Browsing by Author "Tiddy, G. J. T."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Fluorocarbon Surfactant/Water Mesomorphic Phases Part: 1.—A Study of the Ammonium Perfluoro-octanoate+Water System by Optical Microscopy and Low Angle X-ray Diffraction
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (4), 1972) Tiddy, G. J. T.
    The phase diagram of ammonium perfluoro-octanoate+water has been determined over the temperature range 298-373 K using a polarizing microscope. Low angle X-ray scattering measurements confirmed the existence of one isotropic and one lamellar liquid crystalline phase at 298 K. Evidence for the existence of a second isotropic phase was also obtained. The fluorocarbonH-water phase diagram differs from the hydrocarbon4-water system in that no hexagonal phase is formed, and the lamellar phase is formed at lower surfactant concentrations. The thickness of the fluorocarbon layer in the lamellar phase is less than that of the corresponding hydrocarbon at equivalent concentrations.
  • No Thumbnail Available
    Item
    Fluorocarbon Surfactant/Water Mesomorphic Phases: Part 3—XH and 2H Pulsed n.m.r. Study of Water in the Lamellar Phase of Ammonium Perfluoro-octanoate
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (4), 1972) Tiddy, G. J. T.
    Proton and deuteron relaxation times have been measured for water in the lamellar phase of the ammonium perufloro-octanoate + water system. Changes in T1 and T2 with variation of temperature and composition have been determined. Water proton T2 values indicate the presence of a proton exchange reaction between water and ammonium ions with k≃ 102–103 s–1. Most of the water molecules and ammonium ions have motions similar to those of normal liquids. A fraction of water molecules is bound to the fluorocarbon surfactant head groups via hydrogen bonds. The rotational correlation time of these bound molecules is of the order of 10–9 s and an upper limit of 10–6–10–7 s can be placed on the life-time of the surface-water hydrogen bonds.