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The STH conversion efficiency of Z-scheme system for OWS as illustrated here is the highest among photocatalyst ones and is still short for practical use. We studied the electronic structure of the system on solid state physics and proposed several new subjects to be solved.

Water dispersible K4Nb6O17·3H2O-based Janus nanosheets were successfully prepared and exhibited unique behaviour at the water–air interface and at the water–toluene interface.

Bicontinuous microemulsion (BME)-based hydrogel films were integrated with screen-printed electrodes (SPEs) comprising working, counter, and reference electrodes to form stand-alone, semi-solid-state electrochemical systems that do not require an outer electrolyte solution. The gel network of the BME hydrogel only exists in the microaqueous phase and retains the structure of the entire BME gel. Following gelation, a microaqueous phase with sufficient ionic strength ensured effective ionic conductivity, even in thin gel films. This enabled the electrochemical reaction to proceed using a thin gel film as an electrolyte solution. However, an intact micro-oil phase with no gel network enabled efficient extraction from an external oil solution and exhibited rapid electrochemistry that was comparable to that of a BME solution. Cyclic voltammograms of lipophilic redox species in oil using the gel-integrated SPE system demonstrated successfully in the oil itself and in the air with dropped oil onto the system.

Dual-functional Janus nanosheets were prepared by growing poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide) chains on one face of individual negatively-charged nanosheets derived from K4Nb6O...

Janus nanosheets were prepared from K4Nb6O17·3H2O by modifying surfaces of their two distinct interlayers in a regioselective and sequential manner and subsequent exfoliation. The surface properties of nanosheets were investigated by phase atomic force microscopy imaging and two types of surfaces were discriminated, indicating that Janus nanosheets were successfully prepared.

Bicontinuous microemulsions (BMEs, Winsor III), also called middle-phase microemulsions, are low-viscosity, isotropic, thermodynamically stable, and spontaneously formed mixtures of water, oil, and surfactants. They are unique solution media for electrochemistry. Here, we introduce the recent progress in the electrochemistry of BMEs from their fundamental aspects to their practical applications. Electrochemistry using BMEs has two irreplaceable properties: the coexistence of hydrophilic and lipophilic species with high self-diffusion coefficients; and the dynamic deformation of structures at an oil/water/electrode ternary interface, which is easily changed according to the property of the electrode surface. Electrochemical contact with the micro-saline and oil phases in a BME is alternately or simultaneously achieved by controlling the hydrophilicity and lipophilicity of the electrode surfaces. The selective electrochemical analysis of hydrophilic and lipophilic antioxidants in liquid foods without extraction demonstrated as the use of the unique ternary solution structures of BME on solid surfaces.

Janus nanosheets were prepared from K4Nb6O17·3H2O by modifying surfaces of their two distinct interlayers in a regioselective and sequential manner and subsequent exfoliation. The surface properties of nanosheets were investigated by phase atomic force microscopy imaging and two types of surfaces were discriminated, indicating that Janus nanosheets were successfully prepared.

Continuous porous poly(N-isopropylacrylamide) (pNIPAM) gels were prepared by radical polymerization in a bicontinuous microemulsion (BME) consisting of saline and toluene microphases. The BME gels ...

The assembling properties of single-chain ammonium amphiphiles containing benzylideneaniline and salicylideneaniline units as rigid segments in the formation of aqueous bilayers, cast multi-bilayers, and surface monolayers were studied. Electron microscopy indicated that aggregate morphologies observed in water, such as vesicles and fibers, were dependent on the nature of the aromatic unit and the alkyl-chain length of the component amphiphiles. The patterns of molecular assembly in bilayers were examined by absorption spectroscopy of aqueous bilayers and X-ray diffraction of cast multi-bilayer films. The patterns were virtually identical to those of the corresponding azobenzene bilayers, and commonly determined by combinations of alkyl-chain lengths. This alkyl-chain combination was crucial for formation of stable surface monolayers.

