Ethoxylate Groups Research Articles

Molecular mechanism of the degree of influence of ethoxy and alkyl structures on the wettability of low-rank coal

The mechanisms of the effects of decyl polyoxyethylene ether (DEO6), decyl polyoxyethylene ether (DEO8), and aliphatic alcohol polyoxyethylene ether (AEO6) on the wettability of coal dust from low-rank coal have been investigated in this study. The aim is to reveal the difference in the degree of influence of the structure of the alkyl and ethoxy groups. The surface tension test showed that AEO6, which can form a soft chain structure, could reach the critical micelle concentration (CMC) the fastest, followed by DEO6, and DEO8, which has the strongest polar effect, the slowest. The contact angle, settling time, and water retention experiments revealed that the AEO6-treated coal dust had the strongest wettability and water retention, which could effectively inhibit the coal dust and weaken the possibility of its secondary dust. Fourier transform infrared (FTIR) spectroscopy reveals that AEO6 with long alkyl chains can produce strong nonpolar effects, and in the process of adsorption with coal dust, it can produce strong hydrophobic bonding with nonpolar groups on the surface of low-rank coal, and finally form a directional adsorption conducive to the enhancement of wettability. Scanning electron microscope (SEM) showed a trend from DEO6-coal, DEO8-coal, and AEO6-coal appearing to have surfaces that sequentially become flatter and denser, with a gradual decrease in the number of loose particles and a weakening of the pore structure. Molecular dynamics (MD) simulations agree with the above experimental results. That is, the interaction between water molecules is stronger in the AEO6-modified coal system, followed by the DEO8 system and weakest in the DEO6 system. And the advantage of DEO8-coal is weaker than that of AEO6-coal but better than that of DEO6-coal. Based on the above experimental and simulation results, it can be concluded that the ability of the alkyl structure to influence the wettability of surfactant-modified coal dust is higher than the structure of the ethoxylate group, which will provide theoretical guidance for coal dust management and dust suppression.

Surface Activity of Ethoxylate Surfactants with Different Hydrophobic Architectures: The Effect of Layer Substructure on Surface Tension and Adsorption.

A series of nonionic ethoxylate surfactants containing different combinations of alkyl, phenyl, and adamantyl units in nine different arrangements, each combined with penta- and hexa-ethylene glycol groups, were synthesized and purified. The surface properties of all of the surfactants were investigated at the air-water (A-W) interface using surface tension (ST) to determine the limiting surface excess (Γlim), the limiting surface tension (σlim), and the critical micelle concentration (CMC). A smaller selection was investigated at the hydrophilic silica-water interface by neutron reflectometry to obtain the thickness of the adsorbed layer and the total adsorption at the CMC. An unusual and largely unrecognized feature of the ethoxylate group is that it is both hydrophilic and hydrophobic. It was found possible to account for the variation of σlim and Γlim of all of the adsorbed layers in terms of a balance of the estimated STs of the sublayers forming the overall adsorbed layer, including that of the underlying ethoxylate layer. The values of σlim were found to be highest for phenyl- and adamantyl-capped surfactants and lowest mainly when there was more than one methyl group at the surface. However, in terms of the concentration required to reach a given low ST, increasing the number of attached methyl groups was found to be less effective than using a smaller number of better-placed methyl groups. At the solid-liquid interface, adsorption at or above the CMC was in all cases in the form of a fragmented bilayer whose coverage varied approximately linearly with the packing parameter. However, results on the phenyl-capped surfactants showed that the high ST exhibited by these surfactants at the A-W interface becomes a high cohesion energy in the interior of the bilayer and they exhibited significantly higher adsorption than expected from simple packing arguments.

Robust and recoverable dual cross‐linking networks in pressure‐sensitive adhesives

AbstractPressure‐sensitive adhesives (PSAs) demand the ability to simultaneously improve toughness and adhesion. However, these requirements of PSAs have remained a great challenge because robust and recoverable characteristics are usually contradictory properties of PSAs. Dual cross‐linking networks developed by incorporating dynamic noncovalent bonds into chemical cross‐linking networks have the potential to mitigate these requirements in a wide variety of applications including adhesives, hydrogels, and elastomers. Herein, a facile approach to achieve dual cross‐linking networks of acrylic PSAs with excellent mechanical properties and high‐adhesive performance that integrate physically cross‐linked networks into chemically cross‐linked networks is proposed. Diurethane acrylic monomer‐pentaerythritol ethoxylate (DAM‐PEEL) groups were introduced into the acrylic PSA system through photopolymerization. The PSA/DAM‐PEEL dual cross‐linking networks led to the development of the chemically cross‐linked networks for both PSA and DAM via covalent bonds and the physically cross‐linked networks between the amide groups of DAM and the hydroxyl groups of PEEL via hydrogen bonds. Consequently, the PSA/DAM‐PEEL dual cross‐linking networks were able to simultaneously improve the modulus and stretchability. This design strategy for developing dual cross‐linking networks of materials could offer potential applications for various adhesive‐related applications.

