Anti-Adhesive Behaviors between Solid Hydrate and Liquid Aqueous Phase Induced by Hydrophobic Silica Nanoparticles.

This study introduces an "anti-adhesive force" at the interface of solid hydrate and liquid solution phases. The force was induced by the presence of hydrophobic silica nanoparticles or one of the common anti-agglomerants (AAs), sorbitan monolaurate (Span 20), at the interface. The anti-adhesive force, which is defined as the maximum pushing force that does not induce the formation of a capillary bridge between the cyclopentane (CP) hydrate particle and the aqueous solution, was measured using a microbalance. Both hydrophobic silica nanoparticles and Span 20 can inhibit adhesion between the CP hydrate probe and the aqueous phase because silica nanoparticles have an aggregative property at the interface, and Span 20 enables the hydrate surface to be wetted with oil. Adding water-soluble sodium dodecyl sulfate (SDS) to the nanoparticle system cannot affect the aggregative property or the distribution of silica nanoparticles at the interface and, thus, cannot change the anti-adhesive effect. However, the combined system of Span 20 and SDS dramatically reduces the interfacial tension: emulsion drops were formed at the interface without any energy input and were adsorbed on the CP hydrate surface, which can cause the growth of hydrate particles. Silica nanoparticles have a good anti-adhesive performance with a relatively smaller dosage and are less influenced by the presence of molecular surfactants; consequently, these nanoparticles may have a good potential for hydrate inhibition as AAs.

Assessment of micro-polarity anisotropy as a function of surfactant packing in sodium dodecyl sulphonate-hexane reverse micelles.

The micro-polarity anisotropy behaviour across the aqueous phase of a SDS (sodium dodecyl sulphonate)-hexane reverse micelle (RM) relies on the SDS packing in the oil-water interfacial self-assembled surfactant structure of the RM.

Chemo-enzymatic routes to lipopeptides and their colloidal properties.

A unique chemo-enzymatic route to lipopeptides was demonstrated herein that, relative to alternative methods such as solid-phase peptide synthesis (SPPS) and microbial synthesis, is simple, efficient, and scalable. Homo- and co-oligopeptides were synthesized from amino acid ethyl esters via protease catalysis in an aqueous media, followed by chemical coupling to fatty acids to generate a library of lipopeptides. Synthesized lipopeptides were built from hydrophobic moieties with chain lengths ranging from 8 to 18 and peptides consisting of oligo(L-Glu) or oligo(L-Glu-co-L-Leu) with an average of seven to eight repeating units. The chemical structures of the lipopeptides were characterized and confirmed by NMR and matrix-assisted laser desorption/ionization (MALDI). The colloidal and interfacial properties of these lipopeptides were characterized and compared in terms of the hydrophobic chain length, oligopeptide composition, and solution pH. The results showed correlation between the interfacial activity of the lipopeptides and the hydrophobicity of the fatty acid and oligopeptide headgroup, the effects of which have been semiquantitatively described in the manuscript. Results from these studies provide insights into design principles that can be further expanded in future work to access lipopeptides from protease-catalysis with improved control over sequence and exploring a wider range of peptide and lipid compositions to further tune lipopeptide biochemical and physical properties.

Effect of mixed surfactants on stratum corneum: a drying stress and Raman spectroscopy study.

OBJECTIVE: Stratum corneum (SC) lipids are known to play an important role in barrier properties of skin by maintaining the optimal hydration levels. The disruption of SC lipids by cleanser surfactants is believed to lead to dry skin damage which can be a precursor to other skin disorders. The purpose of this study is to investigate the effects of commonly used anionic and zwitterionic surfactants sodium lauryl ether sulphate (SLES) and cocoamidopropyl betaine (CAPB) on the generation of drying stresses in SC and the role played by lipids. METHODS: Stratum corneum separated from pig skin was treated with various surfactants (SDS, SLES and CAPB) their mixtures and solvents. The tensile response to these treatments was measured by using a dynamic mechanical thermal analyzer. A Raman spectroscopy study of the treated samples was performed to investigate the effects of lipid modification (lipid chain conformational order and lipid removal) on stress generation in SC. RESULTS: The effects of commonly used anionic and zwitterionic surfactants on the generation of drying stresses in SC were studied. Although known to be milder in comparison with SDS, both SLES and CAPB generated high drying stresses individually. In mixtures, SLES-CAPB at 4 : 1 ratio leads to lower drying stress as compared to water alone. A Raman spectroscopic study of surfactant-treated SC shows changes in lipid chain conformational order as well as a decrease in lipid-protein ratio in SC. A chloroform-methanol 2 : 1 treatment leads to the highest drying stress as well delipidization of SC. CONCLUSION: The results show a correlation between generation of drying stress in SC and extent of lipid modification. We propose that the changes in lipid conformational order and removal of lipid components affect the stress relaxation properties of SC leading to high drying stresses.

