ACS Applied Engineering Materials最新文献

Plasticized microbial (single cell) proteins (MPs) can be used to produce ductile and flexible plastic films with good oxygen barrier properties. However, as with other hydrogen-bond-forming oxygen barrier materials, like ethylene-vinyl alcohol copolymer (EVOH), they need to be protected from moisture because moisture decreases the oxygen barrier properties. Here, we solved the problem by producing three-layer laminate films that are fully biobased and biodegradable. Two different MP films (originating from a mixed microbial culture and Delftia tsuruhatensis biomass) were sandwiched between two different moisture-shielding polyhydroxyalkanoate (PHA) films (a poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) and a poly-(3-hydroxybutyrate-co-3-hydroxyhexanoate) material). The low-temperature melting features of the PHAs made them suitable for lamination through hot-pressing with the MPs. Liquid-water-resistant and UV-blocking laminates could be obtained, where the individual layers were also possible to delaminate as a possible recycling solution, where the MP layer could potentially be used as a fertilizer and the PHA mechanically recycled into similar or other products or composted. The laminates showed, in the best cases, an oxygen permeability of 2 cm³ mm/(m² day atm) and a water vapor permeability below 0.1 g mm/(m² day). All in all, the concept is promising as a sustainable biobased alternative to today's fossil-based EVOH-laminate packaging solutions.

Biofilm formation in drinking water distribution systems (DWDSs) presents a significant challenge, compromising both water quality and infrastructure lifetime. Recently, a nanohydrogel coating was demonstrated to have excellent antiadhesive properties toward drinking water microorganisms, making it a promising approach to alleviate biofilm formation in DWDS systems. However, the used coating procedure was not suitable for large surface areas and the stability of the coating under various physicochemical conditions was not assessed. This study proposes an optimized coating procedure for poly-(vinyl chloride) (PVC)-based drinking water piping and evaluates the stability of this poly-(N-isopropylmethacrylamide) (PNIPAM) based nanohydrogel coating and its ability to prevent microbial adhesion under drinking water conditions. Stability was assessed through detailed scanning electron microscopy, atomic force microscopy, and contact angle measurements after accelerated stress tests under different physicochemical conditions, including temperature, pH, salt concentration, and surfactant concentration. Microbial adhesion was tested in 35 day long recirculation experiments performed in a lab-scale DWDS under relevant drinking water conditions. The coating exhibited a very high stability under harsh pH conditions (1.5-13.5), high and low temperatures (4-70 °C) and extreme salt concentrations (0.1-6000 mM). However, at high surfactant concentrations, above the critical micellar concentration, some instability was observed. Against DWDS conditions, the coating remained stable over 35 days, showing a significant reduction (>80%) in adhesion of microorganisms. Overall, these findings support the use of the PNIPAM nanohydrogel coating as a scalable and stable solution to microbial adhesion in drinking water environments, offering a promising alternative or support to disinfection treatments to reduce biofilm formation in DWDS systems but with high potential toward other applications due to the highly stable nature of the nanohydrogel coating.

Nonmetal doping extends the photocatalytic response of TiO₂ nanoparticles (NPs) into the visible light region; however, systematic evaluations of how specific dopants influence their antimicrobial performance remain limited. In this study, we present a direct comparison of carbon-doped TiO₂ (C-TiO₂) and nitrogen-doped TiO₂ (N-TiO₂) NPs synthesized via a sol-gel method. Structural and optoelectronic properties were characterized by powder X-ray diffraction (p-XRD), transmission electron microscopy (TEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS), confirming dopant incorporation and band gap narrowing. Carbon doping resulted in a more pronounced band gap reduction (2.66 eV compared with 3.09 eV for N-TiO₂), which correlated with stronger visible light absorption and increased reactive oxygen species (ROS) generation. Under visible light irradiation, C-TiO₂ NPs achieved 80% eradication of Staphylococcus aureus biofilms and 69% eradication of Escherichia coli biofilms, corresponding to a ∼1.5-fold higher antibiofilm activity relative to N-TiO₂ NPs. Differences in bacterial susceptibility were associated with cell envelope architecture, in which the outer phospholipid membrane of Gram-negative Escherichia coli likely limited ROS penetration and contributed to lower eradication efficiency compared with Gram-positive Staphylococcus aureus. These findings demonstrate that dopant selection directly modulates photocatalytic functionality and identify C-TiO₂ NPs as a broad-spectrum antimicrobial material. The results have implications for the rational design of TiO₂-based nanomaterials in antimicrobial photodynamic therapy (aPDT), indoor building environments where pathogen control is essential, environmental remediation, and the development of next-generation self-disinfecting surfaces.