Removal of metal cations by diatomite treated with microemulsion

The aquatic environments can be contaminated by various metal ions, including Fe3+, Pb2+, Cr6+. In order to capture these ions the industry commonly uses different natural adsorbents or chemically treated. Based on this approach, this work aimed to treat diatomite with a micelle solution and microemulsion systems, formulated with UNITOL L-90, n-butanol, kerosene and distilled water. The diatomite treated with micelle solution did not provide a significant improvement in removal efficiency, reaching 62% for Fe3+, 58% for Pb2+ and 47% for Cr6+. While the diatomite treated with microemulsion had a substantial increase in the capture percentage reaching 99% of Fe3+, 65% for Pb2+ and 66% for Cr6+. Therefore, based on the results it is clear that surfactant is incorporated to diatomite when a microemulsion system is applied, enhancing the use of this systems in water treatment process. The ethoxylate groups present in the diatomite modified with the microemulsion were fundamental to improve the adsorption capacity of the Fe3+, Pb2+ and Cr6+ ions.

Molecular dynamics simulations of nonionic surfactant adsorbed on subbituminous coal model surface based on XPS analysis

ABSTRACTA molecular dynamics (MD) simulation was conducted to study the adsorption behaviour of a nonionic surfactant adsorbed on low-rank coal. Owing to the complicated chemical component and structure of the coal surface, a modified graphite surface with hydroxyl, carboxyl, and carbonyl groups was utilised for a representation of the subbituminous coal surface model. The compositions of the hydroxyl, carbonyl, and carboxyl groups on the coal surface were found to be at a proportion of 25:3:5 according to the X-ray photoelectron spectroscopy (XPS) results. The interaction of nonylphenol ethoxylate with 8 ethylene oxide groups (NPEO-8) using this coal model in an aqueous phase was then simulated. It was revealed that the nonionic surfactant molecules were adsorbed at the interface between water and coal. This agminated structure of the surfactant molecules on the surface of the coal demonstrated an attachment of the surfactant ethoxylate groups to these solid surfaces and an extension of the remaining hydrophobic portions into the solution. Therefore, a coal surface with greater hydrophobicity was created. The dynamic properties of the water molecules characterised through self-diffusion coefficients indicate greater water mobility resulting from the existence of NPEO-8.

Molecular dynamics simulations of removal of nonylphenol pollutants by graphene oxide: Experimental study and modelling

Graphene oxide (GO) performs excellent adsorption property in removing organic pollutant out of the aqueous solution. GO adopted in this research was synthesized by using an improved Hummers approach. With the adoption of X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS), the samples were characterized. The mechanism of removing nonylphenol ethoxylates (NPEO10) in the wastewater by GO was investigated through XPS and molecular simulations. The GO model was constructed on the basis of XPS outcomes and typical molecular formula of GO (C10O1(OH)1(COOH)0.5). The XPS results indicate that the GO surface is significantly within the coverage of NPEO10. From MD simulations, it was shown that NPEO10 molecules adsorbed at GO surface through oxygen-containing functional group, and the polar interactions between the ethoxylate group and oxygen-containing functional group on the GO surface were the primary factors during the process of adsorption. The negative interaction energy existing between NPEO10 and GO model suggests that the GO-water-NPEO10 system becomes more stable after adsorption.

Lepkosprezyste pianki poliuretanowe nadajace sie do wielokrotnego prania

The formulations of non-cytotoxic viscoelastic polyurethane open-cell foams (VEPUR), which are suitable for multiple washing using household automatic washing machine, were developed. The foams were prepared using polyols containing ethoxylate (EO) and propoxylate (PO) groups. In order to ensure no cytotoxicity, the foams with different hardness, including additional polyols containing about 80 % of EO groups and having isocyanate index of 0.9–1.0, were synthesized. The foams were prepared using reactive inhibitors, which allowed to decrease the reaction rate in order to avoid collapsing. The prepared VEPUR foams had promising qualities such as: optimal recovery time (1–8 s), high air permeability (80–150 dm3/min), high water absorption coefficient (1700–2100 %), low water retention coefficient (60–70 %) and low volume increase after soaking (less than 15 %). This characteristics makes the developed foams suitable for multiple washing. After five cycles of machine washing the hardness of the foams was changed very slightly, while the users of the foam products observed a substantial improvement of the hygiene and comfort of sleep.