A new class of unique soft gels was produced by gelations of bicontinuous microemulsions (BME). Three alternative composite gel systems, namely BME organogel, hydrogel and an organo/hydro hybrid gel, prepared by hydrogelation and/or organogelation of BME solutions were proposed. These gels were self-supported, and aqueous and oil microphases bicontinuously coexisted and were immobilized in the gels. Even in “one side only” gelation products such as the BME organogel and the BME hydrogel, alternate solvent phases without gelator were also macroscopically immobilized. Microscopic structures of the gels were confirmed by CLSM and SEM observation. The BME organogels or hydrogels and BME hybrid gels showed continuous porous structures and double network structures, respectively. Mesostructures of the gels significantly depended on gelation conditions. It was found that the hierarchical structure of the BME gels was regulated by competition among three synergetic rate factors: immobilization of the BME structur...

Middle-phase microemulsions exhibit the unique properties of an ultra-low interfacial tension and a bicontinuous structure formed from the water and oil components. New developments exploiting these properties are described. In designing such systems, it is important that the spontaneous transition of the oil droplets from Winsor II through Winsor III to the Winsor I state is brought about by diffusion or chemical reaction. The selection of the hydrophobic and lipophilic surfactants is critical when low-energy emulsification systems for highly polar oils are being developed.

Quantitative analyses of olive oil for lipophilic antioxidants, such as α-tocopherol and phenolics, by simple electrochemical measurements were conducted in a bicontinuous microemulsion (BME), which was bicontinuously composed of saline and toluene microphases with a surfactant system. Lipophilic antioxidants in oils were directly monitored in BME solutions using a lipophilic, fluorinated nanocarbon-film electrode (F-ECR). The combination of a well-balanced BME and extremely biased electrodes, such as strongly hydrophilic indium/tin oxide and strongly lipophilic (hydrophobic) F-ECR, allowed individual monitoring of hydrophilic and lipophilic antioxidants in the same BME solution without any required extraction. Furthermore, values for the charge Q, integrated from observed currents, showed good linear relationships with the results of conventional assays for antioxidant activity, namely, total phenolics and oxygen radical absorbance capacity assays, even with practical food samples. This proposed methodology provided a very simple, rapid, easily serviceable, and highly reproducible analysis that possesses great potential for applications to a wide range of chemical mixtures, in terms of analyte and media, beyond food oils.

Qualitative and quantitative analyses of hydrophilic and lipophilic antioxidants, such as polyphenols, by simple electrochemical measurements were conducted in a bicontinuous microemulsion (BME), in which water and oil phases coexisted bicontinuously on a microscopic scale. Hydrophilic and lipophilic antioxidants were individually monitored in the same BME solution using a hydrophilic indium tin oxide (ITO) electrode and a lipophilic fluorinated nanocarbon film electrode (F-ECR), respectively. The combination of well-balanced BME and extremely biased electrodes, such as ITO and F-ECR, in terms of hydrophilic-lipophilic balance allowed us to achieve individual monitoring of hydrophilic and lipophilic antioxidants in the same BME solution without extraction. Furthermore, the antioxidant activities of functional liquid foods, such as coffee and olive oil, were also evaluated by means of electrochemical measurements in BME solutions containing analytes in concentrations of several percent. The technique we propose provides a very simple, rapid, easily serviceable, and highly reproducible analysis and can be extended to a wide range of analytes and media.

Dynamic solution structure of a three-phase interface (oil/water/solid) of a bicontinuous microemulsion (BME) was evaluated electrochemically with apparent diffusion coefficients (Dapp’s) from cycl...

