Lipophilic Surfactant Research Articles

Mucoadhesive aprepitant-loaded nanostructured lipid carriers containing sulfhydryl surfactant for enhanced oral drug bioavailability

The objective of the study was to design mucoadhesive drug-loaded nanostructured lipid carriers (NLCs) for enhancing the bioavailability of a model BCS Class IV drug aprepitant (APT). For this purpose, polyethoxylated surfactant (polyoxyethylene 20 oleyl ether) was thiolated, and mucoadhesive NLCs were designed through nano-template engineering technique using thiolated surfactant, Span 60 (lipophilic surfactant), labrasol (hydrophilic surfactants), miglyol (liquid lipid), stearic acid (solid lipids), and PEG 6000 as a stabilizer. Mucoadhesive NLCs were characterized via size, ζ (zeta potential), polydispersity index (PDI), and scanning electron microscopy (SEM). Moreover, NLCs were evaluated for drug loading capacity and entrapment efficiency, stability, safety, drug release, mucoadhesion, and permeation studies. Furthermore, in-vivo studies were conducted on Sprague-Dawley rats to prove enhanced oral bioavailability of APT. The APT-loaded NLCs revealed a particle size of 185 ± 12 nm, zeta potential of about −23.5 ± 3 mV, a PDI of 0.190 ± 0.01, having spherical shape, with 6.7 ± 0.8 % and 86 ± 3 % drug loading and entrapment efficiency, respectively. The APT-loaded NLCs were found stable at different conditions and demonstrated the sustained release of the drug. NLCs were found safe as more than 80 % cells were found viable after 24 h. Moreover, drug-loaded mucoadhesive NLCs showed 3.8-fold improved mucoadhesive properties as compared to control. Mucoadhesive NLCs were found less permeable due to disulfide bond formation with mucus. In-vivo studies confirmed that APT-loaded mucoadhesive NLCs exhibited 2.56-fold improved Cmax. Furthermore, 24.8 % relative bioavailability (Fr) was reached for APT-loaded mucoadhesive NLCs as compared to 9.8 % for APT suspension. On the basis of all the above-stated findings, it can be decided that these NLCs are suitable nanocarriers for delivering the aprepitant orally.

Experimental study on gas separation from the oil–water-emulsion mixture via hydrate method

The gas separation technology based on hydrate method offers several advantages, including a short process flow, simple equipment, no pollution, less corrosion, and lower energy consumption. It has a broad application prospect in the acid gas purification, biogas purification and CO2 sequestration., etc. However, demanding hydrate formation conditions and lower gas separation effects constrain its application. Oil-water emulsion shows promise in improving mass and heat transfer efficiency, enhancing hydrate slurry fluidity, and reducing hydrate aggregates. Thus, this study investigates the effects of different oil–water ratios, promoter concentrations, and surfactants on hydrate formation and separation efficiency in an oil–water emulsion system. At an oil–water ratio of 1:1, the purification rate increased to 6.06, five times higher than in a pure water system. The addition of 1,3-Dioxolane (DIOX) facilitated bidirectional growth properties of hydrate formation on droplet surfaces, enhancing hydrate nucleation and formation, leading to a CO2 recovery increase to 87% with 1.5 wt% DIOX. Furthermore, lipophilic surfactants were more likely to promote hydrate slurry fluidization. The addition of Span80 reduced hydrate agglomeration and increased the rate of hydrate formation as concentration rose. The results suggest that adding DIOX and increasing the concentration of Span80 could improve the hydrate method’s separation efficiency at an oil–water ratio of 1:1.

Co-Processed Crystalline Solids of Ivermectin with Span® 60 as Solubility Enhancers of Ivermectin in Natural Oils

