Dielectric materials with low dielectric constant (κ < 2) are highly needed to overcome a series of problems caused by the decreasing size of microelectronics. An effective way to reduce dielectric constant is introducing void structure in dielectric materials, however challenging in mechanical strength and wetting properties. Herein, porous sp2-bonded boron nitride (BN) films are directly grown on Si substrates via radio frequency magnetron sputtering. The Guinier plot analysis of grazing incidence small-angle X-ray scattering spectra and electron microscopy confirms the pore size of ∼1.85 nm. The porous BN (p-BN) films show a band gap of ∼5.88 eV and a hydrophobic surface, ensuring the stability of dielectric properties. P-BN films exhibit an ultralow-κ of 1.77 at 100 kHz. These porous ultralow-κ BN films are electrically robust and mechanically stable superior to the previously reported porous dielectrics and close to the referent dense amorphous BN and hexagonal BN. Additionally, the p-BN films demonstrate notable diffusion barrier capability, effectively blocking Cu diffusion even with a thickness as low as 3 nm. This work provides a viable approach towards the controlled synthesis of porous ultralow-κ BN films as versatile dielectrics for transistor gate barriers, passivation layers, and capacitor spacers in high-performance electronics.
Genipin-crosslinked chitosan/gelatin composite films incorporating zinc-doped carbon dots (Zn-CDs) were fabricated by solvent casting at genipin concentrations of 0-1.0% (w/w), with parallel Zn-CD-free films serving as controls to decouple the individual and synergistic contributions of chemical crosslinking and Zn-CD incorporation to film properties. Successful Zn doping of the carbon dots was confirmed by comparative FTIR analysis, which revealed characteristic shifts in the carboxyl/hydroxyl stretching region and an emerging ZnO-related feature relative to the undoped precursor. Scanning electron microscopy revealed a progressive transition from rough, phase-separated surfaces to compact, homogeneous matrices with increasing genipin content, reflecting formation of a denser covalent network. Zn-CD incorporation fundamentally altered the mechanical response from monotonic to biphasic, peaking at 0.5% genipin (tensile strength 39.73 ± 0.67 MPa; elongation at break 19.34 ± 0.60%), attributable to a dual physical-chemical crosslink network. Water vapor transmission rate reached a minimum of 3.03 g·m-2·24 h-1 at 0.5% genipin, lower than Zn-CD-free films even at their best value (4.20 g·m-2·24 h-1 at 1.0% genipin), demonstrating that Zn-CDs enhance barrier performance independent of film thickness. FTIR and XRD confirmed molecular-level integration of genipin into the amorphous biopolymer network via covalent amine linkages. Thermal stability increased monotonically with crosslink density, as shown by TGA and DSC. Antioxidant assays on solid-state film extracts showed DPPH scavenging of approximately 50% at the effective genipin/Zn-CD loading, substantially exceeding values obtained from film-forming solutions (4.1-8.6%), confirming meaningful food-contact-relevant antioxidant performance. The films exhibited a multi-stage pH-responsive color transition (blue-green at pH 3-6, near-black at pH 7-8, red-yellow at pH 9-11), corroborated by CIELAB analysis, supporting their potential as naked-eye freshness indicators. MTT/CCK-8 assays on fibroblast cells showed viability above the ISO 10993-5 non-cytotoxicity threshold across all formulations, supporting the preliminary safety of the system for food-contact use. Biodegradability decreased inversely with crosslink density, with all films undergoing meaningful mass loss over 18 days. Collectively, these results establish genipin-crosslinked chitosan/gelatin/Zn-CD films as multifunctional materials combining mechanical integrity, superior barrier performance, functional antioxidant activity, colorimetric freshness sensing, preliminary biocompatibility, and biodegradability for sustainable food packaging.
