Stable Pickering Emulsions Research Articles

Water chestnut starch nanoparticle Pickering emulsion for enhanced apricot seed oil stability: A sustainable functionality approach

The usage of starch nanoparticles for Pickering emulsion stabilization has become more popular for various benefits. This work investigated the potential of nano reduced starch as stabilizer in Pickering emulsions. Two different concentrations of starch nanoparticles (2.5 % and 5 %) were used for stabilization of apricot seed oil-in-water Pickering emulsion. Emulsion stabilized by 5 % starch nanoparticles (PE (5 %)) displayed zeta potential of −46.92 mV and emulsions stabilized by 2.5 % starch nanoparticles (PE (2.5 %)) exhibited zeta potential of −15.33 mV. In PE (2.5 %) after 24 h, creaming index (CI) was 12 %. CI remained zero in PE (5 %) after 30 days of storage period.PE (2.5 %) and apricot oil (AO) showed higher peroxide value than PE (5 %). Malondialdehyde (MDA) content of AO was 156.02 mmol/kg oil after 30 day storage period at 45 °C. Comparatively, PE (5 %) possessed lower MDA content (36.02 mmol/kg oil). The findings revealed that starch nanoparticles can be used as stabilizer in Pickering emulsions for stabilization and preventing lipid oxidation in polyunsaturated fatty acid rich oils. This study introduces a sustainable approach to enhance the stability of apricot seed oil using underutilized starch nanoparticles.

Development of gel-like, high encapsulation efficiency and antibacterial cinnamaldehyde-loaded Pickering emulsion stabilized by EGCG enhanced whey protein isolate-gum arabic ternary nanocomplex

Pickering emulsions (PEs) loaded with essential oils have proven to be a promising delivery system in food preservation, thus attracting increasing research attention. In this study, epigallocatechin gallate (EGCG) enhanced whey protein isolate(WPI)-gum Arabic(GA) ternary spherical nanocomplex (WGE) was fabricated by thermal and pH double-induced method and used to stabilize antibacterial, antioxidant and sustained release Pickering emulsions loaded with cinnamaldehyde. The WGE nanocomplex exhibited biphasic surface wettability (78.2±2.8°), 1.73 times that of WPI, as well as outstanding interfacial tension (5.60 mN/m), 44.6 % lower than that of WPI-GA, mainly due to the electrostatic interactions between WPI and GA and enhanced surface hydrophobicity causing by EGCG, indicating its superb ability to stabilize Pickering emulsions. Using WGE nanocomplex as the Pickering emulsion stabilizer, PEs template was constructed. Confocal laser scanning microscopy (CLSM) showed the formation of a dense oil-water interface layer and gel-like network structure, which demonstrated good storage stability against creaming and coalescence, benefiting to cinnamaldehyde encapsulation. Finally, cinnamaldehyde was encapsulated effectively using this PEs pattern with high encapsulation efficiency under different conditions. The cinnamaldehyde Pickering emulsions (CPEs) demonstrated superior antioxidant ability against DPPH (>85 %) and ABTS (>78 %), as well as effective antibacterial capability against E. coli (>99.9999 %) and S. aureus (>99.99 %) than pure cinnamaldehyde. Moreover, CPEs showed slow sustained-release ability, which could satisfyingly prolong the biological activity of cinnamaldehyde. Therefore, the WGE stabilized cinnamaldehyde Pickering emulsions fabricated in this work might provide a promising alternative for the delivery of antibacterial and controlled release essential oils in the food industry.

An Efficient Bifunctional Core-Shell ZIF-90@ZIF-67 Composite as a Stable Pickering Interfacial Catalyst for the Deacetalization-Knoevenagel Tandem Reaction.