Modification of surface properties of cellulosic substrates by quaternized silicone emulsions.

The present work describes the effect of quaternization of silicones as well as the relevant treatment parameter pH on the frictional, morphological and relaxation properties of fabric substrates. Due to their unique surface properties, silicone polymers are extensively used to modify surface properties of various materials, although the effects of functionalization of silicones and relevant process conditions on modification of substrates are not well understood. Specifically we show a considerable reduction in fabric friction, roughness and waviness upon treatment with quaternized silicones. The treatment at acidic pH results in better deposition of silicone polymers onto the fabric as confirmed through streaming potential measurements which show charge reversal of the fabric. Interestingly, Raman spectroscopy studies show the band of C-O ring stretching mode at ∼1095 cm(-1) shift towards higher wavenumber indicating lowering of stress in fibers upon appropriate silicone treatment. Thus along with the morphological and frictional properties being altered, silicone treatment can lead to a reduction in fabric strain. It is concluded that the electrostatic interactions play an initial role in modification of the fiber substrate followed by multilayer deposition of polymer. This multi-technique approach to study fiber properties upon treatment by combining macro to molecular level methods has helped in understanding of new functional coating materials.

Production and characterization of microbial biosurfactants for potential use in oil-spill remediation.

Two biosurfactants, surfactin and fatty acyl-glutamate, were produced from genetically-modified strains of Bacillus subtilis on 2% glucose and mineral salts media in shake-flasks and bioreactors. Biosurfactant synthesis ceased when the main carbohydrate source was completely depleted. Surfactin titers were ∼30-fold higher than fatty acyl-glutamate in the same medium. When bacteria were grown in large aerated bioreactors, biosurfactants mostly partitioned to the foam fraction, which was recovered. Dispersion effectiveness of surfactin and fatty acyl-glutamate was evaluated by measuring the critical micelle concentration (CMC) and dispersant-to-oil ratio (DOR). The CMC values for surfactin and fatty acyl-glutamate in double deionized distilled water were 0.015 and 0.10 g/L, respectively. However, CMC values were higher, 0.02 and 0.4 g/L for surfactin and fatty acyl-glutamate, respectively, in 12 parts per thousand Instant Ocean®[corrected].sea salt, which has been partly attributed to saline-induced conformational changes in the solvated ionic species of the biosurfactants. The DORs for surfactin and fatty acyl-glutamate were 1:96 and 1:12, respectively, in water. In Instant Ocean® solutions containing 12 ppt sea salt, these decreased to 1:30 and 1:4, respectively, suggesting reduction in oil dispersing efficiency of both surfactants in saline. Surfactant toxicities were assessed using the Gulf killifish, Fundulus grandis, which is common in estuarine habitats of the Gulf of Mexico. Surfactin was 10-fold more toxic than fatty acyl-glutamate. A commercial surfactant, sodium laurel sulfate, had intermediate toxicity. Raising the salinity from 5 to 25 ppt increased the toxicity of all three surfactants; however, the increase was the lowest for fatty acyl-glutamate.

Adsorption of Gemini surfactants onto clathrate hydrates.

This work addresses the adsorption of two Gemini surfactants at the cyclopentane (CP) hydrate-water interface. The Gemini surfactants investigated here are Dowfax C6L and Dowfax 2A1 that have two anionic head groups and one hydrophobic tail group. The adsorption of these surfactants was quantified using adsorption isotherms and the adsorption isotherms were determined using liquid-liquid titrations. Even if the Gemini surfactant adsorption isotherms show multi-layer adsorption, they possess the first Langmuir layer with the second adsorption layer only evident in the 2A1 adsorption isotherm. Zeta potentials of CP hydrate particles in the surfactant solution of various concentrations of Dowfax C6L and Dowfax 2A1 were measured to further explain their adsorption behavior at the CP hydrate-water interface. Zeta potentials of alumina particles as a model particle system in different concentrations of sodium dodecyl sulfate (SDS), Dowfax C6L and Dowfax 2A1 were also measured to confirm the configuration of all the surfactants at the interface. The determination of the isotherms and zeta-potentials provides an understanding framework for the adsorption behavior of the two Gemini surfactants at the hydrate-water interface.

