Effect Of Surfactant Composition Research Articles

Mixed-surfactant perovskites with enhanced photostability

Blue and green emitting methylammonium lead bromide perovskite particles with improved UV-light stability have been developed by tuning structure and stabilization with a mixture of different single- and double-tailed surfactants. The ratio of the long alkyl chain surfactants to the methyl ammonium bromide allows for tailoring of the emission color of ready to use perovskite particles without further purification processes. The combination of single and double tailed surfactants exceeds the properties and geometries of the perovskite particles obtainable with a single surfactant. With a mixture of octylammonium bromide and dimethyldioctadecyl bromide, the perovskite particles show a highly anisotropic shape with a layered pyramid structure. The effect of surfactant composition on the perovskite particles’ structure, morphology and light-emitting properties has been elucidated. As these mixed surfactant perovskites are more robust against UV-light than other perovskite particles, they bear great potential for applications in optical devices such as LEDs.

Viscoelastic surfactant fracturing fluids for use in coal seams: Effects of surfactant composition and formulation

Recently, viscoelastic surfactant (VES) fracturing fluids have attracted wide attention because they are highly viscoelastic and environmentally benign. To optimize fracturing fluid formulations for coal reservoir conditions, 135 groups of VES fracturing fluids were prepared. The influence of the cationic surfactant’s hydrocarbon chain lengths on water loss, wettability, viscosity, and temperature resistance were analyzed. To further improve the surfactant’s aggregation capabilities, zwitterionic surfactants were added to fracturing fluids prepared with stearyl trimethyl ammonium chloride (STAC). We found that STAC can reduce water loss more effectively during fracturing than the cationic surfactant hexadecyl trimethyl ammonium chloride (CTAC). Appropriate amounts of cocoamidopropyl betaine (CAB) increased the viscosity and temperature resistance of the fracturing fluid. It is important to note that as the concentration of sodium salicylate (NaSal) increases, the maximum viscosity of VES fracturing fluid with CAB added is twice that of a fracturing fluid without CAB.

Tunable microstructure of polyacrylate/ZnO nanorods composite emulsion and its film-forming properties

Polyacrylate/ZnO nanorods core-shell emulsion was prepared via emulsion polymerization for the first time. The distribution of ZnO nanorods in and out of the polyacrylate latex was achieved by adjusting the mass ratio of the non-ionic and anionic surfactants. The effects of surfactant composition on the distribution of ZnO nanorods in and out of polyacrylate latex, and the effect of composite latex microstructure on the properties of composite films were investigated in detail. The results showed that when the mass ratio of non-ionic and anionic surfactants was 0:1, the ZnO nanorods were located outside of the polyacrylate latex through electrostatic interaction with only anionic surfactants, forming polyacrylate@ZnO latex. Moreover, the ZnO nanorods can be uniformly dispersed in the composite film, and the tensile strength of the composite film was optimal. When the mass ratio of non-ionic and anionic surfactants was 1.5:1, all ZnO nanorods were encapsulated inside the polyacrylate latex to form ZnO@polyacrylate latex, the elongation at break and water resistance of the composite film were the best. When the mass ratio of non-ionic and anionic surfactants was 2:1, the agglomeration of ZnO nanorods in the composite film resulted in an increase in free volume, and the water vapor permeability of the composite film was optimal. Therefore, the microstructure of the hybrid latex can affect the macroscopic properties of the composite film. This study is expected to provide a theoretical basis for the structural design and performance optimization of the nanocomposite.

Interfacial composition and solubilization of microemulsion systems containing mixed surfactants C12mimBr and Brij35: effects of surfactant composition, temperature, and salinity

The composition of the interfacial layer and solubilization of the microemulsions containing mixed cationic and nonionic surfactants (C12mimBr-Brij35) were studied and compared based on the mass and the number of moles of the surfactants, respectively. As $$ {X}_{C_{12}\mathrm{mimBr}} $$ (mole fractions of C12mimBr in C12mimBr-Brij35 mixture) increases, the total masses of the surfactants ( $$ {m}_S^s $$ ) decrease, whereas the total number of moles of surfactants ( $$ {n}_S^S $$ ) increases in the interfacial layer. This opposite pattern of change between $$ {m}_S^s $$ and $$ {n}_S^S $$ against $$ {X}_{C_{12}\mathrm{mimBr}} $$ is due to the significant difference in the molecular mass between the two surfactants. The mass solubilization parameter of the microemulsions, $$ {\mathrm{SP}}_m^{\ast } $$ , increases and follows a curve that concaves downward as $$ {X}_{C_{12}\mathrm{mimBr}} $$ values increase. However, the molar solubilization parameter, $$ {\mathrm{SP}}_n^{\ast } $$ , would decrease as $$ {X}_{C_{12}\mathrm{mimBr}} $$ increases. The physicochemical properties of the microemulsions are less sensitive to both temperature and salinity.

