Insight Into the Superlubricity and Self-Assembly of Liquid Crystals

Shanchao Tan; Jiayu Tao; Wendi Luo; Hongyu Shi; Bin Tu; Hao Jiang; Yuhong Liu; Haijun Xu; Qingdao Zeng

doi:10.3389/fchem.2021.668794

Insight Into the Superlubricity and Self-Assembly of Liquid Crystals

Front Chem. 2021 Jun 11:9:668794. doi: 10.3389/fchem.2021.668794. eCollection 2021.

Authors

Shanchao Tan^{1

2}, Jiayu Tao³, Wendi Luo⁴, Hongyu Shi^{1

2}, Bin Tu⁴, Hao Jiang³, Yuhong Liu¹, Haijun Xu^{3

5}, Qingdao Zeng^{2

6}

Affiliations

¹ State Key Laboratory of Tribology, Tsinghua University, Beijing, China.
² Chinese Academy of Sciences (CAS) Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, China.
³ Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China.
⁴ Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Ambient Particles Health Effects and Prevention Techniques, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, China.
⁵ School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, China.
⁶ Center of Materials Science and Optoelectonics Engineering, University of Chinese Academy of Sciences, Beijing, China.

Abstract

Liquid crystals are promising molecular materials in the application of lubrication. Herein, the microscale solid superlubricity is accomplished by the construction of uniform and ordered self-assembly of several liquid crystals. The self-assembly structures on a highly oriented pyrolytic graphite (HOPG) surface are explicitly revealed by using scanning tunneling microscopy (STM). Meanwhile, the nanotribological performance of the self-assemblies are measured by using atomic force microscopy (AFM), revealing ultralow friction coefficients lower than 0.01. The interaction energies are calculated by density functional theory (DFT) method, indicating the positive correlation between friction coefficients and interaction strength. The effort on the self-assembly and superlubricity of liquid crystals could enhance the understanding of the nanotribological mechanism and benefit the further application of liquid crystals as lubricants.

Keywords: interaction strength; liquid crystal; nanotribology; self-assembly; superlubricity.