Molecular dynamics simulations of nonylphenol ethoxylate on the Hatcher model of subbituminous coal surface

Nonylphenol ethoxylate can be used to improve the performance of low-rank fine coal flotation. Herein, we utilized experimental and computational methods to investigate the adsorption of nonylphenol ethoxylate with 10 ethylene oxide units (NPEO-10) onto the surface of subbituminous coal, revealing that the adsorption could be described by a Langmuir-type isotherm, in agreement with the negative interaction energy calculated by molecular dynamics simulation. X-ray photoelectron spectroscopy analysis showed that the coverage of oxygen-containing surface groups by NPEO-10 improved the hydrophobicity of subbituminous coal. Moreover, the performed simulations indicated that in the presence of NPEO-10, water molecules were more strongly repelled by the coal surface due to its increased hydrophobicity, which was supported by the results of contact angle measurements at low surfactant concentration. Analysis of surfactant molecule aggregates by head and tail group density profiling revealed that these aggregates were attached to the coal surface via ethoxylate groups. The calculated dynamic properties of NPEO-10 showed that its diffusion was most pronounced in the direction perpendicular to the coal surface due to the hydrophobic interactions of alkyl chains.

Molecular dynamics simulations and contact angle of surfactant at the coal–water interface

Wettability of nonylphenol ethoxylate with four ethylene oxide groups (NP-4) on a subbituminous coal was carried out. As the concentration of NP-4 gradually increases, the contact angle firstly increases and then decreases with maximum contact angle at about critical micelle concentration (CMC) of NP-4. The monolayer adsorption behaviour of NP-4 on the model surface of Hatcher subbituminous coal was investigated by means of molecular dynamics simulations. The surfactant molecules could be detected at the water–coal interface. The water molecules are repelled and stronger hydrophobicity of the coal is obtained in the presence of NP-4, which are consistent with contact angle results at low concentration. The aggregated structure of the surfactant molecules on the coal surface in terms of head group and tail group density profiles along the perpendicular direction shows that the ethoxylate groups of the surfactant are attached at the solid surfaces. The negative interaction energy between NP-4 and the subbituminous coal surface calculated suggests that adsorption process is spontaneous. The self-diffusion coefficients results indicate that the presence of NP-4 causes higher water mobility meaning improving the hydrophobicity of low-rank coal, which is consistent with the experimental results of contact angle.

Adsorption and molecular dynamics simulations of nonionic surfactant on the low rank coal surface

Molecular dynamics simulations were carried out to study the behavior of nonylphenol ethoxylate with 12 ethylene oxide groups (NPEO-12) on model surface of Hatcher subbituminous coal. Firstly, in order to verify simulation results, the adsorption experiments between a typical subbituminous coal obtained from Shenhua Shendong Coal Group Corporation Limited in China and NPEO-12 were performed. The thermodynamic functions indicated that the adsorption was a spontaneous process. XPS analysis showed that coverage of the oxygen-containing groups by NPEO-12 improving hydrophobicity of the subbituminous coal. Among these oxygen-containing groups, the adsorption capacity of CO group for NPEO-12 was higher. Afterwards, the interaction of NPEO-12 with the coal surface in aqueous phase was modelled. The surfactant molecules could be detected at the water-coal interface. The water molecules were repelled and stronger hydrophobicity of the coal was obtained in the presence of NPEO-12. The results of aggregated structure of the surfactant molecules on the coal surface in terms of head group and tail group density profiles along the perpendicular direction showed that the ethoxylate groups of the surfactant were attached at the solid surfaces. The negative interaction energy between NPEO-12 and the subbituminous coal surface calculated suggested that adsorption process was spontaneous, which was consistent with the adsorption experiment measurement.

