Emulsification Process Research Articles

The Effect of Interfacial Tension and Emulsification in Enhancing Oil Recovery During Surfactant Flooding

Abstract The effectiveness of various surfactants in improving crude oil displacement efficiency was evaluated using one-dimensional homogeneous core and three-dimensional heterogeneous models. Emulsification of the crude oil was simulated using an ultrasonic instrument, and the emulsification degree was evaluated based on droplet dispersion, droplet number density, interfacial tension, external phase viscosity, internal phase volume, and demulsification time. Six surfactants could be divided into five emulsifying types: non-emulsification, emulsification inversion, early emulsification, late emulsification, and whole process emulsification. The results showed that the surfactants had varying levels of effectiveness in improving displacement efficiency. The whole process emulsification system can effectively start the residual oil in the pore throat and reduce the free-state and bound-state residual oil saturation. The area of the mainstream zone between the injection and production wells was significantly expanded after the whole process emulsification system was injected. The whole process emulsification is more important than interfacial tension for enhancing oil recovery.

Investigation on the wetting behavior of asphalt emulsion on aggregate for asphalt emulsion mixture

The wetting behavior of asphalt emulsion on aggregate greatly influences the physical bonding interface between asphalt emulsion and aggregate. However, the wetting behavior of asphalt emulsions has not been widely considered. In this work, the wetting behavior of asphalt emulsion on aggregate was investigated in terms of dynamic contact angle. Firstly, the quantitative indicators for evaluating the wetting behavior are proposed. Then, the factors influencing the wetting behavior are analyzed, such as emulsifier dosage, asphalt dosage, wetting agent dosage, aggregate type and surface roughness. Finally, the primary factor affecting the wetting behavior is analyzed using the grey correlation method. The result shows that the wetting process of asphalt emulsion on the aggregate surface could be divided into two stages: the initial linear rapid wetting stage driven by inertial force, the second slow wetting stage driven by viscous forces, which the development of dynamic contact angle can be well illustrated by the power function. The equilibrium contact angle (θe) and wetting velocity (v) are recommended as quantitative indicators of wetting behavior. Grey correlation analysis shows that the emulsifier dosage and wetting agent dosage can significantly affect the wetting behavior. Increasing the emulsifier dosage can increase the equilibrium contact angle and decrease the wetting velocity. Adding the wetting agent can reduce the equilibrium contact angle and increase the wetting velocity. Therefore, to guarantee the good wetting behavior, the emulsifier dosage should not be too high, provided that good emulsification effect is achieved and the wetting agent can be added in asphalt emulsion.

Determination of the Optimum Conditions for Emulsification and Encapsulation of Echium Oil by Response Surface Methodology.

Echium oil (EO) contains substantial amounts of omega-3 fatty acids, which are important because of their benefits to human health. However, they are prone to oxidation. The aim of this study was to obtain the optimum conditions of microencapsulation of EO using spray drying by applying the response surface methodology (RSM). Central composite circumscribed design (CCC) was employed with a ratio of maltodextrin (MD):EmCap modified starch (MS) (80-90%, w/w), oil concentration (15-25%, w/w), and homogenization speed (5-15 × 103 rpm) as independent variables affecting droplet size (μm) and viscosity (Pa·s), which were chosen as responses for the emulsification process. The results revealed that the emulsion conditions containing MD:MS (89.7%:10.3%, w/w), oil concentration of (16.0%), and homogenization speed at (14.8 × 103 rpm) were found to be the optimum conditions. Furthermore, for encapsulation, CCC was employed with inlet temperature of 140-180 °C, air flow of 20-30%, and pump rates of 15-25% as independent variables. Total yield (%) and encapsulation efficiency (%) were chosen as responses for the encapsulation process. On the other hand, optimum conditions for encapsulation were as follows: inlet temperature of 140 °C, airflow rate of (30%) 0.439 m3/h, pump rate of (15%) 4.5 mL/min with respect to selected responses.

