Search Results (108)

Sodium caseinate (SC)-stabilized emulsions are highly susceptible to flocculation and phase separation near the protein isoelectric point (pI), limiting their application in acidified food systems. In this study, high acyl gellan gum (HA) was introduced to construct pH-responsive protein–polysaccharide complexes to modulate the interfacial assembly and stability of SC emulsions. Results demonstrated that HA interacts with SC primarily through electrostatic attraction and multi-site hydrogen bonding. This interaction induces protein conformational rearrangement and, as evidenced by combined structural and computational analyses, facilitates the assembly of a denser, interconnected composite network. The formation of HA–SC complexes significantly enhanced interfacial adsorption, reduced oil–water interfacial tension. Rheological and microrheological analyses revealed the composite system formed an elasticity-dominated weak gel network, restricting droplet mobility and suppressing aggregation. Consequently, HA–SC emulsions exhibited markedly improved pH tolerance and physical stability compared to SC-only emulsions, particularly near the pI, evidenced by reduced droplet size, lower Turbiscan stability indices, and more homogeneous microstructures. Crucially, utilizing a well-defined mechanistic model of fixed HA and SC concentrations, this study quantitatively links molecular interactions, interfacial network reconstruction, and macroscopic emulsion stability across a broad pH continuum. Rank-correlation analysis of pH-resolved descriptors shows the molecular charge state co-varies monotonically with the interfacial network and macroscopic stability, and is inversely coupled to droplet mobility. These findings provide new insights into protein–polysaccharide interfacial engineering, establishing the essential physical-stability foundation for the future rational design of acid-tolerant food emulsions and functional delivery systems. Full article

Reversible emulsion drilling fluids integrate the advantages of water-based and oil-based systems, offering solutions to critical challenges in shale oil and gas development. However, conventional reversible emulsions face limitations including poor stability, high cost, and material scarcity. This research introduces widely available, eco-friendly modified nanocrystalline cellulose (MNCC) as a sustainable alternative. While current reversible drilling fluids primarily depend on organoclays and adopt aqueous phases containing 20–25% CaCl₂ for shale inhibition, pH-responsive MNCC was validated as an effective reversible emulsifier capable of stabilizing emulsions through 48 consecutive phase-inversion cycles. Enhanced emulsion stability was achieved with organoclay at an optimal dosage (≤2.5 g/100 mL), and a composite interfacial film superior to the film formed by pure MNCC was fabricated via the combination of organoclay and MNCC. Increasing the organoclay content elevated the acid requirements for phase inversion (due to its lipophilicity) but reduced the alkali needs. Finally, higher CaCl₂ concentrations in the aqueous phase reduced the acid demand for inversion yet increased alkali consumption and diminished stability in both oil-in-water (O/W) and water-in-oil (W/O) emulsions. These effects are attributed to the dual role of CaCl₂ in compressing the electrical double layer and modifying phase density differences, synergistically governing reversible inversion behavior. This research provides a foundation for applying nanocrystalline cellulose-stabilized reversible emulsion drilling fluids, offering practical solutions for efficient development of sensitive reservoirs like shale. Full article

Renewable drilling fluids have attracted considerable focus due to their impact on marine ecosystems. Regulatory agencies utilize environmental evaluations to oversee the use and discharge of chemicals in marine environments. Common non-aqueous drilling fluids are derived from n-paraffin and internal olefins, with research highlighting biodiesel and ester-based fluids for their non-toxicity and biodegradability under anaerobic conditions, although their performance may vary. This study focused on Hydrotreated Vegetable Oil (HVO) as a base fluid, comparing it with an olefin fluid. Commercially sourced HVO was evaluated at a 60/40 oil-to-water ratio, typical of inverse emulsion fluids. The analysis included rheological properties, filtration, electrical stability, and ecotoxicological aspects. The HVO-based fluid exhibited strong electrical stability (>200 V), appropriate rheological behavior, thixotropic properties, and promising biodegradability, achieving 75% biodegradation in 28 days. The data show HVO’s potential for formulating effective non-aqueous inverse emulsion drilling fluids with suitable viscosity and gel strength. Full article

