Charge-free reverse wormlike micelles in nonaqueous media

Modulating shape transition in surfactant stabilized reverse microemulsions

The formation of reverse microemulsions (RMs) of spherical shape in the oil/water/surfactant ternary mixture at high molar ratio of water to surfactant (ω) is well established. Using dynamic light scattering, small-angle X-ray and neutron scattering, we elucidate the formation of non-spherical reverse microemulsions stabilised by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) at ω = 10 and volume fractions of the dispersed phase, Φ, ranging from 0.005 to 0.20. In addition, we propose a strategy to tune the aspect ratio of non-spherical droplets and colloidal interactions by (i) varying the volume fraction of the dispersed phase (ii) changing the temperature, and (iii) by substituting the aliphatic oil with a mixture of aliphatic and aromatic hydrocarbons. This tunability of anisotropy along with a precise control of the interactions in the RMs, their ability to form spontaneously and their thermodynamic stability is crucial to provide a handle on reaction kinetics, synthesis of anisotropic nanoparticles as well as for their application as lubricants and viscosity modifiers.

Transformation of Lipid Vesicles into Micelles by Adding Nonionic Surfactants: Elucidating the Structural Pathway and the Intermediate Structures

The phospholipid lecithin (L) and the nonionic surfactant Tween 80 (T) are used together in various contexts, including in drug delivery and oil spill remediation. There is hence a need to elucidate the nanostructures in LT mixtures, which is the focus of this paper. We study these mixtures using cryogenic transmission electron microscopy (cryo-TEM), coupled with dynamic light scattering and small-angle neutron scattering. As the concentration of Tween 80 is increased, the vesicles formed by lecithin are transformed into spherical micelles. We identify bicelles (i.e., disc-like micelles) as well as cylindrical micelles as the key stable nanostructures formed at intermediate L/T ratios. The bicelles have diameters ∼13-26 nm, and the bicelle size decreases as the Tween 80 content increases. We propose that the lecithin lipids form the body of the discs, while the Tween 80 surfactants occupy the rims. This hypothesis is consistent with geometric arguments because lecithin is double-tailed and favors minimal curvature, whereas the single-tailed Tween 80 molecules prefer curved interfaces. In the case of cylindrical micelles, cryo-TEM reveals that the micelles are short (length < 22 nm) and flexible. We are able to directly visualize the microstructure of the aggregates formed by lecithin-Tween 80 mixtures, thereby enhancing the understanding of morphological changes in the lecithin-Tween 80 system.

Au(i)-, Ag(i)-, and Pd(ii)-coordination-driven diverse self-assembly of an N-heterocyclic carbene-based amphiphile

Au(i)-, Ag(i)-, and Pd(ii)-coordination-driven diverse self-assembly of an N-heterocyclic carbene (NHC)-based amphiphile was demonstrated herein. The transition metals had significant effects over the whole system, setting the self-assembly direction of the NHC-based amphiphile. More specifically, Au(i)- and Ag(i)-coordination to the NHC-based amphiphile promoted the formation of spherical and hexagonal structures, while Pd(ii)-coordination promoted the formation of cylindrical and lamellar structures.

Au(i)-, Ag(i)-, and Pd(ii)-coordination-driven diverse self-assembly of an N-heterocyclic carbene (NHC)-based amphiphile was demonstrated.

Oil-Tolerant Nonionic Worm-like Micellar Solution

The goal of this work is to study the effect of crude oil on worm-like micelles and identify any oil-tolerant systems. A new class of nonionic surfactants was synthesized that forms viscous worm-like micelles under a wide range of temperature and salinity conditions. Aqueous stability, rheology, cryogenic transmission electron microscopy imaging, and dynamic-light-scattering measurements were performed to understand properties, shape, and size of the micelles formed using these surfactants under different temperatures and salinity conditions and in the presence of hydrocarbons. These micellar solutions maintained high viscosity in the presence of small amounts (up to 8 vol %) of crude oils and pure hydrocarbons. Similar experiments were performed with conventional surfactant systems that were known to form worm-like micelles; they did not show oil tolerance. Larger alkanes and viscous crude oils affect the viscosity and transformation of cylindrical micelles less. These new surfactants are useful for oil and gas operations such as hydraulic fracturing, conformance control, and mobility control as they form viscous worm-like micelles in the presence of small amounts of crude oils.

