up to one order of magnitude (from ∼9 to ∼90 MPa), the friction coefficient reduced to 25% (the lowest value was 0.03), and the wear rate decreased up to two orders of magnitude. Moreover, the mechanical and lubrication properties of the nanocomposites could be adjusted by changing the core-shell ratio, and an appropriate core-shell ratio was beneficial for achieving the desired comprehensive properties. It has been proposed that the properties, such as the confinement effect, improved dispersion capacity, etc., imparted by the core-shell structure effectively lead to high dispersion of the reinforcement phase, improvement of the binding force of the transfer film to the friction surface, and interruption of the wear process of the polymer composite.
核壳纳米球由于其独特的结构特性，在催化、电池、医学等领域得到了广泛应用，这种结构展现了核材料和壳材料的最佳性能与综合功能。为了在理想的聚合物复合材料中同时实现出色的机械性能和显著的润滑性能，采用以聚四氟乙烯（PTFE）为核、聚甲基丙烯酸甲酯（PMMA）为壳的核壳纳米球作为结构单元来形成块状纳米复合材料。我们证明，以核壳纳米球作为连续基体制备的纳米复合材料的机械性能和润滑性能得到了显著改善。具体而言，与纯PTFE相比，PTFE@PMMA纳米复合材料的抗压强度明显提高了一个数量级（从约9MPa提高到约90MPa），摩擦系数降低到25%（最低值为0.03），磨损率降低了两个数量级。此外，纳米复合材料的机械性能和润滑性能可以通过改变核壳比来调节，合适的核壳比对实现所需的综合性能有益。有人提出，核壳结构赋予的诸如限域效应、改善分散能力等性能有效地导致增强相的高分散、转移膜与摩擦表面结合力的提高以及聚合物复合材料磨损过程的中断。
