| Research Abstract |
The aqueous solubility and critical micelle concentration(CMC) of dodecyl-ammonium perfluorocarboxylates(trifluoroacetate(DAPA), pentafluoropropionate(DAPP), and heptafluorobutyrate(DAPB)) were measured, and the effects of the extent of hydrophobicity of counterion on solubility, CMC, and the Krafft point(the micelle temperature range, MTR) were examined. The aqueous solubilities were smaller than those of ionic surfactants with the same dodecyl chain, and the enthalpy changes of dissolution into aqueous media, while positive, were also reduced. The Krafft point of the butyrate was too high to be determined. Mixed CMCs were measured between DAPA and DAPP and between DAPA and DAPB to estimate the interaction between two kinds of the counterions. Almost ideal mixing takes place between PA and PP ions on the micellar surface, while stronger interaction between PA and PB ions results in netative deviation from the ideal mixed CMC.Solubilization of polycylic aromatic compounds(benzene, naph
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thalene, anthrcene, phrene) into DAPA micelle was determined to see the effect of benzene ring on the free energy of solubilization, where a very simple galss vessel was devised as an apparatus to determine the solubilization of volatile or gaseous substances. The apparatus worked well for production of constant chemical potential of the solubilizate.
Surface pressure- and surface potential- area isotherms for monolayrs of octadecylammonium perfluoroalkanoates os six different perfluoroalkyl chains on water and on 4.4 NaCl solution were measured at various temperatures by the Langmuir method and the ionizing electrode method. Some surface pressure-area curves of these long-hydro and short-fluoro salts showed three phase transition points. Judging from the surface potential and the apparent molar quantity, the first was assigned to the transition from the expanded phase to the condensed phase, the second from the condensed phase to another condensed phase, and the third from the latter phase to one other condensed phase. The phase transition pressures were found to change widely depending on the combination of hydrocarbon cation and perfluorocarbon anion lengths. Less
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