E. Abuin et al., EFFECT OF SODIUM COUNTERION SUBSTITUTION BY LITHIUM ON THE INTERACTION OF DODECYL-SULFATE WITH POLY(ETHYLENE OXIDE) IN AQUEOUS-SOLUTION, Boletin de la Sociedad Chilena de Quimica, 40(1), 1995, pp. 65-70
The interaction of sodium dodecylsulfate (SPS) and lithium dodecylsulf
ate (LDS) with poly(ethylene oxide) in aqueous solution has been inves
tigated by surface tension and fluorescence measurements, The critical
concentrations for the onset of micellization of the surfactants on t
he polymer and the amount of the surfactant taken up by the polymer at
saturation were determined. Experiments have been performed in salt-f
ree solutions as well as in the presence of 0.1 M of alkaline halides
containing the same cation as the surfactant counterion. For all the e
xperimental conditions employed it is found that, upon substitution of
sodium by lithium both of the characteristic parameters for the adsor
ption of the surfactant on the polymer are modified in a manner indica
tive of a stronger interaction with SDS than with LDS. The results are
interpreted in terms of a surfactant interaction affected by the affi
nity of the counterion for complexation with the polymer.