Factors and Kinetics Related to the Formation of Heavy Oil-in-Water Emulsions

Oil-in-water emulsions provide an essential contribution to enhanced oil recovery by acting as oil displacement and conformance control systems. However, the dominant factors affecting their emulsification and kinetics are unclear. The emulsification rate is usually defined in terms of changes in the torque, conductivity, or particle size over time, which results in inaccurately calculated emulsified oil amounts. Therefore, the effects of temperature, pH, and NaCl concentration on the emulsified mass and droplet sizes of aqueous emulsions of Jin8-7 and Chen373 oil with octadecyl amine ethoxylate ether as an emulsifier were investigated. The results showed that the formation of oil-in-water emulsions of Jin8-7 and Chen373 under different conditions occurred via a two-stage mechanism: rapid emulsification and emulsion maturation. The emulsified oil mass rapidly increased during the rapid emulsification period and plateaued during the emulsion maturation period. This indicates that the emulsified oil mass largely depended on the short rapid emulsification period. It was also found that increasing the temperature and pH were more conducive to the emulsification of Chen373 oil with a high viscosity and high asphaltene content. The optimal NaCl concentration was determined to be 2% and 4% for Chen373 and Jin8-7 oil, respectively, based on the emulsification mass during the rapid emulsification period. The droplet size decreased first and then increased during the emulsification process under most experimental conditions. A second-order kinetics model for emulsification was proposed, in which the evolution of emulsified oil mass calculated with time agreed with the experimentally measured values. This study can provide theoretical guidance for the implementation of chemical cold production of heavy oil in oilfields.

Natural nanogels crosslinked with S-benzyl-L-cysteine exhibit potent antibacterial activity

Biofilm-forming bacteria E. coli and P. aeruginosa have both exhibited resistance against multiple antibiotics in clinical settings. To find a solution, researchers have turned to antibacterial structurally modified from natural materials that are harmless to the human body. Among these is DNA, a natural polymer composed of deoxyribose that when treated with HCl exposes its aldehyde groups and produces DNA-HCl. Here, we crosslinked these aldehyde groups with the primary amines in S-benzyl-L-cysteine (SBLC) using a Schiff reaction to obtain DNA-HCl-SBLC. We additionally treated alginate acid (AA) with EDAC, obtaining AA-EDAC, and substituting it with SBLC to produce AA-SBLC. We incorporated the above reactions with an emulsification process to produce nanogels (NGs) that were verified to be spherical and possessing benzene rings successfully grafted onto DNA-HCl and AA-EDAC. These natural NGs were proven to be negatively charged through zeta potential analysis and presented low cytotoxicity toward normal cells in cell organoid viability assays. These SBLC-modified polymers provided better inhibition of bacterial growth than those without modification. Moreover, after incubation with SBLC-modified NGs, bacteria expressed intracellular recA or pvdA in a dose-dependent manner, which was consistent with SEM data from damaged bacteria. Out of four tested NGs, DNA-HCl-SBLC NGs suppressed P. aeruginosa-induced sepsis most effectively and extended the lifespan of C. elegans. This study provides an alternative clinical solution to antibiotics-resistant biofilm strains.

Experimental investigation of hydrocarbon-ion interaction in water-oil emulsions: A new insight into asphaltene structure and chemistry

