Adhesive Layer Research Articles

Direct Measurement of the Diffusion Coefficient of Adhesives from Moisture Distribution in Adhesive Layers Using Near-Infrared Spectroscopy.

In this study, we used near-infrared spectroscopy to measure the moisture penetration in epoxy adhesives and investigated the difference in the diffusion coefficients between the bulk and the adhesive layer. Moisture diffusion was evaluated under 100% RH and water immersion conditions. First, the effects of the curing agents and additives on moisture diffusion in the bulk were gravimetrically evaluated using epoxy-coated quartz glass plates. Different diffusion behaviors were observed depending on the curing agent used. The presence of additives resulted in higher diffusion coefficients, whereas the overall moisture content was low. Next, the moisture distribution in the adhesive layer was visualized using a specimen sandwiched between the quartz glass plates, and the diffusion coefficient of the adhesive layer was calculated. The diffusion coefficient in the adhesive layer was larger than that in the bulk. For adhesives cured with hydrophobic diamine, the diffusion coefficient within the adhesive layer increased by approximately 1.5 times compared with that in the bulk, regardless of the exposure environment. The adhesive, composed of a resin, Dicyandiamide, and additives, showed a 2-fold increase in the diffusion coefficient under high-humidity exposure conditions but no significant change under the water immersion condition. Therefore, these results suggest that, for an accurate analysis of moisture distribution, it is important to measure the diffusion coefficient of the adhesive layer directly rather than using the diffusion coefficient of the material itself.

Effects of nanoceramic particle size and content on the wear resistance of micro-arc oxidation coatings for 2A12 aluminum alloy

The 2A12 aluminum alloy, renowned for its exceptional mechanical properties, encounters significant limitations in applications involving abrasive environments or frequent contact with other surfaces due to its inadequate wear resistance. This shortcoming substantially reduces the service life of components and escalate maintenance costs, highlighting the urgent need for advanced surface modification techniques. This study meticulously investigates the influence of nanoceramic particle size and content on the wear resistance of micro-arc oxidation (MAO) coatings, a surface modification technique renowned for forming dense, adherent ceramic layers on aluminum alloys. The systematic experimentation revealed that the incorporation of 150 nm α-Al2O3 nanoparticles into the MAO matrix achieves an optimal dispersion, leading to a substantial enhancement in wear resistance. The sample with a 5 g/L concentration of 150 nm α-Al2O3 nanoparticles doping in the MAO electrolyte demonstrated the lowest mass loss, underscoring its enhanced wear resistance. The enhanced microstructure, enriched with hard ceramic phases such as α-Al2O3 and mullite, plays a pivotal role in withstanding wear. Moreover, this study identified that an optimal balance of surface roughness and coating thickness is essential for achieving enhanced wear resistance. The findings of this research provide a strategy for the design of wear-resistant coatings tailored for high-performance applications across aerospace, automotive, and general engineering industries. By optimizing the particle size and concentration in MAO coatings, this study paves the way for the development of durable materials capable of thriving in demanding environments, thereby extending the service life and reducing maintenance requirements of components.

FE-based machine learning model for predictive damage assessment in bonded composite joints via acoustic emission

This study systematically evaluated the mechanical performance of bonded composite single-lap joints with varying overlap lengths under tensile load. By integrating Acoustic Emission (AE) signals with Finite Element (FE) modeling, this study established a predictive machine learning model to enhance the understanding and prediction of failure mechanisms. Firstly, AE signal features were extracted and utilized as inputs for a hierarchical clustering model to classify AE signals into matrix cracking, fiber breakage, and adhesive debonding. AE signals classified as adhesive debonding were further analyzed by accumulating counts, amplitude, and energy. A cohesive zone-based Finite Element (FE) model was developed to simulate progressive debonding damage in the adhesive layer. After calibration with experimental results, various physical quantities such as stress, the damage initiation indicator, and the stiffness degradation indicator were extracted for correlation analysis. The experiments and simulations unravel the missing relationship between the AE and FE data. A strong correlation was observed between the cumulative count and cumulative amplitude with the damage initiation indicator, and between cumulative energy with the damage propagation indicator. Finally, based on the disclosed relationship between AE and FE data, a Support Vector Regression (SVR) model was established to predict the damage indicator. The developed model accurately predicted testing datasets within low absolute error ranges, underscoring its high predictive accuracy. Comprehensive stress analysis proposed a quantitative damage initiation indicator of 0.32 for structural fractures and a damage indicator of 0.12 for allowable stress levels. Consequently, combining AE techniques with FE modeling provided an effective tool for evaluating damage evolution in bonded composite joints.

