Ionic Surfactant Concentration Research Articles

Modulation of excited state intramolecular proton transfer and intramolecular charge transfer pathways ofsymmetrical azines through micellar medium.

The photophysical studies of fluorescent probes in micellar medium can give a better insight about their interaction with biological membranes. This study attempts to access the photophysical properties of the dual emitting azine based probe diethylamino salicylidene azine dimer (DEASAD) in micellar media. DEASAD showed dual charge transfer emission due to the presence of open enol (480 nm) and closed enol (510 nm) forms in polar protic solvents. Upon increasing the concentration of ionic surfactants, there is a significant increase in the emission intensity of both the enol forms of DEASAD until premicellar concentration. After micellization, occurrence of a new anomalous keto form emission through excited state intramolecular proton transfer (ESIPT) was observed around 530 nm in ionic micelles and its intensity changes depend on the micellar surface charge. The emission studies revealed the position and interaction of DEASAD with the charge of micellar stern layer as confirmed through interaction of metal ion with the probe and control molecules with and without ESIPT and ICT moieties. In contrast, the new anomalous longer wavelength keto form of DEASAD emission was absent in neutral micelles like Triton X-100.

Effect of ionic surfactants on the settling behavior of silt

Ionic surfactants are easily adsorbed by silt and clay particles, thus affecting the flocculation characteristics and settling behavior. The settling velocity, typical size, Zeta potential and surface tension of silt flocs were measured in the presence of two different kinds of ionic surfactants. The results indicated that the cetyltrimethylammonium bromide (CTAB, a typical cationic surfactant) can dramatically accelerate the settling of slit particles, while the linear alkylbenzene sulfonate (LAS, a typical anionic surfactant) slightly retarded silt sedimentation to some extent. In still water, the representative settling velocity dramatically increased from 0.36 cm s−1 to 0.43 cm s−1 with the increase of CTAB concentration, which increased by more than 20%. Oppositely, the sedimentation rate decreased from 0.36 cm s−1 to 0.33 cm s−1 with the increase of LAS concentration. In flowing water, as the flow rate increased from 0 to 20 cm s−1 and the ionic surfactant concentration increased from 0 to 10 mg L−1, the sedimentation rate decreased to 57% and 89% in the presence of CTAB and LAS respectively, which was due to an enhanced dispersion of silt particles and a breaking of flocs. The SEM image test shows that the floc particle size increased 1.5 times of the primary particle size under the high CTAB concentration. The flocculation induced by ionic surfactants greatly influences the sediment size as well as the law of settling velocity. The intrinsic influence mechanism was also discussed based on the variations of silt particle properties. This systematic study can be used for further development of flocculation models and particle size distribution of fine-grained soil.

Theoretical and experimental investigation of CO2 solubility in nanofluids containing NaP zeolite nanocrystals and [C12mim][Cl] ionic liquid

AbstractToday, CO2 separation is very important, both as an environmental issue and also in various industries. In this study, the water‐based nanofluid of NaP zeolite nanocrystals and 1‐dodecyl‐3‐methylimidazolium chloride ([C12mim][Cl]) ionic liquid were mixed and tested experimentally for CO2 absorption in an isothermal high pressure cell equipped with magnetic stirring. Zeolite nanocrystals were synthesized via the hydrothermal approach and characterized. A series of experiments were performed at different conditions to investigate the impact of various parameters, including nanoparticle type, nanoparticle concentration, stabilizer concentration, and the vessel's initial pressure, on CO2 solubility. It was found that 0.02 wt.% of zeolite nanoparticles, 0.4 wt.% of [C12mim][Cl] ionic liquid, and 0.05 wt.% of sodium dodecyl benzene sulphonate (SDBS) in nanofluids result in higher absorption of CO2 compared to other concentrations. Furthermore, CO2 absorption was increased by increasing ionic liquid and surfactant concentration up to a certain value near critical micelle concentration, but after that the CO2 absorption was decreased. The overall CO2 absorption enhancement at 20 bar for 0.02 wt.% zeolite and ZnO water‐based nanofluids with 0.4% [C12mim][Cl] ionic liquid and 0.02 wt.% SDBS were 26.9%, 21.5%, 21.2%, and 17% in comparison to pure water, respectively. In an absorption process using nanofluids, besides the influence of the mentioned parameters, the micro‐convection caused by Brownian motion and the grazing effect of nanoparticles should be noted. Considering the micro‐convection and grazing effects, a theoretical model should take into account the Brownian motion and grazing effects on the mass transfer rate in nanofluids to investigate the absorption enhancement by nano‐particles.