Exploiting advanced solid particles is crucial to the construction of Pickering emulsions catalysis. Recently, metal-organic frameworks (MOFs) have been used as ideal emulsifiers stabilizing Pickering emulsions for interfacial catalysis. Although Pickering emulsions stabilized by core-shell MOFs have significant importance in practical studies, to date there have been very limited reports on this topic. Herein, ZIF-90@ZIF-67, a core-shell material with simultaneous acid-base bifunctionality, was synthesized by seeded epitaxial growth. It was firstly applied as an emulsifier in Pickering emulsions to catalyze the deacetalization-Knoevenagel tandem reaction, which exhibited excellent catalytic properties and achieved extremely high yields. Additionally, ZIF-90@ZIF-67 showed high stability and remained well repeatable after five cycles. This work provides a platform for the design of structurally and functionally diverse MOF-based Pickering emulsions interfacial catalysis.

Pickering Emulsion of Curcumin Stabilized by Cellulose Nanocrystals/Chitosan Oligosaccharide: Effect in Promoting Wound Healing

Background: The stabilization of droplets in Pickering emulsions using solid particles has garnered significant attention through various methods. Cellulose and chitin derivatives in nature offer a sustainable source of Pickering emulsion stabilizers. Methods: In this study, medium-chain triglycerides were used as the oil phase for the preparation of emulsion. This study explores the potential of cellulose nanocrystals (CNC) and shell oligosaccharides (COS) as effective stabilizers for achieving stable Pickering emulsions. Optical microscopy, CLSM, and Cyro-SEM were employed to analyze CNC/COS–Cur, revealing the formation of bright and uniform yellow spherical emulsions. Results: CLSM and SEM results confirmed that CNC/COS formed a continuous and compact shell at the oil–water interface layer, enabling a stable 2~3 microns Pickering emulsion with CNS/COS–Cur as an oil-in-water emulsion stabilizer. Based on FTIR, XRD, and SEM analyses of CNC/COS, along with zeta potential measurements of the emulsion, we found that CNC and COS complexed via electrostatic adsorption, forming irregular rods measuring approximately 200–300 nm in length. An evaluation of the DPPH radical-scavenging ability demonstrated that the CNC/ COS–Cur Pickering emulsion performed well in vitro. In vivo experiments involving full-thickness skin excision surgery in rats revealed that CNC/COS–Cur facilitated wound repair processes. Measurements of the MDA and SOD content in healing tissues indicated that the CNC/COS–Cur Pickering emulsion increased SOD levels and reduced MDA content, effectively countering oxidative stress-induced damage. An assessment based on wound-healing rates and histopathological examination showed that CNC/COS-Cur promoted granulation tissue formation, fibroblast proliferation, angiogenesis, and an accelerated re-epithelialization process within the wound tissue, leading to enhanced collagen deposition and facilitating rapid wound-healing capabilities. An antibacterial efficacy assessment conducted in vitro demonstrated antibacterial activity.

Pickering emulsions stabilized by cellulose nanofibers with tunable surface properties for thermal energy storage

Cellulose nanofibers (CNFs) have been widely used as a renewable emulsifier to stabilize two immiscible liquids due to their intrinsic amphiphilicity and excellent emulsifying ability. However, it remains challenging to fully understand the effects of carboxylate group content and surface charge density on the emulsifying ability of CNFs and the stability of Pickering emulsion. Herein, carboxymethylated CNFs were extracted from bleached kraft pulp using etherification reaction and high-pressure homogenization, allowing for easy surface charge density and size adjustment by changing sodium chloroacetate content and homogenization cycles. The optimizing CNFs possessed a high Zeta potential (−71.2 mV) and a suitable carboxylate group content (1.81 mmol/g), which enabled CNFs to irreversibly adsorb at the hydrophobic paraffin wax (PW) droplet surface and form interfacial steric barriers, providing large electrostatic repulsion between the PW droplets against coalescence. Thus, the CNF-stabilized PW emulsions could be stored for more than 6 months. Moreover, the phase change enthalpy of the freeze-dried emulsion is as high as 193.7 J/g, which provides the emulsion to reversibly store and release heat. This work provides a comprehensive insight into the interfacial stability mechanism of CNFs as stabilizers and facilitates the potential application in thermal energy storage.

