Interface Engineering Approach Research Articles

Stable interphase inducer based on montmorillonite clay mineral to enhance stability and fire safety for lithium metal batteries

Heat buildup from factors like mechanical, electrical, or thermal stress is the main safety issue in lithium metal batteries (LMBs). Even without such stressors, however, LMBs may remain fire-prone because of the development of unstable electrode–electrolyte interphase on charge–discharge, potentially leading to internal short circuits. In this study, a stable cathode-electrolyte interphase inducer (SCEI-I) is proposed to tackle both the cycling stability issue and safety concerns. SCEI-I is synthesized by incorporating montmorillonite, a clay mineral, and methylphosphonic acid dimethyl ester, a flame-retardant material, onto a porous polyethylene film. On cycling, SCEI-I can induce a thin (<8 nm), uniform and robust cathode-electrolyte interphase layer, contributing to a steady and high Coulombic efficiency of 99.6%–99.8% with decreased impedance. SCE-I improves electrochemical performance by reducing the capacity degradation from ∼21.9% to ∼8.9% after 100 cycles. SCE-I also demonstrates strong thermal stability as the endothermic energy of SCEI-I is only –32.4 J/g (24 °C–280 °C), which is less than one-third of that of polypropylene separator (–118.9 J/g). Furthermore, when exposed to fire, the SCEI-I membrane instantly extinguished flames by disrupting combustion chain reaction. The present study proposes an interfacial engineering approach to improve the stability and safety of LMBs.

Cell membrane-inspired regulation of reactant diffusion for active agent microencapsulation via interface engineering

Microencapsulation of hydrophilic amines in nonaqueous emulsions provides opportunities for a variety of applications, such as CO2 absorbents, and adhesives, but also presents challenges due to the intense reactant diffusion and disruptive interfacial reaction kinetics. Drawing inspiration from cellular systems, where cell membranes effectively regulate mass transfer for essential activities, we propose an interface engineering approach to manage interfacial reactant diffusion. This strategy obviates the modification of emulsion phases with additives in literature, which lowered effective core content. To achieve this, a solvent-induced polymer self-assembling method is adopted. The self-assembled polymer effectively formed a stabilizing viscoelastic film, which kinetically traps the microdroplets, serves as a viscous barrier lowering intense amine diffusion and interfacial polymerization kinetics, and provides protection for the microdroplets against the destructive forces from reaction turbulence and emulsion collision. This approach possesses high tolerance against microencapsulation conditions and is technically friendly, laying the groundwork for scalable microencapsulation of amines to meet industrial demands. We successfully synthesized Tetraethylenepentamine (TEPA)-loaded microcapsules with adjustable shell tightness, hierarchical shell structures, high shell strength and high core content. The method's versatility is further evidenced with different species containing reactive hydrogens. The demonstrated potential of TEPA-loaded microcapsules in effective CO2 capture and instant adhesives provides a fresh perspective on the microencapsulation of distinct polar payloads through interface engineering and its wide-ranging applications.

Lamination of >21% Efficient Perovskite Solar Cells with Independent Process Control of Transport Layers and Interfaces.

Transport layer and interface optimization is critical for improving the performance and stability of perovskite solar cells (PSCs) but is restricted by the conventional fabrication approach of sequential layer deposition. While the bottom transport layer is processed with minimum constraints, the narrow thermal and chemical stability window of the halide perovskite (HP) layer severely restricts the choice of top transport layer and its processing conditions. To overcome these limitations, we demonstrate lamination of HPs─where two transport layer-perovskite half-stacks are independently processed and diffusion-bonded at the HP-HP interface─as an alternative fabrication strategy that enables self-encapsulated solar cells. Power conversion efficiencies (PCE) of >21% are realized using cells that incorporate a novel transport layer combination along with dual-interface passivation via self-assembled monolayers, both of which are uniquely enabled by the lamination approach. This is the highest reported PCE for any laminated PSC encapsulated between glass substrates. We further show that this approach expands the processing window beyond traditional fabrication processes and is adaptable for different transport layer compositions. The laminated PSCs retained >75% of their initial PCE after 1000 h of 1-sun illumination at 40 °C in air using an all-inorganic transport layer configuration without additional encapsulation. Furthermore, a laminated 1 cm2 device maintained a Voc of 1.16 V. The scalable lamination strategy in this study enables the implementation of new transport layers and interfacial engineering approaches for improving performance and stability.