Despite being discovered over five decades ago, little is still known about ivermectin. Ivermectin has several physico-chemical properties that can result in it having poor bioavailability. In this study, polymorphic and co-crystal screening was used to see if such solid-state modifications can improve the oil solubility of ivermectin. Span® 60, a lipophilic non-ionic surfactant, was chosen as co-former. The rationale behind attempting to improve oil solubility was to use ivermectin in future topical and transdermal preparations to treat a range of skin conditions like scabies and head lice. Physical mixtures were also prepared in the same molar ratios as the co-crystal candidates, to serve as controls. Solid-state characterization was performed using X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The FTIR spectra of the co-crystal candidates showed the presence of Span® 60’s alkyl chain peaks, which were absent in the spectra of the physical mixtures. Due to the absence of single-crystal X-ray data, co-crystal formation could not be confirmed, and therefore these co-crystal candidates were referred to as co-processed crystalline solids. Following characterization, the solid-state forms, physical mixtures and ivermectin raw material were dissolved in natural penetration enhancers, i.e., avocado oil (AVO) and evening primrose oil (EPO). The co-processed solids showed increased oil solubility by up to 169% compared to ivermectin raw material. The results suggest that co-processing of ivermectin with Span® 60 can be used to increase its oil solubility and can be useful in the development of oil-based drug formulations.Graphical

Simultaneous adjustment on the CO2/oil and CO2/water interface tensions using hydrophilic, lipophilic and CO2-philic surfactants during CO2 flooding to enhance shale oil recovery after hydraulic fracturing

It is an urgent demand to further enhance shale oil recovery after large-scale hydraulic fracturing with a low oil recovery. CO2 flooding technology has been demonstrated to effectively develop shale oil, however, the residual water after hydraulic fracturing can influence the efficiency of CO2 flooding because of the high CO2-water interfacial tension. Here, the hydrophilic, lipophilic and CO2-philic surfactants were investigated to simultaneously adjust the CO2/oil and CO2/water interface tension to accelerate the oil and water flows to enhance shale oil recovery. The results show that the low-carbon alcohol polyoxyethylene polyoxypropylene ether has the hydrophilic, lipophilic and CO2-philic properties. The alkyl chain length and PO groups have great influence on the interfacial tension of CO2-oil, while the presence of EO groups can significantly reduce the interfacial tension of CO2-water. The surfactant of C4EO3PO6 can not only demonstrate the best performance in reducing the interfacial tensions of shale oil-CO2 and water-CO2, but also decrease the minimum miscibility pressure (MMP) of the shale oil-CO2 system to 18.89 MPa from 24.10 MPa. The interfacial tension between water and the CO2 + 1.0 wt% C4EO3PO6 system can be decreased to 6.62 mN/m at 28 MPa and the reduction rate is 56.10 %. The enhancement of surfactants on the extraction effect of CO2 and the mutual diffusion process between CO2 and shale oil or water interface is the major mechanism to decrease the interfacial tensions. Therefore, the addition of surfactant in CO2 can simultaneously decrease the interfacial tensions of CO2-oil and CO2-water and has a potential to enhance shale oil recovery by reducing the capillary resistance of residual water after hydraulic fracturing and increasing the miscibility between CO2 and oil.

Synergistic effect of sodium dodecyl sulfate (SDS) and oleic acid (OA) on gelation and lubrication performance

In this paper, it was found that with the addition of sodium dodecyl sulfate (SDS, a hydrophilic surfactant) and oleic acid (OA, a lipophilic surfactant) in a solvent with a proper composition ratio, a stable gel could be obtained via a simple ultrasonic treatment. The synergistic gelation of OA–SDS was verified in a series of solvents with different polarities, such as white oil (WO), LB-2000, n-hexane, polyalphaolefin (PAO10), and deionized water. The Fourier transform infrared (FTIR) analysis confirms that the gelation of OA–SDS is highly related to the ion exchange reaction between them. However, the xerogel of OA–SDS gelator in deionized water and WO (OSW) exhibited remarkably different morphologies, indicating that the gelation is based on different molecular assembly processes, which is governed by the orientation of the two surfactant molecules in liquid media. Further characterizations of OSW gel presented that the synergistic effect between OA and SDS not only existed in gelation, but also in enhancing the mechanical and thermal stability of WO, and endowing the OSW gel with reliable friction reduction and antiwear performances under variable working conditions. Subsequently, the lubrication mechanism was proposed based on rheological analysis and the morphological and compositional analysis of wear surfaces. This study provides a novel idea for the molecular design of lubricating gelators with wide adaptability to solvent polarity and working conditions.

