Water Barrier Research Articles

Active Poly (Lactic Acid) Films with Rice Straw Aqueous Extracts for Meat Preservation Purposes

Aqueous extracts from rice straw (RS), using ultrasound-assisted reflux heating extraction (USHT) and subcritical water extraction (SWE), under two process conditions (160 °C, 7 bars; and 180 °C, 11 bars), were obtained and characterised as to their phenolic content and antioxidant and antimicrobial capacities. These extracts were incorporated (6% wt.) into poly (lactic acid) (PLA) films by melt blending and compression moulding that were characterised as to their structural and functional properties and their capacity to preserve fresh pork meat, as vacuum thermo-sealed bags, throughout 16 days of cold storage. The extracts slightly reduced the extensibility, resistance to break, and water barrier capacity of the PLA films but enhanced their oxygen barrier capacity and the UV light-blocking effect. The films with RS extracts were effective at preserving meat quality parameters, inhibiting microbial growth, meat oxidation, discolouration, and weight loss. The SWE extract obtained at 180 °C was the most effective at obtaining active films for meat preservation, exhibiting the greatest antioxidant and antibacterial activity. Therefore, the green SWE technique is useful for obtaining active extracts from RS, allowing for its valorisation in the development of biodegradable active materials useful to preserve food quality.

Polyester–melamine coil coating formulation reinforced with surface-modified cellulose nanofibrils

In light of the need to redesign industrially produced materials by utilizing renewable resources, nanoscopic forms of cellulose are regarded as a valuable asset. In this work, the potential of cellulose nanofibrils (CNFs) as an unconventional nanoadditive for a polyester–melamine coil coating formulation is explored. CNFs, hydrophilic nanomaterials with high aspect ratios, were successfully incorporated in the solvent-borne formulation. Coatings were prepared with extremely low loadings of the nanoadditive (0.5 and 0.7 wt%). At these concentrations, the volume fraction of the nanofibrils in the coatings was calculated to be close to their percolation threshold. Two different pathways of CNF surface modification were applied to allow for a good compatibilization in the resin matrix, and the formulations were cured in two different settings. The effective compatibilization of the nanoadditive led to a significant variation of the viscoelastic properties in the coatings containing CNFs. The results from dynamic mechanical analysis (DMA) highlighted the effect of CNFs on the crosslinked network at the nanoscale, resulting in an increase in Tg. Additionally, an increase in the stress at break and Young's modulus was determined by tensile testing, while satisfactory elongation at break was preserved. Other relevant effects induced by the presence of CNFs on the properties of the coatings were highlighted, such as a significant matt effect, increased surface roughness and lower scratch resistance. A preliminary evaluation of the water barrier properties by electrochemical impedance spectroscopy (EIS) is also presented, suggesting that the incorporation of a hydrophilic nanoadditive did not lead to a deterioration of the coatings' performance.

Dynamic covalent bond enabled strong Bio-based polyimide materials with Thermally-driven Adaptivity, healability and recycling

Developing new sustainable materials as plastic replacement has become an urgent task for the rapid accumulation of non-degradable petroleum-based waste plastics. Herein, we report that catalyst-free dynamic reversible exchange operated at room-temperature by Schiff base reaction between dialdehyde cellulose nanofibrils (DACNF) and plant oil-based aliphatic long-chain diamine monomers (LCD). The dynamic imine polymer films are formed using a simple method similar to wet pressing in papermaking, which exhibits excellent mechanical properties and thermally processability for the synergistic of hydrogen bond and dynamic imine bond. The tensile strength and Young's modulus reaches 83.74 MPa and 3.90 GPa, which are significantly higher than those of most traditionally commercial plastics. In addition, the number of hydrogen bonds and dynamic imine bonds from cellulose and dynamic imine polymers are evaluated by molecular dynamics (MD) simulation to gain further insights into the intermolecular interaction. By exploring the mechanism involved in the reversible exchange of dynamic imine bonds and its application in self-healing and recycling, a sustainable adaptive material is expected to be structured. More importantly, the dynamic imine polymers also exhibits excellent water barrier properties, solvent resistance and complete biodegradability, which offers a new strategy for reducing the application of non-degradable plastics.

