Synergisitc mixing of L64 with various surfactants of identical hydrophobicity under the effect of temperature

The steady state pyrene fluorescence, conductivity, and viscosity measurements of triblock polymer L64 with sodium dodecyl sulfate (SDS), 3-(N,N-dimethyldodecylammonio)propane sulfonate (DPS), dodecyltrimethylammonium bromide (DTAB), and dimethylenebis(dodecyldimethylammonium bromide) (12-2-12) have been carried out in the temperature range of 15–45 °C. From these measurements various micellar parameters were evaluated and discussed in terms of the nature of mixed micelle formation under the influence of temperature effect. A variation in the critical micelle concentration (cmc) showed the presence of attractive interactions at relatively higher temperatures, i.e. 35 and 45 °C and which resulted in the appearance of azeotropic phenomenon. The azeotropic phenomenon was mainly occurring in the L64 rich region of the mixture and was attributed to the favorable solubilization of cosurfactant molecules in the L64 aggregates. A variation in the mean micelle aggregation number (Nagg) and relative viscosity (ηr) further supported the presence of azeotropic phenomenon.