Adsorption of sodium dodecyl sulfate onto clathrate hydrates in the presence of salt.

This work presents the effect of NaCl on the adsorption of sodium dodecyl sulfate (SDS) at the cyclopentane (CP) hydrate-water interface. The adsorption isotherms and the SDS solubility in NaCl solutions are obtained using liquid-liquid titrations. The solubility data are determined at typical hydrate forming temperatures (274-287 K) to ensure that the adsorption isotherms are obtained within SDS solubility limits in NaCl solutions. The isotherms show L-S (Langmuir-Step) type behaviors with 1mM and 10mM NaCl solutions while L type isotherm is determined for 25 mM NaCl solutions due to the low SDS solubility in this salt concentration. Zeta potentials of CP hydrate particles in the aqueous solutions support the shape of the adsorption isotherm with the 1mM NaCl solution. The 1mM NaCl case shows the highest SDS adsorption amount among the cases with 0 mM, 10 mM, and 25 mM NaCl solutions. In this case, the competition for adsorption between Cl(-) and DS(-) is not as strong compared to the 10 and 25 mM NaCl cases and the presence of Na(+) ions may reduce the repulsion between DS(-) ions, which results in a higher adsorption of DS(-) ions and enhanced enclathration.

Investigation of colloidal properties of modified silicone polymers emulsified by non-ionic surfactants.

Functionalized silicones are a unique class of hybrid materials due to their simultaneous hydrophobic-oleophobic properties, which results in applications in a variety of surface modification techniques. Prior research has shown that changes in surface charge and turbidity of modified silicone emulsions as a function of pH have a marked effect on their performance in coating applications. The emulsion droplet size is also believed to play significant role in such coating applications. In this work, modified silicone polymer emulsions stabilized by non-ionic surfactants were studied using dynamic light scattering (dilute) and electroacoustic (concentrated) spectroscopy to monitor the emulsion droplet size. The dilute and concentrated regime studies showed the emulsion droplet to be in nanometer range with no appreciable change in size as a function of pH. Electroacoustic studies showed a small fraction of droplets to be present in the micron size range. The emulsions were examined using Cryo-TEM technique, and the effect of pH and dilution on hydrophobicity of nanodomains was studied by employing fluorescence spectroscopy. It is shown from pyrene excimer behavior that both the dilution and pH have an effect on emulsion stability with a presence of critical surfactant concentration after which the emulsion was destabilized. It is proposed that the emulsion stability characteristics and the particle size distribution both play a significant role in their ability to impart desired macro and nano surface properties to treated substrates through electrostatic interactions and selective binding.

Structure-behavior-property relationship study of surfactants as foam stabilizers explored by experimental and molecular simulation approaches.

A multiscale stability study of foams stabilized by sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium polyoxyethylene alkylether sulfate (AES) was conducted, to investigate the relationship of surfactant molecular behavior and interfacial monolayer configuration of foam film to the foam film properties. Molecular dynamic (MD) simulations using a full-atom model was utilized to explore the microscopic features of the air/liquid interface layer. Several parameters such as the distribution of surfactant head groups and the order degree of surfactant hydrophobic tails were used to describe the molecular adsorption behavior. The effect of molecular structure on the nature of the foam film and the impact on the dynamic stability of wet foam is discussed. In the experimental evaluation, the SDBS foam films manifest strong stiffness and low viscoelasticity as shown by the interfacial shear rheology determination as well as texture analyzer (TA) measurement results, which agree very well with the array behavior of SDBS molecules at the air/water interface as described by the simulation results and is identified to be the reason for the poor dynamic stability. Comparing the molecular structure of SDS, SDBS, and AES, the special contributions of the linking groups such as the O atom, the phenyl group, and the EO (oxyethyl) chain to the interfacial array behavior of surfactants were characterized. It is concluded that microhardness of the foam film enhanced by rigid linking groups favors static foam stability but decreases the dynamic foam stability, while viscoelasticity of the foam film enhanced by soft linking groups increases the dynamic foam stability.

Polymer/surfactant interactions and nanostructures: current development for cleansing, release, and deposition of actives.