Emulsification has been proved as one of the mechanisms contributing to improving oil recovery. Regarding the amphiphilic nature of the asphaltene and other polar hydrocarbons, their role should be understood. This research aims to investigate the chemistry and structure of the asphaltene molecules in the emulsions generated by the oil and ion-tuned water. The static bottle tests, containing the aqueous, emulsion, and bulk oil phases, were generated to study the emulsification. To have a mechanistic insight into the participation of asphaltene molecules in the emulsion phase, two oil samples of crude oil and asphaltene-rich toluene were used to generate the emulsions. After extracting the asphaltene from the bulk phases, the analytical techniques of Nuclear Magnetic Resonance (NMR), Fourier transform infrared (FTIR), and Energy-dispersive X-ray (EDX) were employed to study the asphaltene structural parameters, functional groups, and elemental content, respectively. Based on the NMR technique, the asphaltenes with smaller aromatic cores and shorter aliphatic chains, which contain polar functional groups have more tendency to adsorb onto the emulsion phase. It was shown that the magnesium and calcium ions have stronger electrostatic interactions with the asphaltene, leading to more attraction of the asphaltenes in the emulsion phase. In contrast, the sulfate ions showed a weaker attraction force to adsorb the asphaltenes in the emulsion phase. Based on the EDX spectroscopy, the heteroatom (oxygen, nitrogen, and sulfur) contents of the crude asphaltene is more than the bulk one, representing more affinity of the polar asphaltenes toward the emulsion phase. According to the FTIR spectroscopy of the bulk oil, while the aromatic hydrocarbons have a lower affinity toward the emulsion phase, the longer alkanes have more affinity to adsorb onto the emulsion phase. It should be mentioned that the chemistry and structural parameters of the bulk asphaltenes in the emulsions, which were generated by crude oil and asphaltene-rich toluene, were different. This observation indicated that the chemistry of the asphaltenes participating in the emulsion phase is influenced by the presence of other amphiphilic hydrocarbons. In this study, it was shown that chemical functional groups and structural parameters of asphaltene affect the emulsification process. Hence, studying the chemistry of asphaltene and other polar hydrocarbons is a vital step for the formulation of optimum ion-tuned water.

Analysis of crude oil effect for CO2 corrosion of carbon steel - A rotating cylinder electrode approach

Crude oils, especially heavy crude oils, are rarely used in multiphase-flow loop experiments because of the experimental difficulties. Variations in the tested fluid viscosity, emulsification processes, water cut (WC), flow velocity and flow patterns, interactions between the crude oil and brine, the difficulty in obtaining metal/environment electrical continuity by covering the metal surface with crude oil, and the difficulty of selecting appropriate instrumentation to monitor the experiment are some of these problems. Studies indicate that crude oil can change the brine chemistry and influence the preferential oil/water metal-surface wettability, which impacts the corrosion process. Based on the assumption that corrosion would only occur when free water is separated from an emulsion, the risks could be reduced by transporting emulsified crude oils. However, as the solubility of water in crude oil is low, free water can be formed at the bottom of horizontal pipelines when the emulsion destabilizes, causing an increase in corrosion processes. In previous author’s studies, carbon-steel flow-induced corrosion (FIC) tests were carried out in a multiphase-flow corrosion loop containing a liquid phase of brine plus light or heavy crude oils (WC 80) with a gaseous phase of CO2. Higher corrosion rates for heavy crude oil were observed, which were not expected. No experimental studies in multiphase-flow corrosion loops using heavy crude oils in CO2-brine solution were found in the literature. In attempting to understand the reason for the higher aggressiveness of the heavy crude oil, rotating cylinder electrode (RCE) tests were performed under the same conditions used in the multiphase-flow loop.

Analysis of the Use of Euphorbia tirucalli Sap in the Composition of an Asphalt Bio-emulsion

Abstract The reduction in the availability of materials traditionally used in paving, especially the asphalt binder, requires the development of innovative technologies that allow their total or partial replacement in road construction. This work aims to analyze the development and performance of an asphalt bio-emulsion to be used in chip seals, using a bio-binder partially replaced by petroleum plant sap. For this, a two-stage experimental program was developed. The first stage consisted of sap extraction and manufacture of the bio-binder and bio-emulsion, whereas the second phase involved the rheological characterization of these materials in the dynamic shear rheometer and adhesion tests with the binder bond strength (BBS) test. The results indicated that the addition of sap and the emulsification process of the binder reduced its stiffness and increased its phase angle. In terms of the multiple stress creep recovery test, the addition of sap generated changes only at low frequencies, causing the materials to exhibit similar behaviors. The BBS test shows that the material has a better performance than the conventional one. Therefore, according to the rheological analyses following the emulsion performance grade and adhesion tests, the suitability of the bio-emulsion can be verified for paving services with chip seals.

