Composite Surface Research Articles

Wetting of soap bubbles on topographic surfaces

HypothesisThere is a relationship between the static contact angle of droplets and soap bubbles on flat homogeneous surfaces, therefore, it should be possible to derive a relationship between the static contact angle of a soap bubble on a periodic topographic surface and a droplet on a flat homogeneous surface. ExperimentsA free energy model of the static contact angle of soap bubbles on a topographic surface in the Cassie-Baxter state was derived. Polydimethylsiloxane surfaces of varying area fraction (0.125, 0.250, 0.500, 0.750, and 1.00) and periodic topographies (lined and pillared) were fabricated using 3D printed moulds for pattern transfer. A bubble goniometer was developed to accommodate bubbles of 40,000 ± 5,000 mm3 and 50,000 ± 5,000 mm3 volumes. Then, the static contact angle of bubbles of both volumes were measured on the varying topographic surfaces. FindingsThe derived predictions imply that the relationship between the static contact angle for bubbles on a flat homogeneous surface and on a composite surface, has the same form as the Cassie-Baxter equation for a droplet. The experimental results for the measured static contact angle for both bubble volumes on the varying surfaces had good agreement with the predicted trends.

Ambiently Rapid Response and High Selectivity to NO₂ Enabled by Pd-rGO Composite Film-Coated Surface Acoustic Wave Sensor

Ambiently Rapid Response and High Selectivity to NO₂ Enabled by Pd-rGO Composite Film-Coated Surface Acoustic Wave Sensor

Polydopamine-assisted smart bacteria-responsive hydrogel: Switchable antimicrobial and antifouling capabilities for accelerated wound healing

IntroductionWound infections and formation of biofilms caused by multidrug-resistant bacteria have constituted a series of wound deteriorated and life-threatening problems. The in situ resisting bacterial adhesion, killing multidrug-resistance bacteria, and releasing dead bacteria is strongly required to supply a gap of existing sterilization strategies. ObjectivesThis study aims to present a facile approach to construct a bacteria-responsive hydrogel with switchable antimicrobial-antifouling properties through a “resisting-killing-releasing” method. MethodsThe smart bacteria-responsive hydrogel was constructed by two-step immersion strategy: a simple immersion-coating process to construct Polydopamine (pDA) coatings on the surface of a gelatin-chitosan composite hydrogel and followed by grafting of bactericidal quaternary ammonium chitosan (QCS) as well as pH-responsive PMAA to this pDA coating. The in vitro antimicrobial activity, biocompatibility and the in vivo wound healing effects in a mouse MRSA-infected full-thickness defect model of the hydrogel were further evaluated. ResultsAssisted by polydopamine coating, the pH-responsive PMAA and bactericidal QCS are successfully grafted onto a gelatin-chitosan composite hydrogel surface and hydrogels maintain the adequate mechanical properties. At physiological conditions, the PMAA hydration layer endows the hydrogel with resistance to initial bacterial attachment. Once bacteria colonize and acidize local environment, the swelling PMAA chains tend to collapse then expose the bactericidal QCS, realizing the on-demand kill bacteria. Moreover, the dead bacteria can be released and the hydrogel will resume the resistance due to hydrophilicity of PMAA at increased pH, endowing the surface renewable ability. In vitro and in vivo studies demonstrate the favorable biocompatibility and wound healing capacity of hydrogels that can inhibit infection and further facilitate granulation tissue, angiogenesis, and collagen synthesis. ConclusionThis strategy provides a novel methodology for the development and design of smart wound dressing to combat multidrug-resistant bacteria infections.

Preparation and investigation of Ni-W/CeO2 composite coating and its structure and anti-corrosion properties with different ceria content and deposition time

In the current work, CeO2 nanoparticles were embedded in Ni-W alloy matrix by pulse electrochemical deposition on copper substrate to optimize their microstructure and corrosion resistance. The effects of CeO2 concentration and deposition time on Ni-W/CeO2 composite coating were investigated for optimized structure and improved corrosion resistance. The composite coatings present nodular-like surfaces with dense and compact growth profiles, containing 63.03–67.88 wt% Ni, 28.73–31.87 wt% W and 0.25–8.24 wt% Ce. The content of incorporated CeO2 in coatings increased with the increase of CeO2 concentration in electrolyte. The addition of CeO2 particles has refined the grains of the prepared coating. The surface became rougher with the extension of electrodeposition time. Ni-W/CeO2 composite coating electrodeposited at 10 g L−1 CeO2 for 60 min possessed the highest corrosion resistance, indicating enhanced corrosion protection and long-term stability. This premium coating can be applied in harsh environments to prolong the lifespan of machinery, equipment, and parts in marine, vehicle, aerospace, and chemical industries.

