Micellization and Adsorption Properties of New Cationic Gemini Surfactants Having Hydroxyisopropyl Group

A series of cationic gemini surfactants, N,N′-bis­(alkyl)-N,N′-bis­(2-hydroxypropyl)­ethylenediammonium dibromide, [CnH2n+1(CH3CH­(OH)­CH2)­NH­(CH2)2NH­(CH2CH­(OH)­CH3)­CnH2n+1]­Br2 (where n is the tail chain length, n = 9, 12, and 14), referred to as CnC2Cn[iso-Pr­(OH)] was synthesized. Via conductometric and tensiometric methods, at different temperatures (283 to 313 K), specific electrical conductivities and surface tensions of the aqueous solutions of these cationic gemini surfactants were determined. According to the obtained values, micellization and adsorption parameters such as critical micellization concentration (CMC), maximum surface excess (Γmax), minimal cross sectional surface area of surfactant polar group (Amin), adsorption efficiency (pC20), surface pressure (π), and binding degree of counterion (β) were calculated. The values of standard Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were also computed. Via the dynamic light scattering method, diameters of aggregates of the synthesized cationic gemini surfactants were determined in water. It was established that the diameters of these aggregates decrease with a temperature rise. Antibacterial properties of the synthesized cationic surfactants against sulfate-reducing bacteria (SRB) were studied.