Generation of droplets of shear-thinning non-Newtonian fluids in T-junction parallelized microchannels

The study of shear-thinning non-Newtonian fluids in T-junction parallelized microchannels provides valuable insights into the emulsification process and droplet generation synchronicity. Silicone oil is used as the continuous phase, and sodium carboxymethyl cellulose (CMC) aqueous solutions are used as the dispersed phase. Based on the evolution of the dispersed phase head and neck characteristic size, the droplet generation is classified into four stages: the waiting stage, filling stage, necking stage, and pinch-off stage. The effects of the two-phase flow rates and rheological characteristics of shear-thinning fluids on the four stages are investigated. Additionally, the coupling of interface evolution between parallelized microchannels is studied, revealing periodic changes between synchronous and asynchronous droplet generation types. The impact of this phenomenon on droplet monodispersity is analyzed, providing crucial information for the preparation of uniform droplets.

Application of response surface methodology in the development of parenteral emulsion using ultrasonic emulsification

Abstract: Intravenous lipid emulsion is a critical component of parenteral nutrition. Long-term administration of such therapy lead to liver dysfunction. As the cause of liver failure can be the size of lipid emulsion droplets, their reduction can positively affect the clinical condition of patients. This study aimed to develop and optimize the preparation process of intravenous lipid emulsions with reduced droplet size compared to commercially available formulations. The response surface methodology was applied to optimize the ultrasonic emulsification. The reduction of lipid droplet size was achieved by the use of a combination of 1.2% (w/w) soy phospholipids and various concentrations of Tween 80 (2, 3, and 4% (w/w)). The other variables were sonication amplitude and time of sonication. During the optimization process, fifteen soybeans oil-based intravenous lipid emulsions were developed. All formulations were characterized by the physicochemical properties appropriate for intravenous administration, i.e., MDD ranging from 119.1 ± 0.6 nm to 177.1 ± 2.1 nm, PdI below 0,219 ± 0,009. The pH and osmolarity ranged from 6.23 ± 0.01 to 6.58 ± 0 and from 328 ± 3 to 568 ± 8 mOsm/kg, respectively. The Box Behnken methodology allowed for optimizing the preparation of intravenous lipid emulsion using ultrasonic emulsification.

Effect of pH adjustment on production and physicochemical properties of cheese feed made of Irish Cheddar cheese

The effect of emulsification pH on the composition and colloidal stability of cheese feed (the spray dryer feed of cheese powder) was investigated in the absence of emulsifying salts (ES) to understand the sole effect of emulsification pH and to give insights into ES removal from cheese powder production. Cheese feeds were prepared at six different pH values from 5.1 to 6.8. Adjustments of pH during feed production had a significant impact on the mass fraction of several components (i.e., fat, calcium) between feed and retained mass (RM) obtained after sieving. These differences were primarily attributed to electrostatic changes among proteins during the emulsification process. pH-induced alterations in feed composition were associated with a significant change in particle size, viscosity, and colloidal stability. Confocal microscopy images of feeds revealed differences in protein aggregation and fat cluster formations. Raman spectroscopy of RM indicated alterations in protein structure by increased pH.

Experimental study on the effect of high water cut on the emulsifying properties of crude oil

Most waterflooding oilfields have entered the high water cut stage, but significant amounts of crude oil remain in the formation. Therefore, understanding the emulsifying characteristics of crude oil with high water content is crucial. This study investigates the effects of shear time, shear rate, temperature, water content, and re-emulsification at high water content on the emulsifying properties of crude oil. Results indicate that shear time, temperature, and water content play a role in enhancing the emulsifying capacity of crude oil. Additionally, the initial water content of the emulsion affects the solubilization ability of crude oil; lower initial water content leads to stronger solubilization ability, while higher total water content leads to weaker solubilization capacity. Under an optical microscope, the morphology of the emulsion was observed, revealing that an increase in water content resulted in an increase in particle size and quantity of emulsion droplets, leading to more uniform droplets. However, at high water content, the particle size of emulsion decreased, the number of droplets decreased, and the droplets became uneven. Furthermore, the particle size of re-emulsified emulsion was smaller than that of the emulsion with the same moisture content, indicating that re-emulsification can lead to instability. The interfacial characteristics of the emulsion were also analyzed, showing that an increase in water content caused an increase in interfacial tension and expansion modulus of emulsion compared to crude oil. Finally, the study elucidates the influence mechanism of high-water content on the emulsifying performance of crude oil, which includes the destruction of molecular forces on and between interfaces, weakening the steric hindrance effect. Unstable film and non-uniform droplets can promote coalescence and fragmentation of droplets, limiting the emulsifying performance of crude oil. The results of this study provide a better understanding of the formation and fracture process of emulsion under high water cut conditions, offering a theoretical basis for further enhanced oil recovery.

