Hironobu Kunieda

Yokohama National University

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Kenji Aramaki

Yokohama National University

Carlos Rodríguez‐Abreu

Institute of Advanced Chemistry of Catalonia

Durga P. Acharya

CSIRO Manufacturing

Kōzō Shinoda

Tohoku University

Kazuyoshi Nakamura

Kumamoto Medical Center

Masahiko Ishitobi

Mitsubishi Group (Japan)

Md Hemayet Uddin

Melbourne Centre for Nanofabrication

M. Arturo López‐Quintela

Universidade de Santiago de Compostela

Conxita Solans

Institute of Advanced Chemistry of Catalonia

Masaya Kaneko

Tokyo Metropolitan University

Cooperative Institutions

Yokohama National University

The University of Tokyo

Tokyo University of Science

Consejo Superior de Investigaciones Científicas

Tohoku University

Waseda University

Lund University

Tokyo Institute of Technology

Universidade de Santiago de Compostela

Hokkaido University

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Spontaneous Formation of Highly Concentrated Water-in-Oil Emulsions (Gel-Emulsions)

Langmuir (1996)

Hironobu Kunieda Yoji Fukui Hirotaka Uchiyama Conxita Solans

Water-in-Oil-type gel-emulsions (or highly concentrated emulsions) are spontaneously formed from oil-swollen micellar solutions or oil-in-water (O/W) microemulsions in a water/tetraoxyethylene dodecyl ether/oil system with an abrupt increase in temperature. The phase change occurs from water-continuous microemulsion to water-in-oil (W/O) gel-emulsion via a lamellar liquid crystal and a bicontinuous surfactant phase (L3 phase). Hence, the spontaneous curvature of the surfactant layer is continuously changed with temperature change because the gel-emulsion consists of a reverse micellar solution and an excess water phase. In a narrow temperature range above the single L3-phase region, there is a two-phase region consisting of L3 and an excess water phase (W) in which emulsions are extremely unstable. The electroconductivity curve as a function of temperature monotonically decreases with increasing temperature when the final temperature is high and the temperature change is fast. If the temperature change is very slow, the electroconductivity has a maximum at the temperature where the L3 + W region is found because excess water is separated. In this case, the water droplet size in the final concentrated emulsion is very large. Therefore, it is important to change the temperature quickly to form fine gel-emulsions.

Microemulsion

Atmospheric temperature range

10.1021/la950752k

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Citations (118)

Effect of Mixing Oils on the Hexagonal Liquid Crystalline Structures

The Journal of Physical Chemistry B (2000)

Hironobu Kunieda Go Umizu Kenji Aramaki

Structural change in hexagonal liquid crystal (H1) in the water/heptaoxyethylene dodecyl ether (C12EO7) system upon addition of mixed oil (m-xylene + decane) is investigated by phase study and small-angle X-ray scattering (SAXS). The surfactant layer curvature tends to be less positive or negative upon addition of the mixed oil at a high m-xylene/decane ratio, and the H1−Lα (lamellar liquid crystal) transition takes place. At a low m-xylene/decane ratio, however, the H1−I1 transition occurs with increasing mixed oil content, where I1 is a discontinuous micellar cubic phase. An excess oil phase directly separates from the H1 phase at a moderate m-xylene/decane ratio. The change in the effective cross sectional area per surfactant, aS, as a function of oil content was also measured at each mixing fraction of oils by SAXS. m-Xylene molecules tend to penetrate the surfactant palisade layer and widen aS, whereas decane molecules tend to be solubilized in the deep core of surfactant hydrophobic moieties and the aS is not largely expanded. The aS does not jump at each transition of H1−I1 and H1−Lα. Considering the volume of polyoxyethylene chain (EO chain), the repulsion between the EO chains may increase upon addition of decane, whereas it would decrease upon addition of m-xylene. To balance the repulsion with the attraction due to the interfacial tension between water and the lipophilic part without the big change in aS, the phase transitions take place but the change in the surfactant layer curvature is opposite in both oil systems.

Decane

Small-angle X-ray scattering

10.1021/jp992957y

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Citations (57)

Effect of ionic surfactants on the phase behavior and structure of sucrose ester/water/oil systems

Journal of Colloid and Interface Science (2003)

Carlos Rodríguez‐Abreu Durga P. Acharya Shigeki Hinata Masahiko Ishitobi Hironobu Kunieda

Microemulsion

Dilution

Lamellar phase

10.1016/s0021-9797(03)00260-1

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Citations (41)

Interactions between Water-soluble Dye and Cationic Surfactant and Effects of Added Alcohol

Journal of Japan Oil Chemists Society (2000)

Yoko Yamaguchi Hidemi Taoka Hironobu Kunieda

In water-soluble dye, possessing -SO3- groups and the cationic surfactant (DTAB or CTAB) system, phase separation with precipitation and redissolution of precipitation were observed to result from cooperative-way between the dye and surfactant. On adding cationic surfactant to the dye aqueous solution, insoluble sedimentation occured. With further increase in cationic surfactant, precipitation was completely redissolved in aqueous solution. Flocculation was due to the electrostatic interaction between the dye and cationic surfactant and a hydrophobic layer would be formed on the dye since the tails of surfactant were facing the water phase. Redissolution was the cause for adsorption of cationic surfactant as micelles on the dye.Redissolved solution in dye/DTAB or CTAB/water systems showed high viscosity. The addition of short-chain alcohol (1-propanol) lead to lower viscosity and prevention of aggregation. Surface tension, electro-conductivity and static light scattering measurements clearly indicated 1-propanol to be essential to interactions between the surfactant and dye.