This study presents a novel galvanic deposition method to create antimony sulfide thin films on FTO glass. The presence of palladium as a top layer on the surface of Sb2S3 (designated as Sb2S3:Pd) promotes hydrogen production and dye degradation. Four differently treated Sb2S3 films were studied. In neutral buffer medium, maximum efficiency related to water splitting for hydrogen evolution was observed for the annealed Sb2S3:Pd films, displaying a low onset potential of -116 mV and a Tafel slope of 64 mV/decade. The inclusion of Pd boosts the HER performance, which exhibits a current density of 10 mAcm-2 at a comparatively lower overpotential of -204 mV with significant stability. Sb2S3:Pd films also demonstrated improved dye degradation capability in comparison to Sb2S3 films without Pd.
Efficient, reliable preparation of high-quality films of covalent organic frameworks (COFs) is essential for fully exploring the potential of this class of porous crystalline compounds in, for example, sensing and catalysis. To this end, in situ polymerization on substrates offers a promising route; however, it remains a challenge to achieve highly crystalline, smooth, and oriented COF films through this method. Here, we present a humidity-controlled, drop-casting-based approach for the formation of imine-COF films, using the monomer pair 1,3,6,8-tetrakis(4-aminophenyl)pyrene and terephthalaldehyde as a representative example, along with additional pairs to highlight the method's versatility. This method affords homogeneous, face-on-oriented films with excellent reproducibility and efficiency. The key to this effect is regulating the environmental humidity during solvent evaporation, which presumably enables spatiotemporal modulation of the polymerization and crystallization processes. Such control over the film structure allows statistical evaluation of morphology-dependent variations in chemiresistive response, demonstrating that this operationally simple approach provides a robust platform for both fundamental studies and technological development of COF films.
The incorporation of hybrid nanofillers with complementary functionalities into packaging materials has emerged as an effective strategy for achieving multifunctionality. In this study, multifunctional PVA/chitosan-based films were fabricated by simultaneously incorporating broccoli leaf-derived N,S-doped carbon dots (CDs) and in situ synthesized Ag/AgCl nanoparticles (0-0.70% Ag relative to polymer mass). CDs served as reducing agents for the formation of ∼27.4 nm Ag/AgCl nanoparticles within the polymer matrix. The resulting films exhibited tunable mechanical and functional properties depending on the Ag content. At 0.45% Ag loading, the composite film displayed enhanced mechanical properties (tensile strength of 61.1 MPa and elongation at break of 190%) and excellent UV-shielding (∼93% UVA and nearly 100% UVB/UVC blocking). The films also showed strong antioxidant activity (∼93% 2,2-diphenyl-1-picrylhydrazyl scavenging), mainly attributed to CDs. Furthermore, the films demonstrated significant antibacterial activity against Escherichia coli and Staphylococcus aureus, primarily attributed to Ag/AgCl nanoparticles, with inhibition zones of 13.4 and 12.9 mm, respectively. Practical tests confirmed that the composite film significantly extended the shelf life of guavas and strawberries, outperforming commercial polyethylene films. These results highlight its strong potential for multifunctional food packaging applications.
Kombucha is commonly regarded as a functional fermented beverage, and fruit pomace was evaluated as a co-substrate to modulate its fermentation and concurrently enable bacterial cellulose (BC) production. Sweetened black tea was co-fermented with 1% (w/v) apple, lemon, banana, kiwi, or blueberry pomace, and the resulting beverages and regenerated BC films were characterized in terms of functional metabolites, volatile composition, and bioactivity. The pomace type strongly governed functional outcomes. The blueberry pomace group (BLK) produced the greatest antioxidant enhancement, increased ABTS and DPPH radical scavenging activities by 63.5% and 26.8%, respectively, relative to the control. Organic-acid profiles markedly differed among pomace groups: the banana pomace group (BAK) increased glucuronic acid to 2.28-fold of the control, the kiwi pomace group (KIK) maximized acetic acid formation (1.95-fold vs. the control), and the BLK yielded the largest succinic acid accumulation (5.20-fold vs. pre-fermentation). Headspace HS-SPME-GC/MS revealed pomace-specific volatile fingerprints, demonstrating systematic shifts in aroma-related compounds across pomace groups rather than uniform flavor intensification. Importantly, pomace-altered kombuchas (PKs) served as effective media for BC biosynthesis, and regenerated films retained the cellulose I diffraction signature while exhibiting pomace-dependent thermal/structural responses. PK-derived BC films displayed significantly enhanced antimicrobial activity compared to control BC, with inhibition zones increased by 1.43-fold against Escherichia coli (lemon pomace group (LK)/BLK), 1.2-fold against Staphylococcus aureus (KIK), and 1.6-fold against Pseudomonas paraeruginosa (BLK). Overall, this dual valorization strategy advances circular bioprocessing by converting juice-processing residues into functionally tailored kombucha and antimicrobial BC biomaterials with potential utility in active food packaging and wound-care materials.