Spotlight on reversible emulsification and demulsification of tetradecane-water mixtures using CO2/N2 switchable surfactants: Molecular dynamics (MD) simulation

CO2/N2 switchable surfactants have recently attracted significant attention in enhanced oil recovery. Their environmental and economic benefits are the main driving forces for their application in the oil and gas industry. This study evaluated mixtures of sodium dodecyl sulfate (SDS), C18 naphthalene sulfonate (C18PS), and CO2-switchable acetamidine surfactant N′-dodecyl-N, N-dimethylacetamidine (C12DMAA) in water/dodecane systems by using molecular dynamics (MD) simulation. The effects of the molecular structure of anionic surfactant and surfactant concentration on switchable emulsification and demulsification in an oil/water/SDS or C18PS/C12DMAA system triggered by CO2/N2 injection were investigated. The molecule mobility, hydration behavior, density field analysis, diffusion coefficient, radial distribution functions (RDFs), and the density profiles of various systems were thoroughly examined. Based on MD simulation outputs, increasing surfactant concentration can intensify a demulsification process and create a clear phase separation between water and tetradecane. On the other hand, during an emulsification process, adding more surfactant monomers improved a hydration layer around oil droplets and increased hydrogen bonds; however, the contribution of hydrogen bonds between water and N′-dodecyl-N, N-dimethylacetamidinium (C12DMAAH+) compared to SDS and C18PS is limited. MD simulations proved the switchability of SDS/C12DMAA and C18PS/C12DMAA for emulsification and demulsification processes. The results of the current study will be beneficial for developing and optimizing the switchable surfactant structures for further use in the oil and gas industry through surfactant injection.

Organic disulfide crosslinked nucleic acid-based nanocarriers for anticancer drug applications

To improve the delivery efficiency of chemotherapeutic agents, selective drug carriers have been developed to encapsulate chemotherapeutic drugs. Green biomaterials, highly biocompatible with and non-toxic to organisms, have been attracting attention in the biomedical field. Kiwifruit-derived nucleic acids were treated with HCl to expose the aldehyde groups in their deoxyriboses. The product, DNA-HCl, was then crosslinked with two disulfides, cystamine (CTM) or cystine (CYS) under an emulsification process. As the aldehyde groups react with the primary amine in the disulfides, stable imine bonds form. When DNA-HCl-CTM and DNA-HCl-CYS enter cancerous microenvironments, the disulfide bonds will be catalyzed by overexpressed GSH and release the chemotherapeutic agent, DOX. We also found that when both solutions contain GSH, the above NGs release more DOX in the one with weak acidity than the one with a neutral pH. Therefore, when compared to cancer cells treated with free DOX and DOX/DNA-HCl NGs, those dosed with DOX/DNA-HCl-CTM and DOX/DNA-HCl-CYS NGs showed a higher uptake. The enhanced uptake of DOX induced apoptosis in cancer cells and cancer organoids, evidenced by DAPI-stained condensed DNA as well as caspase-3 and PARP expression. The results of this study verify a new approach to encapsulating chemotherapeutic drugs with modified nucleic acid while selectively triggering the cytotoxic effects in cancer cells.