Dirhamnolipid ester - formation of reverse wormlike micelles in a binary (primerless) system

We report new dirhamnolipid ester forming reverse wormlike micelles in nonpolar solvents without the addition of any primer. Therefore, these compounds represent a rare case of a binary system showing this gel-like behavior. In this study, the influence of the concentration of the rhamnolipid ester and the ester alkyl chain length on the rheological properties of the reverse wormlike micelles in toluene was investigated in detail. Highly viscoelastic solutions were obtained even at a relatively low concentration of less than 1 wt %. The phase transition temperatures indicate that the formation of reverse wormlike micelles is favored for dirhamnolipid esters with shorter alkyl chain lengths. Oscillatory shear measurements for the viscoelastic samples reveal that the storage modulus (G') and the loss modulus (G'') cross each other and fit the Maxwell model very well in the low-ω region. As is typical for wormlike micelle systems, the normalized Cole-Cole plot of G''/G'' max against G'/G'' max was obtained as a semicircle centered at G'/G'' max = 1. The formation of network structures was also verified by polarized light microscopy. The sample was birefringent at ambient temperature and anisotropic at an elevated temperature. Differential scanning calorimetry analysis yielded a transition enthalpy of about ΔH SG/GS = ±7.2 kJ/mol. This value corresponds to a strong dispersion energy and explains the formation of the highly viscous gels by the entanglement of wormlike micelles through the interaction of the alkyl chains.

Demonstration of a Novel Charge-Free Reverse Wormlike Micelle System

We demonstrate a novel charge-free reverse wormlike micelle (RWLM) consisting of a ternary mixture of a nonionic amphiphilic block copolymer, fatty acid alkyl ester oil, and water under ambient conditions. Nonionic amphiphile tetra-[poly(oxyethylene)-poly(oxybutylene)]pentaerythrityl ether (TEBPE) self-assembled into spheroid-type micelles in nonaqueous media isopropyl myristate (IPM) with viscosity comparable to that of IPM. The addition of water increases viscosity only slightly up to a certain concentration of water and then drastically, demonstrating the sphere-to-wormlike micelle transition as confirmed by small-angle X-ray scattering. Further increase in water decreases the viscosity after attaining a maximum value. The zero shear viscosity (η₀) of the 10 wt % TEBPE/IPM system reached the maximum at 2.6 wt % water and ca. 56 Pa·s, which is ∼fivefold higher than that of water. Dynamic rheological measurements on the highly viscous solutions confirmed the viscoelastic behavior and could be described by the Maxwell model. Conductivity, measured in the presence of a conductive probe, 1-ethyl-3-methylimidazolium tetrafluoroborate, was found to be higher for viscous samples compared to the nonviscous samples, suggesting the static percolation caused by the RWLM formation. Decrease in η₀ and conductivity beyond a maximum suggests the shortening of reverse micelles. A similar behavior has been observed in other fatty acid alkyl ester oils of different alkyl chain lengths. Note that most of the RWLM systems previously reported are based on phosphatidylcholine (PC). Formulation and structure-properties related to non-PC-based RWLMs have been rarely explored. Non-PC-based RWLMs using chemically stable and low-cost synthetic molecules can be applied not only in pharmaceuticals and cosmetics but also in a wide range of applications including drag reduction agents for nonaqueous fluids and as a template for nanomaterial synthesis.

Highly Viscoelastic Reverse Wormlike Micellar Systems from a Mixture of Lecithin, Polyglycerol Fatty Acid Monoesters, and an Oil

We report new lecithin reverse wormlike micelles with high viscoelasticity formed using lecithin/polyglycerol fatty acid monoester (PGLFA)/oil systems. In this study, the influence of the amphiphilicity (i.e., hydrophile-lipophile balance, HLB) of PGLFA on the phase behavior and rheological properties of reverse wormlike micelles was investigated in detail. PGLFAs with degrees of polymerization of polyglycerol varying between 6-40 and constituent fatty acids with chains between 6-18 carbon atoms long were used. Partial phase diagrams of the lecithin/PGLFA/n-decane systems indicated that the appropriate PGLFA could change the lecithin/oil solution into a highly viscoelastic solution comprising reverse wormlike micelles. Rheological measurements showed that all systems that formed reverse wormlike micelles exhibited an unusual phenomenon called "shear-thickening". Furthermore, reverse wormlike micelles grew as the PGLFA concentration increased and the zero-shear viscosity (η₀) of the solution rapidly increased. Our results indicate that the magnitude of the maximum η₀ depends on the degree of polymerization of the constituent polyglycerol in the PGLFA, while the size of the reverse micellar region and the highly viscous region in the phase diagram depends on the HLB value of the PGLFA.

