Physicochemical Properties of Dodecyltrimethylammonium Bromide (DTAB) and SodiumDodecyl Sulphate (SDS) Rich Surfactants in Aqueous Medium, At T ¼ 293.15, 298.15, and 303.15 K K. M. Sachin, Sameer Karpe, Man Singh, and Ajaya Bhattarai* The physicochemical properties of Dodecyltrimethylammonium Bromide (DTAB) and Sodium Dodecylsulfate (SDS) rich surfactants in aqueous medium have been studied by surface tension, viscosity, density, and sound velocity at T ¼ 293.15, 298.15, and 303.15 K. The DTAB concentration varies from 0.0001 to 0.03 mol  L 1 in the presence of 0.01 mol  L 1 SDS and the SDS concentration varies from 0.001 to 0.015 mol  L 1 in the presence of 0.005 mol  L 1 DTAB, so that the concentrations of cationic (DTAB-rich) and anionic (SDS-rich) solutions are taken in the ratio of 3:1. The density (ρ) and sound velocity (μ) data are used for calculating apparent molar volume (V ϕ ), friccohesity (σ), isentropic compressibility (K s,ϕ ), surface tension (γ), and viscosity (η). These parameters reveals that the relative solute-solvent and solute-solute interactions of SDS-DTAB and DTAB-SDS in an aqueous medium with the help of physicochemical properties (PCPs). 1. Introduction Catanionic surfactant systems have unique physiochemical properties that are different from those of their individual constituents, including lower critical aggregation concentrations and higher surface activities, which are important for detergency applications. [1,2] The interactive behavior of cationic and anionic surfactants in the aqueous medium is of numerous importance for basic science and technological applications. [3] Catanionic surfactant systems have also been used as semi-permanent wall coatings for fused silica capillaries [4] in capillary electrophoresis (CE) applications or as pseudo-stationary phases in micellar electro kinetic chromatography (MEKC). The mixer of two anionic and cationic surfactants together can produce interesting microstructures not formed by the pure components (e.g., vesicles and or rod-like micelles) and can dramatically decrease the concentration at which liquid crystalline phases form. [5] There are im- portant physicochemical aspects that need intensive attention for understanding both the fundamental and application pros- pects [6,7] ; such as, formations of aggrega- tions and their dependence on environmental factors (temperatures and additives, etc.), their thermodynamics of formation, counter ion binding, aggrega- tion numbers, etc. Bagheri et al. [8] have been studied the physicochemical properties (hydrophobic- ity, cloud point, Kraft point, etc.) of mixed surfactants. Das et al. [9] have been reported amphiphilic chemical structure, the surfac- tant has a preference toward interfacial adsorption at low concentration region; whereas above a critical concentration, it self-aggregates to form assembled structure whose size, shape, and an average number of amphiphile per aggregated structure depend on the amphiphile concentration and other physicochemical parameters like temperature, the presence of salt. Lakra et al. [10] have been reported physicochemical properties of single and binary mixtures have been determined by various techniques like conductivity, surface tensiometry, potentiometric, spectroscopic methods, etc. In last few years, mixed surfactants have received especial attention due to their high efficiency of solubilization, dispersion, suspension, and transpor- tation abilities. [11–13] Song et al. [14] have been reported physico- chemical properties and surface tension prediction of mixed surfactant systems: Triton X-100 with dodecylpyridinium bromide and Triton X-100 with sodium dodecylsulfate. And more other research studies have been done likes extensive reports exist in the literature on studies of the different combination of mixed surfactant system viz. cationic-cationic, [15,16] nonionic-non- ionic, [15–17] anionic-cationic, [18,19] anionic-nonionic, [15,20] and cat- ionic-nonionic. [20,21] Ionic/nonionic surfactant mixtures are important from fundamental as well as application point of view as they exhibit highly nonideal behavior on mixing and also their behavior can be complementary in the mixed micelle causing the critical concentration concentration (cmc) to decrease. K. M. Sachin, S. Karpe, M. Singh School of Chemical Sciences Central University of Gujarat Gandhinagar, Gujarat, India A. Bhattarai Department of Chemistry M. M. A. M. C Tribhuvan University Biratnagar, Nepal E-mail: bkajaya@yahoo.com DOI: 10.1002/masy.201700034 Macromolecular Symposia Friccohesity www.ms-journal.de FULL PAPER Macromol. Symp. 2018, 379, 1700034 © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1700034 (1 of 9)