Fat crystallization and physical characteristics of mung bean protein-based frozen whipped emulsions: Effect of lipophilic surfactants and quinoa hydrolysate

Yogurt ice cream (acid frozen whipped emulsion) is a complex frozen emulsion-foam system. The study investigated the impact of three lipophilic surfactant emulsifiers [glyceryl monostearate (GMS), polyglycerol ester (PGE), and sucrose ester 970 (S970)] and quinoa hydrolysate (QH) on fat crystallization, physical properties, and morphology of frozen whipped emulsions containing fermented mung bean protein. QH serves as a sustainable and health-conscious alternative to traditional emulsifiers. pH12-shifting treatment was utilized to modulate fermentation performance of mung bean protein. Yogurt-like ice creams (10% coconut oil) were formulated using pre-whipped emulsions comprising fermented pH12-treated mung bean protein (FMP12) or native mung bean protein (NFMP), along with 0.5% (w/w) emulsifiers or QH. Pre-whipped FMP12 emulsions exhibited significantly higher emulsification stability (P < 0.05) compared to NFMP emulsions, owing to the better-balanced hydrophilic-lipophilic nature of FMP12. The individual addition of surfactants and QH promoted fat crystallization and improved the stability and viscous of FMP12 emulsion by competitively adsorbing with FMP12 at the O/W interface. Upon freezing, all three surfactants in whipped creams resulted in uniform and fine ice crystals with a moderate accumulation of oil droplets, showing a comparable effect to QH. Consequently, FMP12 frozen whipped emulsions with surfactants or QH both exhibited superior hardness and overrun, attributed to the presence of fine ice crystals and a stable fat crystal skeleton structure. These findings indicate the prospective utility of QH as a substitute for conventional small chemical emulsifiers, thereby enhancing the quality attributes of plant-based yogurt ice cream.

Impact of Xanthan Gum on Stability and Rheological Properties of Multiple Emulsions Type Water-in-Oil-in-Water

The aim of this study was to improve the stability and rheological properties of water-in-oil-in-water (W/O/W) multiple emulsions containing 30 wt% paraffin oil, and 4 wt% polyglycerol-3-polycinoleate (PGPR) as a lipophilic surfactant. This was done by adding different concentrations of xanthan gum (GX) and the hydrophilic surfactants (Polyoxyethylene (80) sorbitan monooleate (Tween® 80), poloxamer 407(Lutrol® F127) using the emulsification in a two-steps process. The stability of the W/O/W multiple emulsions was analyzed over one-month storage period using physicochemical and rheological measurements. An excellent structure appeared with 0.175 wt% of xanthan gum in the outer aqueous phase and 1 wt% of Tween® 80. The modified Cross model was successfully applied to fit the flow curves of multiple W/O/W emulsions at different concentrations of xanthan gum. The incorporation of xanthan gum in a concentration range of 0.05-0.175 wt% induced an increase in the yield stress, in the zero-shear rate viscosity, and in the infinite shear rate viscosity of the multiple emulsions. The study also showed that adding xanthan gum in a concentration range of 0.05-0.175 wt% to W/O/W emulsions caused an increase in the viscosity of the system in the Newtonian regime and viscoelastic behavior.

Influence of Dimethyl Carbonate and Dispersant Added Graphene Nanoplatelets in Diesel-Biodiesel Blends: Combustion, Performance, and Emission Characteristics of Diesel Engine

The aim of the current study is to investigate the combustion, performance, and emission characteristics of a diesel engine adopting graphene nanoplatelets and 10% v / v dimethyl carbonate as fuel additives in a 30% biodiesel and 70% diesel blend. The novel findings are documented in the subsequent sections. The surface modification of graphene nanoplatelets using a lipophilic surfactant was used which gave highest stability in fuel samples which is a main distinctive in this research work. Nanofuels were prepared using 30, 60, and 90 ppm concentrations of nanoparticles through ultrasonication. The behaviour of graphene nanoplatelet was characterized using field emission scanning gun-electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared, and X-ray diffraction. A diesel engine having uniform speed of 1500 rpm was used for the experiment at various load conditions to assess the engine operating parameters for all the prepared samples, including baseline diesel. It was observed that the combustion characteristics were found to be greatly enhanced, such as cylinder pressure and heat release rate, increased by about 15.45% and 9.63%, respectively, for B30GNP60DMC10 sample than diesel at higher loads. Performance parameters such as brake thermal efficiency (elevated by 8.98%) and brake-specific fuel consumption (diminished by 25.54%) have been significantly analyzed and compared to diesel. While the emissions (such as hydrocarbons and carbon monoxide) were found to be reduced by 22.87% and 25.67%, respectively, for B30DMC10, the nitrous oxide and smoke opacity were also reduced by 9.57% and 12.4%, respectively, for the B30GNP60DMC10 sample. Hence, a combining operation of graphene nanoplatelets and dimethyl carbonate additives in a biodiesel blend presented great potential in terms of performance improvement and reduction in emission parameters in diesel engine.

