Mixed Micellization Behavior of Gemini and Conventional Surfactants: Influence of Spacer Length and Temperature

Abstract

Mixed micellar behavior of gemini surfactant butanediyl-1,4-bis(dimethyldodecylammonium bromide) (12-4-12) with conventional surfactant tetradecyl trimethylammonium bromide (TTAB) has been studied in aqueous and in aqueous polyvinyl pyrrolidone (PVP) solutions at various temperatures (288.15 K, 298.15 K, 308.15 K, and 318.15 K) using conductometric method. The behavior of the mixed system has been analyzed in light of Rubingh's regular solution theory. The study indicates that the above system behaves nonideally with mutual antagonism which increases with temperature. The mixed micelle mole fraction of 12-4-12 has also been determined and is found to be almost same with its ideal state value at all the studied temperatures indicating that mixed micelles are equally occupied by both the surfactants in the whole mole fraction range. In the presence of PVP, the critical aggregation concentration and critical micellar concentration values were found to decrease with increase in mole fraction of 12-4-12 whereas these values increase with PVP concentration as well as temperature. Various thermodynamic parameters associated with transfer of surfactant monomers from the medium consisting of polymer-free mixed micelles to polymer-bound mixed micelles like , ,and at various temperatures have been evaluated and discussed.