Physicochemical Properties of Quaternary Ammonium Surfactants with Hydroxyethyl Groups

Abstract

Abstract Two cationic quaternary ammonium surfactants with hydroxyethyl groups, dodecyl-(2-hydroxyethyl)-dimethylammonium chloride (DHDAC), and dodecyl-di(2-hydroxyethyl)-methylammonium chloride (DHHAC) were synthesized. Their physicochemical properties were investigated systematically by surface tension and conductivity measurements. Various physicochemical parameters were calculated to evaluate the surface activities of these surfactants. The results show that the surface activity increases with increasing the number of hydroxyethyl groups on hydrophilic groups of surfactants. The degrees of counterion binding to micelles of these surfactants were also discussed. The thermodynamic parameters obtained from electric conductivity measurements show that the micelle formation of DHHAC is entropy-driven in the temperature range investigated. However, it is enthalpy-driven for DHDAC.