Polymeric microspheres synthesized via Pickering emulsion polymerization offer structural tunability, making them attractive platforms for dye adsorption. This study investigates the adsorption behavior of methylene blue onto two classes of polymeric microspheres—poly(methacrylic acid) crosslinked with ethylene glycol dimethacrylate (PM), containing both micro- and nanopores, and poly(methacrylic acid) crosslinked with divinylbenzene (PD), containing only nanopores. The adsorption kinetics were modeled using a dual-process approach that distinguishes between diffusion-controlled transport and surface-controlled kinetic adsorption. We quantified the relative contributions of these mechanisms and correlated them with particle architecture. In the PM particles, diffusion plays a significant role in smaller particles with larger macropores, enabling methylene blue to penetrate the interior. As the particle size increased and macroporosity decreased, adsorption becomes increasingly dominated by surface kinetics. In contrast, PD particles —which lack macropores—showed the opposite trend: smaller particles were primarily governed by fast surface adsorption, while in larger particles, diffusion through nanopores became increasingly relevant. Correlation analysis between adsorption rate constants and structural parameters such as particle diameter and pore sizes revealed strong, opposing trends. In PD particles, a near-perfect inverse correlation was observed between the diffusion and kinetic components, indicating competitive suppression, where the dominance of one mechanism limited the contribution of the other. These results demonstrated that internal pore architecture played a central role in controlling the adsorption mechanism. Tuning particle size and porosity allowed deliberate control over the balance between diffusion and surface kinetics, enabling the rational design of microparticle adsorbents with tailored uptake behavior for water purification and dye removal applications. Full article

Wellbore instability in shale formations represents a worldwide challenge in drilling engineering. The development of high-performance shale stabilizers is crucial for enhancing wellbore stability. A core–shell structured shale stabilizer, designated AAD-CaCO₃, was synthesized via inverse emulsion polymerization using acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and dimethyl diallyl ammonium chloride (DMDAAC) as monomers. Nano-CaCO₃ was generated in situ by reacting calcium chloride and sodium carbonate. Sodium bisulfite and ammonium persulfate were used as initiators. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Its effects on the rheological properties and filtration performance of a bentonite-based mud were evaluated. The stabilizer’s efficacy in inhibiting shale hydration swelling and dispersion was evaluated through linear swelling tests and shale rolling dispersion experiments, while its plugging performance was examined via a filtration loss test with a nanoporous membrane and spontaneous imbibition tests. The results indicated that AAD-CaCO₃ possesses a core–shell structure with the nano-CaCO₃ encapsulated by the polymer. It moderately improved the rheology of the bentonite-based mud and significantly reduced both the low-temperature and low-pressure (LTLP) filtration loss and the high-temperature and high-pressure (HTHP) filtration loss. AAD-CaCO₃ could be adsorbed onto shale surfaces through electrostatic attraction, resulting in substantially reduced clay hydration swelling and an increased shale cutting recovery rate. Effective plugging of micro-nanopores in shale was achieved, demonstrating a dual mechanism of chemical inhibition and physical plugging. Full article

Slickwater fracturing has become an adopted technology for enhancing hydrocarbon recovery from unconventional, low-permeability reservoirs such as shale and tight formations, owing to its ability to generate complex fracture networks at a low cost. Polyacrylamide and polyacrylamide-based gels serve as key additives in these fluids, primarily functioning as drag reducers and thickeners. However, downhole environments of high-temperature (>120 °C) and high-salinity (>1 × 10⁴ mg/L) reservoirs pose challenges, leading to thermal degradation and chain collapse of conventional polyacrylamide, which results in performance loss. To address these limitations, synthesis methods including aqueous solution polymerization, inverse emulsion polymerization, and aqueous dispersion polymerization have been developed. This review provides an overview of molecular design methods aimed at enhancing performance stability of polyacrylamide-based polymers under extreme conditions. Approaches for improving thermal stability involve synthesis of ultra-high-molecular-weight polyacrylamide, copolymerization with resistant monomers, and incorporation of nanoparticles. Methods for enhancing salt tolerance focus on grafting anionic, cationic, or zwitterionic side chains onto the polymer backbone. The drag reduction mechanisms and gelation methods of these polymers in slickwater fracturing fluids are discussed. Finally, this review outlines research directions for developing next-generation polyacrylamide polymers tailored for extreme reservoir conditions, offering insights for academic research and field applications. Full article

