Uptake of iron (III)-ethylenediamine-N, N, N', N'-tetraacetic acid complex by phosphatidylcholine lipid film. Part II. Effect of film curvature.

Mixed micelles formed in a ternary-solute aqueous solution of NaOH, iron (III)-ethylenediamine-N, N, N', N'-tetraacetic acid complex (Fe-EDTA) and 1,2-diheptanoyl-sn-glycero-3-phosphatidyl choline (DHPC) were studied and compared with the mixed adsorbed film reported in Part I of this series to clarify the effect of the curvature of molecular assemblies on the interactions between their Fe-EDTA and DHPC constituents. The critical micelle concentrations (CMCs), surface tension at the CMC, and solution pH were measured as functions of the mole fractions of NaOH and DHPC. Rigorous thermodynamic equations were derived, in which the overall proton dissociation equilibria of Fe-EDTA and DHPC were taken into consideration, and applied to experimental data to obtain phase diagrams of micelle formation and the micelle-adsorbed film equilibrium.

Uptake of iron (III)-ethylenediamine-N,N,N',N'-tetraacetic acid complex by phosphatidylcholine lipid film: Part I. Effect of bulk pH.

We studied a ternary solutes aqueous solution of NaOH, iron (III)-ethylenediamine-N,N,N',N'-tetraacetic acid complex (Fe-edta), and 1,2-diheptanoyl-sn-glycero-3-phosphatidylcholine (DHPC)/air interface system to clarify the interactions between iron complexes and lipids with a phosphatidylcholine head group. The solution surface tension and pH were measured as functions of the total molality of NaOH, Fe-edta and DHPC, and the mole fractions of NaOH and DHPC. Rigorous thermodynamic equations were derived, in which the overall proton dissociation equilibria of Fe-edta and DHPC were taken into consideration, and applied to experimental data to obtain phase diagram of adsorption.

Effect of alkane chain length and counterion on the freezing transition of cationic surfactant adsorbed film at alkane mixture - water interfaces.

Penetration of alkane molecules into the adsorbed film gives rise to a surface freezing transition of cationic surfactant at the alkane-water interface. To examine the effect of the alkane chain length and counterion on the surface freezing, we employed interfacial tensiometry and ellipsometry to study the interface of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride aqueous solutions against dodecane, tetradecane, hexadecane, and their mixtures. Applying theoretical equations to the experimental results obtained, we found that the alkane molecules that have the same chain length as the surfactant adsorb preferentially into the surface freezing film.

Surface freezing and molecular miscibility of binary alkane-alkane and fluoroalkane-alkane liquid mixtures.

The surface freezing (SF) of liquid n-heptadecane (C17)-n-octadecane (C18) and 1-perfluorooctyl decane (F8H10)-C18 mixtures were studied by surface tension and external reflection absorption FTIR (ERA-FTIR) measurements. The surface tension versus temperature curves of all pure liquids show a sharp break point at Ts corresponding to a surface liquid (SL)-SF transition. The entropy of surface formation is very negative, indicating a well-ordered structure of the SF layer.

Miscibility and multilayer formation of fluoroalkane-α,ω-diol mixtures at the air/water interface.

The surface tension γ of the aqueous solution of 1H,1H,6H,6H-perfluorohexane-1,6-diol (FC₆diol) and 1H,1H,8H,8H-perfluorooctane-1,8-diol (FC8diol) mixtures was measured as a function of total molality m and composition of FC₈diol in the mixture X₂ at 293.15 K under atmospheric pressure. The γ vs m curves except at X₂ = 0 and 0.

Molecular orientation and multilayer formation in the adsorbed film of 1H,1H,10H,10H-perfluorodecane-1,10-diol at the hexane/water interface; pressure effect on the adsorption of fluoroalkane-diol.

The adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10diol) at the hexane solution/water interface was investigated by the measurement of interfacial tension gamma as a function of pressure p and concentration m1 and the thermodynamic data analysis. The results obtained were compared with those of 1H,1H,2H,2H-perfluorodecanol (TFC10OH) in order to clarify the effect of molecular orientation on the structure and property of the adsorbed film from the viewpoint of volume change of adsorption. The interfacial pressure pi versus mean area per adsorbed molecule A curve revealed two types of phase transitions among expanded, parallel condensed, and multilayer states.

Effect of omega-hydrogenation on the adsorption of fluorononanols at the hexane/water interface: pressure effect on the adsorption of fluorononanols.

The interfacial tension gamma of the hexane solution of 1H,1H-perfluorononanol (FDFC(9)OH) and its omega-hydrogenated analogue, 1H,1H,9H-perfluorononanol (HDFC(9)OH), against water was measured as a function of pressure and concentration at 298.15 K in order to clarify the effect of omega-dipole on the orientation of fluorononanol molecules from the viewpoint of volume. The adsorbed films of both alcohols exhibit two kinds of phase transitions among three different states: the gaseous, expanded, and condensed states.

Effect of omega-hydrogenation on the adsorption of fluorononanols at the hexane/water interface: Temperature effect on the adsorption of fluorononanols.

The interfacial tensions (gamma) of the hexane solutions of 1H,1H-perfluorononanol (FDFC9OH) and its omega-hydrogenated analogue 1H,1H,9H-perfluorononanol (HDFC9OH) against water were measured as a function of temperature and concentration under atmospheric pressure in order to know the effect of omega-dipoles on the adsorption behavior of fluorononanols. The interfacial pressure (pi) versus mean area per adsorbed molecule (A) curves consist of two discontinuous changes among three different states: the gaseous, expanded, and condensed states. The A values at given pi in the gaseous and expanded states are larger for HDFC9OH than for FDFC9OH.

Adsorption and phase transition of alkanol and fluoroalkanol at electrified mercury/aqueous solution interface.

The adsorption behavior and the phase transition of alkanol and fluoroalkanol at the electrified mercury/aqueous solution interface were investigated by the interfacial tension measurements and the thermodynamic analysis. In the alkanol system, it is found that the phase transitions in low interfacial densities occur: the ones from the zero adsorption to the gaseous or the expanded state and the gaseous to the expanded state at the electrified interface depending on the electrostatic nature as well as the concentration in the bulk phase. These phase transitions were verified by the thermodynamic equations derived by the assumption of coexistence of two phases at the electrified interface.