Nature exhibits a variety of remarkable phenomena that are useful but difficult to be imitated in real life. Examples are a "touch me not" plant folding up upon being attacked or microbes depositing on ocean vessels even under hostile conditions. Understanding of mechanisms governing these phenomena can prove powerful for developing new classes of cosmetic products. Systems based on polymer/surfactant colloid chemistry are being developed for achieving transport and release of cosmetic and pharmaceutical molecules at desired rates and desired sites. Modifications of the surfactants and polymers provide cleansing properties such as scavenging of odor and sebaceous body excretions and controlled delivery and deposition of sensory/hygienic attributes. New surfactants (sugar based and bio surfactants), hybrid polymers (silicone based and hydrophobically modified) and nanogels have been recently synthesized which may have applications in fields of cosmetics/fragrances/drugs etc. Due to the associative nature of the hydrophobic groups, hybrid polymers can form intramolecular nanodomains at all concentrations of the polymer and inter-molecular aggregates at high concentrations. New hybrid polymers and nano-gel particles can be developed with ability to extract and deliver actives by varying such properties as swelling/shrinking capacity and sensitivity to temperature, shear and dilution. Control of such properties as size, shape and cross linking of nanohybrid particles offer maximum opportunity for producing families of nanovehicles in personal and homecare industry. This review article provides an insight into current developments in field of nano-surfactant science, comprising discussions on nanogel particles, hybrid polymer and liposomes.

Mechanisms of fibrinogen-acebutolol interactions: Insights from DSC, CD and LS.

The complex formed due to the interaction of the amphiphilic betablocker acebutolol with fibrinogen in a buffer solution (50mN glycine, pH of 8.5) has been investigated using a multipronged physicochemical approach. Differential scanning calorimetry measurements of the complexes have shown no reversibility of thermal denaturation as indicated by the three observed peaks and the opposite role that acebutolol plays in the folding different domains of the fibrinogen molecule and the stability of such domains. While circular dichroism measurements have revealed that interaction of acebutolol with fibrinogen affects the protein secondary structure to a different extent depending on the temperature and drug concentration, dynamic light scattering analysis showed evidence for protein aggregation mainly to tetramers and dimers.

On the origin of an unusual dependence of (bio)chemical reactivity of ferric hydroxides on nanoparticle size.

Application of in situ UV-Vis absorption spectroscopy and ex situ X-ray photoelectron spectroscopy (XPS) makes it possible to resolve the controversies about the electronic properties of hematite (α-Fe(2)O(3)) nanoparticles (NPs) and, on this basis, to rationalize the unusual dependence of aquatic (bio)chemistry of these NPs on NP size. 2-Line ferrihydrite (FH) is also included in the study as the end polymorph of the size-driven phase transformation of hematite NPs in aqueous media. It is shown that the absorption edge of all NPs studied is due to the direct O 2p-Fe 3d charge transfer (CT) process, while a manifold of weak bands superimposed onto two main p-d CT bands is attributed to the d-d ligand field transitions. The band gap decreases from 2.95 to 2.18 eV with increasing NP size from 7 nm to 120 nm. This effect is attributed to restoration of hematite lattice structure, which ultimately results in an increase in the O 2p-Fe 3d hybridization, stabilization of the valence band, and delocalization of valence electrons, as confirmed by XPS. Finally, we show that the optical effects such as the Mie resonance significantly distort absorption spectra of hematite NPs larger than ∼120 nm. Possible impacts of these findings on (photo)catalytic and biochemical properties of ferric (hydr)oxide NPs are discussed.

Modeling and analysis of nanoscale interaction forces between Acidithiobacillus ferrooxidans and AFM tip.

The specificity exhibited by Acidithiobacillus ferrooxidans, a chemolithoautotrophic acidophile, in their attachment to different sulphide minerals has resulted in effective physical separation of these minerals. This can be explained in terms of surface forces of interaction between the cells and substrates using AFM. In the light of this, the present study reports interaction studies with A. ferrooxidans cells and an AFM silicon nitride tip. The aim of the present investigation is to probe the nanoscale interactions between A. ferrooxidans cells and silicon nitride tip of an AFM, model the approach and retraction forces, and elucidate the effects of pH, ionic strength and surface biopolymers on interfacial forces.

Competitive adsorption between SDS and carbonate on tetrahydrofuran hydrates.

