SOLUBILITY OF FLUOROCARBONS IN WATER AS A KEY PARAMETER DETERMINING FLUOROCARBON EMULSION STABILITY

The kinetics of particle size growth in emulsions of 14 fluorocarbons has been studied by means of photon correlation spectroscopy. It was assumed that Ostwald ripening is the mechanism of emulsion coarsening with time; solubility of fluorocarbons in water (about 10(-6)- 10(-10)ml/ml being the key parameter determining fluorocarbon emulsion stabilities. The solubilities of fluorocarbons in water were calculated from the Ostwald ripening kinetics data and a solubility-fluorocarbon structure relationship was established. In a homologous series of normal chain fluorocarbons the solubility in water decreased by a factor of approximately 8.0 for each -CF2- group. For a given carbon number, ring formation and branching increased water solubility of the fluorocarbons. A correlation between fluorocarbon solubility in water and solvent cavity surface area was found which allows prediction of the fluorocarbon emulsion stability from the structure of the fluorocarbon.