κ-Carrageenan-essential oil loaded composite biomaterial film facilitates mechanosensing and tissue regenerative wound healing

Polysaccharides κ-carrageenan (κ-Car) have become a predominant source in developing bioactive materials. We aimed to develop biopolymer composite materials of κ-Car with coriander essential oil (CEO) (κ-Car-CEO) films for fibroblast-associated wound healing. Initially, we loaded the CEO in to κ-Car and CEO through homogenization and ultrasonication to fabricate composite film bioactive materials. After performing morphological and chemical characterizations, we validated the developed material functionalities in both in vitro and in vivo models. The chemical and morphological analysis with physical structure, swelling ratio, encapsulation efficiency, CEO release, and water barrier properties of films examined and showed the structural interaction of κ-Car and CEO-loaded into the polymer network. Furthermore, the bioactive applications of CEO release showed initial burst release followed by controlled release from the κ-Car composite film with fibroblast (L929) cell adhesive capabilities and mechanosensing. Our results proved that the CEO-loaded into the κ-Car film impacts cell adhesion, F-actin organization, and collagen synthesis, followed by in vitro mechanosensing activation, further promoting wound healing in vivo. Our innovative perspectives of active polysaccharide (κ-Car)-based CEO functional film materials could potentially accomplish regenerative medicine.

Hygrothermal degradation of MWCNT/epoxy brittle materials under I/II combined mode loading conditions: An experimental, micro structural and theoretical study

The effects of carboxylated multi-walled carbon nanotubes (MWCNTs) are studied experimentally and theoretically on mixed-mode (I/II) fracture behavior of epoxy resin at the presence of hygrothermal aging conditions. In this paper, the mixed-mode fracture of MWCNT/epoxy is experimentally measured using Short Beam Bending (SBB) samples with different crack inclination angles (α) ranging from pure mode I (i.e., α = 0°) to pure mode II (i.e., α = 39°). To examine the effects of hygrothermal aging conditions and water barrier properties of MWCNTs, four groups of samples including a group of neat epoxy specimens, and three groups of MWCNT/epoxy specimens (with 0.1, 0.3, and 0.5 wt% of MWCNTs) were manufactured and immersed into hot deionized water for 15 days at 60 °C temperature and similarly four groups were placed at room temperature conditions (26 °C and 25–35% relative humidity) for 15 days. According to the experimental results, toughening the epoxy resin by incorporating nanotubes with 0.1, 0.3, and 0.5 wt% of MWCNTs improved the fracture toughness at both environmental conditions, but the highest fracture toughness was obtained for composition containing 0.3 wt% nanoparticles. The variations of fracture loads were dependent on the ambient environment, MWCNTs content, and mode mixity. The relationship between the obtained experimental results, microstructure and morphology of fracture in the tested samples was also investigated. In addition, the load-carrying capacity of the SBB samples made of the neat and MWCNTs modified epoxy material was also predicted well using a two-term based fracture model called Generalized Maximum Tangential Stress (GMTS) criterion.

Beaver Dams and Fallen Trees as Ecological Corridors Allowing Movements of Mammals across Water Barriers-A Case Study with the Application of Novel Substrate for Tracking Tunnels.

Physical obstacles within animal habitats create barriers to individual movements. To cross those barriers, specific corridors are used, some of them created by keystone species such as Eurasian beavers (Castor fiber). Their dams on rivers may also increase habitat connectivity for terrestrial mammals, but the significance of that function has never been quantified. To investigate this, we placed tracking tunnels on beaver dams, fallen trees, and-as a control-on floating rafts. Additionally, we tested kinetic sand as a novel substrate for collecting tracks and found the paws of small mustelids precisely imprinted in that medium, allowing easy identification. However, we needed to lump all shrews and rodents smaller than water voles (Arvicola amphibius) into one category as they can only be detected but not identified. The highest mammalian activity was observed on dams, as they may provide shelter, offering protection from predators during a river crossing or permanent residence, and even the opportunity to hunt invertebrates. Slightly higher diversity was found on logs because of a higher proportion of mustelids, which select exposed locations for scent marking. Our results increase our body of knowledge about the beaver as an ecosystem engineer and provide a novel tool for the monitoring of mammal activity.