Sodium dodecyl sulfate (SDS) has been well known as a promoter for the formation of hydrates. However, the use of SDS to enhance the formation of CO(2) hydrates has not been effective. This work will present an idea of competitive adsorption that will provide insights into the nonpromoting effect of SDS under high carbonate concentrations. The competitive adsorption is studied between DS(-) monomers and carbonate ions on tetrahydrofuran (THF) hydrates. The adsorption is qualitatively investigated by using pyrene fluorescence measurements. The SDS concentration at which hydrophobic domains occur on the hydrate surface increases with the increased carbonate concentration and this trend is less dependent on the order of addition of these two species. This concentration is 0.17 mM at carbonate concentrations less than 2 microM and it shifts to 3.47 mM at carbonate concentrations higher than 2.5 microM. Thus, using carbonate with its concentration higher than 2.5 microM would be enough to displace the hydrophobic domains formed by SDS up to the solubility limit.

Monitoring nanoparticles in the presence of larger particles in liquids using acoustics and electron microscopy.

Monitoring the presence of nanoparticles in dispersions having broad particle size distributions can be a problem for many measurement techniques because large particles or even aggregates of the smaller particles can mask the presence of the sought after nanoparticles. The ability of many existing techniques to detect the nanoparticles when present in broad polydisperse systems is largely unknown, yet it is critical for proper selection of the measuring technique for characterizing a particular nanodispersion. Acoustic spectroscopy is already a known and proven tool for studying nanoparticles in systems with a narrow size distribution. The purpose of this paper is to evaluate the sensitivity of acoustic spectroscopy for determining the nanoparticle content of very polydisperse systems. We used eight different ZnO powders from different manufacturers to prepare 5wt.% dispersions, each dispersed in water. The stability of each dispersion was optimized by pH adjustment and addition of sodium hexametaphosphate as determined by maximizing the measured zeta-potential. According to the acoustic measurement, the median size of these different ZnO dispersions varied from 200nm to 700nm. Independent TEM photographs in general confirmed the size variation between the samples. Independent DLS measurements failed to provide particle size data correlating with TEM. The acoustic measurements further showed that each dispersion contained a different relative content in the nanoparticle fraction. The precision with which the nanoparticle fraction could be determined was better than 2% of the total solid loading for all samples. In order to verify consistency of this measurement we performed a mixing study by adding dispersion with the largest nanoparticle content to the dispersion with the smallest nanoparticle content, in small increments. This test confirms that the acoustic sensitivity threshold is about 2% of nanoparticles in the broad polydisperse dispersions of dense metal oxide particles.

Variation in emulsion stabilization behavior of hybrid silicone polymers with change in molecular structure: Phase diagram study.

Silicone oils are widely used in cosmetics and personal care applications to improve softness and condition skin and hair. Being insoluble in water and most hydrocarbons, a common mode of delivering them is in the form of emulsions. Currently most applications use polyoxyethylene (non-ionic) modified siloxanes as emulsifiers to stabilize silicone oil emulsions. However, ionically grafted silicone polymers have not received much attention. Ionic silicones have significantly different properties than the non-ionic counterpart. Thus considerable potential exists to formulate emulsions of silicones with different water/silicone oil ratios for novel applications. In order to understand the mechanisms underlying the effects of hydrophilic modifications on the ability of hybrid silicone polymers to stabilize various emulsions, this article focuses on the phase diagram studies for silicone emulsions. The emulsifying ability of functional silicones was seen to depend on a number of factors including hydrophilicity of the polymer, nature of the functional groups, the extent of modification, and the method of emulsification. It was observed that the region of stable emulsion in a phase diagram expanded with increase in shear rate. At a given shear rate, the region of stable emulsion and the nature of emulsion (water-in-oil or oil-in-water) was observed to depend on hydrophilic-hydrophobic balance of the hybrid silicone emulsifier. At a fixed amount of modification, the non-ionically modified silicone stabilized an oil-in-water emulsion, whereas the ionic silicones stabilized inverse water-in-oil emulsions. This was attributed to the greater hydrophilicity of the polyoxyethylene modified silicones than the ionic counterparts. In general, it is postulated that with progressive increase in hydrophilicity of hybrid silicone emulsifiers, their tendency to stabilize water-in-oil emulsion decreases with corresponding increase in oil-in-water emulsion. Further, this behavior is hypothesized to depend on the nature of modifying functional groups. Thus a hybrid silicone polymer can be tailored by selecting the nature and degree of hydrophilicity to obtain a desired silicone emulsion.

