Chen Liping, Ge Lingling, Fan Lei, Guo Rong
School of Chemistry and Chemical Engineering , Yangzhou University , Yangzhou 225002 , P. R. China.
Department of Chemical Engineering , Yangzhou Polytechnic Institute , Yangzhou 225127 , P. R. China.
Langmuir. 2019 Mar 19;35(11):4037-4045. doi: 10.1021/acs.langmuir.8b04144. Epub 2019 Mar 6.
Lamellar liquid crystals (LLCs) have been shown to have lubrication properties in many documents due to their bilayer structure. Ionic liquids are often used as additive or surfactant in LLCs. However, ionic liquids used as cosurfactants, which lead to a transition from the hexagonal liquid crystals to LLCs, are relatively rare. Herein, the microstructure of Triton X-100/C mimNTf/HO LLCs formed by using 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid (C mimNTf, n = 8, 12, 16) as cosurfactant has been determined by polarized light microscopy, small angle X-ray scattering, and H NMR technique, and their rheological and tribological properties were investigated. These LLCs show good friction-reducing and antiwear performances. The correlation between the microstructure of the LLCs and their lubricating mechanism is established. The increase of the concentration of C mimNTf and the length of alkyl chain in the LLCs can lead to an obvious reduction in friction coefficients and wear volumes, which are attributed to the higher order of amphiphilic molecules, the thickness of the amphiphilic bilayer, and the smaller cross-sectional area of the polar head group at the hydrophilic and hydrophobic interfaces. The protective film formed by the physical adsorption of ionic liquid LLCs on the surface of friction disk pair and the tribochemical reaction has effectively promoted the lubrication effect. The good lubricating property and antiwear capability indicate their promising and potential applications in water lubrication and biological lubrication.
层状液晶（LLCs）由于其双层结构，在许多文献中已显示出具有润滑性能。离子液体常被用作层状液晶中的添加剂或表面活性剂。然而，用作助表面活性剂导致从六方液晶转变为层状液晶的离子液体相对较少。在此，通过偏光显微镜、小角X射线散射和核磁共振技术确定了以1-烷基-3-甲基咪唑双（三氟甲基磺酰）亚胺离子液体（C mimNTf，n = 8、12、16）作为助表面活性剂形成的Triton X-100/C mimNTf/HO层状液晶的微观结构，并研究了它们的流变学和摩擦学性质。这些层状液晶表现出良好的减摩和抗磨性能。建立了层状液晶的微观结构与其润滑机制之间的相关性。层状液晶中C mimNTf浓度的增加和烷基链长度的增加可导致摩擦系数和磨损体积明显降低，这归因于两亲分子的更高有序度、两亲双层的厚度以及亲水和疏水界面处极性头基团的较小横截面积。离子液体层状液晶在摩擦盘副表面物理吸附形成的保护膜以及摩擦化学反应有效地促进了润滑效果。良好的润滑性能和抗磨能力表明它们在水润滑和生物润滑方面具有广阔的应用前景和潜力。