Characterization and comparison of physical properties and in vitro simulated digestion of multi-component oleogels with different molecular weights prepared by the direct method

Due to the hazards of trans fatty acids and saturated fatty acids to human health, research on novel structured lipid-oleogels as lipid substitutes has attracted increasing attention. However, oleogelators of different molecular weights, oils of different properties, and adding lipophilic bioactive substances (LBAS) and/or surfactants to the system lead to differences in oleogel properties. This study characterized and compared the physical properties and in vitro simulated digestion of different multi-component oleogels of carnauba wax oleogels (CWOs), β-sitosterol/lecithin oleogels (S/LOs), and ethyl cellulose oleogels (ECOs) prepared by the direct method. Oleogel strength decreased in the order ECOs > CWOs > S/LOs and peanut oil oleogels > soybean oil oleogels. Regardless of oleogel type, resveratrol (RE) loading and surfactant addition altered the self-assembly or co-assembly behavior of oleogels, which improved their hardness, oil binding capacity (OBC), thermal stability, solid fat content (SFC), viscoelasticity, and RE loading capacity/encapsulation efficiency. The network structure of the different oleogels and the molecular properties of the oleogelators led to differences in the in vitro digestion of multi-component oleogels. Differences in oleogel processing conditions altered their degree of lipolysis and the bioavailability of RE within it. This research sets the direction toward the development of healthier fat substitutes in the future.

Formulation and Evaluation of Multiple Emulation of Diclofenac Sodium

Abstract: Multiple emulsion is novel approach of drug delivery system for enhancement of bioavailability and pharmacological activity. It is important to prevent the problem of oral drugdelivery system and they are stabilized by using of combination of hydrophilic and lipophilic surfactant. The specific ratio of surfactant concentration is responsible for maintaining the stability of multiple emulsions, the importance of this study was to prepare multiple emulsion of Diclofenac sodium by using two step emulsification process, by using the non-ionic surfactant units. In multiple emulsion, the stability of multiple emulsion was evaluated, percent entrapment efficiency as well as in vitro studies are conducted. The objective of this study was to prepare multiple emulsion of Valsartan by two step emulsification using different nonionic surfactants, Tweens &amp; Spans, and evaluate for stability,percentage drug entrapment, in vitro drug release.

Cinnamon bark oil in water nanoemulsion formulation, characterization, and antimicrobial activities

The nano-emulsion of cinnamon bark oil (CBON) was formulated and investigated for stability and antimicrobial properties. The requisite hydrophilic lipophilic balance (rHLB) and surfactant concentration (Smix) of CBON were found to be 10 and 15%, respectively. A nano-emulsion prepared using 10 g/100 mL CBO and 15 g/100 mL Smix at ultrasonication for 2 min resulted in the smallest droplet size and polydispersity index (PDI) (d = 94.51 ± 0.19 PDI = 0.283 ± 0.009). The droplet size and PDI of the CBO was found to be influenced by HLB value, treatment time, and smix concentration. This study also aimed to evaluate the antimicrobial properties of the prepared oil-in water nano-emulsion of cinnamon oil against E. coli, S. aureus, and S. cerevisiae. The CBON were found to be more efficient in inhibiting and inactivating microorganisms than the crude CBO. The sensitivity of microorganism towards CBON depend on the type of microorganism with S. cerevisiae being the most sensitive followed by E. coli and S. aureus. S. aureus were inhibited with a complete 6 log reduction within 60 min of incubation with CBON. Whereas in the case of E. coli, and S. aureus a reduction of 6 log CFU and 5 log CFU respectively were reported after 120 min of exposure.

