Conductance and viscosity studies of sodium dodecylsulfate in aqueous solutions of dimethylsulfoxide and methanol

In this paper, we report the effect of dimethylsulfoxide (DMSO) and methanol (MeOH) on solution behaviour of sodium dodecylsulfate (SDS) in pre- as well as in post-micelle regions of aqueous solutions from conductance and viscosity measurements. The data demonstrate the inhibitory effect of both these additives on miccilization of SDS, which however is relatively large in case of DMSO. Such an effect of these additives is attributed to dehydration of micelle surface as a result of strong intermolecular interactions, and reduction in counterion binding resulting from its preferential solvation with DMSO and MeOH. To aid this evaluation, a transition-state treatment of the relative viscosity of SDS solutions is also described in pre- and post-micelle regions.