Classification Method of Composite Insulator Surface Image Based on GAN and CNN

Classification Method of Composite Insulator Surface Image Based on GAN and CNN

Construction of high-performance g-C3N4/MoS2 heterojunction humidity sensor and investigation of its application

In the paper, a g-C3N4/MoS2 humidity sensor with high response, low hysteresis and fast response/recovery for skin health status detection was prepared. The synthesis of g-C3N4/MoS2 heterojunction materials increases the interfacial barrier and improves the sensitivity of sensor. The edge unsaturated bonds and S defects of g-C3N4/MoS2 composites together enhance the adsorption of H2O, which in turn improves the sensitivity of sensor. The consequent acceleration of electron transfer between the material surface and water molecules led to an improvement in the response/recovery speed and humidity hysteresis. The N-H on the composite surface promotes the formation of physically adsorbed water layer and enhances the sensor recovery capability. The g-C3N4/MoS2 sensor shows high sensitivity (204875 Ω/%RH), fast response/recovery speed (11/9 s), and low hysteresis (2.0 %) at the 11 %-95 % RH range. In this study, the sensors were successfully used for the detection of skin health conditions, providing a viable solution for skin detection.

Encapsulating Fe3O4 Nanoparticles and Carbon Dots in a Metal-Organic Framework for Magnetic Fluorescent Taggants.

Magnetic fluorescent composite nanomaterials have broad application prospects in the fields of biological imaging, anticounterfeiting identification, suspicious object tracking, and identification of latent fingerprints in forensic medicine. For an effective taggant, a clearly visible identifying mark is necessary to enable observers to capture labeling information quickly and accurately, even from a distance. The preparation method of magnetic fluorescent composite materials is complicated and usually needs different surface modification and assembly processes. The limited loading capacity of fluorescent materials also limits the fluorescence properties of the composite, so it is difficult to produce obvious fluorescence as a taggant to meet the requirements of visible labeling. In this study, a core-shell structure of a magnetic fluorescent composite was prepared by using the metal-organic framework ZIF-8 as the host of fluorescent materials and an encapsulation shell coated on the Fe3O4 nanoparticles. The porous ZIF-8 is beneficial for increasing the loading capacity of fluorescent materials to ensure the fluorescence performance of the composite materials. Further modification of the composite surface prevented the desorption of fluorescent materials from the pores of ZIF-8, enabling the samples to maintain good fluorescence properties even after multiple washing cycles. The preparation method is simple, rapid, and cost-effective, and the prepared magnetic fluorescent composite nanomaterial has high magnetic separation performance and fluorescence performance, making it a promising material for identification, marking, and tracking.

Synthesis and analysis of multifunctional graphene oxide/Ag2O-PVA/chitosan hybrid polymeric composite for wound healing applications

The requirement for accurate treatments for skin diseases and wounds, generated a rising interest towards multifunctional polymer composites, that are capable of mimicking the natural compositions in human body. Also, electroactive composite films disseminate endogenous electrical stimulations that encourage cell migration and its proliferation at wound site, proposing greater opportunities in upgrading the conventional wound patches. In this work, the composite film made of graphene oxide, Ag2O, PVA and chitosan were developed for wound healing applications, by the solution casting method. The even dispersibility of nanofiller in polymeric matrix was validated from the physicochemical analyses. The increment in roughness of the composite film surface was noted from AFM images. The thermal stability and porous nature of the polymer composite were also verified. A conductivity value of 0.16 × 10−4 Scm−1 was obtained for the film. From MTT assay, it was noted that the films were non-cytotoxic and supported cell adhesion along with cell proliferation of macrophage (RAW 264.7) cells. Moreover, the composite film also demonstrated non-hemolytic activity of <2 %, as well as excellent antibacterial activity towards E. coli and S. aureus. Thus, the obtained results validated that the prepared composite film could be chosen as an innovative candidate for developing state-of-the-art wound dressings.

