1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 2Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061 3Graduate School of the Chinese Academy of Sciences, Beijing 100049
Morphology and Wettability of [Bmim][PF6] Ionic Liquid on HOPG Substrate
1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 2Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061 3Graduate School of the Chinese Academy of Sciences, Beijing 100049
We investigate the morphology and wettability of [Bmim][PF6] ionic liquid (IL) on a highly oriented pyrolitic graphite (HOPG) substrate using atomic force microscopy. Thin films, nanometer-sized droplets, and "drop-on-layer'' structures of the IL are found on the substrate. Films with a thickness of up to 2 nm (about 4 IL layers) show the solid-like behavior. In contrast, a dewetting phenomenon is observed for thicker IL films, indicating that the IL films retain liquid properties. The contact angle of a buck IL droplet on the HOPG is measured to be about 35º. The wettability of the bulk IL droplet on the HOPG is found to be quite different from that of IL films. These results indicate that the IL molecules can be organized into various micro-morphologies when they are confined to a solid substrate and show characteristic behavior at nanometer scales.
We investigate the morphology and wettability of [Bmim][PF6] ionic liquid (IL) on a highly oriented pyrolitic graphite (HOPG) substrate using atomic force microscopy. Thin films, nanometer-sized droplets, and "drop-on-layer'' structures of the IL are found on the substrate. Films with a thickness of up to 2 nm (about 4 IL layers) show the solid-like behavior. In contrast, a dewetting phenomenon is observed for thicker IL films, indicating that the IL films retain liquid properties. The contact angle of a buck IL droplet on the HOPG is measured to be about 35º. The wettability of the bulk IL droplet on the HOPG is found to be quite different from that of IL films. These results indicate that the IL molecules can be organized into various micro-morphologies when they are confined to a solid substrate and show characteristic behavior at nanometer scales.
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