Films of a perylene diimide derivative (PDIN-H) processed with varying silver acetate (AgOAc) concentrations were fabricated. Films were stable in aqueous media and demonstrated antimicrobial activity (90-99.9%) against a variety of bacterial pathogens. These results show the potential of a PDIN-H/AgOAc ink for coating various surfaces to provide bactericidal properties.
Flexible thermoelectrics convert body heat into electricity, offering a promising route towards self-powered wearable electronics while overcoming the limitations of conventional batteries. Among emerging flexible thermoelectric materials, silver selenide (Ag2Se) has attracted widespread attention because it combines outstanding near-room-temperature thermoelectric performance with low cost, excellent mechanical flexibility, and superior biocompatibility. Over the past five years, orientation engineering has emerged as an effective strategy for simultaneously enhancing carrier transport and suppressing carrier scattering, leading to remarkable improvements in both material properties and device performance. In this Perspective, we systematically review recent progress in highly oriented Ag2Se films, including deposited, nanowire-based, selenized, and free-standing architectures. We further propose film thickness together with near-room-temperature power factor as practical metrics for benchmarking their application potential. By correlating fabrication strategies, microstructural evolution, crystallographic orientation, and thermoelectric performance, we establish a unified framework for understanding orientation-dependent charge transport in Ag2Se films. Finally, we discuss the remaining scientific and technological challenges and highlight future opportunities for developing scalable, mechanically robust, and high-performance Ag2Se films for next-generation wearable thermoelectric energy harvesters and self-powered physiological monitoring systems.
The widespread pollution arose from petroleum-source non-degradable plastics has driven urgent demand for biodegradable green packaging materials. Starch is an attractive feedstock because of its low cost, renewability, and complete biodegradability, but its poor melt processability and low mechanical strength hinder practical applications, particularly in blow molding. Herein, we report a micro-crosslinked pure starch film fabricated via reactive extrusion and blow molding using cassava starch, antibacterial hexamethylene guanidine hydrochloride and a multi-epoxy functional aromatic copolymer (AE) as a crosslinking agent. The micro-crosslinking network effectively enhances melt strength at low shear rates, enabling stable blow molding of pure starch films. With 0.5 wt% AE content, the film exhibits optimal mechanical properties, achieving a tensile strength at 5.71 MPa, 262% elongation at break, and 583% increase in Young's modulus. Notably, the starch film exhibits outstanding long-lasting bactericidal efficacy, even following a four-week aqueous immersion, it retains more than 98.4% growth suppression toward Escherichia coli and Staphylococcus aureus, corresponding to a 74.3% conjugation yield. Moreover, the incorporation of rigid benzene ring segments slows down the degradation rate, which decelerate the degradation rate and thus prolong the service life, with ultimate biodegradation taking place afterwards. This study provides a feasible strategy to prepare high-strength, long-lasting antibacterial pure starch films via micro-crosslinking and blow molding, promoting sustainable packaging applications.
In response to a rapidly changing background environment, carbon nanotubes (CNTs)-based infrared electrochromic materials have emerged as a research focus due to their fast response kinetics and high flexibility. Nevertheless, the microscopic mechanism governing the relationship between infrared emissivity and applied bias voltage remains vague. In this work, a defect-engineering strategy is employed to fabricate sulfur/nitrogen co-doped CNTs (SNCNT) films as a model system for mechanism investigation. It is revealed that the core process lies in ion enrichment-mediated charge transfer, regulating macroscopic conductivity. Specifically, accumulated ions can dynamically reconstruct the film architecture, facilitating ion-electron interactions within an electrical double-layer capacitive framework. This process presents an asymmetric operation mechanism that anions induce hole doping, while cations promote electron doping. First-principles calculations further correlate ion-specific modulation with orbital energy depth and π-conjugation degree. By integrating these insights, a multi-dimension qualitative model is proposed to correlate infrared emissivity with interfacial contact resistance, charge-transfer dynamics, and atomic-scale structure. The optimized SNCNT film system demonstrates an infrared modulation width of Δε = 0.601, accompanied by notable bia-removal memory behavior (Δε/Δt = -0.0018 s-1), underscoring its potential in infrared camouflage, information encryption, and electromagnetic shielding.