Corn Stover-derived nanocellulose and lignin-modified particles: Pickering emulsion stabilizers and potential quercetin sustained-release carriers

Corn Stover-derived nanocellulose and lignin-modified particles: Pickering emulsion stabilizers and potential quercetin sustained-release carriers

Construction of myofibrillar protein-based pickering emulsion for grass carp (Ctenopharyngodon idellus) based on interfacial self-assembly of spice aldehyde molecules: Mechanism and application of imine reaction-stabilized emulsion.

The purpose of this research is to investigate multiple structural spice aldehydes (cinnamaldehyde (CA), citronellal (CN), and melonal (MA)) interact with myofibrillar protein in grass carp (GCMP) and the effects of interfacial interactions on stability properties of Pickering emulsion. It was demonstrated that the functional characteristics of interfacial protein might be greatly improved by the complexation of spice aldehydes with protein particles at the water-oil interface. The fluorescence quenching and molecular docking results revealed that the binding mode of spice aldehyde is primarily dominated by hydrophobic interactions, yet there are hydrogen bonding interactions exist in special structure. When comparing multiple structure aldehyde, CA has a greater binding affinity than CN and MA, as well as the most binding sites at different temperatures. Among them, the interaction of CA and GCMP is enhanced by forming hydrogen bonds through π-bonds owing to its special aromatic ring structure. The O/W structure was further stabilized by the formation of conjugated and unconjugated imines of interfacial protein with spice aldehydes. This work provides a theoretical basis for the interaction and development of protein particles with spice aldehyde in Pickering emulsion stabilization and novel ideas for the application of low value aquatic protein for high quality.

Investigation on the interfacial and emulsion stabilized behavior of dextran/ferritin/resveratrol composite nanoparticles

Glycation of ferritin provides a viable approach to enhance its physicochemical and functional properties. However, there is limited research on the interfacial adsorption properties of glycated ferritin-based colloidal particles. Therefore, this study selected recombinant human H-chain ferritin (rHuHF), rHuHF encapsulated with resveratrol (rHuHF–Res), and rHuHF–dextran glycoconjugates loaded with resveratrol (Dex–rHuHF–Res) as emulsifiers to investigate their interfacial adsorption properties. The results revealed that Dex–rHuHF–Res exhibited superior emulsifying properties and rheological behavior. It also increased the hydrophobicity of the microenvironment around Tyr and Trp residues, while hydrogen bonds, hydrophobic force, and salt bridge were identified as the most important intermolecular interactions. Dex–rHuHF–Res exhibited the biggest contact angle and lowest interface tension, which further reduced the diffusion (Kdiff) from the aqueous phase to the interface but promoted the penetration (Kp) and rearrangement (Kr) rates at the interface. Meanwhile, the emulsion stabilized by Dex–rHuHF–Res displayed excellent freeze-thaw stability, and Dex–rHuHF–Res can be more densely accumulated at the O/W interface to form an interface layer. These findings highlight the promising application of glycated ferritin in stabilizing Pickering emulsions, and deepen our understanding of the interplay among particle interaction, interface adsorption properties, and emulsion stability.

Study on the stability, functional activity and preservation effect of oregano essential oil Pickering emulsion with different proportions of chicken bone gelatin/bacterial cellulose during storage

In this study, chicken bone gelatin (CBG) was extracted as a new substitute for traditional pig bone gelatin, and bacterial cellulose (BC) was used as the compound to prepare Oregano essential oil (OEO) Pickering emulsion. To explore a protein/polysaccharide emulsion system that can effectively prolong the functional activity of OEO during storage. The results indicated that the variation in CBG and BC content significantly influenced the physicochemical properties of the emulsions. The optimal formulation of OEO Pickering emulsion, prepared with a CBG-BC ratio of 6:2 (v/v), exhibited superior characteristics including appearance, encapsulation efficiency, and stability during preservation. After 7 d of storage at 4 °C, the rheological properties remained stable, with no significant differences observed in antioxidant and antibacterial activities. It was verified in the beef fresh-keeping experiment that the shelf life of beef samples in the 6-2-2 treatment group was 6 d longer than that in the control group and 3 d longer than that in the pure OEO group. This experiment enhanced the utilization of poultry by-products and provided a valuable reference for exploring suitable protein-polysaccharide systems embedding active substances for food preservation.