Achieving enhanced multifunctional performance for structural composite supercapacitors by reinforcing interfaces with polymer coating

Carbon fiber structural composite supercapacitors possess the multifunctionality of storing electrochemical energy and withstanding mechanical loads simultaneously, attracting increased attention in electric vehicles, drones, and aircraft sectors. A polymer-based coating was meticulously constructed at the electrode/electrolyte interface to enhance adhesion and stability between active materials and the carbon fiber fabric collector under diverse conditions, especially mechanical stress. Mechanical testing and corresponding physical characterization substantiated the superior performance of the polymer coating. With the protective polymer coating, the optimized structural composite Zn-ion supercapacitor (SZSC), consisting of carbon fiber@active carbon-P (CF@AC-P) cathode, ionogel electrolyte, and Zn anode, displayed a maximum energy density of 164.6 mWh kg−1, at power density of 563.3 mW kg−1. Moreover, the optimized SZSC demonstrated stable operation over more than 8000 cycles at 0.3 mA cm−2 without capacity degradation. The optimized SZSC exhibited a tensile strength of 399.7 MPa and Young's modulus of 11.5 GPa. Furthermore, employing vacuum infusion techniques, the fabricated three-dimensional (3D) wing skin model shell and tube shell curved-surface structural composite Zn-ion supercapacitor component composites showcased exceptional electrochemical performance. These achievements further validate the practicality of 3D multifunctional composites. Consequently, this research presented a practical and straightforward interface engineering approach to develop multifunctional structural devices with remarkable electrochemical and mechanical properties.

Synergistic Effect of 3D Elastomer/Super‐Ionic Conductor Hybrid Fiber Networks Enables Zinc Anode Protection for Aqueous Zinc‐Ion Batteries

AbstractAqueous zinc‐ion batteries (AZIBs) with the merits of superior security, natural abundance, and inexpensive Zn hold great promises for next‐generation energy storage. Nevertheless, the instabilities of the Zn anodes arising from the unsatisfactory dendrite growth and parasitic reactions have seriously restricted their practical application. Herein, an interfacial protection engineering approach is proposed for stabilizing Zn anode via in‐situ constructing 3D hybrid fiber networks within high elastic polyether‐type polyurethane (TPEU) and super‐ionic conductor NaTi2(PO4)3 (NTP). This 3D NTP@TPEU fiber framework demonstrates synergistic effects of enhancing Zn2+ immigration kinetics and improving the desolvation process. Subsequently, such a superior protected interface induces a highly reversible Zn (002) deposition/stripping with a dendrites‐free feature. Moreover, the NTP@TPEU/Zn displays an ultralong lifespan of over 2000 cycles with an average Coulombic efficiency (CE) of 99.5% in the half‐cell configuration. To highlight, a full battery matched with Ca‐doped VO2 on carbon cloth cathode acquires an enhanced CE as high as 99.8% and delivers good cycling stability with a capacity retention of 81.6% at 2 A g−1 over 3000 cycles. These excellent outcomes provide a distinctive perspective of designing a highly stable zinc anode for the practical application of AZIBs.