Rheological behavior of mixed system of ionic liquid [C8mim]Br and sodium oleate in water

We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [C8mim]Br (1-octyl-3-methylimidazolium bromide) and anionic surfactant sodium oleate (NaOA) in aqueous solution. The effects of surfactant composition, total surfactant concentration, added salts, and temperature were investigated. The prevailing surfactant effect at lower concentration and the leading cosolvent effect at higher concentration of [C8mim]Br may be the main reasons for appearance of well-established maximum in key rheological parameters with variation of surfactant composition and total surfactant concentration. The Cole-Cole plots demonstrate that the systems (total surfactant concentration falls within 0.17–0.35 mol·L–1 and molar ratio 0.33≤R≤0.50) fit the Maxwell’s mechanical model as linear viscoelastic fluid. The addition of NaBr or sodium salicylate decreases significantly the viscosity and the relaxation time of the wormlike micelle solution but cannot change the value of plateau modulus G0. The present system has low rheological tolerance to temperature. The increase of temperature decreases the average contour length and viscosity of wormlike micelles and thus strengthens the relaxation progress of diffusion and weakens the relaxation progress of reptation. Increasing the temperature also decreases the value of plateau modulus G0 and shifts the minimum value of the loss modulus G″min to higher frequencies.

The effect of surfactant composition on the chemical and structural properties of nanostructured lipid carriers

Fine-tuning the nanoscale structure and morphology of nanostructured lipid carriers (NLCs) is central to improving drug loading and stability of the particles. The role of surfactant charge on controlling the structure, the physicochemical properties and the stability of NLCs has been investigated using three surfactant types (cationic, anionic, non-ionic), and mixed surfactants. Either one, a mixture of two, or a mixture of three surfactants were used to coat the NLCs, with these classified as one, two and three surfactant systems, respectively. The mixed (two and three) surfactant systems produced smaller NLC particles and yielded NLCs with lower crystallinity than the one surfactant system. The combined effects of the ionic and the non-ionic surfactants may play a key role in assisting the lipid-oil mixing, as well as maintaining colloidal repulsion between NLC particles. In contrast, for the three surfactant system, the lipid–oil mixture in the NLCs appeared less homogenous. This was also reflected in the results of the stability study, which indicated that NLC particle sizes in two surfactant systems appeared to be retained over longer periods than for other surfactant systems.

Formulation and Characterization of Nanoemulsion Intranasal Adjuvants: Effects of Surfactant Composition on Mucoadhesion and Immunogenicity

The development of effective intranasal vaccines is of great interest due to their potential to induce both mucosal and systemic immunity. Here we produced oil-in-water nanoemulsion (NE) formulations containing various cationic and nonionic surfactants for use as adjuvants for the intranasal delivery of vaccine antigens. NE induced immunogenicity and antigen delivery are believed to be facilitated through initial contact interactions between the NE droplet and mucosal surfaces which promote prolonged residence of the vaccine at the site of application, and thus cellular uptake. However, the details of this mechanism have yet to be fully characterized experimentally. We have studied the physicochemical properties of the NE droplet surfactant components and demonstrate that properties such as charge and polar headgroup geometry influence the association of the adjuvant with the mucus protein, mucin. Association of NE droplets with mucin in vitro was characterized by various biophysical and imaging methods including dynamic light scattering (DLS), zeta potential (ZP), and surface plasmon resonance (SPR) measurements as well as transmission electron microscopy (TEM). Emulsion surfactant compositions were varied in a systematic manner to evaluate the effects of hydrophobicity and polar group charge/size on the NE-mucin interaction. Several cationic NE formulations were found to facilitate cellular uptake of the model antigen, ovalbumin (OVA), in a nasal epithelial cell line. Furthermore, fluorescent images of tissue sections from mice intranasally immunized with the same NEs containing green fluorescent protein (GFP) antigen demonstrated that these NEs also enhanced mucosal layer penetration and cellular uptake of antigen in vivo. NE-mucin interactions observed through biophysical measurements corresponded with the ability of the NE to enhance cellular uptake. Formulations that enhanced antigen uptake in vitro and in vivo also led to the induction of a more consistent antigen specific immune response in mice immunized with NEs containing OVA, linking NE-facilitated mucosal layer penetration and cellular uptake to enhancement of the immune response. These findings suggest that biophysical measurement of the mucoadhesive properties of emulsion based vaccines constitutes an effective in vitro strategy for selecting NE candidates for further evaluation in vivo as mucosal adjuvants.