Microfluidics potential for developing food-grade microstructures through emulsification processes and their application

The food sector continues to face challenges in developing techniques to increase the bioavailability of bioactive chemicals. Utilising microstructures capable of encapsulating diverse compounds has been proposed as a technological solution for their transport both in food and into the gastrointestinal tract. The present review discusses the primary elements that influence the emulsification process in microfluidic systems to form different microstructures for food applications. In microfluidic systems, reactions occur within small reaction channels (1–1000 μm), using small amounts of samples and reactants, ca. 102–103 times less than conventional assays. This geometry provides several advantages for emulsion and encapsulating structure production, like less waste generation, lower cost and gentle assays. Also, from a food application perspective, it allows the decrease in particle dispersion, resulting in a highly repeatable and efficient synthesis method that also improves the palatability of the food products into which the encapsulates are incorporated. However, it also entails some particular requirements. It is important to obtain a low Reynolds number (Re < approx. 250) for greater precision in droplet formation. Also, microfluidics requires fluid viscosity typically between 0.3 and 1400 mPa s at 20 °C. So, it is a challenge to find food-grade fluids that can operate at the micro-scale of these systems. Microfluidic systems can be used to synthesise different food-grade microstructures: microemulsions, solid lipid microparticles, microgels, or self-assembled structures like liposomes, niosomes, or polymersomes. Besides, microfluidics is particularly useful for accurately encapsulating bacterial cells to control their delivery and release on the action site. However, despite the significant advancement in these systems' development over the past several years, developing and implementing these systems on an industrial scale remains challenging for the food industry.

Evaluation of the Survival of Lactobacillus fermentum K73 during the Production of High-Oleic Palm Oil Macroemulsion Powders Using Rotor-Stator Homogenizer and Spray-Drying Technique.

This study aimed to evaluate the survival of the probiotic Lactobacillus fermentum when it is encapsulated in powdered macroemulsions to develop a probiotic product with low water activity. For this purpose, the effect of the rotational speed of the rotor-stator and the spray-drying process was assessed on the microorganism survival and physical properties of probiotic high-oleic palm oil (HOPO) emulsions and powders. Two Box-Behnken experimental designs were carried out: in the first one, for the effect of the macro emulsification process, the numerical factors were the amount of HOPO, the velocity of the rotor-stator, and time, while the factors for the second one, the drying process, were the amount of HOPO, inoculum, and the inlet temperature. It was found that the droplet size (ADS) and polydispersity index (PdI) were influenced by HOPO concentration and time, ζ-potential by HOPO concentration and velocity, and creaming index (CI) by speed and time of homogenization. Additionally, HOPO concentration affected bacterial survival; the viability was between 78-99% after emulsion preparation and 83-107% after seven days. The spray-drying process showed a similar viable cell count before and after the drying process, a reduction between 0.04 and 0.8 Log10 CFUg-1; the moisture varied between 2.4% and 3.7%, values highly acceptable for probiotic products. We concluded that encapsulation of L. fermentum in powdered macroemulsions at the conditions studied is effective in obtaining a functional food from HOPO with optimal physical and probiotic properties according to national legislation (>106 CFU mL-1 or g-1).

Design of CsPbBr3 NCs/MnO2 based sensing system for multi-mode detection of D-penicillamine

Herein, a multi-mode assay platform was constructed for the detection of D-penicillamine based on perovskite nanocrystals (CsPbBr3 NCs) and MnO2 nanosheets. The water-dispersible CsPbBr3 NCs synthesized via aqueous emulsion process has a strong fluorescence emission at 520 nm. The electrostatic interaction between positively charged CsPbBr3 NCs and negatively charged MnO2 nanosheets would lead to the fluorescence quenching of CsPbBr3 NCs on account of the inner filter effect (IFE). The addition of D-penicillamine could convert MnO2 nanosheets to Mn2+ and weaken inner filter effect, resulting in distinct recovery of fluorescence at 520 nm and the decrease of the absorption of CsPbBr3 NCs/MnO2 at 375 nm. Therefore, the fluorescence and colorimetric assay system for D-penicillamine was developed. The fluorescence and colorimetric sensing system could detect D-penicillamine ranging from 0.1 to 40 µM and 0.5 to 40 µM with the limits of detection (LOD) were 0.061 µM and 0.24 µM, respectively. The developed assay system could be applied to analyze D-penicillamine in real samples and acquired satisfactory results. Furthermore, a portable intelligent detection device was developed based on the mobile phone and RGB analysis software, demonstrating the practicability and potential of the sensing system.