Sewable high-performance poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/layered double hydroxide core-shell fiber electrodes for flexible supercapacitors

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based fibers are one of the most competitive fiber-type electrodes but still suffer from low electrochemical surface areas (ECSAs) and oversensitivity to humidity for fiber supercapacitor applications. Herein, through rational design, a sewable core-shell fiber electrode of PEDOT:PSS/waterborne polyurethane (WPU) fiber wrapped with nickel/cobalt-layered double hydroxides (NiCo-LDH) has been synthesized via wet-spinning and solution reaction. The fiber core acts as a conductive channel for charge carrier transport. The NiCo-LDH shell possesses unique hybrid architectures of honeycomb-like nanosheet array and hollow nanocages, which provide numerous electrochemical active sites. Simultaneously, the water barrier effect of the NiCo-LDH shell and the interaction between Co2+/Ni2+ and PSS reduce fiber water uptake, thus endowing the fiber with a better geometric stability with low swelling ratio. The as-prepared PEDOT:PSS/LDH fiber has a large ECSA (4060 cm2 g−1) and ultrahigh conductivities no matter in dry (1237.3 S cm−1) or wet (1018.7 S cm−1) state. It also exhibits a high capacitance (188.5 F g−1 at 1 A g−1) and long lifespan (capacitance retention of 94% after 10,000 cycles). The fiber-based supercapacitor shows superb flexibility with stable capacitive behavior under deformation. These characteristics manifest the potential of PEDOT:PSS/LDH fibers for stable high-performance energy storage to support wearable electronics.

Development and Characterization of an Edible Zein/Shellac Composite Film Loaded with Curcumin.

The development of functional edible films is promising for the food industry, and improving the water barrier of edible films has been a research challenge in recent years. In this study, curcumin (Cur) was added to zein (Z) and shellac (S) to prepare an edible composite film with a strong water barrier and antioxidant properties. The addition of curcumin significantly reduced the water vapor permeability (WVP), water solubility (WS), and elongation at break (EB), and it clearly improved the tensile strength (TS), water contact angle (WCA), and optical properties of the composite film. The ZS-Cur films were characterized by SEM, FT-IR, XRD, DSC, and TGA; the results indicated that hydrogen bonds were formed among the curcumin, zein, and shellac, which changed the microstructure and improved the thermal stability of the film. A test of curcumin release behavior showed controlled release of curcumin from the film matrix. ZS-Cur films displayed remarkable pH responsiveness, strong antioxidant properties, and inhibitory effects on E. coli. Therefore, the insoluble active food packaging prepared in this study provides a new strategy for the development of functional edible films and also provides a possibility for the application of edible films to extend the shelf life of fresh food.

Effects of co-plasticization of glycerol and small molecular esters on the physicochemical properties of extrusion-blown high-content starch/poly(butylene adipate-co-terephthalate) films.

Poor mechanical and water barrier properties of starch-based films severely restrict their applications as packaging materials. In this study, glycerol was combined with various small molecular esters (SMEs) with different molecular structures to plasticize high-content starch/poly(butylene adipate-co-terephthalate) (80/20, w/w) films (SPFs) prepared by extrusion blowing. The effects of co-plasticization on the physicochemical properties and film-forming mechanism of SPFs were investigated. The addition of glycerides to SPFs reduced intermolecular interaction, increased molecular chain mobility, and decreased glass transition, melting temperatures, and crystallinity. Mechanical and water barrier properties of SPFs were improved significantly with the co-plasticization of glycerol and SMEs. The incorporation of triacetate glyceride increased tensile strength of SPFs by 54% and the water contact angle by up to 95°. The SPF with diacetate glyceride exhibited the minimum water vapor permeability, which decreased by 39%. The levels of hydrophilic/hydrophobic groups in SMEs and their molecular weights were essential for the plasticizing effects. Glycerides tended to infiltrate into starch for effective plasticization compared with citrates. The combination of glycerol and glycerides had better plasticizing effects on starch. © 2023 Society of Chemical Industry.