Effect of surfactant composition on reservoir wettability and scale inhibitor squeeze lifetime in oil wet carbonate reservoir

Abstract In the oil industry, scale inhibitor (SI) squeeze treatment is an established method to prevent deposition of inorganic scales in the wellbore and near wellbore formation. Most scale inhibitor chemicals are water soluble and therefore typically deployed as an aqueous solution. However, most carbonate reservoirs being preferentially oil-wet, SI squeeze treatment could be short lived, because of the competition for adsorption surface between the native oil and the SI. Although several authors studied surfactant activities on reservoir rock and fluid properties in relation to enhanced oil recovery, the literature lacks information on the effect of surfactant based preflush treatment on rock characteristics in relation to SI squeeze lifetime. It is obvious that a proper design of preflush, based on a detailed understanding of rock–fluid properties, could be as important as designing the main treatment (SI) itself. The objective of this study was to develop an understanding of surfactant composition and pH in altering carbonate rock wettability, and its impact on scale inhibitor squeeze performance. A set of carbonate core plugs with oil wet characteristics, crude oil and treatment chemicals (anionic surfactant and SI) were collected from an offshore oilfield. Surfactant preflush compositions with and without alkalis were evaluated for their ability to minimize oil–brine IFT and the extent of rock wettability alteration. A series of coreflood studies were conducted with selected preflush compositions and SI, followed by injecting incompatible brines. SI squeeze lifetimes were determined through observation of core permeability damage. The scale inhibitor and strontium return profile analyzed through ICP-MS studies also validated the onset of permeability damage. The study clearly established a correlation between rock wettability and scale inhibitor lifecycle. Extended SI lifecycle is evidenced in the core with a strongly water wet core and vice versa. The importance of proper preflush design based on rock–fluid characteristics and the role of alkali in changing wettability characteristics, surfactant adsorption and inhibitor lifecycle are discussed with experimental evidence.

Electrophoresis of human brain microvascular endothelial cells with uptake of cationic solid lipid nanoparticles: Effect of surfactant composition

This study analyzes the effects of Tween 80 and Span 20 on the electrical interaction between cationic solid lipid nanoparticles (CSLNs) and human brain microvascular endothelial cells (HBMECs). Electrophoretic mobility, zeta potential and fixed charge density of CSLNs and HBMECs with uptake of CSLNs were also investigated. The results revealed that a higher molar ratio of Tween 80 yielded smaller CSLNs, higher charge of CSLNs and larger electrical attraction energy between CSLNs and HBMECs. On the contrary, a decrease in the molar ratio of Tween 80 enhanced the absolute values of electrophoretic mobility and zeta potential of CSLNs-incorporating HBMECs. In addition, a higher concentration of CSLNs in the dispersion medium led to lower charge of CSLNs-incorporating HBMECs. An increased concentration of glutamate from 1 to 2 mg/mL enhanced the absolute values of electrophoretic properties of CSLNs-incorporating HBMECs. In the case of increasing concentration of glutamate, pure Tween 80 was stronger in charge enhancement than pure Span 20.

Dispersibility of crude oil in fresh water

The effects of surfactant composition on the ability of chemical dispersants to disperse crude oil in fresh water were investigated. The objective of this research was to determine whether effective fresh water dispersants can be designed in case this technology is ever considered for use in fresh water environments. Previous studies on the chemical dispersion of crude oil in fresh water neither identified the dispersants that were investigated nor described the chemistry of the surfactants used. This information is necessary for developing a more fundamental understanding of chemical dispersion of crude oil at low salinity. Therefore, we evaluated the relationship between surfactant chemistry and dispersion effectiveness. We found that dispersants can be designed to drive an oil slick into the freshwater column with the same efficiency as in salt water as long as the hydrophilic–lipophilic balance is optimum.

