Association of anionic surfactant mixed micelles with hydrophobically modified ethyl(hydroxyethyl)cellulose

Some aspects of ethyl(hydroxyethyl)cellulose (EHEC) aqueous behavior in the presence of ionic surfactants are described in the literature; however, most of the studies reported deal with moderately concentrated solutions. Few studies have been carried out in the dilute regime using mixtures of anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecanoate (SDoD). The main proposal of this work is to investigate the interaction of EHEC in diluted regime and to verify the mixtures of the surfactants SDS and SDoD. Mixtures of EHEC and SDoD were investigated using surface tension, conductivity and transmittance measurements. Parallel experiments with EHEC in mixtures with SDS were carried out. The formation of micelles of SDoD mixed with SDS in the absence and presence of EHEC was also investigated. The transmittance vs. [SDS] and [SDoD] profiles exhibit bands that, in conjunction with conductivity and surface tension data, aid a better understanding of the behaviors of EHEC–SDS–SDoD–water solutions.

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► The mixture formed by the surfactants SDS and SDoD is an ideal system.
► The process of association between the SDS–SDoD surfactant mixture and the polymer is strongly cooperative.
► The polymer does not influence the degree of ionization below the cac and above the psp.
► The transmittance profiles give support to explain the behaviors of EHEC–SDS–SDoD–water solutions.