Effects of types and concentrations of modified Cloisite Clays on properties of chitosan nanocomposites for food packaging

AbstractBiodegradable chitosan has excellent film‐forming properties compared to other biodegradables but also some limitations, such as poor water barrier and low mechanical strength. Thus, in this research, the effects of various types (Cloisite Ca, 15A, 20A, and 30B) and concentrations (0.5, 1, 2.5, and 5 wt%) of Cloisite on barrier, mechanical, structural and thermal properties on chitosan films were investigated. Cloisite was revealed to significantly lower the lightness (L*) depending on the type and concentration of Cloisite. The films containing Cloisite significantly improved oxygen barrier properties by 34.5%–73.6% compared to control, particularly Cloisite 30B. Cloisite 20A and Ca were found to significantly improve the water barrier by up to 84.61%, and Cloisite 20A and 30 B the tensile properties by up to 30%. The chitosan with less Cloisite content exhibited better smoothness and elongation. The dispersed Cloisite clays improved the thermal stability and enhanced the barrier and tensile properties of the chitosan with the increased Cloisite loading.

Hygrothermic Wood Actuated Robotic Hand.

Stimulus-responsive actuators play a vital role in the new generation of intelligent systems. However, poor mechanical performance, complicated fabrication processes, and the inability to complex deformation limit their practical applications. Herein, these challenges are overcome via designing a strong hygrothermic wood actuator with asymmetric water affinity. The actuator is readily constructed by sandwiching polypyrrole-coated wood with a Ni complex hygroscopic gel top layer for moisture absorption and a polyimide bottom layer as the water barrier. The resulting hygrothermic wood spontaneously stretches and bends itself in response to moisture and thermal/light stimulation. A robotic hand and a series of grippers made of hygrothermic wood demonstrate dexterous object-hand interactions during grasping and holding, while the reversible hygrothermic property allows the actuator to be potentially applied in fire rescue scenarios to rescue trapped objects. A combination of good mechanical properties, multi-stimulus-response, complex deformation, wide working temperature range, low manufacturing cost, and biocompatibility are simultaneously realized by one device. It is thus believed that such a strong wood actuator will open up a new avenue for building intelligent robotic hand systems.

Structural and material characterization of quercetin incorporated soy protein isolate films

Owing to their degradability and fair film forming properties, protein films are captivating interest for development of packaging materials. However, poor water barrier properties and low mechanical strength limits its commercial application. Incorporation of additives such as phenolic compounds are reported to overcome these limitations. Our study aimed to explore the effect of quercetin and different processing methods on structural and mechanical properties of soy protein films. In our work, quercetin (flavonoid) was used to improve the material properties of proteinous films. The prepared films were evaluated for their physical properties, mechanical properties and water barrier capacity. The incorporation of quercetin had an obvious influence on the colour of film due to inherent pigmentation nature and resulted in generation of intense brown coloration of modified films. The opacity and cross linking of films were linearly increased with addition of quercetin. The mechanical properties of modified films were improved as indicated by increased tensile strength compared to the unmodified films. The incorporation of quercetin shifted the film towards hydrophilicity as indicated by increased water uptake activity of modified films compared to control films. Quercetin was found to form stable interaction with SPI as there was very little leaching observed from films. The results demonstrated that quercetin holds the potential to enhance the properties of SPI films which could be possibly employed in the development of packaging materials.

