The determination and nature of the lyotropic liquid crystalline phase transitions in the ammonium pentadecafluorooctanoate deuterium oxide system : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University

Abstract

The work presented in this thesis is the first stage in an investigation into the role of the counter-ion in determining phase behaviour. Specifically a high resolution phase diagram of the system ammonium pentadecafluorooctanoate/heavy water has been obtained and compared with that of the system caesium pentadecafluorooctanoate/heavy water. Three physical techniques were used, namely; deuterium NMR spectroscopy, differential scanning calorimetry and conductivity measurements. The main method used for phase transition identification was deuterium NMR spectroscopy and therefore a detailed NMR theory section is included. Experimental evidence indicates no difference in the nature of the mesophases for the different counter-ion systems studied. There is, however, a difference in the temperatures and compositions at which the phase transitions occur in the two systems. These differences are interpreted in terms of differences in the solubilities of the salts and the hydration energies of the counterions.