Synergistic effect and mechanism of stabilization of Pickering emulsion by carboxymethyl starch and xanthan gum

Pickering emulsions were prepared using different proportions of carboxymethyl starch (CMS) and xanthan gum (XG) combined systems as emulsifying stabilizers (The mass ratios of CMS and XG were 10:0, 9:1, 7:1, 5:1, 3:1 and 1:1, respectively). The synergistic mechanism between CMS and XG was also explored. The results demonstrated that CMS particles were uniformly and densely embedded in the gel-like structure formed by XG, and the electrostatic repulsion between CMS and XG led to a reduction in droplet size (from 3370 nm to 482 nm), resulting in a more compact and orderly droplet distribution. Combined systems of CMS and XG at different proportions enhanced the hardness (3.05–8.36 g), adhesiveness (3.26–8.41 g), and chewiness (4.05–8.20 g) of the emulsion. AFM observed that the emulsion particles were finer and more evenly dispersed. After heat treatment at 25 °C, 60 °C and 80 °C, the emulsion showed no significant stratification phenomenon, and CMS/XG enhanced the heat stability of the emulsion. LF-NMR confirmed that the oil and water could be evenly distributed and the emulsification of the system was complete. Especially when the ratio of CMS and XG was 3:1 and 1:1, the emulsion with a stable and long storage period could be obtained.

Rice husk derived lignin/silica hybrid nanoparticles stabilized pickering emulsion for phytosterol ester biosynthesis

This study investigates the production of lignin/silica hybrid nanoparticles (LSNPs) from rice husks, an abundant agricultural waste, and their capacity to stabilize Pickering emulsions for biocatalysis. Lignin extracted from rice husks under alkaline conditions was co-precipitated with silica to produce LSNPs in the presence or absence of ethanol as a co-solvent. Characterization of LSNPs revealed that ethanol played a key role in forming uniform, spherical nanoparticles and minimizing aggregation. Lignin imparted amphiphilicity to the LSNPs, which significantly improved their capacity to form stable Pickering emulsions. LSNPs were able to form stable oil-in-water Pickering emulsions while droplet size and emulsion stability were influenced by LSNPs concentration, oil/water ratio, temperature and pH. LSNPs-stabilized Pickering emulsions were evaluated for lipase-mediated biosynthesis of phytosterol esters, which are plant bioactive compounds that can reduce dietary cholesterol uptake. LSNPs-stabilized emulsions provided 1.915 × 106 times larger interfacial areas compared to conventional biphasic systems which facilitated improved mass transfer and lipase activity. Under optimal conditions, LSNPs-stabilized Pickering emulsion systems delivered 90.6 % phytosterol ester conversion in 4 h, compared to 10 h in biphasic systems. This research highlights the potential of sustainable, biomass-derived nanoparticles in Pickering emulsion applications and offers an environmentally friendly approach to produce bioactive compounds.

Unveiling the synergistic effect of octenyl succinic anhydride and pulsed electric field on starch nanoparticles

In this study, guinea starch nanoparticles (GSNP) were prepared by nanoprecipitation technique and modified with octenyl succinic anhydride (3 %) and pulsed electric field (1.5, 3.0, and 4.5 kV/cm). The effect of dual modification on the physicochemical, structural, morphological, thermo-pasting, and rheological properties of GSNP was investigated. The dual modification successfully incorporated octenyl groups into GSNP, as confirmed by 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The degree of substitution increased from 0.0254 to 0.0347, with particle size ranging from 241.30 to 292.50 nm and zeta potential of −23.11 to −29.98 mV. TEM micrographs revealed that all SNP samples had self-aggregated granules with a mean size below 120 nm, and XRD confirmed a V-type crystalline structure. The amylose content and water absorption capacity decreased from 34.02 % to 24.63 % and from 2.45 to 1.91 g/g, respectively, while the oil absorption capacity and relative crystallinity increased from 3.42 to 4.01 g/g and from 17.82 % to 34.76 %, with modification. The gelatinization and degradation temperature of modified samples were higher while pasting properties exhibited variation with modification. The rheological properties of modified SNP samples exhibited more pronounced shear thinning, attributed to their weaker gel structure and fluid-like gel network. Overall, results suggested that modified GSNPs have potential for stabilizing Pickering emulsion and delivery of carrier materials for active functional substances.