Nanoscale Pumping Effect of Perovskite via Supported Bilayer Electron Transport Layer for Efficient Printable Mesoscopic Solar Cells

Recently, enhancing the photovoltaic performance of printable mesoscopic perovskite solar cells (p‐MPSCs) poses a significant challenge, particularly in improving the diffusion of perovskite precursor solutions during device assembly. In this research, effective gap‐driven diffusion of the precursor solution perovskite is successfully achieved, leading to the formation of well‐filled and crystallized perovskite through TiO2 nanorod arrays. By incorporating upper‐layer TiO2 nanoparticles, a bilayer electron transport layer with dual crystal phase is developed, establishing a cascaded energy level structure that exhibits superior capabilities in electron collection and directional transport. The effective suppression of nonradiative recombination and efficient charge transfer result in notable enhancements in both open‐circuit voltage and short‐circuit current density. Consequently, the power conversion efficiency of p‐MPSCs devices based on MAPbI3 γ‐butyrolactone solution increases from 14.32% to 16.07% (highest reported value in the literature is 16.21%). These findings highlight a novel interface engineering approach for the fabrication of high‐performance p‐MPSCs devices.

Interface engineering driven molybdenum disulfide coupled polyaniline functionalized carbon fabric with high mass loading anode for fiber lithium-ion batteries

Carbon fiber (CF) cloth presents a preeminent substrate for growing numerous active materials, emerging as a promising electrode design in fiber lithium-ion batteries (F-LiBs) for powering future wearable electronics. Nevertheless, the hydrophobic nature of CF affects the interaction between the active materials and CF, leading to inferior battery performance. Herein, we report a polyaniline (PANi) driven interface-engineering approach to address the recurring issue associated with CF. To demonstrate the concept, molybdenum disulfide (MoS2), a two-dimensional layered anode was grown on PANi-functionalized CF (MoS2/PANi/CF). The nitrogen functionalities of the PANi backbone enriched the surface functionality and facilitated the coupling adhesion between MoS2 and CF. This key feature influenced the charge transport kinetics across the MoS2/CF interface and preserved the structural integrity. More importantly, the strong coordination interaction between MoS2 and PANi improved the growth density of MoS2, resulting in high mass loading. Given these merits, the interfacially coupled MoS2/PANi/CF anode delivered a high specific capacity and enhanced rate and cycling performances. This study verifies the significance of the interface engineering approach, which can be extended to developing wide arrays of flexible electrodes for other wearable battery chemistries.

Advanced Interface Engineering in Gradient Core/Shell Quantum Dots Enables Efficient Photoelectrochemical Hydrogen Evolution.

Semiconductor core/shell quantum dots (QDs) are considered promising building blocks to fabricate photoelectrochemical (PEC) cells for the direct conversion of solar energy into hydrogen (H2). However, the lattice mismatch between core and shell in such QDs results in undesirable defects and severe carrier recombination, limiting photo-induced carrier separation/transfer and solar-to-fuel conversion efficiency. Here, an interface engineering approach is explored to minimize the core-shell lattice mismatch in CdS/CdSexS1-x (x = 0.09-1) core/shell QDs (g-CSG). As a proof-of-concept, PEC cells based on g-CSG QDs yield a remarkable photocurrent density of 13.1mAcm-2 under AM 1.5 G one-sun illumination (100mWcm-2), which is ≈54.1% and ≈33.7% higher compared to that in CdS/CdSe0.5S0.5 (g-CSA) and CdS/CdSe QDs (g-CS), respectively. Theoretical calculations and carrier dynamics confirm more efficient carrier separation and charge transfer rate in g-CSG QDs with respect to g-CSA and g-CS QDs. These results are attributed to the minimization of the core-shell lattice mismatch by the cascade gradient shell in g-CSG QDs, which modifies carrier confinement potential and reduces interfacial defects. This work provides fundamental insights into the interface engineering of core/shell QDs and may open up new avenues to boost the performance of PEC cells for H2 evolution and other QDs-based optoelectronic devices.