This article focuses on the oil–water emulsification problem during steam injection in heavy oil thermal recovery. Emulsions were prepared through one-dimensional flow experiments, and key parameters including the inversion point water cut and micro-morphological characteristics (particle size and distribution range) of the emulsions were systematically measured under varied conditions (temperature: 150–360 °C; salinity: 0–7500 mg/L; water cut: 10.07–72.22%). By analyzing the experimental data, the emulsification mechanism and influencing rules were revealed: under the combined conditions of high temperature (150–360 °C), high salinity (up to 7500 mg/L), and low water cut (10.07–19.35%), crude oil and formation water form oil-in-water emulsions under the shear action of porous media. During this process, active substances in crude oil react with inorganic salts in formation water to generate natural surfactants, which reduce the oil–water interfacial tension and enhance emulsion stability, enabling the emulsion to maintain stability even at a high water cut of up to 72.22%, with particle sizes ranging from 1 μm to 350 μm and distribution spans varying from 4 μm to 50 μm. The formation of such emulsions leads to a significant increase in viscosity, adversely affecting oil recovery. In production practice, it is recommended to add chemical agents during the early stage of steam huff and puff development (water cut: 10.07–37.50%). This measure aims to destroy the oil–water liquid film, promote water droplet coalescence (narrowing the particle size distribution span), and facilitate emulsion breaking and phase inversion, thereby effectively mitigating the adverse impacts of oil–water emulsions and improving heavy oil recovery efficiency. Full article

Geothermal energy, recognized as a sustainable and clean resource, is playing an increasingly critical role in the global shift toward low-carbon energy systems. Nevertheless, the exploitation of fractured geothermal reservoirs is often impeded by severe lost circulation during drilling, where conventional plugging materials fail under high-temperature, high-salinity, and high-pressure conditions due to inadequate mechanical strength, poor thermal resistance, and lack of self-adaptive sealing behavior. In response, self-healing materials have emerged as an innovative strategy for developing intelligent lost circulation control technologies. Herein, we report a novel self-healing gel (XFFD) synthesized via inverse emulsion polymerization using acrylamide (AM), acrylic acid (AA), p-nitroblue tetrazolium (PNBT), and modified silica nanoparticles (PAS). The resulting material exhibits exceptional thermal stability, with decomposition onset above 356 °C, as determined by thermogravimetric analysis. Rheological and mechanical assessments reveal outstanding viscoelasticity, moderate swelling capacity (4.17-fold in deionized water), and a high self-recovery efficiency of 91.15%, accompanied by a bearing strength of 3.65 MPa. Mechanistic investigations indicate that the autonomous repair capability stems from dynamic non-covalent interactions—primarily hydrogen bonding and ionic associations—enabled by amide and carboxyl groups within the polymer network. Sand bed filtration tests under simulated geothermal conditions (150 °C, 8% salinity) demonstrate that XFFD forms a robust sealing barrier with significantly shallower invasion depth compared to conventional materials such as sulfonated asphalt and calcium carbonate. This work presents an effective self-healing gel system that ensures reliable wellbore strengthening and fluid loss control in challenging high-temperature, high-salinity geothermal drilling operations. Full article

New cosmeceuticals formulas (direct emulsion, inverse emulsion and hydrogel), that synergistically combine bioglass with retinol, were prepared and characterized in order to attenuate the irritant potential of retinoids and prolong their therapeutic efficacy. The study evaluates the physicochemical, microbiological and stability characteristics of these formulations. Thus, TGA and DSC analyses revealed stronger interactions between water molecules and those of other organic compounds, with much more being observed in the case of emulsions than in the case of hydrogel, materialized by the delay in water evaporation. The stability of the three types of formulations has been evaluated in two ways: by determining the backscattering variation with the height of the container and analyzing the sample for 6 h and by counting the fraction of small droplets. Both methods demonstrated high stability in the three types of formulations. Full article