Biocompatible Pickering emulsions and films: Unlocking the chitosan-polyvinyl alcohol synergy for multifaceted capabilities

The exciting potential of harnessing the synergy between polysaccharides and bioactive components is attracting significant scientific interest. This research paves the way for the development of novel materials that can improve human health. Therefore, current research is conducted to explore the innovative use of chitosan, polyvinyl alcohol (PVA) complex (CHN-PVA), olive oil-stabilized Pickering emulsions (PEs), and films with multifaceted applications. The sonication stabilized Pickering emulsions (PEs at different pH values 3, 5, 7, 9, and 11) exhibited decrease in particle size compared to control PEs. The pH significantly impacted the zeta potential of PEs. Fourier-transform infrared spectroscopy (FTIR) confirmed the non-covalent linkages. The antibacterial activity of the PEs revealed greater efficacy against gram-positive bacteria than gram-negative bacteria. The CHN-PVA synergy greatly impacted the mechanical properties of films, resulting in tremendous increase of tensile strength and elongation at break compared to CHN film. The PEs efficiently delivered quercetin at neutral pH. The electro spraying of PEs significantly extended strawberry shelf life. Finally, the films exhibited promising properties of adsorbent and the results depicted that pH had a significant impact on methylene blue removal. Conclusively, this investigation underscores the potential of CHN-PVA films in food, health, and environmental fields.

Effect of pH-Shifting on Sunflower Meal Protein Isolate: Improved Stability and Interfacial Properties of Chitosan-stabilized Pickering Emulsion

Effect of pH-Shifting on Sunflower Meal Protein Isolate: Improved Stability and Interfacial Properties of Chitosan-stabilized Pickering Emulsion

Rheological investigation of heavy oil-in-water pickering emulsions for potential applications of fracturing fluids

Pickering emulsions as a kind of emulsified fracturing fluids can enhance the efficacy of shale fracturing. Investigation of the rheological properties of Pickering emulsions yields valuable insights for their in-situ fracturing applications. In this work, nano-clay particles and heavy crude oil were employed to form oil-in-water (O/W) Pickering emulsions. The impact of salinity, pH, and temperature on the rheological properties, including viscosity property and viscoelastic property, of Pickering emulsions were tested and analyzed. The results showed that the viscosity of heavy O/W Pickering emulsions were significantly affected by the change of salinity and pH values, with higher salinity or lower pH resulting in increased viscosity. Under ultra-high salinities (>5 wt% NaCl), the coalescence stability of Pickering emulsion strengthens and creaming stability declines. The massive formation of clay clusters leads to a reduction in the number of nano-clay particles used to generate the network, causing instability in the emulsion creaming. The heavy O/W Pickering emulsions exhibited high stability and high viscosity characteristics, which were mainly caused by the change of surface charge of nano-clay particles and the corresponding change of particle adsorption on droplet surface and particle-particle interactions. At a salinity of 2.5% NaCl and a pH of 4.6, the emulsion system remained stable at a temperature up to 120 °C, holding a viscosity reaching 74.1 mPa s at a shear rate of 6.81 s−1. Besides, heavy O/W Pickering emulsions were viscoelastic fluids, with both noticeable viscous property and elastic property at the same time. Elastic modulus (G′) and viscous modulus (G″) of the emulsion increased with increasing salinity and decreasing pH, enhancing great deformation capacity. Remarkably, the Pickering emulsions could maintain its viscoelastic behavior at varying temperature conditions. For the first time, rheological study of Pickering emulsions formed by nano-clay nanoparticles as a single emulsifier to heavy oil. Our study underscores the emulsifying ability of nano-clay particles to heavy crude oils, under a wide range of salinity and pH, yielding Pickering emulsions with exceptional stability and rheological properties. This novel emulsion system, possessing high resistance to temperature and salinity, holds promise for a high-performance fracturing fluid design.