This work blends polydimethylsiloxane (PDMS) with poly-(lactic acid) (PLA) using polyhydroxyurethane (PHU) structures. The PHU is synthesized from mannitol biscarbonate and a short-chain PDMS-based diamine. The main objectives are, first, to explore the application of the PDMS-based PHU as an additive for PLA and, second, to enhance the flexibility and hydrophobicity of PLA for potential applications in sustainable packaging and biomedical nonwoven materials, such as face masks. PLA/PHU blends are prepared via melt-blending at various weight ratios and characterized using spectroscopic, thermal, rheological, morphological, and mechanical analyses. The blend containing 5 wt % PHU exhibits the optimal performance, with a 9-fold increase in elongation at break and an 18° increase in water contact angle compared to neat PLA, indicating improved toughness and hydrophobicity. Fourier-transform infrared spectroscopy and rheological studies confirm the presence of hydrogen bonding interactions between PLA and PHU, while differential scanning calorimetry confirms the partial miscibility of the blends. Then, electrospinning of neat PLA and the blend with 5 wt % PHU is optimized using a low-toxicity dioxane/acetone (40/60 wt/wt) solvent system. The resulting nonwoven mats exhibit similar physical properties between neat PLA and the blend, and they demonstrate higher porosity, smaller fiber and pore diameters, and superior hydrophobicity than polypropylene (PP) outer and middle face mask layers. Besides, hydrolytic degradation testing reveals accelerated degradation of PLA films with the introduction of the PHU and complete degradation of PLA mats in basic media. Finally, biofilm formation assays, using Staphylococcus aureus and Pseudomonas aeruginosa, validate the antibiofouling potential of both PLA and PLA/PHU films and mats.

Spirulina platensis is a promising bioresource for developing structural materials, offering a renewable alternative to conventional polymers due to its rapid growth and characteristic helical microstructure. While its biochemical properties have been widely studied, the role of cellular morphology in determining macroscale mechanical performance remains underexplored. In this work, we examine how maintaining versus disrupting Spirulina's native trichome structure and cell walls impacts the cohesion, rheology, and mechanical behavior of 3D-printed biomaterials. Using hydroxyethyl cellulose (HEC) as a binder, we developed two classes of bioinks: trichome biocomposites, based on freeze-dried Spirulina trichomes, and lysed biocomposites, formed from thermally lysed Spirulina cells. Differential scanning calorimetry revealed stronger molecular interactions between lysed cells and HEC, while trichomes contributed instead via physical interlocking and structural integrity of the cell wall. Despite weaker molecular interactions, trichome-based biocomposite bioinks exhibited higher viscosity, improved printability, and higher rheological yield stress by up to 499%. Upon dehydration, trichome biocomposites showed lower shrinkage and higher mechanical performance under compression, with normalized compressive modulus and yield strength significantly exceeding that of lysed biocomposites (by up to 107% and 108%, respectively). These effects are attributed to mechanical interlocking and enhanced stress transfer through intact cell walls. Our findings demonstrate that preserving biological microstructure may enable improved material cohesion and function, offering design principles for scalable, sustainable biofabrication of algae-based structural materials.

This study presents a method for creating effective electromagnetic interference (EMI) shields that are transparent, lightweight, and flexible, which is vital to address the needs of emerging flexible electronics. By integrating laser-induced graphene (LIG) with kirigamia technique of cutting and folding polymer filmsspatial patterns of highly conductive 3D porous graphene is produced. The entire fabrication utilizes a single laser system for both LIG and cutting, which makes the direct-write process versatile and scalable. The resulting 3D graphene is highly conductive with resistance under 25 ohm/mm and good quality with G/D ratio at 1.66 and 2D/G ratio at 0.46. The films achieve an EMI shielding efficiency (SE) over 50 dB at a low density of 0.04 g/cm^∧3. By leveraging the kirigami process to tune the SE and transparency, we achieve an SE of 17 dB while maintaining over 80% transparency, which exceeds previously reported values of 2D graphene. Additionally, our results address challenges in the flexibility and weight of EMI shields, achieving an exceptional EMI specific shielding efficiency (SSE) of 1362.2 dB cm³/g, competing with the previously reported values across thicknesses ranging from 10 to several hundred micrometers.

Per- and polyfluoroalkyl substances (PFAS), a diverse range of anthropogenic organic compounds, pose significant concerns to society due to their potential harmful impacts on human health and ecosystems. While there are other methods for removing PFAS from water, adsorption remains a viable and efficient option. The present research reports an adsorptive nanofiber membrane prepared through electrospinning in the presence of poly-(vinyl alcohol) (PVA) and a cationic surfactant, cetyltrimethylammonium chloride (CTAC), blended solution. This modified PVA membrane was observed to achieve nearly 100% capture of all 10 target PFAS, each at 10 μg/L in deionized water. The pseudo-second-order model most accurately represented the adsorption kinetics, characterized by rapid adsorption (within 60 s). The Toth isotherm model effectively fitted the isotherm data, indicating that the adsorption of PFAS onto the membrane involved complex interactions. The hypothesized adsorption mechanisms, including electrostatic and hydrophobic interactions, were validated through detailed adsorption kinetics, isotherms, thermodynamic analyses, and physicochemical characterization. Remarkably, the performance of the modified system remained unaffected by variations in solution pH and natural organic matter, while being slightly affected by ionic strength, with 90-100% removal effectiveness of PFAS in stormwater. This work highlights the significance of electrospun nanofiber membrane-based adsorbents for the efficient removal of PFAS from real water.

