Shi Hongyu, Lu Xinchun, Liu Yuhong, Song Jian, Deng Ke, Zeng Qingdao, Wang Chen
State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China.
CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology (NCNST) , Beijing 100190 , China.
ACS Nano. 2018 Aug 28;12(8):8781-8790. doi: 10.1021/acsnano.8b05045. Epub 2018 Aug 2.
Nanotribology has been given increasing attention by researchers in pursuing the nature of friction. In the present work, an approach that combines the supramolecular assembly and nanotribology is introduced. Herein, the nanotribological study was carried out on seven supramolecular template networks [namely, hydrogen bond induced tricarboxylic acids and van der Waals force induced hexaphenylbenzene (HPB) derivatives]. The template networks, as well as the host-guest assemblies of template molecules induced by different forces, were constructed on the highly oriented pyrolytic graphite (HOPG) surface and explicitly characterized using scanning tunneling microscopy (STM). Meanwhile, the nanotribological properties of the template networks were measured using atomic force microscopy (AFM). Together with the theoretical calculation using the density functional theory (DFT) method, it was revealed that the friction coefficients were positively correlated with the interaction strength. The frictional energy dissipation mainly derives from both the intermolecular interaction energy and the interaction energy between molecules and the substrate. The efforts not only help us gain insight into the competitive mechanisms of hydrogen bond and van der Waals force in supramolecular assembly but also shed light on the origin of friction and the relationship between the assembly structures and the nanotribological properties at the molecular level.
在探索摩擦本质的过程中，纳米摩擦学越来越受到研究人员的关注。在本工作中，引入了一种将超分子组装与纳米摩擦学相结合的方法。在此，对七个超分子模板网络（即氢键诱导的三羧酸和范德华力诱导的六苯基苯（HPB）衍生物）进行了纳米摩擦学研究。在高度取向热解石墨（HOPG）表面构建了模板网络以及由不同力诱导的模板分子的主客体组装体，并使用扫描隧道显微镜（STM）进行了明确表征。同时，使用原子力显微镜（AFM）测量了模板网络的纳米摩擦学性质。结合使用密度泛函理论（DFT）方法进行的理论计算，结果表明摩擦系数与相互作用强度呈正相关。摩擦能量耗散主要源于分子间相互作用能以及分子与基底之间的相互作用能。这些工作不仅有助于我们深入了解超分子组装中氢键和范德华力的竞争机制，还揭示了摩擦的起源以及分子水平上组装结构与纳米摩擦学性质之间的关系。
