A neutron reflectivity study of the adsorption of aerosol-OT on self-assembled monolayers on silicon

Journal Article · Mon Mar 25 04:00:00 EST 1996 · Journal of Colloid and Interface Science

DOI:https://doi.org/10.1006/jcis.1996.0148· OSTI ID:238017

Fragneto, G; Li, Z X; Thomas, R K ^[1]; Rennie, A R ^[2]; Penfold, J ^[3]

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1. Physical and Theoretical Chemistry Lab., Oxford (United Kingdom)
2. Cavendish Lab., Cambridge (United Kingdom)
3. Rutherford Appleton Lab., Chilton (United Kingdom)

The structure of surfactants in bulk solution and at interfaces is of great importance in industrial processes involving detergency, paints, food chemistry, and oil recovery. The structure and composition of layers of the anionic surfactant sodium bis-(2-ethyl-1-hexanol) sulphosuccinate (AOT) adsorbed from aqueous solution onto self-assembled monolayers of octadecyltrichlorosilane (OTS) on silicon oxide have been determined in situ using specular neutron reflection. At its critical micelle concentration (cmc) AOT forms a monolayer with an area per molecule of 80 {+-} 5 {angstrom}{sup 2} and a thickness of 15 {+-} 2 {angstrom}. These values are similar to those of the monolayer formed at the air/water interface at the cmc. Separate isotopic labeling of two parts of the AOT surfactant shows that the molecule is oriented with the ethyl hexanol chains toward the hydrophobic OTS surface and that there is some penetration of the OTS layer by the chains. The adsorption of AOT is found to persist at lower concentrations than the nonionic surfactant tetraethylene glycol monododecyl ether (C{sub 12}E{sub 4}) over the concentration range cmc/100 to cmc.

• OSTI ID: 238017
• Journal Information: Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 2 Vol. 178; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
DISPLACEMENT FLUIDS
EMULSIONS
ENHANCED RECOVERY
INTERFACES
MICELLAR SYSTEMS
MICROEMULSIONS
MORPHOLOGY
NEUTRON DIFFRACTION
PETROLEUM
SILICON OXIDES
SORPTION
SURFACE PROPERTIES
SURFACTANTS