Influence of seawater on interfacial Properties, foam performance and aggregation behaviour of Fluorocarbon/Hydrocarbon surfactant mixtures

• Adding seawater lowers surface activity and adsorption kinetics of SDS/FS-50 mixtures. • Ca 2+ , Mg 2+ and K + have greater adverse effects on foaming ability than Na + in seawater. • Dual effects of salts on foam stability are observed at different surfactant concentrations. • Spontaneous transition from vesicle to micelle is observed after mixing SDS and FS-50. In this work, the influence of seawater on interfacial properties, foam performance and aggregation behaviour of fluorocarbon/hydrocarbon surfactant mixtures was systematically investigated. Two model foaming solutions containing different surfactants (nonionic APG, anionic SDS, and amphoteric FS-50) were prepared by deionized water and seawater, respectively. Multi-scale methods including surface tension measurements, foam ageing tests and cryogenic-transmission electron microscopy (cryo-TEM) were used. The results show that the addition of seawater reduces the equilibrium surface tension, foaming ability and adsorption kinetics of SDS/FS-50 mixtures. Among the counterions in seawater, Na + can lower the surface tension and slightly improve the foaming ability, while the presence of Ca 2+ , Mg 2+ and K + allows the formation of surfactant precipitate to weaken the foaming ability of the solution. It turns out that seawater has dual effects on foam stability and the defoaming/stabilizing effects of seawater are related to ionic surfactant concentrations. Besides, it is confirmed that the spontaneous transition from single-lamellar vesicle to rod-like micelle occurs after mixing FS-50 with SDS in the deionized water, while only multi-lamellar vesicles and surfactant crystals can be observed in the seawater. The aggregation behaviour strongly affects solution viscosity as well as foam performance. At high SDS concentrations, the surfactant precipitate/aggregate can inhibit the liquid drainage process and improve foam stability.

Comparative effects of zinc oxide nanoparticles over the interfacial properties of low concentrations of ionic surfactants at interfaces

Nanoparticles (NPs) are well-known for their surface activities and recently their use in petroleum industry is on rise which call for better understanding of implications of interactions of NPs and surfactants. Furthermore, this study can provide additional benefits because zinc oxide nanoparticles (ZnO NPs) are widely used in the industrial products and are therefore of special importance. Surfactants, on the other hand are also industrial chemicals and almost an essential constituent of every other formulation with or without the presence of nanoparticles. The self-assembling properties of surfactants on the interface and remarkable surface activities of nanoparticles led to the studies of interactions between nanoparticles and surfactants in a hope to tune the interfacial properties. The surface of ZnO NPs is charged and therefore they can electrostatically interact with ionic surfactants molecules as well as their self-assembled structures such as monolayers at the interfaces and micelles in solutions. This work is set to find how and to what degree, the self-assembling properties of surfactants are affected by ZnO NPs interactions under the influence of change in pH, and ionic strength using sodium chloride which is commonly used among many other ions to simulate “low salinity environment”. Surface tension (ST), dynamic light scattering technique with hydrodynamic size (Dh) and zeta potential (ζ) measurements were used to characterize the possible interactions of nanoparticles with surfactants. Commercially important sodium dodecyl sulfate (SDS) and cetrimonium bromide (CTAB) were chosen ionic surfactants for their interactions with ZnO NPs. The study concluded that the interactions of particles with surfactants, due to change in pH, and ionic strength have an appreciable impact on the activities of SDS and CTAB at the air-water (A/W) and n-hexane (oil)-water (O/W) interfaces. The effect of electrolytes was found more prominent in the case of CTAB+ZnO NPs system, while the effect of pH was more pronounced for SDS+ZnO NPs system i.e., in case of both A/W and O/W interfaces. The study will help to improve the understanding and use of ZnO NPs in combination with surfactants and similar systems in enhanced oil recovery and many other processes of industrial importance.