Strain measurement of CFRP-Steel bonded joints using distributed optical fibre sensors

ABSTRACT Externally bonded carbon fibre reinforced polymer (CFRP) is widely employed for strengthening steel structures. The CFRP-steel bond behaviour is typically conducted using the single-lap joint (SLJ) and double-lap joint (DLJ) shear tests. This study utilizes advanced distributed optical fibre sensors (DOFS) to measure strains in CFRP-steel SLJs and DLJs, with a specific focus on examining the bending effect. An experimental investigation was conducted to verify the appropriate adhesive and fibre coating materials, achieving synergistic deformation between optical fibre sensors and adherends. The strain results reveal that PI-coated fibres bonded with epoxy resin enhance deformation compatibility. The CFRP strain distributions within the joints are accurately measured by DOFS, enabling the calculation of bending strain to assess joint bending effects. The observed strain aligns well with the finite element (FE) predictions. A more significant bending effect is observed in SLJs compared to DLJs, predominantly concentrated at the loaded end. It can be inferred that the SLJs are subjected to mixed-mode I/II loading in shear tests, and the DLJs appears to be mainly influenced by mode II loading. Additionally, the verified FE model demonstrates that the shear strain across the thickness of the adhesive layer exhibits significant variation at the bond ends.

Impact of plasma treatment of Au electrodes on response of EIS biosensors used in aquaculture pathogen detection

This study examines the effect of plasma treatment on gold electrodes used in construction of biosensors. Plasma treatment aims to improve the adhesion of bioreceptor layers, enhancing sensor performance. Gold substrates were exposed to plasma for different durations, and their reactivity was analyzed using electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Results show that plasma treatment significantly enhances the hydrophilicity of gold surfaces, leading to better formation of bioreceptor layer. Optimal treatment duration was found to be around 60 s, beyond which improvements in impedance values diminished. Plasma-treated electrodes displayed superior bioreceptor adhesion without altering surface topography. In conclusion, plasma treatment improves biosensor performance by enhancing bioreceptor layer adhesion. Integrating this process into biosensor production can lead to more efficient and reliable pathogen detection in aquaculture, promoting healthier aquatic environments and sustainable food production.

Repairability of rubber-backed vitrimer composites under variations of impact damage

This study evaluates the effectiveness of rapid heat pressing repair on composites made of vitrimer matrix, a reshapable and recyclable polymer, subjected to varying degrees of impact damage. Two types of composites were fabricated for impact testing: randomly oriented glass fiber reinforced vitrimers (GFRV) and woven carbon fiber reinforced vitrimers (CFRV). Izod pendulum impact tests were conducted on samples along both the thickness and width. Impacts with varying energy levels were applied to induce different degrees of damage, allowing for the assessment of impact strength degradation and repair effectiveness. Additionally, a rubber adhesive layer was applied to the back of composites to quantitatively measure the increase in energy absorption and its effect on repair performance. The findings demonstrate the potential of rapid heat pressing repair in restoring the mechanical integrity of vitrimer composites and highlight the influence of a rubber adhesive layer in enhancing energy absorption and repair efficacy.