Effects of Reverse Micellar Structure on the Particle Charging Capabilities of the Span Surfactant Series

This paper investigates the effects of reverse micellar core size on the particle charging behavior of a series of acidic surfactants in apolar media. A series of Span surfactants was dissolved in deuterated decane at concentrations above the critical micelle concentration. The structures of the reverse micelles were measured using small-angle neutron scattering. It was determined that as the tail length of the surfactant increased, the size of the polar reverse micellar core decreased. Tritailed surfactants formed reverse micelles with the smallest polar cores, with radii of ∼4 Å. The sizes of the polar cores were correlated with the particle charging behavior of the Span surfactant series, as measured in a previous study. It was found that reverse micelles with intermediate core sizes imparted the largest electrophoretic mobilities to the particles. Reverse micelles with very small cores did not offer a large enough polar environment to favor charge stabilization, while very large polar cores favored disproportionation reactions in the bulk, resulting in increased electrostatic screening.

The Formation of pH-Sensitive Wormlike Micelles in Ionic Liquids Driven by the Binding Ability of Anthranilic Acid

Wormlike micelles are typically formed by mixing cationic and anionic surfactants because of attractive interactions in oppositely charged head-groups. The structural transitions of wormlike micelles triggered by pH in ionic liquids composed of N-alkyl-N-methylpyrrolidinium bromide-based ILs (ionic liquids) and anthranilic acid were investigated. These structures were found responsible for the variations in flow properties identified by rheology and dynamic light scattering, and account for the structures observed with cryogenic transmission electron microscopy (Cryo-TEM). High-viscosity, shear-thinning behavior, and Maxwell-type dynamic rheology shown by the system at certain pH values suggested that spherical micelles grow into entangled wormlike micelles. Light scattering profiles also supported the notion of pH-sensitive microstructural transitions in the solution. Cryo-TEM images confirmed the presence of spherical micelles in the low-viscosity sample and entangled wormlike micelles in the peak viscosity sample. Nuclear magnetic resonance spectroscopy analysis revealed that the pH sensitivity of ionic liquid systems originated from the pH-dependent binding ability of anthranilic acid to the cationic headgroup of ionic liquids.

Impact of Alkyl Chain Length on the Transition of Hexagonal Liquid Crystal-Wormlike Micelle-Gel in Ionic Liquid-Type Surfactant Aqueous Solutions without Any Additive

The search for functional supramolecular aggregations with different structure has attracted interest of chemists because they have the potential in industrial and technological application. Hydrophobic interaction has great influence on the formation of these aggregations, such as hexagonal liquid crystals, wormlike micelles, hydrogels, etc. So a systematical investigation was done to investigate the influence of alkyl chain length of surfactants on the aggregation behavior in water. The aggregation behavior of 1-hexadecyl-3-alkyl imidazolium bromide and water has been systematically investigated. These ionic liquid surfactants are denoted as C16-Cn (n = 2, 3, 4, 6, 8, 9, 10, 12, 14, 16). The rheological behavior and microstructure were characterized via a combination of rheology, cryo-etch scanning electron microscopy, polarization optical microscopy, and X-ray crystallography. The alkyl chain has great influence on the formation of surfactant aggregates in water at the molecular level. With increasing alkyl chain length, different aggregates, such as hexagonal liquid crystals, wormlike micelles, and hydrogels can be fabricated: C16-C2 aqueous solution only forms hexagonal liquid crystal; C16-C3 aqueous solution forms wormlike micelle and hexagonal liquid crystal; C16-C4, C16-C6 and C16-C8 aqueous solutions only form wormlike micelle; C16-C9 aqueous solution experiences a transition between wormlike micelle and hydrogel; C16-C10, C16-C12, C16-C14 and C16-C16 only form hydrogel. The mechanism of the transition of different aggregation with increasing alkyl chain length was also proposed.