High-temperature dielectric energy storage films with self-co-assembled hot-electron blocking nanocoatings

Polymer thin films operable under concurrent electric and thermal extremes represent critical building blocks of capacitive energy storage and electrical isolator for modern power and electronic systems with ever-increasing demands for power density and payload efficiency. However, polymer dielectrics are prone to fast aging under high fields due to hot electrons injected from electrodes. Especially, performance high-heat polymers such as polyimides with high aromaticity suffer fast aging induced by non-thermalized electrons even at moderate fields due to their intrinsically low bandgap and injection barrier. Herein, a facile, low-cost, and scalable interface-engineering approach utilizing the highly ordered organic/inorganic layered nanocoatings is reported, which serve as a retrofittable solution to break this design constraint. By probing the energetic modes of transport and aging at pre-breakdown field, we demonstrate that our 2D montmorillonite (MMT) self-co-assembly nanocoatings can effectively boost the dielectric properties of substrate polyimide (PI) film by suppressing the charge injection and shifting the fast mode of hot-electron aging to a slow, ultimately thermalized process. This aging-impeding scheme imparts PI films with an exceptional endurance capability (enhanced by 100 MV/m) and a 6× improved charge-discharge efficiency at an elevated temperature of 175 °C. The nanostructured interface engineering disclosed in this work thus opens a new pathway of boosting the performance of a spectrum of high-heat polymer dielectrics already commercially available in thin gauges of films for applications in zero-emission electric aircraft and renewable energy integration.

Interfacial engineering of α-Fe2O3 coupled Co3O4 heterostructures anchored on g-C3N4 structure for enhanced electrocatalytic performance in alkaline oxygen evolution reaction

Creating an efficient electrocatalytic oxygen evolution reaction (OER) by developing a low-cost, stable metal oxide nanocomposite based on earth-abundant materials is an essential and highly efficient method to meet the increasing demand for sustainable energy. For this reason, we have proposed a simple and effective interfacial engineering approach to construct a novel graphitic carbon nitride (g-C3N4) strongly coupled with α-Fe2O3 and Co3O4 as dual co-catalysts for highly active electrocatalysts (ECs) OER in a typical alkaline electrolyte. The detailed structural, chemical, and morphological characterizations were performed by various analyses. The as-synthesized g-C3N4/Co3O4/α-Fe2O3 (GCFO) nanocomposite ECs exhibited efficient and stable OER performances with low overpotentials of 359 mV to attain a 10 mA/cm2 current density and a less Tafel slope of 116 mV dec−1, resulting in better durability after 14 h of the i-t test. A strong coupling interaction was found at the interface between the g-C3N4 and the α-Fe2O3/Co3O4 heterostructure, which acts as an effective electron transport channel and exposes more catalytically active sites to explore the outstanding performances for electrocatalysis OER. These results show that a novel approach for the rational coupling of composite heterostructures could be an alternative to using noble metals for sustainable energy-related applications.

Electrolyte-electrode interface: A key factor for advanced protonic ceramic electrochemical cells

Protonic ceramic fuel/electrolysis cells (PCFCs/PCECs) show great potential for the efficient and reversible conversion of chemical and electrical energy. The electrolyte and oxygen electrode interface in PCFCs/PCECs is particularly crucial for achieving optimal performance. In this work, Ba evaporation and Y enrichment phenomena are investigated on the surface of a BaCe0.7Zr0.1Y0.2O3-δ electrolyte during high-temperature sintering. Furthermore, an interfacial engineering strategy is proposed by removing the non-stoichiometric perovskite surface layer via a facile polishing process to enable a comparative analysis of the detrimental effects of the undesired layer on the cell performance. Polishing the electrolyte leads to a remarkable ∼50 % enhancement in PCFC performance and ∼120 % enhancement in PCEC performance at 650 °C. Electrochemical impedance spectroscopy coupled with distribution of relaxation time analysis reveals that the improved performance of the polished cell can be attributed to reductions in both the ohmic and polarization losses, with the latter primarily influenced by the facilitated oxygen electrode reactions. This interfacial engineering approach restores the high proton conductivity at the electrolyte surface and strengthens the physical and chemical adhesion between the electrolyte and the oxygen electrode. Our findings shed light on the existing challenges at the electrolyte-electrode interface and underscore the significance of interfacial engineering in enhancing PCFC/PCEC performance.

