Measurement of the Dynamic Surface Excess of the Nonionic Surfactant C<sub>8</sub>E<sub>4</sub>OMe by Neutron Reflection and Ellipsometry

Valkovska, Dimitrina S.; Wilkinson, Katherine M.; Campbell, Richard A.; Bain, Colin D.; Wat, Ray; Eastoe, Julian

doi:10.1021/la034053g

Cited by 20 publications

(59 citation statements)

References 17 publications

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“…3, solid circles). We have shown previously that for a related nonionic surfactant (C 8 E 4 OMe) scales linearly with the surface excess, ÿ, of adsorbed surfactant [11]. It is reasonable to assume a linear relationship between and ÿ for C 14 E 8 also (right-hand axis in Fig.…”

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confidence: 85%

Adsorption Kinetics in Micellar Solutions of Nonionic Surfactants

Colegate

Bain

2005

Phys. Rev. Lett.

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Standard models of the adsorption kinetics of surfactants at the air-water surface assume that micelles break down into monomers in the bulk solution and that only monomers adsorb. We show here that micelles of the nonionic surfactant C14E8 adsorb to the surface of a liquid jet at a diffusion-controlled rate. Micellar adsorption can be switched off by incorporation of a small amount of ionic surfactant into the micelle and switched on again by addition of salt. More sophisticated models of adsorption processes in micellar solutions are required that permit a kinetic flux of micelles to the air-water interface.

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confidence: 85%

Adsorption Kinetics in Micellar Solutions of Nonionic Surfactants

Colegate

Bain

2005

Phys. Rev. Lett.

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“…Experimentally we have found a good linear relationship between r and the surface excess, G, for a number of a simple surfactant systems (data for C 8 E 4 OMe may be found in ref. 13). 14,15 Consequently, we convert values of r into values of G using a linear interpolation between the value of r for pure water in the OFC (typically 0.35 Â 10 À3 ) and for the surfactant at its limiting surface excess (measured on a stagnant solution above the CMC).…”

Section: Ellipsometrymentioning

confidence: 99%

“…Fig 13. Effect of addition of CTAB on the coefficient of ellipticity of a 0.56 mM solution of C 16 E 6 in the OFC.…”

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Adsorption kinetics of non-ionic surfactants in micellar solutions: effects of added charge

2013

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The kinetics of adsorption of micellar solutions of non-ionic surfactants have been studied in an overflowing cylinder. The addition of small amounts (< 10% of the total surfactant concentration) of ionic surfactants, CTAB and STS, to solutions of C16E8 causes a dramatic reduction in the rate of adsorption of the nonionic surfactant. The results are rationalised by a combination of monomer and micelle adsorption to the air-water interface. In the presence of trace ionic surfactants, only uncharged micelles adsorb. The adsorption kinetics are independent of the sign of the charge on the micelles, only on its magnitude. The influence of ionic surfactants on the adsorption rate is reversed by addition of millimolar concentrations of salt. Electrolyte screens the repulsions between micelles and the adsorbed monolayer and allows charged micelles to adsorb without first breaking down into monomers.

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“…The overflowing cylinder has been used extensively to examine the dynamics of adsorption of surfactants at the air-water interface. [8][9][10][11][12][13][14][15][16][17][18][19] In an OFC, liquid flows vertically up an inner cylinder and then pours over the horizontal rim to create a continually expanding interface. The liquid surface expands radially from a stagnation point in the center of the cylinder at a dilation rate that is approximately uniform across the surface.…”

Section: Introductionmentioning

confidence: 99%

External Reflection Fourier Transform Infrared Spectroscopy of Surfactants at the Air—Water Interface: Separation of Bulk and Adsorbed Surfactant Signals

2005

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External reflection Fourier transform infrared spectroscopy (ERFTIRS) has been used to obtain spectra of monolayers of the hydrocarbon surfactant octaethylene glycol monodecyl ether (C(10)E(8)) and the fluorocarbon surfactant ammonium perfluorononanoate (APFN) at the expanding liquid surface of an overflowing cylinder. The use of target factor analysis (TFA) to separate out the contributions of water, adsorbed surfactant, and dissolved surfactant is demonstrated. For both surfactants, there is a linear relationship between the component weight of the adsorbed surfactant, obtained by TFA, and the surface excess determined independently by ellipsometry or neutron reflection. This linear relationship suggests that the monolayers behave like isotropic films with a constant density. A sensitivity of less than 10% of a monolayer is demonstrated. The benefits of using a multivariate curve fitting procedure to analyze sets of ER-FTIR spectra are discussed and some potential pitfalls are identified. This technique is also applicable to static interfaces.

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Measurement of the Dynamic Surface Excess of the Nonionic Surfactant C₈E₄OMe by Neutron Reflection and Ellipsometry

Cited by 20 publications

References 17 publications

Adsorption Kinetics in Micellar Solutions of Nonionic Surfactants

Adsorption Kinetics in Micellar Solutions of Nonionic Surfactants

Adsorption kinetics of non-ionic surfactants in micellar solutions: effects of added charge

External Reflection Fourier Transform Infrared Spectroscopy of Surfactants at the Air—Water Interface: Separation of Bulk and Adsorbed Surfactant Signals

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Measurement of the Dynamic Surface Excess of the Nonionic Surfactant C8E4OMe by Neutron Reflection and Ellipsometry

Cited by 20 publications

References 17 publications

Adsorption Kinetics in Micellar Solutions of Nonionic Surfactants

Adsorption Kinetics in Micellar Solutions of Nonionic Surfactants

Adsorption kinetics of non-ionic surfactants in micellar solutions: effects of added charge

External Reflection Fourier Transform Infrared Spectroscopy of Surfactants at the Air—Water Interface: Separation of Bulk and Adsorbed Surfactant Signals

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Measurement of the Dynamic Surface Excess of the Nonionic Surfactant C₈E₄OMe by Neutron Reflection and Ellipsometry