Improving Hydrophobicity and Water Vapor Barrier Properties in Paper Using Cellulose Nanofiber-Stabilized Cocoa Butter and PLA Emulsions

This study explores the use of cellulose nanofiber (CNF)-stabilized Pickering emulsions for paper coatings, focusing on their rheological properties and effects on hydrophilicity and water vapor transmission rate (WVTR). Two types of Pickering emulsions, oil-in-water (O/W), were stabilized with 1 wt% CNF extracted from fique by-products. The oily phases of the emulsions were composed of poly(lactic acid) (PLA) and cocoa butter (CB). The physical stability, viscosity, and viscoelasticity of the emulsions were characterized. The emulsions were applied to the surfaces of Bond and Kraft papers using the rod-coating method. The coating process involved first applying a layer of the PLA emulsion followed by a layer of the CB emulsion. The coated papers were then evaluated by FE-SEM, contact angle, adhesion work, and water vapor transmission rate (WVTR). The results indicated that the coatings effectively produced a slightly hydrophobic surface on the papers, with contact angles approaching 90°. Initially, Kraft paper exhibited a WVTR value of 29.20 ± 1.13 g/m2·h, which significantly decreased to 7.06 ± 2.80 g/m2·h after coating, representing a reduction of 75.82%. Similarly, natural Bond paper showed a WVTR value of 30.56 ± 0.34 g/m2·h, which decreased to 14.37 ± 5.91 g/m2·h after coating, indicating a reduction of 47.02%. These findings demonstrate the potential of CNF-stabilized Pickering emulsions for enhancing the performance of paper coatings in terms of hydrophobicity and moisture barrier properties. The approach of this study aligns with global sustainability goals in packaging materials combining the use of PLA and CB to develop a waterborne coating to enhance the moisture barrier properties, demonstrated by a substantial reduction in water vapor transmission rates, and an improved hydrophobicity of coated papers.

Photo-responsive Pickering emulsions triggered by in-situ pH modulation using a photoacid generator

HypothesisPickering emulsions that respond to changes in pH by the addition of acid or alkali have been extensively studied, but the development of photo-responsive Pickering emulsions has been more challenging. This study attempts to demonstrate a novel approach to achieve photo-responsiveness in Pickering emulsions by incorporating a photoacid generator (PAG) into the oil phase. Upon UV irradiation, the PAG is expected to release protons (H+), which can then regulate the pH of the emulsion system and control its stability. ExperimentsAmphiphilic colloidal particles obtained by modifying silica particles with poly (2-(dimethylamino)ethyl methacrylate) (SiO2-PDMAEMA) are used to stabilize the Pickering emulsions. The protonation and deprotonation of the SiO2-PDMAEMA particles at different pH values allow for the tuning of emulsion stability. By introducing the PAG into the stable Pickering emulsion system and applying UV irradiation to trigger the in-situ release of H+, the pH of the emulsion is systematically decreased, and the corresponding changes in emulsion stability are investigated. FindingsThe results show that UV irradiation alone cannot induce emulsion instability. However, when PAG is added to the oil phase, the Pickering emulsions exhibit a significant decrease in pH under UV irradiation, ultimately leading to emulsion destabilization and phase separation. At a UV intensity of 20 mW/cm2 for 2 min, the H+ release from the PAG significantly lower the emulsion’s pH, causing the SiO2-PDMAEMA particles to detach from the oil–water interface and resulting in emulsion instability. Higher concentrations of SiO2-PDMAEMA particles in the emulsion require more PAG to induce instability, as confirm by confocal laser scanning microscopy (CLSM) image. This study presents a versatile approach to develop photo-responsive Pickering emulsions which can have potential applications in areas such as drug delivery, cosmetics, and responsive materials.

Highly Bioadaptive Scaffolds with Tuned Porous Structure Templated by Xylan Nanocrystal High Internal Phase Pickering Emulsions.

