Influences of diols and nonionic hydrotrope on the aggregation and physico-chemical properties of sodium dodecyl sulfate and polyvinyl alcohol mixture at numerous experimental temperatures

Abstract

This study investigates the interaction between sodium dodecyl sulfate (SDS) and polyvinyl alcohol (PVA) in the presence of additives (ethylene glycol (EG), propylene glycol (PG), 2,3-butanediol (2,3-BD), and resorcinol). The critical micelle concentration (CMC) of the surfactant system was estimated by using the conductometric technique. The influence of temperature, concentration, and additive composition on the physicochemical variables (CMC, micelle ionization (α) and counter ion binding (β)) were also investigated. The observed variation in CMC was attributed to several factors, such as the concentration of additives, the nature of hydrophobicity, and the magnitude of the dielectric constant of the mixed solvents. The CMC of the SDS + PVA mixed system was increased with increasing temperature due to the dominance of hydrophobic hydration over the hydrophilic one. The evaluation of thermodynamic parameters, such as change in standard Gibbs free energy (ΔGmo), enthalpy (ΔHmo), and entropy (ΔSmo) and the estimation of β value for the SDS + PVA mixed system indicate the feasibility and viability of the micelle formation. The negative values of ΔGmo observed within the temperature range of 298.15 to 323.15 K suggest a favorable condition for the formation of surfactant micelle. The that the binding forces in the SDS + PVA mixed system are hydrophobic and ion–dipole interactions in nature. The investigation of the intrinsic enthalpy (ΔHm0,∗) determines the stability of the surfactant system, while the compensation temperature (Tc) serves as an indicator of the solute-solvent interaction.