Atomic Layer Deposition of Nickel Using Ni(dmamb)2 and ZnO Adhesion Layer Without Plasma

In this study, a novel deposition technique that utilizes diethylzinc (C4H10ZnO) with H2O to form a ZnO adhesion layer was proposed. This technique was followed by the deposition of vaporized nickel(II) 1-dimethylamino-2-methyl-2-butoxide (Ni(dmamb)2) and H2 gas to facilitate the deposit of uniform layers of nickel on the ZnO adhesion layer using atomic layer deposition. Deposition temperatures ranged from 220 to 300 °C. Thickness, composition, and crystallographic structure results were analyzed using spectroscopic ellipsometry, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), respectively. An average growth rate of approximately 0.0105 angstroms per cycle at 260 °C was observed via ellipsometry. Uniform deposition of ZnO with less than 1% of Ni was displayed by utilizing the elemental analysis function via SEM, thereby providing high-quality images. XPS revealed ionizations consistent with nickel and ZnO through the kinetic and binding energies of each detected electron. XRD provided supplemental information regarding the validity of ZnO by exhibiting crystalline attributes, revealing the presence of its hexagonal wurtzite structure.

Non-destructive testing for thickness measurement of the adhesive layer and defect detection in ceramic-metal bonded structures using THz waves

Ceramics, owing to their superior thermal barrier properties, are employed by bonding them to primary structures exposed to elevated temperatures, such as the external components of aircraft and spacecraft. However, when these bonded structures are subjected to thermal impact resulting from high-temperature environments or rapid temperature variations, issues such as debonding, crack formation, and degradation may ensue. These issues can significantly undermine the reliability of the structures, necessitating nondestructive testing (NDT) to monitor the condition of the adhesive layer before and after thermal impact. In this article, we evaluated the integrity of adhesive structures before and after thermal impact using Terahertz (THz) waves, which offer exceptional penetration and resolution for NDT of nonmetallic materials without causing damage to the structure. To achieve this, ceramic-metal bonded structures were mounted on a robotic arm, and scanning was performed over a 70 mm area at 1 mm intervals and 0.5° increments. The peak-to-peak time of the THz signal through the adhesive layer was calculated to determine the thickness distribution. Based on experimental results, the average thickness of the ceramic layer before thermal shock was measured at 9.48 mm (standard deviation: 0.03) and the average thickness of the adhesive layer was 0.234 mm (standard deviation: 0.03). Additionally, four suspected defect areas within the adhesive layer were identified. After thermal shock, the ceramic layer’s thickness decreased by an average of 0.02 mm (0.17%), resulting in an average thickness of 9.46 mm, and the adhesive layer’s thickness decreased by an average of 0.002 mm (0.99%), resulting in an average thickness of 0.232 mm. The four suspected defect areas were confirmed to be in the same locations before thermal impact. To validate the NDT method using THz wave, the ceramic-metal bonded structure was cut to identify debonding defects in the suspected areas. The difference between the thickness distribution obtained using the THz wave-based NDT and that measured using optical microscopy after cutting was 4.4%, confirming the accuracy of the THz wave-based method for defect detection and thickness measurement.

Bioinspired Asymmetric-Adhesion Janus Hydrogel Patch Regulating by Zwitterionic Polymers for Wet Tissues Adhesion and Postoperative Adhesion Prevention.

Asymmetrically adhesive hydrogel patch with robust wet tissue adhesion simultaneously anti-postoperative adhesion is essential for clinical applications in internal soft-tissue repair and postoperative anti-adhesion. Herein, inspired by the lubricative role of serosa and the underwater adhesion mechanism of mussels, an asymmetrically adhesive hydrogel Janus patch is developed with adhesion layer (AL) and anti-adhesion layer (anti-AL) through an in situ step-by-step polymerization process in the mold. The AL exhibits excellent adhesion to internal soft-tissues. In contrast, the anti-AL demonstrated ultralow fouling property against protein and fibroblasts, which hinders the early and advanced stages of development of the adhesion. Moreover, the Janus patch simultaneously promotes tissue regeneration via ROS clearance capability of catechol moieties in the AL. Results from in vivo experiments with rabbits and rats demonstrate that the AL strongly adheres to traumatized tissue, while the anti-AL surface demonstrate efficacy in preventing of post-abdominal surgery adhesions in contrast to clinical patches. Considering the advantages in terms of therapeutic efficacy and off the shelf, the Janus patch developed in this work presents a promise for preventing postoperative adhesions and promoting regeneration of internal tissue defects.

