Surface adsorption and micelle formation of surfactant N-alkyl-N-methylmorpholinium bromide in aqueous solutions

The surface adsorption and micelle formation of N -alkyl- N -methylmorpholinium bromide ([Mor 1,n ]Br n   =   12, 14, 16) in aqueous solution is investigated in this work. Through surface tension measurements, the effectiveness of surface tension reduction (∏ cmc ), the maximum surface excess concentration (Γ max ) and the minimum area (A min ) occupied per surfactant molecule at the air/water interface at 25   °C can be deduced. Moreover, the critical micelle concentration (cmc) and various thermodynamic parameters (the standard Gibbs energy (ΔG m 0 ), the enthalpy (∆   H m 0 ), and the entropy (∆   S m 0 )) are calculated by the electrical conductivity measurements at different temperatures. The results of thermodynamic parameters show that the micellization process is driven by entropy.