Synergistic Self-Assembly in a Surface-Active Ionic Liquid and an Anionic Surfactant Mixed System: A Comprehensive Physicochemical Analysis

The present investigation is undertaken to develop and characterize mixed aggregates formed from a surface-active ionic liquid (SAIL), 1-hexadecyl-3-methylimidazolium chloride (C(16)mimCl), and two anionic surfactants, sodium oleate or sodium linoleate. The micellization behavior of the cationic SAIL and anionic surfactants was investigated using the tensiometric method. The obtained surface tension data have been analyzed by Rubingh's regular solution theory (RST) and Clint's theory for mixed binary systems. Surface tension data offer additional insight into the change in the critical micelle concentration (CMC) and surface activity as a function of the mole fraction of the SAIL. The negative value of interaction parameters and low CMC values imply the synergism between micelle-forming units at the all-mole fraction investigated. The interfacial and thermodynamic parameters for mixed micelles and mixed monolayers at various mole fractions of C(16)mimCl have been calculated and discussed. A thorough insight into the correlation between the molecular orbital energy level of C(16)mimCl and sodium oleate or sodium linoleate is provided by optimized parameters, which are obtained from a computational simulation approach. The obtained results highlight the compatibility of SAILs with anionic surfactants in formulating the mixed nanoaggregates for desired applications.