Additive Manufacturing of Waste Electrical and Electronic Equipment (WEEE) Produced From Acrylonitrile Butadiene Styrene (ABS)

Objective: To evaluate the feasibility of producing recycled acrylonitrile-butadiene-styrene (r-ABS) filaments from waste electrical and electronic equipment (W EEE) casings, specifically discarded monitors and televisions, and to compare their properties with those of virgin ABS. Theoretical Framework: The research was based on a literature review of additive manufacturing, WEEE recycling, and the thermal, mechanical, rheological, and microscopic characterizations of recycled polymers, with an emphasis on fused deposition modeling (FDM). Method: WEEE casings were collected and mechanically recycled to produce r-ABS filaments. These filaments were characterized and compared with virgin ABS filaments using infrared spectroscopy (FTIR), thermal analyses (TGA and DSC), rheological, mechanical, and microscopic evaluations. Results and Conclusion: The results indicated that r-ABS filaments exhibit properties comparable to those of virgin ABS. FTIR analysis revealed the presence of the main functional groups of ABS in the recycled samples. Thermal analysis showed similar behavior between the recycled and virgin materials, with a single thermal decomposition event. Rheological analysis demonstrated that r-ABS possesses viscoelastic properties suitable for the FDM process, and mechanical characterization showed that r-ABS exhibited tensile strength close to virgin ABS. Microscopic analysis revealed good layer adhesion and a low number of voids, factors that contribute to the quality of the printed objects. Research Implications: This study contributes to the valorization of polymeric waste, promoting the use of recycled materials in additive manufacturing processes, which can benefit both the environment and the 3D printing industry. Originality/Value: The research addresses a topic still underexplored in the literature, especially concerning the recycling of WEEE casings for the production of ABS filaments.

Parameters Tailoring on the Deposition of Hydroxyapatite by Pulsed Electrical Discharge.

The creation of strong adhesive layers of hydroxyapatite-based bioceramics (with or without bioinert metals, such as Ta, Ag, and Ti) on biocompatible metallic supports enhances the local biofunctionalization of surfaces. The processing of electroconductive materials using electrical impulse discharges is versatile, enabling precise coating of selected areas with perfectly adherent layers of varying thicknesses. This study aims to quantify the effects of varying the electrical power from the source generating the impulse discharge and the specific processing time per unit area of the cathode (made of titanium alloy) on the relative mass increase of the cathode. The anode comprised a mixture of hydroxyapatite powder and a self-polymerizing electroconductive acrylic resin in a tantalum sheath. The effects of the parameter adjustments on single-layer deposition adherence were quantified using a central composite design to build a second-order orthogonal model. The most significant difference in relative mass was observed with a low-power source (5 W) ensuring the electrical discharge impulse, combined with the longest specified surface treatment time (17.5 s/cm2 on a 4 cm2 surface) for a single layer presenting the largest mass increase of 0.153% of the original mass. This study aimed to enhance the performance of medical implants by optimizing surface biofunctionalization through robust hydroxyapatite-based bioceramic adhesive layers on metallic supports, determining the optimal electrical power and processing time for cathode mass increase during deposition processes, and analyzing parameter adjustments using second-order statistical orthogonal central composite programming, with a focus on single-layer deposition to identify significant differences in relative mass under specific conditions.

