Dynamic Interfacial Tension of a Gemini Surfactant: N,N′-Didodecyl-2-Hydroxyl-N,N,N′,N′-Tetramethyl-Dichloride at n-Decane/Water Interface

Abstract

Dynamic interfacial tension (DIT) between aqueous solution of N,N′-didodecyl-2-hydroxyl-N,N,N′,N′-tetramethyl-dichloride (G12NCl) and n-decane was measured using spinning drop method. The effects of G12NCl concentration below its CMC and temperature on DIT have been investigated. The effective diffusion coefficient, D a , and the adsorption barrier of energy, ϵ a , have been obtained with extended Word-Tordai equation. The results show that the higher the concentration of the gemini, the smaller the DIT. With the increasing of concentration in bulk aqueous solution of G12NCl, D a decreases and ϵ a increases, while as the temperature ascends from 35°C to 55°C, D a of G12NCl in solution increases from 3.16 × 10−11 m2·s−1 to 10.40 × 10−11 m2·s−1 and ϵa decreases from 7.64 kJ·mol−1 to 5.78 kJ·mol−1 at the concentration 2.0 × 10−4 mol·dm−3. This indicates that the diffusion tendency becomes weak with the strengthening of the interaction between surfactant molecules and that the thermo-motion of molecules benefits interface adsorption.