Pressureless sinter-joining of micron-Ag flake pastes at 160 °C enabled by solvent and interface engineering

Pressureless sinter-joining of cost-effective micron-Ag flake pastes at temperatures below 200 °C poses significant challenges due to their poor surface activity and low tapped density. Herein, we propose a novel solvent and interface engineering approach to enhance the contact among adjacent micron-Ag flakes and between the flakes and substrates. The solvent-enhanced sintering process is proposed, and its effect on the resistivity and shear strength of sintered Ag patterns and joints is studied in detail. Results show that the solvents with high wetting abilities on the Ag flakes and substrates are instrumental in achieving low resistivity and high shear strength in the sintered Ag patterns and joints. In particular, when the solvents possess high surface tension, they generate strong capillary adhesion among Ag flakes and substrates. This reduces the gap between Ag flakes and substrates, thereby promoting bonding among the Ag flakes by minimizing the distance of atom diffusion. Finally, mixed solvents of 50 % α-Terpineol and 50 % dipropyleneglycol methyl ether acetate show a synergistic effect due to the balance between wettability and surface tension, which enables the sintered joints to achieve an exceptional shear strength of 27 MPa even at an ultralow temperature of 160 °C. This achievement represents the state-of-the-art pressureless sinter-joining of Ag pastes and holds promising potential for practical use in power electronic packaging applications.

Lower bound on the spread of valley splitting in Si/SiGe quantum wells induced by atomic rearrangement at the interface

The achievement of universal quantum computing critically relies on scalability. However, ensuring the necessary uniformity for scalable silicon electron spin qubits poses a significant challenge due to the considerable fluctuations in valley splitting energy (E VS) across quantum dot arrays, which impede the initialization of qubit systems comprising multiple spins and give rise to spin–valley entanglement resulting in the loss of spin information. These E VS fluctuations have been attributed to variations in the in-plane averaged alloy concentration along the confinement direction of Si/SiGe quantum wells. In this study, employing atomistic pseudopotential calculations, we unveil a significant spectrum of E VS even in the absence of such concentration fluctuations. This spectrum represents the lower limit of the wide range of E VS observed in numerous Si/SiGe quantum devices. By constructing simplified interface atomic step models, we analytically demonstrate that the lower bound of the E VS spread originates from the in-plane random distribution of Si and Ge atoms within SiGe barriers — an inherent characteristic that has been previously overlooked. Additionally, we propose an interface engineering approach to mitigate the in-plane randomness-induced fluctuations in E VS by inserting a few monolayers of pure Ge barrier at the Si/SiGe interface. Our findings provide valuable insights into the critical role of in-plane randomness in determining E VS in Si/SiGe quantum devices and offer reliable methods to enhance the feasibility of scalable Si-based spin qubits.

Polymeric interfacial engineering approach to perovskite-functionalized organic transistor-type gas sensors

Organic semiconductors (OSCs) are promising sensing materials for printed organic gas sensors. Although OSCs show promise since they are mechanically flexible, cost-effective, and lightweight, they still face challenges related to low sensitivity and poor stability under ambient conditions; their development therefore lags that of inorganic-based gas sensors. Functional nanomaterials can be incorporated into organic semiconductors to complement the gas sensitivity and stability. Herein, we describe the fabrication of novel organic–inorganic hybrid gas sensors via the blending of perovskite nanocrystals and conductive polymer. We introduced a perovskite-structured material, CsPbBr3, into a conductive polymer matrix, which substantially improved its gas-sensing performance while maintaining its high responsivity and response rates. To further improve the adsorption of target gas molecules, we modified the surface of the perovskite using a zwitterionic polymer subjected to a hydration treatment. The results demonstrate that the amide group of the encapsulation polymer exhibits high affinity toward NO2 gas molecules and that this affinity becomes more pronounced upon hydration of the polymer. We also demonstrate the perovskite materials in the semiconducting polymer layer can protect the polymer thin film against oxidation during prolonged storage under ambient conditions because of the perovskite crystals’ ability to adsorb oxidizing molecules.