Nonionic amphiphile nanoarchitectonics: self-assembly into micelles and lyotropic liquid crystals

Amphiphiles, molecules that possess both hydrophilic and hydrophobic moieties, are architecturally simple molecules that can spontaneously self-assemble into complex hierarchical structures from lower to higher dimensions either in the bulk phase or at an interface. Recent developments in multifunctional nanostructure design using the advanced concept of nanoarchitectonics utilize this simple process of assembly. Amphiphilic self-assemblies involving lipids or proteins mimic the structure of biological systems, thus highlighting the necessity of a fundamental physical understanding of amphiphilic self-assembly towards a realization of the complex mechanisms operating in nature. Herein, we describe self-assembled microstructures of biocompatible and biodegradable tetraglycerol lauryl ether (C12G4) nonionic surfactant in an aqueous solvent system. Temperature-composition analyses of equilibrium phases identified by using small-angle x-ray scattering (SAXS) provide strong evidence of various spontaneously self-assembled mesostructures, such as normal micelles (Wm), hexagonal liquid crystal (H1), and reverse micelles (Om). In contrast to conventional poly(oxyethylene) nonionic surfactants, C12G4 did not exhibit the clouding phenomenon at higher temperatures (phase separation was not observed up to 100 °C), demonstrating the greater thermal stability of the self-assembled mesophases. Generalized indirect Fourier transformation (GIFT) evaluation of the SAXS data confirmed the formation of core-shell-type spherical micelles with a maximum dimension ca. 8.7 nm. The shape and size of the C12G4 micelles remained apparently unchanged over a wide range of concentrations (up to 20%), but intermicellar interactions increased and could be described by the Percus-Yevick (PY) theory (after Carnahan and Starling), which provides a very accurate analytical expression for the osmotic pressure of a monodisperse hard sphere.

Mixtures of lecithin and bile salt can form highly viscous wormlike micellar solutions in water

The self-assembly of biological surfactants in water is an important topic for study because of its relevance to physiological processes. Two common types of biosurfactants are lecithin (phosphatidylcholine) and bile salts, which are both present in bile and involved in digestion. Previous studies on lecithin-bile salt mixtures have reported the formation of short, rodlike micelles. Here, we show that lecithin-bile salt micelles can be further induced to grow into long, flexible wormlike structures. The formation of long worms and their resultant entanglement into transient networks is reflected in the rheology: the fluids become viscoelastic and exhibit Maxwellian behavior, and their zero-shear viscosity can be up to a 1000-fold higher than that of water. The presence of worms is further confirmed by data from small-angle neutron and X-ray scattering and from cryo-transmission electron microscopy (cryo-TEM). We find that micellar growth peaks at a specific molar ratio (near equimolar) of bile salt:lecithin, which suggests a strong binding interaction between the two species. In addition, micellar growth also requires a sufficient concentration of background electrolyte such as NaCl or sodium citrate that serves to screen the electrostatic repulsion of the amphiphiles and to "salt out" the amphiphiles. We postulate a mechanism based on changes in the molecular geometry caused by bile salts and electrolytes to explain the micellar growth.

Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: a kinetic approach

The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.

A SAXS study of aggregation in the synergistic TBP-HDBP solvent extraction system