As-deposited and dewetted Cu layers on plasma treated glass: Adhesion study and its effect on biological response

Improving the adhesion of nanosized copper films to a glass substrate is vital for their application in electronics and medicine, as it enhances their overall reliability. For this purpose, we employed Ar plasma etching (240 s) and magnetron sputtering to create copper layers on a glass substrate. Furthermore, we investigated the effect of subsequent solid state dewetting (at 300 °C) of Cu nanolayers on the interface stability. Increasing the sputtering time resulted in elevated copper concentration, UV-Vis absorption, conductivity, and surface roughness. The as-deposited and dewetted samples exhibited very good wettability with water contact angles below 60°. Importantly, plasma treatment improved the adhesion of the Cu layers to the glass. Subsequent dewetting accelerated surface diffusion and the oxidation of Cu atoms, causing structural and morphological changes. The presence of CuO after dewetting caused loss of the surface plasmon resonance (SPR) band in the UV-Vis spectrum and a decrease in sample conductivity due to the transformation of the copper layer from a metal to an oxide. Biological testing revealed a more pronounced bactericidal effect for the as-deposited Cu layer against E. coli and S. epidermidis on contrary to dewetted samples. The similar cytotoxic trend was observed for human dermal fibroblasts and hepatocytes. Nonetheless, biological testing confirmed better cell adhesion on dewetted Cu layers compared to the as-deposited ones. Therefore, our copper nanostructured samples could find application as antibacterial coatings of biomedical devices.

Interface mechanical properties of CFRP-seawater sea sand concrete under simulated seawater immersion

In this study, the interfacial mechanical properties of carbon fiber-reinforced polymer (CFRP) sheet reinforced seawater sea sand concrete (SSSC) in simulated seawater immersion environment were studied. The results present that the interface bearing capacity of CFRP-SSSC decreases significantly after seawater immersion. The decreasing rate increases greatly with the extending of immersion periods. Seawater immersion also affects the failure mode of interface between CFRP and SSSC, which leads to the damaged surface expanding from the base layer of concrete to the junction section of resin and aggregate. The distribution of strain and stress along the bonding direction presents the load transfer from the loading end to the free end. The shear stress peak locates near the loading end and decreased about 15–20 % due to seawater immersion as a result of the deterioration of the interfacial property. The analysis on the microstructure of CFRP-SSSC interface proves that the chemical ions in seawater causes the hydrolyzation of epoxy resin adhesive layer. The CFRP-SSSC interface presents a lower interfacial bonding properties than CFRP reinforced normal concrete (NC). The improvement of strength grade of concrete from C30 to C50 increases the bonding properties of the CFRP about 9–12 % and mitigates the influence of seawater immersion. The obtained bond-slip curve indicates that the seawater immersion decreases the interface ductility. A modified Popovics model is applied to predict the bond-slip curve and presents a high fitting degree.

Effect of ultra high-performance concrete thickness on the mechanical behavior of orthotropic steel bridge deck

Orthotropic steel bridge decks structures (OSBDs) have been widely used in long-span bridges to reduce the dead load of the bridge. However, over time, the asphalt wearing course of the bridge deck structure has shown many damages. Recently, ultra-high-performance concrete (UHPC) has been employed to repair and reinforce these structures. Therefore, this paper focuses on the effect of UHPC thickness on the mechanical behavior of the orthotropic deck. The five-point bending beam test model using the finite element method is used in this investigation to clarify the effect of UHPC thickness, the ratio of adhesion failure, and temperature on the mechanical behavior of the OSBDs. The UHPC thickness varies from 30 to 50 mm, the ratio of adhesion failure varies from 0.1 to 0.3, and the temperature changes from 30°C to 60°C. The results show that the presence of the UHPC layer significantly reduces the impact of adhesive layer damage and temperature on the behavior of the OSBDs

A Janus hydrogel that enables wet tissue adhesion and resists abdominal adhesions