Hydrophilic nonwovens by Forcespinning™ of isotactic polypropylene blended with amphiphilic surfactants

As a widely applied polymer, hydrophilic modification of polypropylene (PP) has been an important research field. Forcespinning™ uses centrifugal force to fabricate nanofibers rather than electrostatic force as in conventional electrospinning. The absence of electric fields provides a board opportunity for low dielectric materials and the utilization of centrifugal forces significantly increases the yield compared to electrospinning. Hydrophilic nonwovens from isotactic polypropylene (iPP) melt blended with amphihilic surfactant TWEEN20 and TWEEN60 were obtained by Forcespinning™. The factors were investigated by SEM and DSC, which determined fiber diameter distribution and crystallinity. The meshes showed continuous homogeneity along the length of the fiber when the system was employed at 225 °C and the rotational speed at 14,000 rpm. Blending with surfactants bearing ethoxylate groups led to increased oxygen content of the meshes surface as confirmed by ATR-FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). XPS results indicated preferential distribution of additives on surfaces. The forcespun meshes exhibited excellent hygroscopicity even when the load of TWEEN20 was 10 %.

Cure‐on‐demand wood adhesive based on the frontal polymerization of acrylates

ABSTRACTWe demonstrated for the first time a cure‐on‐demand wood adhesive using thermal frontal polymerization with Southern Pine wood. Monomer structure, initiator loading, and filler loading all had an impact on the strength of the adhesive and the cure‐on‐demand ability. More flexible, ethoxylated monomers produced stronger adhesives; though, the ethoxylate groups reduce the ability of the system to be polymerized frontally. Addition of a highly reactive comonomer (acrylic acid) to increase molecular weight between crosslinks along with the ethoxylated triacrylate increased the propensity for frontal polymerization and made a tougher polymer. Increasing initiator loading could help ensure front propagation, but a maximum initiator loading was reached where the gaseous byproducts of the peroxide initiator made the network highly porous and thus lacking strength. Fillers such as kaolin and sawdust helped overcome decreases in strength at high initiator loadings. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44064.

Preparation and Surface Activities of Modified Soy Protein–Dextrin Surfactants

AbstractA series of polymeric surfactants has been prepared through the reaction of soy protein with polyethoxylated stearyl ethers of various hydrophilic chain lengths. These surfactants exhibited surface activity, evaluated using surface tension, foaming, and wetting power that was superior to that of traditional surfactants containing only one hydrophobic moiety and one hydrophilic head group. Changing the ethoxylate (EO) group length had a significant effect on the surface activity. Increasing the EO group length decreased the critical micelle concentration (CMC) and increased the surface tension at the CMC (γCMC). The good surface properties of these polysaccharide/protein‐type surfactants suggest that they could be used as emulsifiers to prepare oil‐in‐water emulsions displaying good stability.

Competitive solubilization of 4,4′-dibromodiphenyl ether, naphthalene, and pyrene mixtures in Triton X series surfactant micelles: The effect of hydrophilic chains

The present study investigated the solubilization and cosolubilization of 4,4′-dibromodiphenyl ether, naphthalene, and pyrene in a series of Triton X surfactant systems with different polyethylene oxide chain lengths. Cosolubilization effects were quantified in terms of molar solubilization ratio, micelle-water partition coefficient, and synergistic/inhibitive ratio. During cosolubilization, a stronger synergism was observed for naphthalene/pyrene and 4,4′-dibromodiphenyl ether/pyrene when the polyethylene oxide chain length increased. In contrast, inhibition was observed for 4,4′-dibromodiphenyl ether/naphthalene in Triton X-305 and Triton X-405 surfactant systems, indicating that 4,4′-dibromodiphenyl ether probably had a partitioning behavior similar to naphthalene which led to an appreciable amount of 4,4′-dibromodiphenyl ether in the palisade layer. This assumption was supported by 1H NMR and FTIR data showing that: (i) the protons on the outer hydrophilic chain of each surfactant did not undergo any upfield shifts, and the upfield shifts that occurred on the innermost ethoxylate group gradually disappeared as the polyethylene oxide chain length increased; (ii) the C–Br stretching and torsional frequencies of 4,4′-dibromodiphenyl ether decreased slightly as Triton X-100 monomers were added. The results of this study provide valuable information on the interactions between solutes and surfactant hydrophilic chains that may improve the remediation of PBDEs- and PAHs-contaminated soils and non-aqueous phase liquids (NAPLs) treated with surfactant enhanced remediation (SER) technology.