Synergistic adsorption of mixtures of cationic gemini and nonionic sugar-based surfactant on silica.

Adsorption behavior of cationic C(12)-C(4)-C(12) gemini surfactant on silica has been investigated, along with that of nonionic surfactant n-dodecyl-beta-D-maltoside (DM). While DM alone shows meager adsorption on silica, because of the lack of any electrostatic adsorption, cationic gemini adsorbs significantly on the oppositely charged silica surface. Due to the electrostatic nature of cationic gemini adsorption on silica, solution pH affects adsorption of C(12)-C(4)-C(12) gemini dramatically. Meanwhile, C(12)-C(4)-C(12) gemini hemimicelle size at silica/water interface does not seem to change with solution pH. For the mixtures of DM and cationic C(12)-C(4)-C(12) gemini, there is a sharp increase of DM adsorption at silica/water interface, up to 100 times more than DM alone. After mixing with DM, saturation adsorption of cationic C(12)-C(4)-C(12) gemini decreases, due to competition for adsorption sites from DM. At the same time, in its mixture with DM, there is an increased adsorption of C(12)-C(4)-C(12) gemini in the rising part of the adsorption isotherm. Hydrophobic chain-chain interactions, especially with two hydrophobic chains in one C(12)-C(4)-C(12) gemini molecule, and adsorbed C(12)-C(4)-C(12) gemini molecule acting as an anchor or nucleation sites for forming mixed aggregates with DM on silica surface, are attributed to the marked adsorption synergy between DM and cationic C(12)-C(4)-C(12) gemini. The adsorption of surfactants and their mixtures has a marked effect on silica surface charge and silica's wettability.

Adsorption of surfactants on two different hydrates.

The interaction between surfactants and hydrates provides insight into the role of surfactants in promoting hydrate formation. This work aims at understanding the adsorption behavior of sodium dodecyl sulfate (SDS) on cyclopentane (CP) hydrates and its derivative surfactant on tetrabutylammonium bromide (TBAB) hydrates. Cyclopentane (CP) is a hydrophobic former whereas tetrabutylammonium bromide (TBAB) is a salt that forms semiclathrate hydrates. The adsorption on these two hydrates was studied by zeta potential and pyrene fluorescence measurements. CP hydrates have a negative surface charge in the absence of SDS, and it decreases to a minimum as the SDS concentration increases from 0 to 0.17 mM. Then, it increases with further increased SDS concentration. The adsorption density of DS (-) on CP hydrates reaches a saturated value at 1.73 mM SDS. The micropolarity parameter of the TBAB hydrate/water interface starts to increase rapidly at 0.17 mM SDS and levels off at 1.73 mM SDS. The presence of Br (-) in TBAB hydrate suspensions could compete with TBADS (from association of DS (-) and TBA (+)) and DS (-) for the adsorption on the hydrate surface, but they have a much stronger affinity for the hydrates than does Br (-). From the fluorescence measurements, it was found that the micropolarity of the hydrate/water interface is mainly dependent on the polarity of hydrate formers.

Mechanism of stabilization of silicone oil-water emulsions using hybrid siloxane polymers.

Silicone polymers, due to their high lubricity and good spreading properties, are widely used in industrial applications. Being insoluble in water and most hydrocarbons, a common mode of delivering silicones is in the form of emulsions. To stabilize silicones in the emulsion form more efficiently, it is useful to understand the mechanism of emulsion stabilization. Two different mechanisms of emulsion stabilization have been proposed in the past: film formation and precipitation (known as the Pickering mechanism). These two mechanisms are different, and there is a need to further investigate this issue. The aim of the present work was to investigate the mechanism of stabilizing silicone emulsions and to propose a generalized behavior. Several experiments including the measurement of Langmuir isotherms, rheology experiments, phase diagram studies, and microscopy experiments were conducted. All of the above techniques indicated that the functional groups interact strongly with the water phase. The emulsions were found to be stable only if the emulsifiers were soluble in silicone oil or the water phase, and the stability decreased as the emulsifier precipitated. In most cases tested here, the emulsifiers were not observed to precipitate as reported earlier for the Pickering mechanism, and the emulsion stabilization followed film formation. These results should help to predict emulsion stabilization for unknown systems.