Drops containing a hydrocarbon, the anionic surfactant Aerosol-OT (AOT), and water were injected into water at 30 °C, and the resulting behavior was observed by videomicroscopy. Spontaneous emulsification of most of the injected oil yielding droplets a few microns in diameter was seen when n-octane was the hydrocarbon and when the initial drop contained at least 25 wt % AOT and no more than about 10 wt % water. Emulsification was also observed when the initial drop contained small amounts of NaCl solution instead of water and for suitable conditions when n-hexane was the hydrocarbon. However, much less emulsification occurred for n-decane and n-dodecane, probably because surfactant-rich phases in equilibrium with excess oil in these systems solubilized little hydrocarbon. The mechanism of emulsification is closely related to that of an earlier study by Rang and Miller (Prog. Colloid Polym. Sci. 1998, 109, 101) using drops containing n-hexadecane, the pure nonionic surfactant C12E6, and n-octanol. In both ...

The structural changes in a bicontinuous microemulsion gel system in a sol-gel state were elucidated via determination of the apparent diffusion coefficients, which were estimated electrochemically. The temperature dependence of D(app) in the micro oil phase or the saline phase revealed complementary hysteresis, which occurred as a result of formation of a gel network and subsequent mesoscopic phase separation.

Bilayer membranes of chiral double-chain ammonium amphiphiles incorporated an anionic tridentate ligand in enantiomeric orientations, as confirmed by induced circular dichroism. Complexation of aqueous CoSO4 with the bilayer-bound ligand led to formation of chiral Co(III) complexes.

Equimolar mixtures of cyclam amphiphiles and malonate amphiphiles produced uniformly paired bilayers. Absorption spectra and X-ray diffraction measurements showed that molecular alignments were determined by combinations of the alkyl chain length of paired bilayer components as in the respective single-component bilayers.

Cast films prepared from benzylideneaniline- and salicylideneaniline-containing ammonium amphiphiles at room temperature possess interdigitated bilayer structures. These molecular assemblies show various types of crystalline modifications above their transition temperatures.

The steric structures of helices and vesicles formed from bilayer membranes of ammonium amphiphiles were observed without metal coating by high-resolution scanning electron microscopy. These observations agreed with those made by transmission electron microscopy.

Single-chain ammonium amphiphiles which contain the salicylideneaniline unit formed stable bilayer membranes in water. The component orientation is either parallel or tilted depending on the alkyl chain length, as inferred from X-ray diffraction patterns and absorption spectral shifts.

Spontaneous emulsification of small oil droplets was produced in three different systems by chemical reactions which converted lipophilic surfactants initially dissolved in the oil phase to hydrophilic surfactants. The resulting reversal of spontaneous curvature from a water-in-oil to an oil-in-water configuration reduced the solubilization capacity for oil to such an extent that supersaturation occurred, leading to nucleation of oil droplets. In one case a dilute solution of phenylboronic acid in water diffused into an oil phase containing a monoglyceride. The reaction converted the monoglyceride to an anionic surfactant. In another case a dilute aqueous solution of the sodium salt of EDTA diffused into an oil phase containing a calcium sulfonate surfactant. The EDTA complexed calcium ions, releasing sodium ions which formed the more hydrophilic sodium salt of the sulfonate. Finally, an enzyme was used to split a double-chain phospholipid into a lysolecithin and a fatty acid. Copyright 2001 Academic Press.

The electrochemical contact with the micro aqueous phase and the micro organic solvent phase in the “middle phase” microemulsion, in which the water phase and the oil phase bicontinuously coexist o...

Mesoporous silica was successfully synthesized via a sol–gel process in a bicontinuous microemulsion of tetradecane/didodecyldimethylammonium bromide/aq HCl ternary system. The surface area, pore s...

Mesoporous TiO2 with high surface area was synthesized via a sol–gel process in a bicontinuous microemulsion. The mesoporous structure was retained to some extent even if the anatase-TiO2 nanocryst...

A “middle phase” microemulsion, which bicontinuously composed of saline and toluene microphases, with sodium dodecylsulfate (SDS) and n-butanol was electrochemically characterized. When electrochemistry was performed in the “middle phase” microemulsion, reversible redox peaks of the Fe(CN)6 ion in the micro water phase and the ferrocene in the micro toluene phase could be observed simultaneously, although the electrolyte was present only in the water phase.