Formulation, development and characterization of ibuprofen microemulgel for arthritis

Objective: Microemulgel is composed of aqueous phase, lipophilic phase, along with surfactant and co-surfactant, a suitable gelling agent is also incorporated. The drug Ibuprofen is non-steroidal anti-inflammatory drug. Its oral administration associated with many GIT, hepatic and renal problems. The main objective of the study was to formulate a stable topical microemulgel of ibuprofen in order to achieve the highest bioavailability with least side effects. Method: Pseudo ternary phase diagram was constructed in order to get the suitable concentrations of lipophilic phase, surfactant and co-surfactant. Phase titration method was used to prepare microemulsion, with surfactant and co-surfactant in a ratio of 2:1 respectively, along with gelling agent to form microemulgel. Formulations were evaluated to check appearance, pH, flowability, particle size, drug content, spreadability, drug release and skin irritation. Results: The globule size of microemulsion was 400 nm and zeta potential was -14 mV showing acceptable stability. Formulated emulgel showed good physical characteristics, suitable pH of 6.4 for skin. The drug content was 98.474%. The stability study showed that the ibuprofen was stable in phosphate buffer pH of 6.8. The carbopol 940 as a gelling agent showed high release rate values. The release rate of the optimized formulation, F1 was 94% and it followed Korsmeyer Peppas model (n=0.467). Conclusion: The prepared formulation was cost-effective because of promising highest bioavailability. The results suggest the potential use of developed microemulgel is mainly for topical delivery of ibuprofen, ensuring the safe use.

Effect of dispersant added graphene nanoplatelets with diesel–Sterculia foetida seed oil biodiesel blends on diesel engine: engine combustion, performance and exhaust emissions

In this experimental study, the effect of graphene nanoplatelets (GNPs) on the performance, combustion, and emissions of a diesel engine using Sterculia foetida seed oil biodiesel (SFOME20) was investigated. The novelty of the present study is the surface modification of GNPs with a lipophilic surfactant at different ratios to achieve stable dispersion of GNPs in fuel blends. The homogeneity of the nano-additives in the fuel was tested by ultraviolet spectrometry, and an optimized amount of surfactant was found. The GNPs are dispersed in SFOME20 in different compositions such as 25, 50 and 75 ppm. The experiments were performed at a constant speed under different load conditions. Significant improvements in performance were oberved: brake thermal efficiencywas increased by 8.48%, and brake-specific fuel consumption was decreased by 16.53%. Emission levels Hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx)) were reduced by 28.3%, 24.16% and 10.43%, respectively, at 50 ppm in SFOME20. Significant improvement in combustion parameters was noted in the form of reduced ignition delay (ID), decreased combustion duration, and improved peak pressure and heat release rate under full load conditions. The GNPs were found to be promising additives for biodiesel blends to improve the overall performance, combustion and emission characteristics of the engine.

Formulation and Evaluation of Multiple Emulsion of Repaglinide

Repaglinide (Prandin) is an oral insulin secretagogue of the meglitinide class (Antidiabetic) of BCS Class ІІ has low bioavailability. It is used to treat type 2 diabetes (condition in which the body does not use insulin normally and, therefore, cannot control the amount of sugar in the blood). The Multiple Emulsion is the complex polydispersed system in which an emulsion is incorporated in another emulsion therefore they are also known as “Emulsion of Emulsion”. The aim was to prepare a stable Multiple Emulsion of Repaglinide by incorporating various hydophilic and lipophilic surfactants at different concentrations. The characterization of drug sample was done using spectrophotometric analysis and melting point determination. All the observations and recorded data were identical to the values reported in literature. Calibration curves of Repaglinide in 0.1N HCl and phosphate buffer (pH 7.4) were prepared using a double beam UV-visible spectrophotometer (Shimadzu 1800)The different formulations of multiple emulsion were evaluated on the basis of their drug entrapment efficiency and stability. The multiple emulsion was stable and had good entrapment efficiency. There were no drug-excipients interactions. From the result and conclusion of the research work we can summarize that the multiple emulsions can be optimized for good stability and higher entrapment efficiency by optimizing different formulation variables like type and proportion of primary and secondary emulsifier incorporated in Primary Emulsion and Multiple Emulsion.

