Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (7): 1722-1726.doi: 10.3866/PKU.WHXB2016032807

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Investigation of Interfaces of Ionic Liquid via Kelvin Probe Force Microscopy at Room Temperature

Xiao-Ning ZHANG1,*(),Hong-Mei HU2   

  1. 1 Department of Mathematics, Sciences and Technology, Paine College, Augusta 30901, Georgia, USA
    2 Key Laboratory of Mariculture and Enhancement of Zhejiang Province, Marine Fishery Institute of Zhejiang Province, Zhoushan 316021, Zhejiang Province, P. R. China
  • Received:2015-12-25 Published:2016-07-08
  • Contact: Xiao-Ning ZHANG
  • Supported by:
    the National Science Foundation, USA(HRD-1505197)


The alignment of the ionic liquid (IL) cation and anion at the interface is of interest because it would affect the surface structures and properties of IL at the interfaces. In this study, Kelvin probe force microscopy (KPFM), a scanning probe microscopy technique, was used to investigate the interfacial properties of the IL at room temperature. A model molecule, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), was selectively assembled on the lyophilic chemical patterns prepared on a substrate, forming ultrathin solid-like adsorbate layers and droplets. Because the surface potential is a direct indicator of the surface dipole, which is useful for examining molecular orientation, the surface potential maps captured by KPFM indicated that the [Bmim]Cl molecules demonstrated different orientations at the gas-liquid interface (in the form of a droplet) and at the gassolid interface (in the form of a solid-like adsorbate layer). Our results indicate that KPFM has potential for the characterization of IL molecular alignment at interfaces.

Key words: Kelvin probe force microscopy, 1-Butyl-3-methylimidazolium chloride, Surface potential, Ionic liquid molecular arrangement, Interface


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