Polymer blend particles with dual-phase morphology prepared using a novel one-pot method via a phase inversion emulsion procedure

We develop a new method for preparing polymer blend particles with dual-phase morphology based on a phase inversion emulsion process. Using this method, the polystyrene (PS)/ethylene–vinyl acetate (EVA) copolymer particles were prepared and analyzed. The preparation procedure included a emulsification of liquid styrene monomer with dissolved EVA and a following free radical polymerization to convert the monomer droplets into solid blend particles.The obtained PS/EVA particles had a dual-phase morphology. With increasing EVA content, the structure of EVA dispersed in PS matrix switched from spherical, stripe to nearly co-continuous morphology and the particles become significantly tougher and the maximum impact strength reached 9.13 KJ/m2. This method provides the opportunity to prepare a number of new kinds of polymer blend particles with tailored performance even though the composed polymers are condensation polymers or unreachable at atmospheric pressure.

Properties of non-conventional direct O/W Pickering emulsions stabilized by partially hydrophobic silica particles controlled by rotor-stator or ultrasonic emulsification

There has been a significant increase in interest in Pickering emulsions over the last two decades due to their high stability. As the nature of emulsions is crucial for applications, Bancroft’s rule has been proposed to help in the formulation. However, several studies show that this law is far from being generic and that hydrophilic particles can also stabilize water-in-oil (W/O) emulsions. In the frame of this idea, we suggest in this study to evaluate the wetting history of particles and the emulsification process by considering the structural and the rheological properties of the emulsions. In this study, non-conventional or anti-bancroft O/W Pickering emulsions stabilized by partially hydrophobic silica particles are addressed. The latter are based on water and paraffin oil at 20 and 50 vol%. Stabilization is ensured by partially hydrophobic silica particles initially dispersed at 1 or 4 wt% in the aqueous phase. Emulsification is achieved using two mixers: a high-energy sonicator (∼109 W/m3) and a less energetic rotor-stator (∼107 W/m3). Regardless of the mixing device, silica particles adsorb at the O/W interfaces and generate stable emulsions over 2 months with a drop size that slightly decreases with increasing particle concentration. However, the sonicator leads to a finer disaggregation of the silica particles and to drops around 10 times smaller than with the rotor-stator but, surprisingly, an interface 3 orders of magnitude more concentrated in silica particles. The viscosity of the emulsions seems to be little dependent on the oil volume fraction contrary to particle content. In all cases, the emulsion produced by the sonicator are more viscous than those obtained by the rotor-stator. These results clearly indicate the importance of emulsification procedure on the characteristics of the final emulsions.

Self-Assembly and In Situ Quaternization of Triblock Bottlebrush Block Copolymers via Organized Spontaneous Emulsification for Effective Loading of DNA.

Microspheres bearing large pores are useful in the capture and separation of biomolecules. However, pore size is typically poorly controlled, leading to disordered porous structures with limited performances. Herein, ordered porous spheres with a layer of cations on the internal surface of the nanopores are facilely fabricated in a single step for effective loading of DNA bearing negative charges. Triblock bottlebrush copolymers (BBCPs), (polynorbornene-g-polystyrene)-b-(polynorbornene-g-polyethylene oxide)-b-(polynorbornene-g-bromoethane) (PNPS-b-PNPEO-b-PNBr), are designed and synthesized for fabrication of the positively charged porous spheres through self-assembly and in situ quaternization during an organized spontaneous emulsification (OSE) process. Pore diameter as well as charge density increase with the increase of PNBr content, resulting in a significant increase of loading density from 4.79 to 22.5ngµg-1 within the spheres. This work provides a general strategy for efficient loading and encapsulation of DNA, which may be extended to a variety of different areas for different real applications.