Pickering emulsions have emerged as promising multiphase systems owing to their high stability and diverse applications in materials and chemical engineering. However, achieving precise and stimuli-responsive regulation of emulsion type, particularly reversible phase inversion between oil-in-water and water-in-oil states under fixed formulation without additional stabilizers, remains a considerable challenge. In this work, we developed a sol–gel strategy, i.e., in situ hydrolysis and condensation of silane precursors to form a silica shell directly on responsive microgels, to produce H-SiO₂@P(NIPAM-co-MAA) hybrid microgels. The resulting hybrid particles simultaneously retained pH and temperature responsiveness, enabling the transfer of these properties from the polymeric network to the emulsion interface. When employed as stabilizers, the hybrid microgels allowed the controlled formation of Pickering emulsions that remained stable for one week under testing conditions. More importantly, they facilitated in situ reversible phase inversion under external stimuli. Overall, this work establishes a sol–gel approach to fabricate organic–inorganic hybrid microgels with well-defined dispersion and uniform silica deposition, while preserving dual responsiveness and enabling controlled phase inversion of Pickering emulsions. Full article

The design of emulsions at the nanoscale is a significant application of nanotechnology. For spherical droplets and a given volume of dispersed phase, the nanometre size of droplets inversely increases the total area, $A={\displaystyle \frac{3V}{r}}$, allowing greater contact with organic and inorganic materials during application. In topical applications, not only is cell contact increased, but also permeability in the cell membrane. Nanoemulsions typically achieve kinetic stability rather than thermodynamic stability, so their commercial application requires reasonable resistance to flocculation and coalescence, which can be affected by temperature changes. Therefore, their thermoresponsive characterisation becomes relevant. In this work, we analyse this response in an O/W nanoemulsion of Palmarosa for antibacterial purposes that has already shown stability for one year at controlled room temperature. We now study hysteresis processes and the behaviour of the statistical distribution in droplet size by Dynamic Light Scattering, obtaining remarkable stability under temperature changes up to 50 °C. This includes a maintained chemical composition observed using Fourier Transform Infrared Spectroscopy and the preservation of antibacterial properties analysed through optical density tests on cultures and the Spread-Plate technique for bacteria colony counting. We obtain practically closed hysteresis curves for some tracers of droplet size distributions through controlled thermal cycles between 10 °C and 50 °C, exhibiting a non-linear behaviour in their distribution. In general, the results show notable physical, chemical, and antibacterial stability, suitable for commercial applications. Full article

Protein-polyphenol-based delivery vehicles are effective strategies for encapsulating bioactive compounds, thereby enhancing their solubility and bioaccessibility. In this study, dihydromyricetin/soy protein isolate (DHM/SPI) complexes were used as emulsifiers to prepare Pickering emulsions for DHM delivery. The results show that DHM and SPI form negatively charged complexes through hydrogen bonding, and the complex size decreases and stabilizes with increasing DHM addition. The size of the emulsion droplets was inversely related to the concentration of DHM addition (c), particle concentration (w), and ionic strength (i). Conversely, the increasing oil phase concentration (φ) was positively correlated with droplet size. The CLSM results confirmed the expected oil-in-water emulsion, while the rheological behavior of the Pickering emulsion highlighted its elastic, gel-like network structure and non-Newtonian fluid properties. Moreover, DHM effectively slowed lipid oxidation in the emulsion, and the bioaccessibility of DHM reached 33.51 ± 0.31% after in vitro simulated digestion. In conclusion, this emulsion system shows promising potential for delivering DHM and harnessing its bioactive effects. Full article

