Characterization of the 1-heptodecafluorodecyl-pyridinium iodide in solution: Partial phase diagram and micellar properties from conductivity and surface tension

Dissolution and micelle formation of 1-heptodecafluorodecyl-pyridinium iodide (HFDPyI) in aqueous solution has been studied by two experimental methods, conductivity and surface tension, with a particular attention focused on the first one. Parameters such as the critical micelle concentration (cmc), Kraft temperature (TK), average micelle aggregation number (m), and the change of solubility with temperature were determined. From cmc data, the free energies of formation and adsorption of micelle were calculated according to both the phase separation and mass action models. A partial phase diagram of HFDPyI in water shows that only the second model can explain satisfactorily the data collected. Enthalpy and entropy contributions to the micellization process have been also calculated and discussed.