ADSORPTION AT THE AIR-WATER-INTERFACE FROM AN AQUEOUS-SOLUTION OF POLY(VINYLPYRROLIDONE) AND SODIUM DODECYL-SULFATE

The adsorption of sodium dodecyl sulfate (SDS) and poly(vinylpyrrolidone) (PVP) at the air/water interface from an aqueous solution containing both components is studied by using the radiotracer technique and surface tension measurements. The increase in surface tension accompanying the conversion of a micellar solution of SDS (in the presence of 10(-3) M NaCl) to a solution containing PVP-SDS assemblies in the bulk phase by the addition of PVP is explained on the basis of desorption of SDS and adsorption of the polymer at the air/water interface. The concentration of SDS at the interface is reduced to 2/3 of the value in the absence of the polymer. The results suggest that SDS and PVP form two-dimensional aggregates at the interface similar in structure to the assemblies in the bulk phase.