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SUMMARY:Ionic Liquids Confined to Thin Films: Structure and Lubricity - Su
 san Perkin\, Dept of Chemistry\, University College London
DTSTART:20120517T103000Z
DTEND:20120517T113000Z
UID:TALK37687@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:Room temperature ionic liquids (ILs) are salts in the liquid s
 tate under ambient conditions. Recently many stable and benign ILs have be
 en developed\, and these present new possibilities as electrolytes in appl
 ications such as solar cells\, supercapacitors (double-layer capacitors)\,
  fuel cells and electro-actuators. The structure of ILs at interfaces is n
 ot yet well understood because the standard theories used to explain the n
 ature of dilute electrolytes do not apply at such high ion concentrations.
  I will present recent measurements of the interaction force between atomi
 cally smooth solid surfaces across confined films of ILs which reveal stru
 ctural and dynamic characteristics. We observe oscillatory 'structural for
 ces’ due to a layered arrangement of ions at the surfaces. By changing t
 he nature of the cation\, it is possible to alter the layer structure from
  alternate cation-anion ‘stripes’ to cation ‘bilayers’ in toe-to-t
 oe orientation1. We have measured the viscosity and lubrication characteri
 stics of these films as a function of their thickness\, with sub-molecular
  resolution down to a single ion layer\, demonstrating strikingly low fric
 tion coefficients between the surfaces and ‘quantized’ friction coeffi
 cients dependent on the number of ion layers in the film2\, 3. 
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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