Enhancement of NiOx/Poly‐Si Contact Performance by Insertion of an Ultrathin Metallic Ni Interlayer

Nickel oxide () is a promising hole transport material for perovskite/Si tandem solar cells. Various silicon cell architectures may be used as bottom cells. The polycrystalline (poly‐Si) tunnel diode is expected to be a high‐efficiency interconnection scheme between the two subcells of monolithic tandems in p‐i‐n configuration with a high thermal budget, excellent passivation properties, and low contact resistivity. However, is then interfaced to poly‐Si() and the chemical integrity of the interface due to the necessity of annealing treatments has to be questioned. For this purpose, the /poly‐Si contact resistivity for different annealing temperatures is investigated between 100 and 500 °C, and two different deposition techniques, namely, wet‐chemically applied and sputter‐deposited . The values of more than are obtained. The insertion of a nm‐thin metallic Ni interlayer is shown to enable a tremendous decrease of the contact resistivity by 2–3 orders of magnitude. The formation of is proven by highly resolved (scanning) transmission electron microscopy ((S)TEM) coupled with energy‐dispersive X‐ray spectroscopy (EDXS). This interfacial engineering approach is expected to provide an effective way of improving the contact properties and integrability of into various tandem cell processes.

Phase interface manipulation by adjusting atomic ordering in metal-organic framework to facilitate microwave absorption

Metal-organic frames (MOFs) have been a suitable template for high-performance microwave absorbing materials. However, there has been a lack of effective solutions for the agglomeration and inadequate graphitization transformation of metal nanoparticles after annealing of MOFs. In this work, a simple and safe metal ion exchange method for the experimental process is proposed to etch the surface of Fe MOF (MIL-88) template using nickel metal salts, and the subsequent heat treatment to synthesize Fe-Ni/C nanorods. These fine and uniform metal particles and carefully designed phase engineering have excellent electromagnetic attenuation and good impedance matching. In particular, suitable defects and rich heterogeneous interfaces cause polarization loss to increase, and more obviously, hysteresis loss and natural resonance increase magnetic loss. The experimental results show that the materials have good broadband absorption (6.13 GHz) and high-efficiency loss (−35 dB) microwave absorbing (MA) performance. This work provides a generalized phase interface engineering approach for polymetallic nanorods and provides a useful reference for microwave absorbing materials.

Improving vertical charge transport in organic Schottky diodes via interface engineering of large-area conducting polymer thin films fabricated on hydrophilic liquid surface of tunable surface energy

Molecular orientation and stacking genre proved to be one of the decisive factors for the performance of conducting polymer (CP) based electronic devices. In this context, harnessing the key advantages of the ribbon shaped “floating-film transfer method” (FTM) along with an interfacial engineering approach has been utilized for molecular rearrangement in polymer thin-films formed on the surface of a high surface energy hydrophilic liquid mixture. In this novel subphase modified floating-film transfer method (SM-FTM), dodecyl benzene sulfonic acid (DBSA) has been used to control the molecular backbone stacking proximate to the solution-liquid interface and regioregular-poly(3-hexylthiophen-2,5-diyl) (rr-P3HT) was used as the model CP to probe the polymer-DBSA interaction. The molecular arrangements in microcrystalline domains, electronic band structures, and the evolution of surface texture at the solution-liquid interface have been investigated through multiple characterization tools. After that, the electrical performances of Schottky barrier diodes (SBDs) were studied in an ITO/P3HT/AlOx/Al sandwiched structure and a dramatic enhancement of rectification ratio up to 8.2 × 106 at ± 6 V was achieved. Further, an analytical model for SM-FTM, developed using lubrication theory and thin-film dynamics, has also been presented to elucidate the polymer spreading dynamics and the mechanism of molecular rearrangement at the interface.

