Key Laboratory of Standardization and Measurement for Nanotechnology, the Chinese Academy of Sciences, National Center for Nanoscience and Technology, Beijing 100190, China.
Langmuir. 2011 Jun 21;27(12):7603-8. doi: 10.1021/la200983y. Epub 2011 May 23.
We report the study of electrowetting (EW) effects under strong electric field on poly(methyl methacrylate) (PMMA) surface by using friction force microscopy (FFM). The friction force dependence on the electric field at nanometer scale can be closely related to electrowetting process based on the fact that at this scale frictional behavior is highly affected by capillary phenomena. By measuring the frictional signal between a conductive atomic force microscopy (AFM) tip and the PMMA surface, the ideal EW region (Young-Lippmann equation) and the EW saturation were identified. The change in the interfacial contact between the tip and the PMMA surface with the electric field strength is closely associated with the transition from the ideal EW region to the EW saturation. In addition, a reduction of the friction coefficient was observed when increasing the applied electric field in the ideal EW region.
我们通过摩擦力显微镜（FFM）研究了强电场下聚甲基丙烯酸甲酯（PMMA）表面的电润湿（EW）效应。基于摩擦力在纳米尺度上受到毛细现象的强烈影响这一事实，摩擦力与电润湿过程之间存在密切关系，因此可以通过纳米尺度上的电场来密切相关地研究摩擦力对电场的依赖关系。通过测量导电原子力显微镜（AFM）探针和 PMMA 表面之间的摩擦信号，确定了理想的 EW 区域（杨氏-利珀曼方程）和 EW 饱和。探针与 PMMA 表面之间的界面接触随电场强度的变化与从理想 EW 区域到 EW 饱和的转变密切相关。此外，在理想的 EW 区域增加外加电场时，观察到摩擦系数降低。