Hygrothermal performance optimization of lightweight steel-framed wall assemblies in hot–humid regions using orthogonal experimental design and a validated simulation model

As a layered construction, lightweight steel-framed (LSF) wall assemblies are applicable to different climates and used worldwide. Due to ill-informed construction and material designs, moisture-related durability problems occur, especially in hot–humid areas. Here, a hygrothermal simulation model of typical LSF wall assemblies was validated, and the influences of six construction layers (each with three sets of parameters) on the overall properties and performance were investigated via orthogonal experimental design (OED). Each layer exhibited various impact trends and contribution ratios at different positions. To reduce moisture risks, LSF wall assemblies should generally prevent the infiltration of outdoor moisture as much as possible while strengthening the inward drying capacity. The optimal configuration should comprise multiple water and vapour barriers with a ventilated layer, external insulation, permeable cavity insulation and interior sheathing board with a finish. Finally, this optimization method comprising the hygrothermal simulation and OED techniques could be applied to the hygrothermal performance of LSF wall assemblies under certain climatic conditions.

Influence of MXene, graphene nanoplatelet and multi-walled carbon nanotube on mechanical properties, swelling and flammability behaviour of hybrid sisal/glass fibre reinforced epoxy laminate composites

The research work aims to utilize one of the cheapest and most abundantly available natural fibre, sisal fibre, to fabricate a hybrid nanocomposite possessing high performance efficiency. Glass fibre (GFC), sisal fibre (SFC) and hybrid glass/sisal fibre reinforced epoxy laminate composites (HFC) were prepared and subsequently, three of the most promising nano-fillers, MXene (HFCMXN), Graphene nanoplatelet (HFCGNP) and Multi-walled carbon nanotube (HFCCNT), were added into the hybrid composite. The fabricated composites were comprehensively assessed and analysed for their mechanical properties, swelling and flammability behaviour. It was observed that the glass fibre reinforced composite had lowest void content (6.3%) and glass/sisal fibre reinforced laminate had the highest void content (17.2%). The addition of nano-fillers did not further enhance the void content owing to the relatively uniform dispersion of the nanoparticle, which was particularly ensured during the whole fabrication process. The incorporation of nano-fillers led to a significant enhancement in the mechanical properties; tensile and flexural strength being highest for composites containing two dimensional nano-fillers. The GFC exhibited minimum weight gain (2.25%) and least swelling thickness (1.66%) upon soaking. Among hybrid composites, nano-filler reinforced composites had relatively less weight gain post in comparison to the hybrid composite without any nano-filler. HFCGNP had a weight gain of 6.69%, as opposed to 8.51% observed in case of HFC. The nano-fillers acted as an effective water barrier that reduced the tendency of water absorption. Furthermore, upon flammability test it was found that the burning rate decreased in order of GFC, HFC, HFCCNT, HFCMXN, HFCGNP and SFC. The addition of nano-fillers led to a decrease in the burning rate owing to the promising flame retardant properties of graphene which suppressed flame propagation and helped in extinguishing the flame.

Effect of Beeswax on hydrophobicity, moisture resistance and transparency of UV curable linseed oil based coating for compostable paper packaging

Compostable bio-sourced moisture barrier coating is among the most emerging material alternative to non-degradable single use plastics liner in paper packaging applications. In the current work, highly unsaturated linseed oil is epoxidized and acrylated to form UV curable bio-acrylate resin (Acrylated Linseed Oil) to be used as bio-coating material for paper substrate to improve its barrier properties. Beeswax has been proposed as an excellent barrier to water vapour permeability, the hydrophobicity being imparted by esters of long chain fatty alcohols, acids and long chain alkanes present within. Beeswax is incorporated into AELO resin to enhance the water and moisture barrier property of the coating due to its hydrophobicity and food compatibility. The addition of beeswax has significantly reduced the Water Vapour Transmission Rate (WVTR) to 20 g/m2.day.atm while improving the Water Contact Angle (WCA) to 111° for 10 wt% beeswax loading. Further, the WCA remains above 90° even after 50 cycles of abrasion revealing the durability of the coating. The hydrophobicity is further reinstated by the SEM images which show microscale roughness imparted by uniformly dispersed beeswax. Beeswax thus improves hydrophobicity both by virtue of its composition and the surface roughness imparted. Improved transparency (>95% UV–vis transmittance), higher thermal stability (T5 >250 °C, T10 >300 °C), and reasonable glass transition temperature of the bio-coatings reveals its wide application in the field of packaging. The compostability of the coating in soil and paper repulpability after removal of the coating, both explored its potential in paper-based food packaging by replacing single use plastics.

