The effect of added electrolyte on the phase behaviour of the micellar liquid crystal system caesium pentadecafluorooctanoate/water: a thesis presented in the partial fulfilment of the requirements for the degree of Master of Science in chemistry at Massy [i.e. Massey] University

Abstract

This thesis is a study of the effects of added electrolyte (CsCl) on the aggregate structure and hence on the macroscopic phase behaviour of the micellar liquid crystal system caesium pentadecafluorooctanoate / heavy water. The techniques used were 2H, 133Cs and 35Cl N.M.R. spectroscopy. The relationship between the quadrupole splittings of these nuclei and the structure and order of the liquid crystal mesophase is discussed in detail. A partial phase diagram for the CsPFO / CsCl / 2H2O system at a fixed 1 : 1 weight ratio of CsPFO to 2H2O is presented. The phase behaviour has been compared with that for a hydrocarbon surfactant. The changes in phase transition temperatures with added salt has been shown to be due to an increase in the micellar size. This increases with added electrolyte but is constant along the lamellar to nematic transition line. It is shown that there is a strong coupling between micelle size and the micellar fractional surface charge.

Specifically the effect of caesium chloride on the CsPFO / 2H2O system was investigated using 2H, 133Cs and 35CI N.M.R. spectroscopy to probe the micellar structure and identify the phase transitions. A full description of the N.M.R theory pertaining to this work is presented.