Influence of ionic strength and surfactant concentration on the alkane contaminant desorption in solution: A molecular dynamics simulation

The cleaning of the optical and mechanical components in a high-power laser system is essential for the cleaning control of the high-power laser system. Many factors affect the cleaning efficiency of the solution cleaning. Ion concentration, surfactant concentration and molecular weight of organic molecules are three key factors. In this article, equilibrium and nonequilibrium molecular dynamics simulations are performed to investigate the interfacial interaction among fluid, substrate and oil droplets and the dynamic desorption process of the oil droplet. As the increase of ion concentration, the contact angle of the oil droplet decreases, and the height of the oil droplet decreases slightly. Higher ion concentrations make the oil droplet more hydrophobic because of the reduction in hydrogen bonds between oil droplets and water and the reduction in residual time. In water flow simulation, high ion concentration is not beneficial to the desorption of oil droplets. Pure water flooding is not effective as brine flooding, which is related to water flow velocity. High surfactant concentration is beneficial to the desorption of oil droplets without water flow. Alkane molecule with larger molecular weight is difficult to detach from the solid surface, since the higher interaction energy between alkane molecule and substrate.

Two-dimensional colloidal particle assembly in ionic surfactant solutions under an oscillatory electric field

Assembling colloidal particles under oscillatory electric field (OEF) has become an emerging bottom-up technique to synthesize advanced materials and fabricate micro/nano devices. Surfactants have often been used in colloidal dispersions to improve their stability. However, the precise role of surfactants in particle assembly processes under OEF is unknown. Here, we systematically study the effects of ionic surfactants on the colloidal particle assembly process subject to a fixed OEF, by using an anionic surfactant (sodium dodecyl sulfate) and a cationic surfactant (cetyltrimethylammonium bromide). In the concentration range below the critical micelle concentration (CMC), the particles tend to form three different aggregate structures, including randomly close-packed, hexagonally close-packed crystals, and randomly non close-packed structures. In the concentration range at CMC and above, the particles cannot assemble into any aggregate structures under the given OEF. With increasing surfactant concentration, the average interparticle separation distance within the aggregate can be regulated in a wide range. We qualitatively interpret the observed variation of particle assembly behaviors in different surfactant solutions based on the particle/particle interaction energy, implying that the repulsive electric double-layer interaction is significantly enhanced with increasing ionic surfactant concentration and hinders the particles approaching close to the high-energy barrier. These results suggest that the particle aggregate structure and interparticle separation distance of the two-dimensional colloidal assembly can be manipulated by controlling the ionic surfactant concentration according to the requirements of practical applications.

Relation between ionic surfactant concentration and thickness of foam film stabilized by ionic – nonionic surfactant mixed adsorbed films

In this paper, we compared the thickness of common black films stabilized by four different ionic-nonionic surfactant mixed adsorbed films. For the cetyltrimethylammonium chloride (CTAC) - pentaethyleneglycol monododecyl ether (C12E5), SDS - tetraethyleneglycol monodecyl ether (C10E4), and dodecyltrimethylammonium bromide (DTAB) - tetraethyleneglycol monooctyl ether (C8E4) systems, the foam film thickness measured by using Scheludko–Exerowa glass ring method coincided very well when the foam film thickness was plotted as a function of bulk ionic surfactant (1:1 electrolyte) concentration. In addition, by using the phase diagram of mixed adsorbed film obtained from the thermodynamic analysis of the surface tension data, it was also demonstrated that the surface charge density and surface tension have a minor effect on the equilibrium film thickness. On the other hand, the foam film stabilized by the 1-decyl-3-methyl imidazolium tetrafluoroborate (DMIMBF4) - C10E4 mixed adsorbed film showed much smaller thickness values compared to the above-mentioned systems. Irregular behavior observed in the DMIMBF4 - C10E4 system was discussed based on the specific interaction between imidazolium head groups and BF4- ions through hydrogen bonding in an ion-concentrated environment in the Stern layer.