Cationic polymerization

10.5650/jos1996.49.245

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Citations (2)

Phase Behavior of Cationic Microemulsions near the Tricritical Point

Langmuir (1999)

Yoko Yamaguchi Reiko Aoki N. Azemar Conxita Solans Hironobu Kunieda

The three-phase behavior of a microemulsion was investigated near the tricritical point in a NaBr/water/hexadecyl-trimethylammonium bromide (CTAB)/butanol/decane system at 25 °C. The three-phase body, consisting of water-rich, microemulsion (surfactant), and oil-rich phases, exists between two critical endpoints where the water (or oil) phase becomes identical with the microemulsion phase. It is found in the phase diagram that the three-phase body shrinks with the change of NaBr concentration in water, and eventually disappears at the optimum concentration 0.5 wt % of NaBr. Not only the salinity but also the butanol/decane ratio effects the reduction of the three-phase body. This system was characterized by means of density, interfacial tension, and static light scattering measurements. The change of the density values of two phases near the tricritical point where the three-phase body is not observed, apparently showed that the oil droplets disperse in water (O/W type) in the lower phase, while in the upper phase the water droplets disperse in oil (W/O type). Under a fixed decane/butanol ratio, the tricritical point tends to be reached with increasing CTAB concentration. As the tricritical point was approached, at which two phases look bluish, the light scattering experiment showed that the microemulsion droplets in the upper and the lower phases increased in size and their sizes become of the same order. At the tricritical point, the microemulsions with the maximum solubilization of water or oil merge with each other due to efficient droplet size and strengthened interaction between the particles. Consequently, the bicontinuous structure was formed.

Microemulsion

Tricritical point

Decane

10.1021/la9813026

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Citations (15)

Solubilization of Polar Oils in Surfactant Self-Organized Structures

Journal of Colloid and Interface Science (2001)

Hironobu Kunieda Makiko Horii Masako Koyama Kazutami Sakamoto

Dodecanol

Microemulsion

10.1006/jcis.2000.7393

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Citations (79)

Effect of Added Fragrances on the Foaming Properties of Aqueous Surfactant Solutions

Journal of Society of Cosmetic Chemists of Japan (2005)

Noriko Kanei Tomoyoshi Harigai Hironobu Kunieda

身体洗浄剤や整髪料, 髭剃り処理剤等の製品にとって, 泡の特性は重要であり, これらの製品には洗浄・起泡剤として界面活性剤が配合されている。一方, 香料はさまざまな香粧品に配合されているが, 香料の種類によっては, 香粧品の起泡性, すなわち界面活性剤水溶液の起泡性に影響を与えるものと考えられる。そこで, われわれは洗浄・起泡剤のモデルとしてドデシル硫酸ナトリウム (SDS) を用いて, SDS水溶液の初期の泡立ち, および泡の安定性に及ぼす香料の影響について検討した。その結果, 0.1wt%, 0.3wt%SDS水溶液の初期の泡立ちは, Geraniol (GL), Eugenol (EL) の添加により向上した。動的表面張力測定より, これらの香料は, より短時間に表面張力を低下させていることから, 気/液界面に素早く吸着し, 界面活性剤と混合膜を形成するので, 泡立ちを向上させるものと考えられる。さらに, GL, ELは泡の安定性も向上させており, 起泡助剤として有用であることが確認された。毛髪を用いたシャンプーの起泡力評価においても, GLを添加したシャンプーは, 泡立ち, 泡の安定性ともに優れていることが確認された。

10.5107/sccj.39.2_100

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Citations (3)

Formation of Cubic-Phase Microemulsions with Anionic and Cationic Surfactants at Equal Amounts of Oil and Water

Journal of Colloid and Interface Science (2000)

Xingfu Li Hironobu Kunieda

Cationic polymerization

Microemulsion

Sodium dodecyl sulfate

Hexagonal phase

Brine

Mole fraction

10.1006/jcis.2000.7128

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Citations (14)

Mixing of nonionic surfactants at water-oil interfaces in microemulsions

Langmuir (1993)

Hironobu Kunieda Motoo Yamagata

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMixing of nonionic surfactants at water-oil interfaces in microemulsionsHironobu Kunieda and Motoo YamagataCite this: Langmuir 1993, 9, 12, 3345–3351Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://pubs.acs.org/doi/10.1021/la00036a005https://doi.org/10.1021/la00036a005research-articleACS PublicationsRequest reuse permissionsArticle Views461Altmetric-Citations73LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

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Microemulsion

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10.1021/la00036a005

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Citations (82)

Phase behavior of poly(oxyethylene) cholesteryl ether/novel alkanolamide/water systems

Journal of Colloid and Interface Science (2004)

M. Khalid Hossain Durga P. Acharya Takaya Sakai Hironobu Kunieda

10.1016/j.jcis.2004.04.062

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Citations (28)