Effects of Surfactant Composition and Concentration on Shape, Size and Photocatalytic Activity of TiO2 Nanoparticles

Various shapes and sizes, including spherical, cubic nanoparticles and hexagonal nanorods with the dimensions of 50-500nm, of TiO2 were prepared through hydrolysis of titanium butoxide in sol-gel method with the introduction of different surfactant composition and concentrations during preparation. Prepared TiO2 nanoparticles were studied for photocatalytic decomposition of methyl orange (MO) in fixed film batch reactors. The results showed that shape, size and photocatalytic activity of TiO2 depend not only on surfactant composition but also on surfactant concentration. Photocatalytic decomposition of MO followed the first order kinetic reaction. The analysis of reaction rate constants showed that the shape is more important than the size in determining the photocatalytic activity of shape- and size-controlled TiO2 nanoparticles. TiO2 nanorods had higher photocatalytic activities than spherical and cubic TiO2 nanoparticles.

Microemulsion formation and detergency with oily soils: I. Phase behavior and interfacial tension

AbstractThe ultimate objective of the project was to investigate the relationship between microemulsion phase behavior and detergency for oily soils. In this study, surfactant phase behavior was evaluated for hexadecane and motor oil as model oily soils. Producing microemulsions with these oils is particularly challenging because of their large hydrophobic character. To produce the desired phase behavior we included three surfactants with a wide range of hydrophilic/lipophilic character: alkyl diphenyl oxide disulfonate (highly hydrophilic), dioctyl sodium sulfosuccinate (intermediate character), and sorbitan monooleate (highly hydrophobic). This mixed surfactant was able to bridge the hydrophilic/lipophilic gap between the water and the oil phases, producing microemulsions with substantial solubilization and ultralow interfacial tension. The effects of surfactant composition, temperature, and salinity on system performance were investigated. The transition of microemulsion phases could be observed for both systems with hexadecane and motor oil. In addition, the use of surfactant mixtures containing both anionic and nonionic surfactants leads to systems that are robust with respect to temperature compared to single‐surfactant systems. Under conditions corresponding to “supersolubilization”, the solubilization parameters and oil/microemulsion interfacial tensions are not substantially worse than at optimal condition for a middle‐phase system, so a middle‐phase microemulsion is not necessary to attain quite low interfacial tensions. A potential drawback of the formulations developed here is the fairly high salinity (e.g., 5 wt% NaCl) needed to attain optimal middle‐phase systems. The correlation between interfacial tension and solubilization follows the trend predicted by the Chun‐Huh equation.

Effect of Surfactant Composition on Aeration Characteristics and Stability of Foams in Aerated Food Products

ABSTRACT: We studied the synergistic effect of surfactants on aeration characteristics and long‐term stability of aerated mesophase. It was observed that bubble size and volume of air incorporated (overrun) depend to a small extent on the dynamic film tension and to a greater extent on the viscosity of the mesophase, both properties being functions of surfactant chemistry and concentration. The overrun of the aerated product decreased over time due to the diffusive transport of air to the atmosphere, leading to its destabilization. The relative rate of destabilization of the aerated mesophase (as function of surfactant composition) has been correlated with the diffusion rate of air from the bulk to the surface.

Separation of naphthalene-2,3-dicarboxaldehyde-derivatized-substance P and its metabolites by micellar electrokinetic chromatography

This paper describes the development of analytical methodology for the separation of naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized substance P (CBI-SP) and five lysine-containing metabolites by micellar electrokinetic chromatography (MEKC). The effect of surfactant composition and organic modifiers on the separation was investigated. The final separation buffer consisted of 80 mM sodium cholate in 50 mM N-tris (hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), pH 7. All six lysine-containing peptides were separated under these conditions.

Separation of naphthalene-2,3-dicarboxaldehyde-derivatized-substance P and its metabolites by micellar electrokinetic chromatography.

This paper describes the development of analytical methodology for the separation of naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized substance P (CBI-SP) and five lysine-containing metabolites by micellar electrokinetic chromatography (MEKC). The effect of surfactant composition and organic modifiers on the separation was investigated. The final separation buffer consisted of 80 mM sodium cholate in 50 mM N-tris (hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), pH 7. All six lysine-containing peptides were separated under these conditions.

The selection of surfactants for specific household applications

AbstractThe various criteria involved in choosing a surfactant for laundry products, light‐duty liquids, shampoos and liquid soap products are discussed. These include cleaning performance, foam characteristics, formulatability, tolerance to water hardness, processability, and cost. The effect of surfactant composition on performance is also discussed.