Investigation on the Structure of Water/AOT/IPM/Alcohols Reverse Micelles by Conductivity, Dynamic Light Scattering, and Small Angle X-ray Scattering

Abstract

We have systematically investigated the effect of alcohols (ethanol, propanol, butanol, and pentanol) on the structure of the water/AOT/IPM system using conductivity, dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS) techniques. The results show that no percolation phenomenon is observed in the water/AOT/IPM system, whereas the addition of ethanol (propanol and butanol) induces apparently percolation. The threshold water content (W(p)) depends closely on the alcohol type and concentration. The effect of alcohols on the conductance behavior is discussed from the physical properties of alcohols, the interfacial flexibility, and the attractive interactions between droplets. The hydrodynamic diameter of droplets (d(H)) obtained from DLS increases markedly with the increase in water content (W(0)); however, it decreases gradually with increasing alcohol chain length and concentration. SAXS measurements display distinctly the shoulder, the low hump peaks, and the heavy tail phenomenon in the pair distance distribution function p(r) profile, which rely strongly on the alcohol species and its concentration. The gyration radius (R(g)) increases with increasing W(0), and decreases with the increase of alcohol chain length and concentration. Schematic diagram of the conductance mechanism of water/AOT/IPM/alcohol systems is primarily depicted. Three different phases of the discrete droplets, the oligomers, and the isolated ellipsoidal droplets existed in the different W(0) ranges correspond to three different stages in the conductivity-W(0) curve. Coupling the structure characteristics of reverse micelles obtained from DLS and SAXS techniques with conductivity could be greatly helpful to deeply understand the percolation mechanism of water/AOT/IPM/alcohols systems.

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

“…Additional water then goes primarily to the inner core, leading to a continuous increase in the volume of core water with a further increase in ω and results in a shift in the distribution of surfactant molecules to cover the increased volume of water. As a result, smaller droplets are combined into larger ones [64,66]. Such results are consistent with the results obtained for different microemulsions reported earlier [51,64].…”

“…As a result, smaller droplets are combined into larger ones [64,66]. Such results are consistent with the results obtained for different microemulsions reported earlier [51,64].…”

“…Both of these effects increase the packing parameter (P) and consequently, d h decreases. Similar observation was reported earlier by Zhang et al [64] for water/AOT/Bu or Pn/IPM microemulsions.…”

“…Also, with the increase in water content of the microemulsions, formation of swollen micelles with more open structures was evidenced, which facilitates the exchange of contents between the fusing droplets and percolation initiates at a fixed temperature [5,30]. This phenomenon corroborates well with the reports found in literature [63,64].…”

Physiological and Transcriptional Responses of Saccharomyces cerevisiae to d -Limonene Show Changes to the Cell Wall but Not to the Plasma Membrane

“…In a recent study (3), limonene toxicity was dramatically reduced in the presence of an inert extractant. The extractive solvents dibutyl phthalate (DBP) and isopropyl myristate (IPM), for example, are harmless to yeast cells and are at least an order of magnitude more viscous than limonene ( limonene ϭ 0.008 P [60], DBP ϭ 0.166 P [61], and IPM ϭ 0.043 P [62]). The viscosity of a fluid has a strong influence on droplet size, which affects the dispersion's overall surface area (63).…”