Adsorption of Polydisperse Surfactants on Solid Surfaces: An Ellipsometric Study

Luciani, L.; Denoyel, Renaud

doi:10.1006/jcis.1996.4724

Cited by 24 publications

(30 citation statements)

References 38 publications

(17 reference statements)

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“…Adsorption and the resulting surface structures have been studied by different experimental techniques such as streaming potentialmethod, 1 calorimetry, 2 neutronreflection, 3-5 ellipsometry [6][7][8] and fluorescence spectroscopy, 9,10 and atomic force microscopy (AFM). [11][12][13][14][15][16][17][18] Of these, AFM provides the most detailed information on the topology of the assembled surfactant structures at molecular scales: Manne et al first provided evidence of hexadecyltrimethylammonium bromide (C 16 TAB) organization in parallel stripes at the interface between graphite and aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

Structure and Dynamics of Surfactant and Hydrocarbon Aggregates on Graphite: A Molecular Dynamics Simulation Study

2008

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We have examined the structure and dynamics of sodium dodecyl sulfate (SDS) and dodecane (C 12 ) molecular aggregates at varying surface coverages on the basal plane of graphite via classical molecular dynamics simulations. Our results suggest that graphite-hydrocarbon chain interactions favor specific molecular orientations at the single-molecule level via alignment of the tail along the crystallographic directions. This orientational bias is reduced greatly upon increasing the surface coverage for both molecules due to intermolecular interactions, leading to very weak bias at intermediate surface coverages. Interestingly, for complete monolayers, we find a re-emergent orientational bias. Furthermore, by comparing the SDS behavior with C 12 , we demonstrate that the charged head group plays a key role in the aggregate structures: SDS molecules display a tendency to form linear file-like aggregates while C 12 forms tightly bound planar ones. The observed orientational bias for SDS molecules is in agreement with experimental observations of hemimicelle orientation and provides support for the belief that an initial oriented layer governs the orientation of hemimicellar aggregates.

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Section: Introductionmentioning

confidence: 99%

Structure and Dynamics of Surfactant and Hydrocarbon Aggregates on Graphite: A Molecular Dynamics Simulation Study

2008

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“…Similar conclusions were drawn for polydisperse (Triton) nonionics adsorbed on silica and their sulfonated derivatives on titania. 28 On hydrophobic (dimethyloctylsilylated silica) surfaces, ellipsometric studies are consistent with a laterally coherent monolayer. This differs from AFM observations for both ionic 29,30 and nonionic 31 surfactants on graphite.…”

Section: Ellipsometrymentioning

confidence: 90%

Supramolecular Structure of Surfactants Confined to Interfaces

Manne¹,

Warr²

1999

ACS Symposium Series

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The mounting evidence for the existence of surfactant aggregates at solid/solution interfaces prompts a re-examination of common experimental techniques for studying surfactant adsorption. The simple models of a surfactant monolayer or bilayer, while reasonable in the face of older experimental data, are now seen to be inadequate to describe the rich range of order seen by atomic force microscopy and other techniques. In this manuscript we review the results of atomic force microscopy which demonstrate the existence of surface micelles, look again at the experimental results which pointed towards surface aggregates, and also look ahead at how the existence of surface micelles requires us to revise the interpretation of other experimental studies and our entire picture of adsorbed films.

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“…The headgroup area determined from tensiometry reflects the area for the hydrophobes with no or very few oxyethylene units. The value is therefore not representative of the average surfactant present in bulk solution (10)(11)(12). This effect must be taken into account in the analysis of the tensiometry measurements.…”

Section: Adsorption At An Interfacementioning

confidence: 97%