Wetting of Surfactant Solutions by Alkanes

Wilkinson, Katherine M.; Bain, Colin D.; Matsubara, Hiroki; Aratono, Makoto

doi:10.1002/cphc.200400514

Cited by 47 publications

(53 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A detailed analysis of the ellipsometry data was carried out by Bain et al 10,26 Here, we would like to discuss the qualitative features that can be deduced from our ellipsometric results. The ρ ̅ is expressed by the Drude equation 10…”

Section: Resultsmentioning

confidence: 98%

Effect of Alkane Chain Length and Counterion on the Freezing Transition of Cationic Surfactant Adsorbed Film at Alkane Mixture – Water Interfaces

et al. 2015

Self Cite

View full text Add to dashboard Cite

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. Furthermore, we demonstrated that the freezing transition temperature of cationic surfactant adsorbed film was independent of the kind of counterion.

show abstract

Section: Resultsmentioning

confidence: 98%

Effect of Alkane Chain Length and Counterion on the Freezing Transition of Cationic Surfactant Adsorbed Film at Alkane Mixture – Water Interfaces

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, only appropriate surfactants, which form a compact adsorption layer on the solid–water interface and, thus, decrease significantly the value of γ sw , are able to induce such a dewetting process. As the area per molecule of the surfactants studied is larger than the cross-section of their hydrocarbon tails50, we expect that such compact layers could be formed only by including interdigitated alkane molecules5152 (Fig. 4e).…”

Section: Resultsmentioning

confidence: 99%

Efficient self-emulsification via cooling-heating cycles

et al. 2017

View full text Add to dashboard Cite

In self-emulsification higher-energy micrometre and sub-micrometre oil droplets are spontaneously produced from larger ones and only a few such methods are known. They usually involve a one-time reduction in oil solubility in the continuous medium via changing temperature or solvents or a phase inversion in which the preferred curvature of the interfacial surfactant layer changes its sign. Here we harness narrow-range temperature cycling to cause repeated breakup of droplets to higher-energy states. We describe three drop breakup mechanisms that lead the drops to burst spontaneously into thousands of smaller droplets. One of these mechanisms includes the remarkable phenomenon of lipid crystal dewetting from its own melt. The method works with various oil–surfactant combinations and has several important advantages. It enables low surfactant emulsion formulations with temperature-sensitive compounds, is scalable to industrial emulsification and applicable to fabricating particulate drug carriers with desired size and shape.

show abstract

“…Also, the compressive Casimir force between the monolayer's two interfaces at the l∕v interface (28) is greatly reduced at the l∕l one. Both effects drive for a thicker liquid monolayer at the l∕l interface than at the l∕v one (28,30,31). …”

Section: Resultsmentioning

confidence: 99%

Modification of deeply buried hydrophobic interfaces by ionic surfactants

Tamam

Pontoni

Sapir

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Hydrophobicity, the spontaneous segregation of oil and water, can be modified by surfactants. The way this modification occurs is studied at the oil-water interface for a range of alkanes and two ionic surfactants. A liquid interfacial monolayer, consisting of a mixture of alkane molecules and surfactant tails, is found. Upon cooling, it freezes at T s , well above the alkane's bulk freezing temperature, T b . The monolayer's phase diagram, derived by surface tensiometry, is accounted for by a mixtures-based theory. The monolayer's structure is measured by high-energy X-ray reflectivity above and below T s . A solid-solid transition in the frozen monolayer, occurring approximately 3°C below T s , is discovered and tentatively suggested to be a rotator-to-crystal transition.H ydrophobicity (1) is abundant in nature and in technology (2). It plays a dominant role in fields ranging from the structure of living matter, like cell membrane stabilization and protein folding, to microemulsion-mediated nanoparticle and quantum dot formation (1,(3)(4)(5)(6)(7). Although the macroscopic phenomenology of hydrophobicity is well studied, its theoretical understanding, particularly on a molecular level, is still incomplete (1,8). Recent progress in X-ray scattering from buried interfaces allowed determination of the structure of hydrophobic interfaces (including the oil-water one) with near-atomic resolution, leading to an animated debate on the molecular-scale origin and manifestations of the hydrophobic interaction (9-13). Surfactants are often used to modify the hydrophobic interactions in a manner that reduces the interfacial free energy. However, the microscopic structure of surfactant-modified bulk oil-water interfaces, the subject of the present study, has been studied by X-ray methods only for nonionic alkanol surfactants (14, 15). X-ray measurements for oil-water interfaces modified by ionic surfactants are not available in the literature. Macroscopic optical measurements have uncovered intriguing interface structure modifications (16), indicating that these more widely used and more complex electrically charged surfactants, which also have bulkier headgroups, may modify the interface differently from the nonionic ones. Thus, a key ingredient in the fundamental understanding of the relation between ionic surfactants and the hydrophobic interaction is still missing.Using X-ray reflectivity (XR) and surface tensiometry, we measured the atomic-resolution structure and thermodynamics of oil-water interfaces decorated by ionic surfactants (see Fig. 1A). Two different interfacial phases are observed. At high temperatures, a liquid interfacial monolayer is found; upon cooling, a frozen monolayer forms at the interface, separating the bulk liquid oil and aqueous phases. We measured the interfacial phase diagram and offer a simple thermodynamic model which fully accounts for the interfacial freezing (IF). At a lower temperature, the frozen monolayer is found to undergo an additional transition to full crystallinity where the m...

show abstract

Wetting of Surfactant Solutions by Alkanes

Cited by 47 publications

References 61 publications

Effect of Alkane Chain Length and Counterion on the Freezing Transition of Cationic Surfactant Adsorbed Film at Alkane Mixture – Water Interfaces

Effect of Alkane Chain Length and Counterion on the Freezing Transition of Cationic Surfactant Adsorbed Film at Alkane Mixture – Water Interfaces

Efficient self-emulsification via cooling-heating cycles

Modification of deeply buried hydrophobic interfaces by ionic surfactants

Contact Info

Product

Resources

About