Effect of polymers and temperature on critical micelle concentration of some gemini and monomeric surfactants

Graphical abstract: The figure shows that the CMC of CDEEAB in presence of polyethylene glycols increase with increasing molar mass and percentages of PEG but CMC values decrease with higher molecular mass of PEG. Highlights: • The CMC values of cationic gemini and monomeric surfactants increase with increasing percentage of polymers. • The CMC and α values of cationic surfactant increased with increasing temperature. • The values of (ΔGm°) are negative in all cases and indicate that the micelle formation process is spontaneous. • The values of negative enthalpy indicate the importance of the London dispersion forces for micellization. -- Abstract: The effect of polymers on the physicochemical properties of cationic gemini (16-4-16 MEA, 2Br−) and monomeric surfactants (cetyldiethylethanolammonium bromide, (CDEEAB) and cetyldimethylethanolammonium bromide (CDMEAB) have been studied by conductivity measurements. The critical micelle concentration (cmc) value increases by increasing the percentage and molecular mass of polymers (poly (ethylene glycol), PEG-X, where X = 400, 600) while it decreases with higher molecular mass (X = 4000, 6000, 20,000). Thermodynamic parameters (standard Gibbs energy (ΔGm°), enthalpy (ΔHm°), and entropy (ΔSm°), of micellization) have also been investigated. Hydrophobic interactions and the ability to form hydrogen bonds play a role in the polymer–surfactant association. This associative behavior was shown to depend significantly on the polymer and surfactant concentrations. The enthalpies of micellization are much more exothermic for the gemini surfactants than for the monomeric surfactants. All of the surfactants exhibited the enthalpy–entropy compensation phenomenon