A comprehensive methodology to study double emulsion stability

HypothesisThe stability of emulsions requires the fast formation of viscoelastic interfaces between water and oil phases. In double emulsions, two surfactant types (hydrophilic and lipophilic) are present and two interfacial films are involved. Understanding cooperative adsorption of these surfactants and its implication on properties of water/oil/water interfacial films will enable replacing the empirical methodologies used in designing double emulsion systems with a knowledge-based approach. Experiments and modelThe distribution of surfactants between the water/oil interfaces was investigated using single droplet diffusion experiments and simulation of equilibrium surfactant density profiles. The stability of the interfaces against coalescence was characterized by dye transport in a leach cell and coalescence time of single droplets in a model experiment. The conformation of the surfactants at an interface was then examined via surface rheology, sum frequency generation spectroscopy, and dissipative particle dynamics simulation. FindingsTwo selected hydrophilic surfactants combined with a lipophilic surfactant induce very different properties at water/oil interfaces and different dye release behaviour from their corresponding double emulsions. Competitive adsorption of sodium dodecyl sulfate and lipophilic surfactant results in the improvement of encapsulation efficiency, elasticity of the interface, and resistance against coalescence due to the intercalation of surfactant alkyl chains into the oil chains.

Influence of Surfactant Concentration on Spontaneous Emulsification Kinetics

The kinetics of spontaneous emulsification is investigated on aqueous pendant drops in paraffin oil. Optical microscopy in transmission mode is used for high-spatial-resolution image recording. The influence of a lipophilic surfactant (Span 80) and two water-soluble surfactants (CTAB and SDS) is investigated. As time runs, the drop interface turns opaque due to the formation of microstructures associated with spontaneous emulsification. The time evolution of this phenomenon is shown to depend upon temperature and surfactant concentration, which leads to an overall shrinkage due to gradual water uptake and transport into paraffin oil. Spontaneous emulsification kinetics depends upon the chemical composition. Higher concentrations of Span 80 and CTAB (resp. SDS) are shown to promote (resp. hinder) water transport. This work provides new insights into the understanding of spontaneous emulsification when combining the properties of non-ionic and ionic surfactants.

Synergism between lipophilic surfactant and lipophilic SiO2 nanoparticles enhances self-emulsification performance

Water control technology for high-temperature and -salinity gas wells is immature, and there is a lack of effective water control methods for condensate gas reservoirs and horizontal wells. Water control can be achieved by conducting subsurface self-emulsification to generate nanoparticle emulsions (Pickering emulsions). While this has been tested in oilfields, the overall success rate is low. Elucidating the mechanism of nanoparticle and surfactant synergy would help to improve the success rate of using self-emulsifying water-in-oil (W/O) Pickering emulsions for water control in gas wells. In this study, a self-emulsification process was simulated based on the formation conditions of the Tahe gas well using an active oil (diesel containing 1 wt% non-ionic surfactant) containing various concentrations of nanoparticles. By measuring the droplet size, viscosity, viscoelasticity and high-temperature stability of the emulsion, and in combination with previous research results, the synergistic effects of nanoparticles and surfactant on the generation and stability of emulsions were clarified. Finally, we explored the conditions under which synergy at the oil-water interface occurs and whether the nanoparticle surfaces were secondarily modified under formation conditions. The strength of the synergistic effect in the self-emulsifying system was found to be strongest at a 1:1 nanoparticle-to-surfactant concentration ratio. The strength of the synergistic effect was proportional to the emulsion's volume, droplet size, viscosity, viscoelasticity and other properties. The most synergistic self-emulsifying emulsion had up to five times the volume of emulsions made at other oil-to-water ratios. The emulsion droplet size showed a bimodal distribution, with mean particle sizes of 3 μm and 100 μm, respectively. The viscosity of the emulsion generated at 80 °C reached 2000 mPa s−1 at room temperature (26 °C) and increased to 2500 mPa s−1 as the temperature increased to 80 °C. Viscoelastic tests at 80 °C show that the emulsion generated at a concentration ratio of 1:1 exhibited the greatest and most stable elastic properties and that agglomerations of emulsion plugging pore throats were not easily penetrated by subsurface fluids. At this point, the nanoparticles were uniformly distributed at the droplet interface and the particle surfaces remained unchanged. The mechanism by which the synergistic effect stabilizes the emulsion changed at high temperatures (140 °C). The nanoparticles at the interface were wrapped in a thick oil film of high viscosity, like the inner phase of an emulsion. Then, concave high-viscosity oil-phase channels were formed between the ‘emulsified-like nanoparticles’. This change at the oil-water interface ensured the stability of the W/O emulsion at high temperatures. The synergy between the surfactant and nanoparticles was primarily based on the formation of an emulsion at the oil-water interface by the surfactant, followed by the gradual adsorption of nanoparticles at the interface, which enhanced the emulsion properties. The nanoparticle interface did not undergo secondary modification under formation conditions, and the synergistic effect of the surfactant and nanoparticles remained dominated by electrostatic forces.