This study presents the first quantitative comparison of catastrophic phase inversion behavior of water-in-oil emulsions stabilized by nanocrystalline cellulose (NCC) and molecular surfactants with different headgroup charge types: anionic (sodium dodecyl sulfate referred to as SDS), cationic (octadecyltrimethylammonium chloride referred to as OTAC), nonionic (C12–14 alcohol ethoxylate referred to as Alfonic), and zwitterionic (cetyl betaine referred to as Amphosol). By using conductivity measurements under controlled mixing and pendant drop tensiometry, this study shows that NCC markedly delays catastrophic phase inversion through interfacial jamming, whereas surfactant-stabilized systems exhibit concentration-dependent inversion driven by interfacial saturation. Specifically, NCC-stabilized emulsions exhibited a nonlinear increase in the critical aqueous phase volume fraction required for inversion, ranging from 0.253 (0 wt% NCC) to 0.545 (1.5 wt% NCC), consistent with enhanced resistance to inversion typically associated with the formation of rigid interfacial layers in Pickering emulsions. In contrast, surfactant-stabilized systems exhibited a concentration-dependent inversion trend with opposing effects. At low concentrations, limited interfacial coverage delayed inversion, while at higher concentrations, increased surfactant availability and interfacial saturation promoted earlier inversion and favored the formation of oil-in-water structures. Pendant drop tensiometry confirmed negligible surface activity for NCC, while all surfactants significantly lowered interfacial tension. Despite its weak surface activity, NCC imparted strong coalescence resistance above 0.2 wt%, attributed to steric stabilization. These findings establish distinct mechanisms for governing phase inversion in particle- versus surfactant-stabilized systems. To our knowledge, this is the first study to quantitively characterize the catastrophic phase inversion behavior of water-in-oil emulsions using NCC. This work supports the use of NCC as an effective stabilizer for emulsions with high internal phase volume. Full article

Hydrogel particles, renowned for their high water content and biocompatibility in drug delivery and tissue engineering, typically rely on complex, costly microfluidic systems to reach sub 5 µm dimensions. We present a vortex-based inverse-emulsion polymerization strategy in which UV crosslinking of polyethylene glycol diacrylate (PEGDA) dispersed in n-hexadecane and squalene yields tunable micro- and nanogels while delineating the parameters that govern particle size and uniformity. Systematic variation in surfactant concentration, vessel volume, continuous phase viscosity, vortex speed and duration, oil-to-polymer ratio, polymer molecular weight, and pulsed vortexing revealed that increases in surfactant level, vortex intensity/duration, vessel volume, and oil-to-polymer ratio each reduced mean diameter and PDI, whereas higher polymer molecular weight and continuous phase viscosity broadened the size distribution. We further investigated how these same parameters can be tuned to shift particle populations between nano- and microscale regimes. Under optimized conditions, microhydrogels achieved a coefficient of variation of 0.26 and a PDI of 0.07, with excellent reproducibility, and nanogels measured 161 nm (PDI = 0.05). This rapid, cost-effective method enables precise and scalable control over hydrogel dimensions using only standard laboratory equipment, without specialized training. Full article

The development of eco-friendly surfactants is pivotal for enhanced oil recovery (EOR). In this study, a novel lignin-derived zwitterionic surfactant (DMS) was synthesized through a two-step chemical process involving esterification and free radical polymerization, utilizing renewable alkali lignin, maleic anhydride, dimethylamino propyl methacrylamide (DMAPMA), and sulfobetaine methacrylate (SBMA) as precursors. Comprehensive characterization via ¹H NMR, FTIR, and XPS validated the successful integration of amphiphilic functionalities. Hydrophilic–lipophilic balance (HLB) analysis showed a strong tendency to form stable oil-in-water (O/W) emulsions. The experimental results showed a remarkable 91.6% viscosity reduction in Xinjiang heavy crude oil emulsions at an optimum dosage of 1000 mg/L. Notably, DMS retained an 84.8% viscosity reduction efficiency under hypersaline conditions (total dissolved solids, TDS = 200,460 mg/L), demonstrating exceptional salt tolerance. Mechanistic insights derived from zeta potential measurements and molecular dynamics simulations revealed dual functionalities: interfacial modification by DMS-induced O/W phase inversion and electrostatic repulsion (zeta potential: −30.89 mV) stabilized the emulsion while disrupting π–π interactions between asphaltenes and resins, thereby mitigating macromolecular aggregation in the oil phase. As a green, bio-based viscosity suppressor, DMS exhibits significant potential for heavy oil recovery in high-salinity reservoirs, addressing the persistent challenge of salinity-induced inefficacy in conventional chemical solutions and offering a sustainable pathway for enhanced oil recovery. Full article