Effect of spacer nature on surface properties of new counterion coupled gemini surfactants based on dodecyldiisopropylol amine and dicarboxylic acids

New counterion coupled gemini (cocogem) surfactants were synthesized by interaction of dodecyldiisopropylol amine with dicarboxylic (oxalic, succinic, adipic, sebacic, maleic, fumaric, isophthalic) acids. By tensiometric method surface activity of aqueous solutions of the synthesized cocogem surfactants at the border with air and by conductometric method specific electrical conductivity of these solutions have been determined. On the basis of the results of these measurements the degree of counterion binding (β), critical micelle concentration (CMC), effectiveness of surface tension reduction (πCMC), surface excess concentration (Γmax), area per molecule at the interface (Amin), changes of Gibbs free energies of adsorption (ΔGad) and micellization (ΔGmic) have been calculated. The average diameter of self-aggregates has been determined by the method of dynamic light scattering. The character of change of the colloidal-chemical indices depending on spacer-group nature and length has been clarified. The obtained cocogem surfactants having a saturated aliphatic chain in the spacer exhibit a considerably higher bactericidal effectiveness against sulfate-reducing bacteria. © 2018 Elsevier B.V.