Herein, we reveal the temperature-dependent broadening of the Mott gap in layered α-RuCl3, together with a distinct transition in the range of 100-130 K, through surface morphology and electronic structure characterizations using scanning tunneling microscopy and scanning tunneling spectroscopy, respectively. Furthermore, layer-dependent measurements indicate an enhanced phase transition and Kitaev interactions with decreasing thickness. These results show that low-dimensional α-RuCl3 films differ from their bulk state owing to their unique structural and electronic properties, providing an ideal model platform for exploring Kitaev physics.
The proliferation of multidrug-resistant (MDR) bacteria poses a severe threat to food safety and public health, driving the urgent need for advanced packaging solutions that go beyond conventional methods. Herein, we present a nanocomposite film engineered to tackle this challenge. Its active core is a rationally designed CuNCs@ZIF-67/CNF composite, where copper nanoclusters (CuNCs) are embedded in a ZIF-67 matrix and anchored onto chitosan nanofibers (CNF). This design enables synergy: CNF captures bacteria, ZIF-67 provides sustained ion release, and CuNCs generate reactive oxygen species, jointly disrupting biofilms, membranes, and metabolism. The composite demonstrates exceptional, broad-spectrum antibacterial activity, achieving >99% inactivation against Gram-positive/negative bacteria and key MDR pathogens like Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Processed into a polyvinyl alcohol film, it shows excellent flexibility, strength, and biocompatibility. In practical tests on cherry tomatoes, the film effectively inhibited MDR bacteria on surfaces, reduced weight loss to <6% (control >25%), and preserved freshness over 7 days. This work offers a high-performance, sustainable strategy for next-generation active food packaging to combat spoilage and antimicrobial resistance.
This study presents an examination of the development of high-performance Co-doped SnO2 nanocolloidal thin films, which are designed for the highly sensitive and selective detection of NH3. By integrating precise sol-gel synthesis with first-principles Density Functional Theory (DFT), we elucidate the importance of defect engineering in modulating gas surface interactions. The XRD analysis confirmed the tetragonal rutile phase of SnO2, revealing that the 2% Co-doped SnO2 exhibits a significantly reduced crystallite size of 4.88 nm. Furthermore, XPS and PL characterization indicated an increase in surface Ov and OC, while UV-vis results demonstrated band gap narrowing due to doping. The DFT calculations suggested that 2% Co-doping introduces mid-gap 3d states, which enhance electronic sensitization. In comparison to the relatively inert pristine SnO2, the 2% Co-doped variant shows a remarkable 153.54% increase in conductivity upon NH3 adsorption, achieving a selectivity ratio of 31.0 relative to H2. Additionally, kinetic analysis revealed that the addition of Co improves sensor reversibility by lowering the NH3 desorption barrier. The combination of reduced crystallite size, defect-rich surface chemistry, and optimized electronic pathways positions 2% Co-doped SnO2 as an outstanding candidate for highly sensitive NH3 detection.
