Phase Transition and Miscibility of Binary Surfactant Mixtures in Adsorbed Film at the Air/Water Surface

Ohta, Akio; Matsubara, Hiroki; Matsukubo, Tatsuya; Takiue, Takanori; Ikeda, Norihiro; Aratono, Makoto

doi:10.1006/jcis.2002.8607

Cited by 2 publications

(1 citation statement)

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“…Surface (two-dimensional) phase transitions were early observed by means of surface pressure variations in the so-called Langmuir films, − but this was long after the existence of surface films had been proven and used ; they also exist at the solid surface in contact with an infinite fluid reservoir. − Other studies have also identified them with the so-called “prewetting transition”. − According to Cahn 14 and all the theorists cited hereafter, such a prewetting transition is associated with critical points in the bulk as well as in the surface and then falls within fluid−fluid transitions. But of course, liquid−gas and solid−liquid equilibria − as well as smectic−nematic transitions , and others more specific of polymeric systems , have also been observed at various interfaces.…”

Section: Introductionmentioning

confidence: 99%

Surface Phase Diagrams: Evidence of Molecular Arrangements at the Aqueous-Solution/Solid Interface

et al. 2004

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Surface state changes described as phase transitions or simple molecular rearrangements have become a key issue in modern science. Indeed, they have an impact on the development of numerous (nano)technologies; they are also involved in biochemical and chemical mechanisms at the molecular level and also in environmental phenomena. At last, they have been at the origin of flourishing statistical descriptions that have illuminated new and very interesting aspects of surface behaviors. Here, to obtain still lacking coherent sets of experimental data on systems in which molecular interactions and thermodynamic properties are different, the adsorption behaviors of three aqueous mixtures in contact with a dense and homogeneous silica were studied versus concentrations and temperatures. Of course, these mixtures displayed very different bulk phase properties. Their stairlike isotherms are interpreted through surface phase diagrams; each of them is very similar to the corresponding bulk phase diagram. Their comparison gives new insights into the different surface states, the role of solvent in the surface, and the probable molecular mobility.

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Section: Introductionmentioning

confidence: 99%

Surface Phase Diagrams: Evidence of Molecular Arrangements at the Aqueous-Solution/Solid Interface

et al. 2004

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Dynamics of Condensed Monolayer and Multilayer Formation of Hexadecylpyridinium Chloride–Sodium Dodecyl Sulfate Mixed Systems at the Air/Water Interface

Takumi

Noda

Matsubara³

et al. 2012

Chemistry Letters

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The adsorption dynamics of mixed adsorbed films of hexadecylpyridinium chloride (HPC) and sodium dodecyl sulfate (SDS) were investigated through external reflection absorption FTIR (ERA FTIR) and surface tension measurements, following two different experimental approaches. In the first approach (case 1), solutions of SDS and HPC, at the desired total concentration and composition, were first introduced into the measurement cell, and then, the measurement was started. In the second approach (case 2), the HPC solution, at a given concentration, was first introduced into the cell, and after adsorption equilibrium was reached, a certain volume of concentrated SDS solution (to attain the desired total concentration and composition) was added to the cell, and the measurement was continued. The experiments clearly showed that the adsorption rate, as well as the mechanism, differed significantly between the two approaches.There are many researches concerned with the adsorbed film of binary surfactant systems 1 from the thermodynamic 2,3 and spectroscopic 4,5 point of views, and the existence of the three distinguishable surface phases has been confirmed experimentally. The gaseous state is a 2D gas of adsorbed surfactant molecules. An increase in surface density often gives rise to a surface phase transition to the expanded (liquid-like) and the condensed (solid-like) state. These surface phase transitions and the properties of each surface state probably control the stability of colloidal dispersions such as foams and emulsions. Moreover, monolayer formation as well as multilayer formation have been reported in some systems. 6,7 Several anionic and cationic surfactant mixed systems form vesicles owing to ion pairing in aqueous solution.8 For the HPC SDS system, Kawai et al. reported multilayer formation at the air/water interface, 9 while our own studies using ERA FTIR measurements revealed that first the condensed monolayer with a hexagonally packed structure is formed, and then other layers accumulate beneath or over it to form the multilayer. 10 In the present study, we investigate the formation dynamics of both multilayers and condensed monolayers by measuring ERA FTIR and surface tension as a function of time, using two experimental approaches. In the first approach (case 1), mixed solutions of SDS and HPC were first introduced into the measurement cells, at the desired total concentration and composition, after which the measurement was started. In the second approach (case 2), the HPC solution at a given concentration was first introduced into the cell, and after the adsorption equilibrium was reached, the required volume of concentrated SDS solution was added to the cell to reach a certain total concentration and composition, and the measurement was continued.The surface tension was measured by the pendant bubble or drop method, at 298.15 K under atmospheric pressure. 11 The total molality and composition were fixed at the values where multilayer formation was reported, i.e.,X 2 ¼ 0:64 andm ¼ 1:9 and 1.4 mmol ...

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Phase Transition and Miscibility of Binary Surfactant Mixtures in Adsorbed Film at the Air/Water Surface

Cited by 2 publications

References 32 publications

Surface Phase Diagrams: Evidence of Molecular Arrangements at the Aqueous-Solution/Solid Interface

Surface Phase Diagrams: Evidence of Molecular Arrangements at the Aqueous-Solution/Solid Interface

Dynamics of Condensed Monolayer and Multilayer Formation of Hexadecylpyridinium Chloride–Sodium Dodecyl Sulfate Mixed Systems at the Air/Water Interface

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