An electron-hole rich dual-site nickel catalyst for efficient photocatalytic overall water splitting

Photocatalysis offers an attractive strategy to upgrade H2O to renewable fuel H2. However, current photocatalytic hydrogen production technology often relies on additional sacrificial agents and noble metal cocatalysts, and there are limited photocatalysts possessing overall water splitting performance on their own. Here, we successfully construct an efficient catalytic system to realize overall water splitting, where hole-rich nickel phosphides (Ni2P) with polymeric carbon-oxygen semiconductor (PCOS) is the site for oxygen generation and electron-rich Ni2P with nickel sulfide (NiS) serves as the other site for producing H2. The electron-hole rich Ni2P based photocatalyst exhibits fast kinetics and a low thermodynamic energy barrier for overall water splitting with stoichiometric 2:1 hydrogen to oxygen ratio (150.7 μmol h−1 H2 and 70.2 μmol h−1 O2 produced per 100 mg photocatalyst) in a neutral solution. Density functional theory calculations show that the co-loading in Ni2P and its hybridization with PCOS or NiS can effectively regulate the electronic structures of the surface active sites, alter the reaction pathway, reduce the reaction energy barrier, boost the overall water splitting activity. In comparison with reported literatures, such photocatalyst represents the excellent performance among all reported transition-metal oxides and/or transition-metal sulfides and is even superior to noble metal catalyst.

Effect of mastic gum integration on improvement of polylactic acid biodegradable films

AbstractCurrently, 90% of all packaging films are composed of non‐renewable, petroleum‐based materials. However, these materials have a significant environmental footprint. Polylactic acid (PLA) is a well‐known biodegradable thermoplastic polymer. However, the use of PLA poses some inherent challenges, like the brittleness of PLA films. For this study, with the objective of overcoming the shortcomings of PLA films, mastic gum (MG), which is an under‐utilized hydrophobic polymer, was incorporated into PLA, and the resultant films were characterized for their chemical (x‐ray diffraction [XRD], Fourier‐transform infrared [FTIR]), thermal (thermogravimetric analysis [TGA], dynamic mechanical analysis [DMA]), optical (optical microscope, color, and opacity), and barrier properties (water vapor permeability [WVP]). MG addition yielded films with much higher opacities and decreased WVPs up to 80%. Optical microscope images revealed the presence of some defects for films with MG concentrations above 1% g/g solvent, which also decreased the film's tear resistance. Glass transition temperature (Tg) values are reduced with MG addition, resulting in less rigid films at room temperature. In the end, MG incorporation yielded more flexible films with much better water barrier properties. In addition, all other properties of the films were drastically modified with MG addition. Hence, MG/PLA is demonstrated to be a promising biopolymer combination for the preparation of biodegradable films as a food packaging material.

Fully biodegradable, hydrophobic, enhanced barrier starch bio-composites with sandwich structure by simulating wood

Through a single-sided cavity free-form foaming process, composites with open cell structures similar to wood cells were obtained by using corn starch, pulp fiber, and sisal fibers, which was used as the middle layer of the sandwiched composites. Afterwards, more hydrophobic lignin-containing nanocellulose fibrils from pine bark were coated on the surfaces of the open cell composites by high-pressure gun spraying, simulating the bark of wood to impart barrier property to the final product. The water barrier, mechanical property, apparent density, heat insulation, and biodegradability of the sandwich structured bio-composites were characterized. Experimental results indicated that the water contact angle on the surface of the bio-composite was as high as 92°. The apparent density of the bio-composite was very low, at 0.107 g/cm3. The tensile strength of the bio-composites reached 5.3 MPa. After conducting biodegradability tests in soil for 60 days, the bio-composites lost 87 % of its mass.