Recovered plastic mulch films (rMFs) are often burdened with soil contamination, limiting recycling options. While pyrolysis is a promising recycling technology, the effects of soil contamination on rMFs' properties and pyrolytic behavior remain poorly understood. This study investigated the influence of soil contamination on rMFs collected from Washington (WA), Nebraska (NE), Florida (FL), and California (CA). Proximate, elemental, and calorific analyses evaluated the influence of soil texture on rMFs' physicochemical properties, while thermogravimetric analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) assessed thermal degradation and volatile product composition. Controlled experiments using WA vMFs and WA soil (0-80 wt%) statistically evaluated soil loading effects. Results showed that soil contamination altered rMFs' properties. Clay-rich soils (WA and NE) exhibited the greatest effects, reducing volatile matter (VM) by 31% and 24%, and higher heating values (HHV) by 41% and 33%, respectively. Soil contamination also affected all onset thermal degradation temperatures. However, across all locations, hydrocarbons remained the dominant pyrolysis products (68.63-80.53% peak area), with diesel-range compounds (C13-C20) accounting for 38.51-48.95%. Regression analysis confirmed strong linear relationships contents (R > 0.986 and R2 > 0.971), between soil concentration and proximate/elemental components (VM, ash, carbon, and hydrogen). These findings show how soil texture affects rMFs' physicochemical properties and how presence of soil on rMFs affects thermal degradation behavior and volatile product distribution during pyrolysis. Nevertheless, the hydrocarbon-rich products indicate that soil-contaminated rMFs remain promising feedstocks for pyrolysis and fuel production.
Breathing continuously stretches the lungs, providing essential mechanical cues that regulate cellular behavior and disease responses. Mimicking the repetitive out-of-plane deformation of alveolar tissues driven by transpulmonary pressure requires ultrathin stretchable hydrogel membranes that sustain prolonged cyclic loading in hydrated environments. However, membrane thinning inevitably amplifies stress concentration and fatigue failure, making the simultaneous achievement of ultrathin geometry and long-term durability fundamentally incompatible in conventional hydrogel systems. Here, we present a soap film-inspired hydrogel membrane that overcomes this trade-off and enables dynamic breathing lung models. By incorporating acrylamide into gelatin methacryloyl, precursor viscosity and surface tension are systematically tuned to generate ultrathin liquid films governed by Frankel's law, while a hybrid co-polymer network is formed to produce durable, freestanding membranes. Integrated with a negative-pressure bioreactor that reproduces physiological breathing under air-liquid interface culture (10%-15% strain, 12 cycles min-1), the platform establishes a dynamic lung model with physiologically relevant out-of-plane deformation. Cyclic breathing activates YAP-mediated mechanotransduction, drives tissue and extracellular matrix remodeling, and modulates inflammatory and antiviral responses in an influenza A infection model. This work establishes a physics-guided strategy for engineering ultrathin durable hydrogel membranes and advances mechanically faithful in vitro lung models for mechanobiology and respiratory disease research.
Interfacial polymerization (IP) offers a rapid and inexpensive method for fabricating thin polymer films. In this work, a one-step IP reaction between a triacyl chloride monomer and sulfonated diamine monomer is employed to add a dense, charge-selective sulfonated thin-film coating onto a commercial separator to improve selective transport in lithium-sulfur batteries. The coating effectively suppresses polysulfide shuttling, enhancing capacity retention, although at the expense of compromised rate performance due to hindered lithium conduction through the dense film. Fractional substitution of the trifunctionalized acyl chloride monomer for a difunctionalized analogue reduces the film cross-link density, which improves rate performance but decreases uniformity in film coverage. Uniform film coverage is achieved upon addition of a small fraction (0.25 wt %) of higher reactivity, nonsulfonated diamine in the IP reaction. This optimized thin film coating breaks the rate-capacity retention trade-off, enabling a capacity of 711.6 mAh g-1 after 200 cycles at 0.5C while still reaching over 800 mAh g-1 during rate testing at 2C.
As advanced electronic components become more miniaturized and integrated, the performance requirements for polymer dielectric films are becoming increasingly stringent. Although the aromatic polymer polyetherimide (PEI) exhibits excellent thermal stability, the π-π conjugated structures present in its main chain tend to enhance electron delocalization and intermolecular charge transfer, leading to a significant increase in conductance loss under high-temperature conditions, which limits further improvements in its energy storage performance. In contrast to the previously documented trap-modulation strategies, this study proposes an innovative dual-end synergistic modulation strategy that targets both the molecular backbone and terminal groups. The introduction of highly polar sulfone groups into the PEI backbone, in conjunction with 4-phenylacetylene phthalic anhydride (PEPA) into the terminal groups, resulted in the construction of a cross-linked network structure. This process has been shown to enhance the polarization response of the PEI film, whilst concomitantly creating deep-level charge traps. Surprisingly, at an elevated temperature of 150 °C, the characteristic breakdown field strength of SPEI 10%-PEPA was determined to be 575 MV m-1, representing a 15% increase in comparison with the uncross linked SPEI. Concurrently, an ultra-high energy storage density of 4.64 J cm-3 was attained, accompanied by a charge-discharge efficiency that surpassed 90%.