Hydrogels have indeed achieved significant advancements, yet their clinical translation has been hampered by their inherent limitations in wet adhesion properties. Furthermore, the design of adhesive hydrogels that can resist postoperative adhesions remains an intricate challenge. In this study, we introduce a Janus hydrogel (JGP) that offers a novel approach to address these challenges. The JGP hydrogel has two asymmetrical sides, consisting of an adhesion layer (AL) and an anti-adhesion layer (AAL). Specifically, the AL incorporates three key components: N-[tris(hydroxymethyl)methyl]acrylamide (THMA), acrylic acid (AAc), and the acrylic acid N-hydroxysuccinimide ester (AAc-NHS). By drying the AL, it has a rapid water absorption capability. The abundance of hydroxyl and carboxyl groups in the AL enables the formation of robust hydrogen bonds with tissues, thereby achieving superior adhesive properties. Additionally, the synergistic effect of THMA's tridentate hydrogen bonding and the covalent bonding formed by AAc-NHS with tissue ensures long-lasting wet adhesion. To realize the anti-adhesion function, one side of the AL was immersed in a solution of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), which undergoes crosslinking to form the AAL. A comprehensive series of tests have confirmed that the JGP hydrogel exhibits exceptional mechanical properties, efficient and enduring adhesion, excellent biocompatibility, and degradability. Moreover, it possesses remarkable hemostatic properties and robust anti-abdominal adhesion characteristics.

Ultrasensitive Flexible Strain Sensor Made with Carboxymethyl-Cellulose-Anchored Carbon Nanotubes/MXene for Machine-Learning-Assisted Handwriting Recognition.

The combination of wearable sensors with machine learning enables intelligent perception in human-machine interaction and healthcare, but achieving high sensitivity and a wide working range in flexible strain sensors for signal acquisition and accurate recognition remains challenging. Herein, we introduced carboxymethyl cellulose (CMC) into a carbon nanotubes (CNTs)/MXene hybrid network, forming tight anchoring among the conductive materials and, thus, bringing enhanced interaction. The silicone-rubber-encapsulated CMC-anchored CNTs/MXene (CCM) strain sensor exhibits an excellent sensitivity (maximum gauge factor up to 71 294), wide working range (200%), ultralow detection limit (0.05%), and outstanding durability (over 10 000 cycles), which is superior to most of the recently reported counterparts also based on a conductive composite film. Moreover, the sensor achieves seamless integration with human skin with the help of a poly(acrylic acid) adhesive layer, successfully obtaining stable and clear waveforms with meaningful profiles from the human body. On this basis, we proposed and realized a novel in-air handwriting recognition method via extracting multiple features of high-quality strain signals assisted by deep neural networks, achieving a high classification accuracy of 98.00 and 94.85% for Arabic numerals and letters, respectively. Our work provides an effective approach for significantly improving strain sensing performance, thereby facilitating innovative applications of flexible sensors.

Experimental study on combustion characteristics of engineered bamboo considering smoldering and self-extinction

Bamboo and wood materials have the characteristics of low carbon and high strength, making them the best building material for building green buildings. Compared to traditional building materials, the easy to burn characteristic has become an obstacle to the promotion and widespread application of bamboo and wood materials, so it is urgent to study their combustion characteristics. This article investigated the combustion characteristics of engineered bamboo at different heat fluxes, taking into account the smoldering and self-extinction characteristics through cone calorimeter experiments. The combustion performance, mass loss rate, heat release rate, etc. were studied, and the self-extinction phenomenon of the specimens was explored. The results indicated that the direction of heating had a certain impact on the combustion characteristics of glued laminated bamboo (LBL), and the fire resistance of parallel strand bamboo (PSB) was better than that of LBL. When the heat flux exceeded 50 kW/m2, the color of the flame on the surface of the specimen would change from bright yellow to strong orange, which is an important sign that the flame will self-extinguish. The self-extinction of flames at different heat fluxes was caused by insufficient supply of combustible gas generated by bamboo pyrolysis, with slightly different specific reasons. The multi-layer structure of glued laminated bamboo also makes it more difficult to self-extinguish than PSB, cross-laminated timber (CLT), and solid wood is the most prone to self-extinguish. The impact of adhesive layer delamination was not considered in this experiment, and further research is needed.