The macroscopic phase behaviors of a solvent system containing two extractants, tri-n-butyl phosphate (TBP) and di-n-butyl phosphoric acid (HDBP) in n-dodecane, were investigated through use of liquid-liquid extraction and small-angle X-ray scattering (SAXS) experiments. Five organic solutions, each containing a total extractant concentration (TBP + HDBP) of 1 M in varying molar ratios (0, 0.25, 0.5, 0.75, and 1.0 [TBP]:[TBP + HDBP]), were contacted with 0.2 M HNO3 aqueous solutions without and with dysprosium(III) at a concentration of 10(-4) M. An enhancement of the extraction of Dy(3+)--due to effects of synergism arising from the binary combination of extractants--was observed. SAXS data were collected for all solution compositions from 0 to 1 mol-fraction end ratios of TBP after contact with the acidic aqueous solutions both in the absence and presence of Dy as well as for the organic phases before aqueous contact. In the precontacted solutions, no notable changes in the SAXS data were observed upon combining the extractants so that the scattering intensity (I) measured at zero angle (Q = 0 Å(-1))--parameter I(0)--the experimental radius of gyration (R(g)), and the maximum linear extent (MLE) of the extractant aggregates were arithmetic averages of the two end members, 1 M HDBP, on the one hand, and 1 M TBP, on the other. In contrast, after contact with the aqueous phases with and without Dy(3+), a significant reorganization occurs with larger aggregates apparent in the extractant mixtures and smaller in the two end member solutions. In particular, the maximum values of the metrical parameters (I(0), R(g), and MLE) correlate with the apparent optimal synergistic extraction mole ratio of 0.25. The SAXS data were further analyzed using the recently developed generalized indirect Fourier transformation (GIFT) method to provide pair-distance distribution functions with real-space information on aggregate morphology. Before aqueous contact, the organic phases show a systematically varying response from globular-like reverse micelles in the case of 1 M TBP to rod-shaped architectures in the case of 1 M HDBP. After aqueous contact, the aggregate morphologies of the mixed extractant systems are not simple linear combinations of those for the two end members. Rather, they have larger and more elongated structures, showing sharp discontinuities in the metrics of the aggregate entities that are coincident with the synergistic extraction mixture for Dy(3+). The results in this initial study suggest a supramolecular, micellization aspect to synergism that remains underexplored and warrants further investigation, especially as it concerns the contemporary relevance to decades-old process chemistry and practices for high throughput separations systems.

Smart wormlike micelles

A major scientific challenge of the past decade pertaining to the field of soft matter has been to craft 'adaptable' materials, inspired by nature, which can dynamically alter their structure and functionality on demand, in response to triggers produced by environmental changes. Amongst these, 'smart' surfactant wormlike micelles, responsive to external stimuli, are a particularly recent area of development, yet highly promising, given the versatility of the materials but simplicity of the design-relying on small amphiphilic molecules and their spontaneous self-assembly. The switching 'on' and 'off' of the micellar assembly structures has been reported using electrical, optical, thermal or pH triggers and is now envisaged for multiple stimuli. The structural changes, in turn, can induce major variations in the macroscopic characteristics, affecting properties such as viscosity and elasticity and sometimes even leading to a spontaneous and effective 'sol-gel' transition. These original smart materials based on wormlike micelles have been successfully used in the oil industry, and offer a significant potential in a wide range of other technological applications, including biomedicine, cleaning processes, drag reduction, template synthesis, to name but a few. This review will report results in this field published over the last few years, describe the potential and practical applications of stimuli-responsive wormlike micelles and point out future challenges.

Molecular interactions between lecithin and bile salts/acids in oils and their effects on reverse micellization

It has been known that the addition of bile salts to lecithin organosols induces the formation of reverse wormlike micelles and that the worms are similar to long polymer chains that entangle each other to form viscoelastic solutions. In this study, we further investigated the effects of different bile salts and bile acids on the growth of lecithin reverse worms in cyclohexane and n-decane. We utilized rheological and small-angle scattering techniques to analyze the properties and structures of the reverse micelles. All of the bile salts can transform the originally spherical lecithin reverse micelles into wormlike micelles and their rheological behaviors can be described by the single-relaxation-time Maxwell model. However, their efficiencies to induce the worms are different. In contrast, before phase separation, bile acids can induce only short cylindrical micelles that are not long enough to impart viscoelasticity. We used Fourier transform infrared spectroscopy to investigate the interactions between lecithin and bile salts/acids and found that different bile salts/acids employ different functional groups to form hydrogen bonds with lecithin. Such effects determine the relative positions of the bile salts/acids in the headgroups of lecithin, thus resulting in varying efficiencies to alter the effective critical packing parameter for the formation of wormlike micelles. This work highlights the importance of intermolecular interactions in molecular self-assembly.

