Micelle Formation of Morpholinium Bromide Surfactants in Aqueous Solution

Abstract

Abstract The micelle formation of N-alkyl-N-methylmorpholinium bromide (CnMMB, n = 12, 14, 16) surfactants in aqueous solution has been investigated. Their critical micelle concentration (CMC), effectiveness and efficiency of the surface tension reduction, and the maximum surface excess concentration were derived from the surface tension curves. Thermodynamic parameters were then evaluated in the temperature range of 25 °C ∼ 45 °C. The results showed that with increasing the alkyl chain length, the CMC values were decreased gradually, which is consistent with the enhancement of hydrophobic effect. Due to the existence of an oxygen atom in the headgroup, an unusual surface activity of CnMMB surfactants was obtained. The obtained results should help to better understand the effect of the hydrophilic headgroup on the micelle behavior of cationic surfactants containing saturated nitrogen-containing heterocycles.