Antimicrobial Nano-Zinc Oxide Biocomposites for Wound Healing Applications: A Review

Chronic wounds are a major concern for global health, affecting millions of individuals worldwide. As their occurrence is correlated with age and age-related comorbidities, their incidence in the population is set to increase in the forthcoming years. This burden is further worsened by the rise of antimicrobial resistance (AMR), which causes wound infections that are increasingly hard to treat with current antibiotics. Antimicrobial bionanocomposites are an emerging class of materials that combine the biocompatibility and tissue-mimicking properties of biomacromolecules with the antimicrobial activity of metal or metal oxide nanoparticles. Among these nanostructured agents, zinc oxide (ZnO) is one of the most promising for its microbicidal effects and its anti-inflammatory properties, and as a source of essential zinc ions. This review analyses the most recent developments in the field of nano-ZnO-bionanocomposite (nZnO-BNC) materials-mainly in the form of films, but also hydrogel or electrospun bandages-from the different preparation techniques to their properties and antibacterial and wound-healing performances. The effect of nanostructured ZnO on the mechanical, water and gas barrier, swelling, optical, thermal, water affinity, and drug-release properties are examined and linked to the preparation methods. Antimicrobial assays over a wide range of bacterial strains are extensively surveyed, and wound-healing studies are finally considered to provide a comprehensive assessment framework. While early results are promising, a systematic and standardised testing procedure for the comparison of antibacterial properties is still lacking, partly because of a not-yet fully understood antimicrobial mechanism. This work, therefore, allowed, on one hand, the determination of the best strategies for the design, engineering, and application of n-ZnO-BNC, and, on the other hand, the identification of the current challenges and opportunities for future research.

Construction and Performance of Superhydrophobic Surfaces for Rusted Iron Artifacts

Ancient iron artifacts need to be protected with a rust layer, often stabilized by tannic acid corrosion inhibition. In humid environments, water vapor could slowly penetrate and trigger galvanic corrosion of metal artefacts. Sealing treatments are generally applied to the artefact surface to isolate water and enhance its corrosion resistance. Superhydrophobic modifications could effectively block the penetration of moisture into the interior of the artefact and provide a nice water barrier. Stearic acid with tannic acid inhibition treatment creates a superhydrophobic protective layer on the surface of rusted iron artifacts and enhances corrosion resistance effectively. Various scientific analyses and testing methods are used in this paper to evaluate the corrosion resistance of rusted surfaces after superhydrophobic modification and investigate the reaction mechanisms. The results indicate that the contact angle of the rusted surface after corrosion inhibition by tannic acid and modified by stearic acid is increased to 152.2°, which means the superhydrophobic protective layer has been successfully constructed. The C/Fe ratio of the rusted surface is increased from 0.21 to 2.10, and the characteristic diffraction peaks of O1s and Fe 2p3/2 shift toward higher binding energy. Stearic acid is combined with the corrosion product layer by chemical bonding. Chelation between rust products, tannic acid, and steric acid is effective, and the chelate is chemically stable. The superhydrophobic surface forms a lamellar wax-like layer as an air barrier to isolate liquid water, resulting in a significant decrease in corrosion current and an increase in Warburg impedance to 217.9 times the original state, with a protection efficiency of 88.3%. Tannic acid corrosion inhibition and stearic acid superhydrophobic modification have an excellent synergistic protective effect on improving the corrosion resistance of iron artifacts, resulting in better corrosion resistance of iron artifact materials. The research provides new ideas and references for the protection of ancient iron artifacts sealing.