Interfacial Engineering of PVDF‐TrFE toward Higher Piezoelectric, Ferroelectric, and Dielectric Performance for Sensing and Energy Harvesting Applications

The electrical properties of pristine fluoropolymers are inferior due to their low polar crystalline phase content and rigid dipoles that tend to retain their fixed moment and orientation. Several strategies, such as electrospinning, electrohydrodynamic pulling, and template-assisted growing, have been proven to enhance the electrical properties of fluoropolymers; however, these techniques are mostly very hard to scale-up and expensive. Here, a facile interfacial engineering approach based on amine-functionalized graphene oxide (AGO) is proposed to manipulate the intermolecular interactions in poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE) to induce β-phase formation, enlarge the lamellae dimensions, and align the micro-dipoles. The coexistence of primary amine and hydroxyl groups on AGO nanosheets offers strong hydrogen bonding with fluorine atoms, which facilitates domain alignment, resulting in an exceptional remnant polarization of 11.3µCcm-2 . PVDF-TrFE films with 0.1wt.% AGO demonstrate voltage coefficient, energy density, and energy-harvesting figure of merit values of 0.30VmN-1 , 4.75Jcm-3 , and 14pm3 J-1 , respectively, making it outstanding compared with state-of-the-art ceramic-free ferroelectric films. It is believed that this work can open-up new insights toward structural and morphological tailoring of fluoropolymers to enhance their electrical and electromechanical performance and pave the way for their industrial deployment in next-generation wearables and human-machine interfaces.

Advances in emulsion-based delivery systems for nutraceuticals: Utilization of interfacial engineering approaches to control bioavailability.

Designing functional foods fortified with nutraceuticals is an important focus of modern food science with the aim of improving human health and wellbeing. However, many nutraceuticals have a low water solubility and poor physiochemical stability, which makes it challenging to incorporate into food matrices. Moreover, nutraceuticals may also have a low bioavailability after oral administration because they can either precipitate or chemically degrade, and/or might not be absorbed in the gastrointestinal tract. Numerous strategies have been developed and applied to encapsulate and deliver nutraceuticals. Emulsions are a kind of colloid delivery system where one phase is dispersed into another immiscible phase in the form of small droplets. These droplets have been widely used as carriers to improve the dispersibility, stability, and absorption of nutraceuticals. Many factors affect the formation and stability of emulsions, with the interfacial coating formed around the droplets by emulsifiers and other stabilizers being one of the most important. Hence, interfacial engineering principles are needed for the design and development of emulsions. Different approaches to interfacial engineering have been developed, which can help to modulate the dispersibility, stability, and bioavailability of nutraceuticals. This chapter summarizes recent research in developing interfacial engineering approaches and their impacts on the bioavailability of nutraceuticals.

Interfacial engineering approaches to improve emulsion performance: Properties of oil droplets coated by mixed, multilayer, or conjugated lactoferrin-hyaluronic acid interfaces

This study investigated the effects of different interfacial structures on the performance of oil-in-water emulsions including their physicochemical stability, lipid digestion profiles, and nutraceutical bioaccessibilities. Emulsions containing oil droplets coated by lactoferrin (LF) and/or hyaluronic acid (HA) were prepared with different structural organizations: (i) LF only; (ii) LF + HA mixtures; (iii) LF + HA bilayers; and (iv) LF-HA covalent conjugates. The bilayers were formed by depositing HA onto LF-coated lipid droplets after homogenization, while the conjugates were formed by covalent attachment of HA to LF before homogenization. The interfacial pressure, adsorption kinetics, interfacial thickness, and surface load were characterized. The physicochemical properties and stability of the four types of emulsions were also measured and compared. The covalent attachment of HA to LF reduced the surface activity of the protein, which was attributed to a reduction in diffusion rate and surface hydrophobicity. The emulsifying activity and emulsion stability index of the LF were enhanced, and the salt stability and freeze-thaw stability of LF-stabilized emulsion were improved when HA was covalently attached to it. This effect was attributed to the formation of a relatively thick (161 nm) and strongly charged (−45.8 mV) interfacial layer that increased the steric and electrostatic repulsion between the oil droplets. Emulsions with mixed, bilayer, or conjugated LF-HA interfaces gave better photostability and bioaccessibility of two encapsulated nutraceuticals (curcumin and resveratrol) than LF interfaces. Overall, however, the LF-HA conjugates were the most effective at improving the performance of the emulsions. These results suggest that interfacial engineering technologies can be utilized to enhance the performance of emulsions.