Boronium ionic liquids (BILs) are an emergent class of electrolytes with high electrochemical stability afforded by charge delocalization across the cation. BILs are of particular interest for electrochemical energy storage (EES) devices because of their large voltage window. Here, a series of BILs were systematically evaluated as electrolytes in symmetric double-layer capacitors equipped with carbon nanofoam paper (CNFP) architected electrodes. First, the operational voltage window and capacitive properties of supercapacitor cells composed of BILs and CNFP electrodes were evaluated in a two-electrode configuration by using cyclic voltammetry (CV). Then, galvanostatic charge-discharge (GCD) cycling was used to assess the capacitance, energy density, power density, and long-term stability of cells assembled with the BIL electrolyte. Our results show excellent capacitive behavior of the cells assembled with a series of ammonium-, imidazolium-, and pyrrolidinium-based BILs, with nearly rectangular CV curves across a range of scan rates. Specifically, the methylpyrrolidinium-substituted BIL electrolyte ([(1-m-pyrr)-N₁₁₁BH₂]-TFSI, TFSI: bis-(trifluoromethane)-sulfonimide) presents higher ionic conductivity (1.82 mS cm^-1 at 25 °C) compared to other BIL analogues and a wide operating voltage window of ∼3.7 V. These properties of [(1-m-pyrr)-N₁₁₁BH₂]-TFSI deliver an appreciable energy density of 16.3 Wh kg^-1 (at a power density of 36.4 W kg^-1), whereas [(1-a-pyrr)-N₁₁₁BH₂]-TFSI achieves a maximum power density of 13.9 kW kg^-1. Overall, these BILs display excellent power density and sufficient energy density with the advantage of steadily delivering the energy at high power density. High cycling durability is also possible with the BILs supercapacitor cells, which maintain a capacitance retention above 90% after undergoing 1000 charge-discharge cycles at a current density of 0.5 A g^-1. Finally, the specific capacitance, energy density, and power density of ammonium- and pyrrolidinium-based BILs exhibit a delicate dependence on temperature intended to facilitate the diffusion kinetics of BILs, confirming thermal resilience with no additional performance advantage.

The increasing urgency to address nitrate (NO₃ ^-) pollution in water sources has intensified research on electrochemical nitrate reduction, a process capable of transforming NO₃ ^- into valuable ammonia (NH₃) by using renewable electricity. Copper (Cu) catalysts can reduce NO₃ ^-, but their activity and selectivity toward NH₃ can vary based on their structure, reaction environment, and support material. This study examines the efficacy of Cu-modified carbon nanofiber (CNF) supports, tailored through electrospinning, in enhancing the electrocatalytic reduction of NO₃ ^- to NH₃. Three variants of CNF supports were synthesized: pristine CNFs, CNFs integrated with carbon nanotubes (CNF/CNTs), and CNFs embedded with titanium dioxide nanoparticles (CNF/TiO₂). Each electrode's physical and electrochemical properties were analyzed before and after Cu electrodeposition. Notably, the CNF/TiO₂/Cu composites demonstrated a selectivity exceeding 40% for the conversion of NO₃ ^- to NH₃ at neutral pHsignificantly outperforming the CNF/CNT/Cu (<5%) and CNF/Cu (20%) configurations when deposited with equivalent amounts of Cu. The CNF/TiO₂/Cu electrode also exhibited consistent and stable performance over the extended experimental duration (|Q| = 70 C), maintaining NH₃ selectivity rates of over 50%. Tafel analysis and operando Raman spectroscopy suggest that TiO₂ plays an active role in hydrogenating nitrogenous reduction products for enhanced selectivity. This research highlights the importance of electrode-catalyst selection in electrochemical NO₃ ^- reduction and identifies TiO₂-containing electrodes as promising solutions in this domain.

This work introduces a class of nitrogen-rich porous polymers synthesized via "knitting polymerization" using a redox-active triphenyltriindole monomer. Two synthetic routes-thermal Friedel-Crafts reaction (TRIPh-d) and solvent-free mechanochemical activation (TRIPh-m) yield polymers with similar chemical structures but markedly different surface areas. Despite this, both materials exhibit exceptional iodine uptake from hexane solution (up to 1.87 g g^-1), placing them among the highest-performing amorphous microporous organic polymers reported to date. The superior adsorption is attributed to the reversible oxidation of triindole units, forming radical cations that enhance iodine capture through electrostatic interactions. Comparative analysis with a truxene-based analog (TX-m) confirms the critical role of nitrogen-rich scaffolds over surface area alone. Beyond iodine sequestration, TRIPh-d also demonstrates outstanding performance as a cathode material in zinc-iodine batteries (ZIBs), delivering a specific capacity of 228 mA h g^-1 at 1 A g^-1, 99% Coulombic efficiency, and 72% capacity retention over 10,000 cycles. This dual functionalitycombining environmental remediation with energy storage-along with the sustainability of the synthesis, positions these redox-active knitting polymers as promising candidates for future applications.