Vibrational spectroscopy in the development of surface hydrophilic elastomer latex (SHEL)

An illustrative example is given to show how various vibrational spectroscopy techniques coupled with two-dimensional (2D) correlation analysis can be effectively utilized in the development of a novel and functional material. Surface-hydrophilic elastomer latex (SHEL) is a material exhibiting rather unusual permanently water-wettable surface feature despite having a soft and rubbery bulk property, which can be successfully analyzed with vibrational spectroscopy. 2D photoacoustic (PAS) IR spectra of a SHEL film indicate the localized surface segregation of long-chain ethoxylate moiety of the oligomeric surfactant used in the preparation of this material. The accumulation of the hydrophilic long-chain ethoxylate produces the high energy polar surface over the hydrophobic bulk phase of SBR copolymer. The persistence of very low water contact angle, even after repeated washing of a SHEL film with an excess amount of water, indicates permanent covalent attachment of long-chain ethoxylate group to the SBR copolymer. 2D Raman spectra generated from the process monitoring of the emulsion copolymerization of SHEL reveal the mechanism of the covalent attachment of long-chain ethoxylate. The reaction involves a separate step of oleyl moiety of the block surfactant reacting with 1,3-butadiene prior to the onset of copolymerization to produce the SBR latex product.

Development of Anti-Wear/Antioxidant Additives for High Quality Metalworking Fluid from Waste Petroleum Products

Surfactants are used for formulation metal working fluids. These fluids are applied to the interface between a cutting tool and the metal working piece to provide friction reduction. In the present paper, poly aromatic ammonium sulphonate and polyaromatic benzyl triethanolamsonium ethoxylate with 6 ethylene oxide units were synthesized and blended with coupling agent like dodecyl alcohol and oleic acid to produce cutting fluid and evaluate as antiwear. Values of surface tension of these additives were measured in oil phase and consequently CMC was determined for all additives and their mixtures in oil phase. The efficiency of these additives depends on their chemical structure and the presence of ether oxygen brings about the association of the surfactant with metal surface, hence very good wetting properties. The antiwear characteristic of surfactants increases with increasing polar linkages in the aromatic moieties forming chelated and coordinated layer. This is due to the increase in the number of sites to chemisorption on the metal surface. The films formed are highly condensed ring aromatic layered structures. These films provide lower wear and depend on the type of surfactants concentration and sliding speed. The surface of metal was analyzed by SEM/EDX techniques. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the surfactants and their film forming. More confirmation for suggested mechanism was investigated by measuring the area occupied per molecule of the surfactant in oil phase. The results indicate that the sulphonate group is less efficient than ethoxylate group. At the same time, the micelle of surfactants acts as oil dispersant and improves adsorption of oil on the metal surface.

Light scattering and NMR studies of Triton X-100 micelles in the presence of short chain alcohols and ethoxylates

Micellar characteristics of nonionic surfactant p-tert-octyl-phenoxy polyethylene (9.5) ether (Triton X-100) in aqueous media containing short-chain alcohols and their ethoxylates CnEm (n=2, 4, 6 and m=0, 1, 2) were examined by dynamic light scattering (DLS) and nuclear magnetic resonance (NMR). The micelle size increased with the addition of C6Em and decreased when C2Em alcohols were added to Triton X-100 solution; the increase and decrease in the micellar size in the presence of varying amounts of C4Em alcohols depends on the number of polar ethoxylate groups. The results are supported by viscosity and cloud point data and explained on the basis of solvophobic interaction. The interaction and location of additives in micelles is examined by 1H and NOESY NMR. The studies indicate that C2Em molecules mostly remain in bulk water; C6Em molecules get solubilized toward the core of the aggregates, while C4Em molecules are localized in the shell region of micelle according to their octanol/water partition coefficient values.

Physicochemical characterization of water-in-oil microemulsions formed by a binary 1,3-dioxolane alkyl ethoxylate/Aerosol-OT surfactant system