Rheological Properties and Emulsification States of the Emulsions Obtained Using Water-Soluble Amphiphilic Polymers and Lipophilic Surfactants

Rheological Properties and Emulsification States of the Emulsions Obtained Using Water-Soluble Amphiphilic Polymers and Lipophilic Surfactants

Phase inversion of hydrophobized hollow TS-1 stabilized Pickering emulsions with addition of lipophilic Span 80

There are few reports concentrated on the interactions between lipophilic surfactants and hydrophobized hollow TS-1 zeolite particles in the stabilization of emulsions. In this study, hydrophobized hollow TS-1 zeolite particles were synthesized and applied as emulsifier to stabilize the W/O Pickering emulsions employing cyclohexanone and water, and the influence of addition of lipophilic Span 80 on the stability of the W/O Pickering emulsions was systematically studied. Surprisingly, a phase inversion was induced by simply changing the Span 80 concentration. At fixed concentration of TS-1 zeolite particles (2 wt%), emulsions are water in oil (W/O) when the concentration of Span 80 is lower than 0.5 mM. Then the emulsions invert to oil in water (O/W) when the Span 80 concentration is between 1 mM and 8 mM. In this process, different emulsifiers dominate the composition of the interfacial layer, and the emulsion type is correspondingly controlled. When Span 80 concentration is lower than 0.5 mM, hydrophobized hollow TS-1 zeolite particles are in domination, and W/O emulsions are obtained. At Span 80 concentration of 1–8 mM, the emulsions are stabilized mainly by Span 80, and the emulsion type is O/W.

Spontaneous Emulsions: Adjusting Spontaneity and Phase Behavior by Hydrophilic-Lipophilic Difference-Guided Surfactant, Salt, and Oil Selection.

Spontaneous emulsion behavior has been difficult to predict and could be influenced by many variables including salinity, temperature, and chemical composition of the oil and surfactant. In this work, the hydrophilic-lipophilic difference (HLD) framework was used to predict the formation of spontaneous emulsions using a mixture of Span-80 and SLES surfactants. The spontaneity and emulsion behavior of different systems were modeled by estimating the HLDmix. The influence of surfactant ratio, salinity, and oil type was investigated. Spontaneous emulsification could only be observed when the HLDmix was between -0.96 and 1.04. Within this range, a negative HLDmix resulted in a greater spontaneity to form o/w emulsion, and a w/o emulsion was more likely to form when the HLDmix was positive. When the HLDmix was close to 0 (between -0.22 and 0.56 in our systems), emulsions were formed in both the oil and aqueous phases with high spontaneity. A combined effect of ultralow interfacial tension, Span-80 micelle swelling, and interfacial turbulence due to Marangoni effects is likely the main mechanism of the spontaneous emulsification observed in this study. A synergistic reduction in interfacial tension was observed between Span-80 and SLES (<1 mN/m). When the HLD of the system was close to 0, a bicontinuous emulsion phase was formed at the oil-water interface. The bicontinuous emulsion broke-up over time due to the ultralow interfacial tension and interfacial turbulence, forming dispersed oil and water droplets. Results from this work provide a practical method to suggest what surfactant composition, salinity, and oil type could promote (or eliminate) the conditions favorable for spontaneous emulsification.