Recently, rutile ruthenium dioxide (RuO2) has attracted renewed interest due to expectations of prominent altermagnetic spin splitting. However, accumulating experimental evidence suggests that, in its bulk and thick-film forms, RuO2 does not display any form of magnetic ordering. Despite this, the spin structure of RuO2 remains largely unexplored in the ultrathin limit, where substrate-imposed epitaxial strain can be substantial. Here, we use spin-resolved angle-resolved photoemission spectroscopy, supported by ab initio calculations, to reveal the electronic structure of 2-nanometer-thick epitaxial RuO2 heterostructures. We observe an unconventional spin texture characterized by the coexistence of mirror-even and mirror-odd momentum-dependent components. A comprehensive symmetry analysis rules out nonmagnetic origins of this spin texture. These findings suggest an emergent nonrelativistic spin structure enabled by epitaxial strain in the ultrathin limit, marking a distinct departure from the behavior of relaxed or bulk RuO2. Our work opens previously unexplored perspectives for exploring symmetry-breaking mechanisms and spin textures in oxide heterostructures.
Here, we synthesized an innovative nanocomposite film (BPAZ) by blending bacterial cellulose (BC) with polyvinyl alcohol (PVA) and reinforced it with Ag/ZnO nanoparticles. Structural and morphological analyses confirmed the uniform dispersion of Ag/ZnO in the BC/PVA matrix. The BPAZ films exhibited enhanced antibacterial and antioxidant properties compared with the BC/PVA film. Remarkably, the BPAZ film containing 0.20 wt% Ag/ZnO (BPAZ-0.20) obtained the strongest antibacterial activity and antioxidant capacity. Also, this film showed good tensile strength (27.45 MPa), low water vapor permeability (0.39 × 10-10 g s-1 m-1 Pa-1), and low oxygen permeability (1.75 × 10-9 kg s-1 m-1). Preservation trials on Vietnamese tangerines revealed that the BPAZ-0.20 wt% film effectively extended fruit shelf life up to 15 days at ambient temperature and minimized weight loss. Therefore, the BPAZ nanocomposite film is a promising candidate for active food packaging.
Chitosan-Spent coffee ground-ZnO (Chi-SCG-ZnO) biobased film has been successfully synthesized and evaluated for its potential application as an active food packaging. The biobased film was prepared via a solution casting method and characterized in terms of mechanical properties, water vapor permeability (WVP), water contact angle (WCA), UV-blocking ability, antibacterial activity, biodegradability, and environmental toxicity. The incorporation of SCG and ZnO improved the physicochemical and functional properties of the film. The tensile strength increases from 5.74 MPa (Chi) to 10.98 MPa (Chi-SCG-ZnO). The Chi-SCG-ZnO film exhibited lower WVP (0.52 g.m-2.h-2) compared with Chi (0.62 g.m-2.h-2), indicating improved moisture barrier properties. The surface hydrophobicity also increased, as shown by a higher WCA (82.98o) compared with Chi (64.25o). In addition, Chi-SCG-ZnO demonstrated excellent UV-blocking ability, reaching 99.74% in the UVB region and 92% in the UVA region. The film also exhibited stronger antibacterial activity against Escherichia coli (9 mm) and Staphylococcus aureus (10 mm) compared with Chi. Application in grape packaging showed that Chi-SCG-ZnO maintained better fruit quality during storage than Chi. The biodegradability test indicated higher degradation of Chi-SCG-ZnO compared with Chi. These results demonstrate that Chi-SCG-ZnO has promising potential as an active and biodegradable food packaging material.