Interfacial composition and characterization of a quaternary water-in-oil mixed surfactant (cationic of different alkyl chain lengths+polyoxyethylene type nonionic) microemulsions in absence and presence of inorganic salts

Influence of chemical architecture of oils and ionic liquid on the physicochemical and thermodynamic properties and microenvironment of anionic surfactant based microemulsion

“…It was reported that water coexists in three 'states' or 'layers' in the w/o microemulsions from FTIR spectroscopic measurements [49,71,84,85]. In the present report, the bands observed for water O H have been fitted as a sum of Gaussian with the help of Gaussian curve fitting program, and the vibrational characteristics, particularly the peak area corresponding to each peak, have been analyzed using three-state models to unravel the states of water inside the nanopool [42,83]. It may be noted that such a vibrational spectroscopic study on IBB or LIM oil derived w/o microemulsions has not been reported earlier.…”

“…We focus our attention in the 3000-3800 cm −1 frequency windows which is a fingerprint region for the symmetric and asymmetric vibrational stretch of O H bonds in water [82]. In order to eliminate the supplementary IR intensity due to O H stretching vibration of Pn molecule (since Pn has been used as a structure forming cosurfactant in the present study), the spectra of Pn (at the similar concentration) has been subtracted from the spectral intensity of O H stretching band at the corresponding ω, and the differential spectra have been analyzed [42,83]. It was reported that water coexists in three 'states' or 'layers' in the w/o microemulsions from FTIR spectroscopic measurements [49,71,84,85].…”

The Schulman Method of Cosurfactant Titration of the Oil/Water Interface (Dilution Method): A Review on a Well‐Known Powerful Technique in Interfacial Science for Characterization of Water‐in‐Oil Microemulsions

“…Very recently, W/O microemulsions or RM systems involving more than one surfactant have been characterized by employing several methods, viz. solubilization [33,[70][71][72], conductivity [70,73], viscosity [34,71], spectroscopic [35,72,74], SANS [25,38] and FTIR and NMR measurements [75] and a significant modification of the rigidity or the flexibility of the oil/water interface and consequently, the states of water organization (water structure) inside the confined environment of these microheterogeneous systems in comparison to the corresponding single surfactant systems. These findings summarize that the effects of surfactant blending on solubilization and other physical properties are a direct consequence of mixing and physicochemical interactions of the constituents at the interface.…”

“…For 1-pentanol and longer alkyl chain cosurfactantbased microemulsions, negligible water solubility of alkanol leads to n a w & 0 [30,31,33,34]. Thus, Eq.…”

“…Moreover, quantitative description of the dependence of the partition equilibrium [particularly in respect of (2)] on the system composition deserves for a full understanding of quaternary systems [26,32]. All these parameters [except (4), which can be determined from Fourier transform infrared spectroscopy, FTIR measurements] [33][34][35][36], can be evaluated from the dilution method without using sophisticated instruments. The pioneering work for characterizing water-in-oil microemulsions systems is due to Bowcott and Schulman [37].…”