Spectroscopic investigation of sodium dodecyl sulfate adsorption on a hydrocarbon monolayer

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00015a042· OSTI ID:7069688

Montgomery, Jr, M E; Wirth, M J ^[1]

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1. Univ. of Delaware, Newark, DE (United States)

Sodium dodecyl sulfate (SDS), adsorbed from aqueous solution onto a monolayer of dimethyloctadecylsiloxane (C[sub 15]) bonded to silica, was characterized spectroscopically. The structural and dynamical properties of the adsorbed SDS were probed by the fluorescence anisotropy of a dilute hydrophobic fluorophor, 1,4-bis(o-methylstyryl)benzene. Just below the critical micelle concentration (cmc) of 8.3 mM, the orientational distribution of the probe is narrowed and tilted more toward the surface normal, and its rotational diffusion slows, as compared to its behavior above the cmc. These properties below the cmc were most extreme at 7 mM in SDS concentration. FTIR spectroscopy was used to measure the amount of adsorbed SDS, and it revealed that there is about 3 times as much SDS adsorbed below the cmc as there is above it. A distinct maximum in the adsorption isotherm occurs at 7 mM, the same concentration at which the rotational diffusion behavior is most extreme. The FTIR spectral bands are narrowed and shifted below the cmc, showing that the adsorbed SDS in the premicellar region is organized densely. 34 refs., 9 figs., 4 tabs.

• DOE Contract Number: FG02-91ER14187
• OSTI ID: 7069688
• Journal Information: Langmuir; (United States), Journal Name: Langmuir; (United States) Vol. 10:3; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ADSORPTION
ALKALI METAL COMPOUNDS
ANISOTROPY
AROMATICS
CHALCOGENIDES
DATA
EXPERIMENTAL DATA
FLUORESCENCE
INFORMATION
INFRARED SPECTRA
LUMINESCENCE
MATHEMATICAL MODELS
MICELLAR SYSTEMS
MICROSCOPY
MINERALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SILOXANES
SODIUM COMPOUNDS
SORPTION
SPECTRA
SURFACTANTS