Abstract
The polar orientation and degree of conformational order of sodium dodecyl sulfate (SDS) adsorbed at the hydrophobic octadecane thiol/aqueous solution interface has been investigated as a function of the surfactant concentration in the presence and absence of a fixed concentration of poly(ethylene oxide) (PEO). Sum frequency vibrational spectroscopy, based on the nonlinear optical phenomenon of sum frequency generation, was employed to obtain spectra of the interfacial surfactant; weak signals from PEO at the interface were also obtained. The phase of the spectra indicated that both the surfactant and the polymer had a net orientation of their CH2 and/or CH3 groups toward the hydrophobic surface. Spectra of SDS in the presence of mixed polymer/surfactant solutions showed increasing conformational order as the surfactant concentration was raised. At the lowest surfactant concentration, the spectra of SDS were weaker in the presence of the polymer than in its absence. Probing interfacial PEO specifically th...
Published Version
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