Mesoscopic aspects of phase transitions in a solvent extraction system

In liquid-liquid extraction, organic phase splitting arises when high concentrations of polar solutes (acids/metal ions) are extracted. Herein, we investigate the mesoscopic roots that underpin phase splitting in alkane phases containing mixed amphiphiles, of contemporary interest in solvent extraction separation systems, by extracting various oxoacids. The oxoacids exhibited individual macroscopic (extractive and physical) behaviors, inducing phase splitting into heavy and light domains under markedly different conditions. Using small-angle X-ray scattering (SAXS) data analyzed using the generalized indirect Fourier transform (GIFT) method, we showed that, in all cases, acid extraction drove the self-assembly of reverse micelles into rods. These grew with increased acid extraction until reaching a critical length of 20 nm, at which point interactions produced interconnected cylinders or lamellar sheets that prelude phase splitting into heavy and light domains. In all cases, the heavy phase contained the same surfactant ratio-TBP (tri-n-butyl phosphate) and CMPO (octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide)-even though the concentrations of acid, water, and amphiphiles were markedly different. The remarkable similarities in structure and amphiphile stoichiometries underpinning phase splitting across the macroscopically different acid extraction series allude to the mesoscopic roots of organic phase behavior in solvent extraction. Our studies show that the structures underpinning phase splitting in solvent extraction systems are more complex than previously thought and are reminiscent of phase transitions in soft matter.

Coordination structures and supramolecular architectures in a cerium(III)-malonamide solvent extraction system

The process chemistry and solution structures investigated in the title system bridge the three ostensibly disparate fields of separation sciences, soft matter research, and coordination chemistry. We have explored this subject with synchrotron radiation research and advanced analyses leading to original insights into aggregation phenomena in solvent extraction. Herein we present findings showing the coagulation of reverse micelles into wormlike aggregates in organic phases (N,N'-dimethyl-N,N'-dibutyltetradecylmalonamide-abbreviated as DMDBTDMA-in n-dodecane) obtained by liquid-liquid extraction following contact with acidic and neutral aqueous media containing trivalent cerium. The growth of solute architectures was shown to prelude phase transition (i.e., the formation of a "third phase"). The presence of acid was shown to promote the growth of these micellar chains and, therefore, promoted third-phase formation. Acid was also shown to hydrate and swell the reverse micelle units, preorganizing them to allow for incorporation of cerium, leading to different coordination structures and enhanced metal extraction. The approach of linking both the coordination environment and supramolecular structures to the process properties of a solvent extraction system in a single study provides perspectives that are not available from independent, uncorrelated experimentation. Moreover, the analysis of small-angle X-ray scattering data from a solvent extraction system using the generalized indirect Fourier transform method to gain real-space information led to insights not otherwise available, showing that micellar assemblies are larger and more ordered than previously thought. This multipronged and multidisciplinary investigation opens new avenues in the evolving understanding of solute architectures in organic phases of practical relevance to solvent extraction and, simultaneously, of fundamental relevance to structured fluids and, in particular, phase transition phenomena.

Intrinsic parameters for the structure control of nonionic reverse micelles in styrene: SAXS and rheometry studies

Shape, size, and internal structure of nonionic reverse micelle in styrene depending on surfactant chain length, concentration, temperature, and water addition have been investigated using a small-angle X-ray scattering (SAXS) technique. The generalized indirect Fourier transformation (GIFT) method has been employed to deduce real-space structural information. The consistency of the GIFT method has been tested by the geometrical model fittings, and the micellar aggregation number (N(agg)) has been determined. It was found that diglycerol monocaprate (C(10)G(2)), diglycerol monolaurate (C(12)G(2)), and diglycerol monomyristate (C(14)G(2)), spontaneously self-assemble into reverse micelles in organic solvent styrene under ambient conditions. The micellar size and the N(agg) decrease with an increase in surfactant chain length, a scenario that could be understood from the modification of the critical packing parameter (cpp). A clear picture of one-dimensional (1-D) micellar growth was observed with an increase in surfactant weight fraction (W(s)) in the C(10)G(2) system, which eventually formed rodlike micelles at W(s) ≥ 15%. On the other hand, micelles shrunk favoring a rod-to-sphere type transition upon heating. Reverse micelles swelled with water, forming a water pool at the micellar core; the size of water-incorporated reverse micelles was much bigger than that of the empty micelles. Model fittings showed that water addition not only increase the micellar size but also increase the N(agg). Zero-shear viscosity was found to decrease with surfactant chain but increase with W(s), supporting the results derived from SAXS.