The physicochemical behavior of the binary surfactant system consisting of the ionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate, or Aerosol-OT (AOT), and the two-tailed cyclic ketal alkyl ethoxylate (2-tridecyl, 2-ethyl-1,3-dioxolan-4-yl) methoxy]-O′-methoxy poly(ethylene glycol)], or CK-2,13, in water/isooctane water-in-oil (w/o-) microemulsion systems enriched in AOT was performed to understand the arrangement of the two surfactants at the interface and the behavior and properties of the microemulsion systems to enable applications. Many of the properties observed were similar to microemulsions formed by AOT/C12E4 or C12E5, the latter two being linear alkyl ethoxylates of comparable tail length and average ethoxylate size, including a decrease of water solubilization and increase of attractive interactions with an increase of ethoxylate surfactant concentration, the latter determined via small-angle neutron scattering (SANS). SANS also demonstrated that the increase of the CK-2,13 fraction among the surfactants from 0.1 to 0.2 to 0.3 induced a change in shape from spheres to ellipsoids to cylinders, a trend not reported for AOT/CiEj binary mixtures, and that the surface area per CK-2,13 molecule was approximately 35Å2, nearly identical to the value reported for C12E5. Profiles of electrical conductivity versus the water-surfactant mole ratio (W0) for microemulsions prepared at low surfactant concentrations (far below the percolation threshold) were bell-shaped, consistent with the charge-fluctuation model, and shifted to lower W0 as the alkyl ethoxylate fraction was increased. The extent of the shift was greater for CK-2,13 than for an equal proportion of C12E4, suggesting CK-2,13 possesses a more profound influence on microemulsion properties. Analysis of the OH stretching region (3100–3700cm−1) of the Fourier Transform Infrared Spectroscopic spectrum for w/o-microemulsions demonstrated that an increase of the CK-2,13 content of the total surfactant led to an increase of water molecules localized near the Na+ counterion of AOT of 0.7mol water per mol surfactant, suggesting the water molecules of hydration for the ethoxylate group reside near AOT's counterion, resulting in increased dissociation of the counterion, hence to an increased hydrophilicity for AOT.

Liquid chromatography fractionation with gas chromatography/mass spectrometry and preparative gas chromatography–nuclear magnetic resonance analysis of selected nonylphenol polyethoxylates

Commercial nonylphenol polyethoxylates, designated as NP nEOs, where n is the number of ethoxy groups, comprise a range of ethoxylate groups. According to the starting material nonylphenol, they may also be composed of a complex mix of isomeric nonyl substituents. In order to study more fully the heterogeneity arising from both the ethoxylate and nonyl groups, a mixture of NP nEOs is first fractionated by normal phase liquid chromatography (NPLC) into separate fractions comprising individual ethoxymers, n. Preparative collection of each early elution ethoxymer fraction allows further separation of different isomeric nonyl group components by using analytical gas chromatography/mass spectrometry (GC/MS). The nonyl isomers are not resolved in the NPLC method. The distribution of the isomeric nonyl side chain of different ethoxymers bears close resemblance with each other, and also with the original nonylphenol starting material, although separation efficiency of the nonyl isomers for each ethoxymer decreases with increasing ethoxymer number. Mass spectrometry of the separated isomers display close similarity for presumed equivalent isomers in each fraction, based on elution order of the nonyl isomers. This suggests that each corresponding peak has the same isomer structure. Mass spectra are interpreted based on branching within the nonyl side chain. Preparative GC coupled with MS and nuclear magnetic resonance spectroscopy elucidated the molecular structure of one of the resolved isomers as 4-(1,3-dimethyl-1-propyl-butyl)-phenol diethoxylate.

An 1H NMR investigation into the loci of solubilization of 4-nitrotoluene, 2,6-dinitrotoluene, and 2,4,6-trinitrotoluene in nonionic surfactant micelles

In this study, the enhancement in solubility of 4-nitrotoluene (4-NT), 2,6-dinitrotoluene (2,6-DNT), and 2,4,6-trinitrotoluene (TNT) and their loci of solubilization were determined in nonionic surfactant solutions containing linear alcohol ethoxylates (Brij-35, Brij-58, Brij-78, Brij-97 and Brij-98), alkylphenol ethoxylates (Tergitol NP-8 to NP-40), and octylphenol ethoxylates (Triton X-100, X-165, and X-305). In all surfactant solutions, 4-NT had the highest molar solubilization ratio (MSR) and TNT the lowest. For all surfactants, increasing the number of ethoxylate groups (EO) while keeping the hydrocarbon chain length constant decreased or did not significantly change the MSR. To determine the locus of solubilization, 1H NMR spectroscopy was used to determine how the presence of a nitroaromatic solute changed the chemical shifts of the various hydrogen atoms on the surfactant molecule. For the linear alcohol ethoxylates, the greatest change in chemical shift for all three nitroarenes occurred at hydrogens in the hydrocarbon core of the micelle. At higher solute concentration, the nitroarenes spread to the first EO group near the core/shell interface. For both the Tritons and Tergitols, the chemical shift for a hydrogen on the phenyl ring changed the most upon the addition of the nitroarenes. As the nitroarene concentration increased, the chemical shifts for the hydrogens on the first EO group changed for all Triton and Tergitol surfactants. For all surfactants with shorter EO chains, the shifts for all ethoxylate hydrogens changed at higher nitroarene concentration. These results suggest that the solutes are preferentially solubilized at the core/shell interface but spread further into the shell and the core as solute concentration increases.