Enhanced anti-icing performance of novel superhydrophobic F-L@KH-SiO2/OTMS coating synergistic preparation with bionic micro-nano structures and modified nanoparticles

Surface icing significantly impacts equipment operation and safety in low-temperature environments. Passive de-icing technologies using superhydrophobic materials are gaining attention for their environmental and cost benefits. This study presents a novel superhydrophobic F-L@KH-SiO2/OTMS coating, fabricated through femtosecond laser etching of aluminum alloy to create bionic micro-nano lattice structures. Subsequently, a hydrophobic epoxy coating was sprayed as an adhesive layer, followed by chemical modification of the ablated aluminum alloy surface using 3-(trimethoxysilyl) propyl methacrylate (KH570) modified silicon dioxide (SiO2) nanoparticles, γ-aminopropyltriethoxysilane (KH550), and octadecyltrimethoxysilane (OTMS) as hydrophobizing agents. The resulting coating exhibits excellent superhydrophobic properties, with a contact angle (CA) of 165.92° and a sliding angle (SA) of only 1.25°. The coating demonstrated superior anti-adhesion and bouncing capabilities, effectively preventing droplet freezing and ice formation, which is attributed to the synergistic effect of the modified silica and the cross-linked lattice structure. Compared to other reported superhydrophobic surfaces, this coating showed a longer freezing delay time of 730 s at −20 °C. These findings highlight the potential of the F-L@KH-SiO2/OTMS coating for efficient anti-icing, de-icing, and defrosting applications.

An Environmentally Stable, Biocompatible, and Multilayered Wound Dressing Film with Reversible and Strong Adhesion.

Reversible adhesives for wound care improve patient experiences by permitting reuse and minimizing further tissue injury. Existing reversible bandages are vulnerable to water and can undergo unwanted deformation during removal and readdressing procedures. Here, a biocompatible, multilayered, reversible wound dressing film that conforms to skin and is waterproof is designed. The inner layer is capable of instant adhesion to various substrates upon activation of the dynamic boronic ester bonds by water; intermediate hydrogel layer and outer silicone backing layer can enhance the dressing's elasticity and load distribution for adhesion, and the silicone outer layer protects the dressing from exposure to water. The adhesive layer is found to be biocompatible with mouse skin. Skin injuries on the mouse skin heal more rapidly with the film compared to no dressing controls. Evaluations of the film on skin of freshly euthanized minipigs corroborate the findings in the mouse model. The film remains attached to skins without delamination despite subjecting to various degrees of deformation. Exposure to water softens the film to allow removal from the skin without pulling any hair off. The multilayered design considers soft mechanics in each layer and will offer new insights to improve wound dressing performance and patient comfort.

Carbon Nitride Nanosheets as an Adhesive Layer for Stable Growth of Vertically-Ordered Mesoporous Silica Film on a Glassy Carbon Electrode and Their Application for CA15-3 Immunosensor.

Vertically ordered mesoporous silica films (VMSF) are a class of porous materials composed of ultrasmall pores and ultrathin perpendicular nanochannels, which are attractive in the areas of electroanalytical sensors and molecular separation. However, VMSF easily falls off from the carbonaceous electrodes and thereby impacts their broad applications. Herein, carbon nitride nanosheets (CNNS) were served as an adhesive layer for stable growth of VMSF on the glassy carbon electrode (GCE). CNNS bearing plentiful oxygen-containing groups can covalently bind with silanol groups of VMSF, effectively promoting the stability of VMSF on the GCE surface. Benefiting from numerous open nanopores of VMSF, modification of VMSF's external surface with carbohydrate antigen 15-3 (CA15-3)-specific antibody allows the target-controlled transport of electrochemical probes through the internal silica nanochannels, yielding sensitive quantitative detection of CA15-3 with a broad detection range of 1 mU/mL to 1000 U/mL and a low limit of detection of 0.47 mU/mL. Furthermore, the proposed VMSF/CNNS/GCE immunosensor is capable of highly selective and accurate determination of CA15-3 in spiked serum samples, which offers a simple and effective electrochemical strategy for detection of various practical biomarkers in complicated biological specimens.