Fabrication of traditional 3D cell culturing scaffolds requires synthetic polymers or additives, posing a risk of poor biocompatibility and low biodegradability. Pickering emulsions stabilized by biobased nanomaterials can be used as templates to produce scaffolds with facile tunable porous structure, excellent cytocompatibility, and biodegradability. In this study, very stable high internal phase Pickering emulsions (HIPPE) with an oil content of 80% were successfully prepared by xylan hydrate nanocrystals (XNC). The HIPPE can exist stably for more than 30 days, exhibiting a high viscosity. By adding cellulose nanofibers (CNF) and removing the oil phase, scaffolds with a tuned porous structure and enhanced cell culturing ability were successfully fabricated. In the HIPPE templated scaffolds with XNC/CNF, XNC plays a major role in stabilizing the emulsions, while CNF improves the mechanical properties of the scaffolds, both of which are vital to the successful fabrication of the scaffolds. Compared with non-HIPPE templated scaffolds, the HIPPE templated scaffold had a higher porosity and a higher median pore size. The HIPPE templated scaffold was able to maintain 80% cell activity and showed an excellent cytocompatibility. The HIPPE templated scaffolds consisting of XNC and CNF demonstrate great potential in 3D cell culturing for medical purpose.

Inverse Pickering emulsion stabilized by modified cellulose nanocrystals for drilling fluid application

With the rise in oil consumption, the production and exploration of oil have increasingly targeted unconventional reservoirs. Oil-based drilling fluids (ODFs) are well-suitable for unconventional reservoirs because of their superior wellbore stability, strong lubrication, and great resistance to contamination. Inverse (water-in-oil, W/O) emulsions have the ability to lower the oil content in conventional ODFs through the addition of water, leading to more cost-effectiveness and eco-friendliness. However, inverse emulsions require the introduction of a large amount of surfactants to stabilize the oil/water interface, which led to environmental pollution. To address these issues, surface modified cellulose nanocrystals (C14-CNCs) were prepared through acylation modification and then used as solid stabilizers to prepare a high-performance inverse Pickering emulsion-based drilling fluid (IPEDF), in which sunflower seed biodiesel was chosen as the oil phase, and organobentonite (i.e., low polarity SD-1 and high polarity SD-2) was used as a viscosifier and filtration loss reducer. The stability and structure of Pickering emulsion can be controlled by altering the hydrophilicity of C14-CNCs through adjusting the reaction time of acylation. Through optimization of the polarity of organobentonite and the hydrophilicity of C14-CNCs, the as-formulated IPEDF exhibits superior shear-thinning behavior, thixotropy, and filtration property. This work provides a promising avenue for using biomass-derived nanomaterials as stabilizers for the high-performance inverse Pickering emulsion drilling fluids.

Study on Preparation and Properties of Pickering Emulsions Prepared by Carboxymethyl Starch‐Xanthan Gum Nanoparticles

AbstractIn this work, carboxymethyl starch‐xanthan gum nanoparticles (CXN) with different ratios are prepared by ethanol precipitation method. The effects of different ratios, NaCl content, and pH on the particle size and zeta potential of the nanoparticles are investigated, as well as the rheological properties and stability of the CXN emulsions. The results show that with the increase of xanthan gum (XG), the particle size, and zeta potential of the nanoparticles decrease and the prepared emulsions have higher shear stress and viscosity, as well as greater thermal and storage stability. Changes in pH and NaCl concentration significantly affect the particle size and zeta potential values of the nanoparticles. Excess acids or bases increase the viscosity of the emulsions. At low salt concentrations (0.05 M), the emulsion viscosity increases significantly, after which the emulsion viscosity decreases with increasing salt concentration. Neutral pH conditions at room temperature are not conducive to the stability of the emulsions. At high temperatures (100 °C), high salt concentrations, excessive acids or bases can destabilize emulsions. This study provides a new way to reduce the particle size of nanoparticles and a feasible strategy for developing long‐term stable Pickering emulsion.