Synthesis and Properties of Cationic Ester-Containing Gemini Surfactants

Abstract

Abstract A series of cationic Ester-containing Gemini surfactants, alkanediyl-α- and ω-bis(dimethyl acyloxyethylammonium bromide), were synthesized and symbolized as II-m-n (m = 12; n = 3, 4, 6). The surfactants were characterized by 1H-NMR. The surface active properties and thermodynamic properties of these surfactants at different temperatures were studied by the measurement of surface tension and electric conductivity. The esterquat Geminis surfactants of this work were found to have strong formation capacity of micellization, and the critical micelle concentration (CMC) of these surfactants are about 2.63 × 10−4 to 4.17 × 10−4 mol L−1, which is one order of magnitude smaller than that of the corresponding esterquat monomer. The Gibbs free energy of surface adsorption (ΔGad 0) and micellization (ΔGm 0) are all negative (−74.73 kJ mol−1 to −82.11 kJ mol−1 and −42.87 kJ mol−1 to −49.38 kJ mol−1). The thermodynamic parameters of these surfactants indicate that the surface adsorption and micellization are all enthalpy driven.