Tuning of micelle adsorption on nanoparticles by combination of surfactants

The interaction of anionic silica nanoparticles with nonionic decaethylene glycol mono-dodecyl ether (C12E10) and ionic surfactants [both anionic sodium dodecyl sulfate (SDS) and cationic dodecyl trimethyl ammonium bromide (DTAB)] has been studied by small-angle neutron scattering and dynamic light scattering. The nonionic and cationic surfactant micelles are adsorbed on nanoparticles, whereas no adsorption of SDS surfactant micelles on nanoparticles is observed. The adsorption of C12E10 micelles provides additional steric stability to nanoparticles. However, the adsorption of cationic micelles leads to micelles-mediated fractal aggregation of nanoparticles. In the case of SDS surfactant, nanoparticles and micelles coexist in the solution. Furthermore, the adsorption behavior of surfactant micelles on nanoparticles has been tuned using a combination of nonionic and ionic surfactants. The combination of nonionic C12E10 with anionic SDS makes surfactant micelles to desorb from nanoparticles, whereas the combination of nonionic C12E10 with cationic DTAB leads to fractal aggregation of nanoparticles. The systematic transitions of micelle adsorption to desorption on nanoparticles with a C12E10–SDS mixed surfactant system and the aggregation of nanoparticles in a C12E10–DTAB mixed surfactant system as a function of ionic surfactant (SDS or DTAB) concentration have been examined. The micelles desorption from nanoparticles follows an exponential decay behavior with an increase in SDS concentration in C12E10–SDS, whereas the aggregate size shows an exponential growth with DTAB in C12E10–DTAB. The electrostatic interactions between nanoparticles and surfactant micelles are found to be dominating for tuning these transitions.

Regulation of crystal growth process of NaP zeolite via the coupling effects of electrostatic interaction and steric hindrance

Due to the rich pore structure, NaP zeolite adsorbent has been widely employed in the adsorption and separation fields. The NaP zeolite crystals with small size and good dispersion were generated with the addition of ionic surfactants using coal fly ash as the raw material. The effects of different types and concentrations of surfactants on the structure of NaP zeolites were investigated by various characterization methods. The optimal concentration of ionic surfactants was 0.5 cmc (critical micelle concentration) for NaP-CTAB and 0.125 cmc for NaP-SDBS. The NaP-SDBS zeolite at 0.125 cmc exhibited higher crystallinity (96.11%), the smallest grain size (2.20 ​μm), and the largest specific surface area (29.1 ​m2/g). The functional groups in the ionic surfactants exerted the electrostatic interaction (attraction and repulsion) and steric hindrance effects together with the negatively charged precursors of NaP zeolite, which provided a favorable foundation for broadening the application fields and improving the adsorption properties. And the introduction of ionic surfactants did not destroy the structure of NaP zeolites synthesized at optimal concentrations. Via the evaluation of Zn(II) adsorption, the NaP-SDBS zeolite showed the adsorption removal rate of 96.27% and the main adsorption manner was the ion exchange. Meanwhile, through the five times adsorption—desorption cycles, the adsorption properties of Zn(II) by NaP zeolites still reached above 95.30%, which demonstrated that NaP zeolite adsorbent is effective in treating industrial sewage.

Mixed Surfactant‐Based Reverse Micellar Extraction Studies of Bovine Lactoperoxidase

AbstractThe suitability of reverse micellar extraction for recovery of bovine lactoperoxidase (LP) from aqueous solution was evaluated using systems formed by ionic and nonionic surfactant mixtures. The influence of ionic surfactant concentration, organic solvent, and pH on the extraction of LP into the reverse micellar phase was studied. The Tween® series surfactants with Aerosol‐OT (bis‐(2‐ethylhexyl) sulfosuccinate) showed better extraction of LP in the reverse micelles (RM) compared to the Triton® and Span® series of surfactants. Complete extraction of LP from an aqueous phase of initial concentration 25 mg L−1 occurred with the RM formed by 90 mM Aerosol‐OT/8 mM Tween® 80 in isooctane. The optimal pH, ionic strength, and positively charged ionic surfactant concentration for back extraction were also studied and a maximum of 95.5% back extraction efficiency and 66% LP activity recovery was obtained for a pH of 10.5,1 M KCl and 60 mM cetyltrimethylammonium bromide system.

Effect of Non Ionic Surfactant Concentration on Pterostilbene Niosome Characteristics

Excessive radiation from UV light can cause skin damage to melanoma, especially UVB rays. Chronic effects from exposure of excessive UVB rays can induce gene mutations because the exposure of excessive UVB rays directly causes damage to cellular DNA by producing ROS in the epidermis, dermis, and skin epithelium cells. The use of sunscreen is very necessary to prevent skin damage. Sunscreen containing antioxidants are highly recommended to protect the skin from free radicals UVB rays. Pterostilbene is one of the phenolic compounds, which has the pharmacological activity of antioxidants and UV filters to be one of the recommended compounds for sunscreen components. A good delivery system is needed to be formulated to improve the pharmacological effects of pterostilbene on topical use. Niosomes are non-ionic surfactant vesicles which are one of the amphiphilic carrier systems which can carry hydrophobic active ingredients such as pterostilbene, which are expected to increase the pharmacological effect by increasing the penetration of pterostilbene into the skin. Pterostilbene niosome using non-ionic surfactant (span 80 and span 60) by thin layer hydration method. The research aimed to examine the effect of surfactant concentration (span 80 and span 60) 2, 4, and 6 g toward the characterization of niosome pterostilbene and determine the optimum formulation by particle size. The results of the study showed that the particle size was smaller with an increase in span concentration. Based on these results, the optimum formulation of pterostilbene niosomes is obtained using span 60 with a concentration of 6 g.

Dependence of Surface Tension on Surface Concentration in Ionic Surfactant Solutions and Influences of Supporting Electrolyte Therein

Abstract It has been well-known that the addition of electrolytes causes the ionic surfactant solution to have a lower surface tension by stimulating the surface adsorption. When the surface concentration of an ionic surfactant remains constant, the solution with supporting electrolyte in the bulk displays a lower surface tension than a solution without electrolyte. From the surface perspective we investigate the dependence of the surface tension of a solution upon the surface concentration of ionic surfactant and the influences of the supporting electrolyte therein, by means of thermodynamics and molecular dynamics simulation. The derived thermodynamic formula and simulation results predict, that at a given surface concentration the supporting electrolyte can change the orientation of the ionic surfactant, which results in a lower surface tension. The conclusions can be useful for the investigation to the surface structure of ionic surfactant solutions and the effects of supporting electrolyte.

Determination of the critical micelle concentration by absorbance and fluorescence techniques using fluorescein probe

We reported a unique and sensitive probe (fluorescein) for determination the critical micelle concentration(CMC) of ionic surfactants based on both fluorescence and absorbance properties of probe in micellar solution. We found that the spectral properties (fluorescence and absorbance) of fluorescein are affected by different types of surfactants. For this purpose spectrophotometric technique using fluorescein as probe to determine the critical micelle concentration of cationic, anionic and zwitterionic surfactants. The critical micelle concentrations of surfactants were determined from the sigmoidal shaped plots or inflection points. The obtained CMC values were in good agreement with the values obtained with conductivity measurements or with literature values.

Imidazolium-based ionic liquid surfactants as pseudostationary in combination with a chiral selector in micellar electrokinetic chromatography.

In recent years, ionic liquid-based surfactants have drawn more and more attention. As a new promising brand of surfactants, ionic liquid-based surfactants have their unique properties and superior aggregation behavior, which can be introduced as micellar pseudostationary in MEKC mode. In this paper, a novel ionic liquid-based surfactant, 1-butyl-3-methylimidazolum dodecyl sulfate [C4MIm][C12SO4], was synthesized through ion exchange reaction and applied for the first time to form micellar as pseudostationary phase for chiral separation with clindamycin phosphate as chiral selector. As observed, compared with conventional non-ionic liquid anionic surfactant, improved separation of tested drug enantiomers was obtained in the established MEKC system with ionic liquid-based surfactant. Parameters such as concentration of ionic liquid-based surfactants, type and proportion of organic modifier, concentration of chiral selector, and pH of buffer solution were systematically investigated to optimize the ionic liquid-based surfactant MEKC system. Graphical abstract.

Potassium, Calcium, and Magnesium Bridging of AOT to Mica at Constant Ionic Strength.

The bridging effect of a series of common cations between the anionic mica surface and the AOT anion has been studied in a condition of constant ionic strength and surfactant concentration. It was found that sodium ions did not show any bridging effect in this system; however, calcium, magnesium, and potassium all caused adsorption of the organic to the mica surface. The concentrations at which bridging occurred was probed, revealing that only a very low bridging cation concentration was required for binding. The bridged layer stability was also investigated, and the interaction was shown to be a weak one, with the bound layer in equilibrium with the species in the bulk and easily removed. Even maintaining ionic strength and bridging ion concentration was not sufficient to retain the layer when the free organic in solution was removed.

The effect of surfactants modification on nanocrystalline cellulose for paclitaxel loading and release study

The Nanocrystalline cellulose (NCC) was prepared from filter paper by acid hydrolysis process. The modification of NCC with cationic, anionic, and nonionic surfactant did not have a tremendous effect on the chemical structure of material based on the characterization of XRD and FTIR. The modified NCCs were employed as a drug carrier for paclitaxel (PTX). Increasing concentration of ionic surfactants can enhance the loading of the hydrophobic drug, while the opposite trend was observed for nonionic surfactant modified nanocrystals. The attachment of surfactant toward the particle was a more likely physical aggregation of micelle on the surface of nanocrystals. Larger particle size was observed after the modification of nanocrystal cellulose. The fitting of Higuchi and sigmoidal models were applied in the release profile to investigate the kinetic release mechanism of paclitaxel at pH 5.8 and 7.4. Cell viability was determined to check the biocompatibility of the materials toward mouse osteoblast cells 7F2 using MTT assay. Toxic behavior was not observed for NCC, while CTAB was completely not compatible with cells.

Diffusiophoresis in ionic surfactants: effect of micelle formation.

We explore the consequences of micelle formation for diffusiophoresis of charged colloidal particles in ionic surfactant concentration gradients, using a quasi-chemical association model for surfactant self assembly. The electrophoretic contribution to diffusiophoresis is determined by re-arranging the Nernst-Planck equations, and the chemiphoretic contribution is estimated by making plausible approximations for the density profiles in the electrical double layer surrounding the particle. For sub-micellar solutions we find that a particle will typically be propelled down the concentration gradient, although electrophoresis and chemiphoresis are finely balanced and the effect is sensitive to the detailed parameter choices and simplifying assumptions in the model. Above the critical micelle concentration (CMC), diffusiophoresis becomes much weaker and may even reverse sign, due to the fact that added surfactant goes into building micelles and not augmenting the monomer or counterion concentrations. We present detailed calculations for sodium dodecyl sulfate (SDS), finding that the typical drift speed for a colloidal particle in a ∼100 μm length scale SDS gradient is ∼1 μm s-1 below the CMC, falling to ⪅0.2 μm s-1 above the CMC. These predictions are broadly in agreement with recent experimental work.

Dispersions of Metal Oxides in the Presence of Anionic Surfactants

We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up to the solubility limit in case of sodium tetradecyl- and hexadecylsulfate. The dispersions were adjusted to different pH (3–11), and 10−3 M NaCl was used as the supporting electrolyte. The solid-to-liquid ratio was strictly controlled in all dispersions, and the behavior of fresh dispersions was compared with dispersions aged for up to eight days. The presence of very low concentrations of ionic surfactants had rather insignificant effects on the ζ potentials of the particles. At sufficient concentrations of ionic surfactants the isoelectric point (IEP) of metal oxides shifted to low pH, and the long-chain surfactants were more efficient in shifting the IEP than their shorter-chain analogues. Once the surfactant concentration reached a critical value, the ζ potentials of the particles reached a pH-independent negative value, which did not change on further increase in the surfactant concentration and/or aging of the dispersion. This critical concentration increases with the solid-to-liquid ratio, and it is rather consistent (for certain oxides and certain surfactants) when it is expressed as the amount of surfactant per unit of surface area. Surprisingly, the surfactant-stabilized dispersions always showed a substantial degree of aggregation; that is, the particle size observed in dispersions by dynamic light scattering was higher than the size of particles observed in dry powders by electron microscopy. Apparently, in spite of relatively high ζ potentials (about 60 mV in absolute value), the surfactant-stabilized dispersions consist of aggregates rather than of primary particles, and in certain dispersions the high concentration of surfactant seems to induce aggregation rather than prevent it.

Modifying interfacial interparticle forces to alter microstructure and viscoelasticity of densely packed particle laden interfaces

HypothesisIt is possible to control the absolute and relative magnitude of repulsive and attractive interactions and hence microstructure of interfacial particles at and air/water interface by adjusting subphase composition. It should be possible to modify interfacial viscoelasticity from elastic to viscous behavior through these changes to interfacial microstructure. ExperimentsParticle laden interfaces are made from micron sized polystyrene at an air/water interface. The inter-particle interactions are controlled by the subphase salt concentration and addition of both non-ionic and ionic surfactants. These interfaces are then characterized using an interfacial rheometer with a custom visualization system. FindingsThree distinct microstructures are observed. Low repulsion and high attraction systems exhibit a soft glassy rheology with a disordered but dense microstructure. Creating high repulsion results in a dense hexagonal crystal. Finally, in systems with reduced repulsion and attraction, a hexatic phase can be observed. Each of these microstructures exhibit unique interfacial viscoelastic behavior. These results indicate that control over the properties of these interfaces, and hence Pickering emulsions, is possible through manipulation of interparticle forces.