Hot corrosion behavior of selective laser melted TiC/GT D222 nickel-based composite in 75% Na2SO4 and 25% K2SO4 molten salt medium at 900°C

PurposeThis paper aims to investigate the differences in hot corrosion behavior of the GTD222 superalloy and TiC/GTD222 composite in a mixed salt of 75% Na2SO4 and 25% K2SO4 at 900°C.Design/methodology/approachThe GTD222 superalloy and TiC/GTD222 nickel-based composite were prepared using selective laser melting (SLM). Subsequently, the hot corrosion behavior of the two alloys was systematically investigated in a salt mixture consisting of 75% Na2SO4 and 25% K2SO4 (Wt.%) at 900°C.FindingsThe TiC/GTD222 composite exhibited better hot corrosion resistance compared to the GTD222 superalloy. First, the addition of alloying elements led to the formation of a protective oxide film on the TiC/GTD222 composites 20 h before hot corrosion. Second, TiC/GTD222 composite corrosion surface has a higher Ti content, after 100 h of hot corrosion, the composite corrosion surface Ti content of 10.8% is more than two times the GTD222 alloy 4% Ti. The Ti and Cr oxides are tightly bonded, effectively resisting the erosion of corrosive elements.Originality/valueThe hot corrosion behavior of GTD222 superalloy and TiC/GTD222 composites prepared by SLM in a mixed salt of 75% Na2SO4 and 25% K2SO4 was studied for the first time. This study provides insights into the design of high-temperature alloys resistant to hot corrosion.

Water Sorption and Solubility of Highly Aesthetic Single-Shade Nano-Hybrid Resin Composites.

Background A single-shade resin composite is a new type of resin composite that was introduced in 2019. There is not much data regarding the water sorption (Wsp) and water solubility (Wsl) of this type of resin composite. Therefore, this study aimed to investigate Wsp and Wsl and their effects on the surface roughness of a single-shade nano-hybrid resin composite in comparison with a conventional nano-hybrid resin composite in accordance with ISO 4049:2019 (Dentistry - Polymer-based Restorative Materials). Material and methods An in vitro study was performed to investigate the Wsp and Wsl of a single-shade supra-nano-hybrid composite (Omnichroma) and a conventional nano-hybrid composite (Filtek™ Z250 XT) in accordance with ISO 4049:2019. Five disks were prepared of each material with dimensions of 15 ± 1 mm in diameter and 1 ± 0.1 mm in thickness, as per ISO 4049:2019. The results were calculated according to the ISO equations for Wsp and Wsl in µg/mm3. Atomic force microscopy (AFM) was used to analyze the surface roughness (Ra) of test specimens. Results The findings showed that the values of Wsl and Wsp of both materials are comparable and revealed no statistically significant difference (P > 0.05). The AFM images showed a higher Ra post-solubility testing, and the statistical analysis indicated a significant difference for both materials. Conclusions The study concluded that the single-shade resin composite (Omnichroma) and the conventional nano-hybrid composite (Filtek™ Z250 XT) are following the requirements of ISO 4049:2019. The AFM analysis indicated that resin composite surfaces are significantly affected when exposed to water for a prolonged period of time. However, the Ra variations of Filtek™ Z250 XT were higher than Omnichroma specimens. These results indicate that resin composite surfaces can be significantly impacted by prolonged water exposure. This knowledge is critical for enhancing the long-term clinical performance and durability of these dental restorative materials.

The Optimum Interval Time of Layered Cement Composites with the Incorporation of Edge-Oxidized Graphene Oxide

The current research focuses on the effect of incorporating edge-oxidized graphene oxide (EOGO) on the performance of layered cement composites cast at different times. The feature of producing flower-shaped hydrated cement products is exploited to enhance the contact surface of two different cement composites. In the current study, the interval time of casting cement composites is the crucial parameter investigated. Consequently, a layer of cement paste with EOGO is cast above a layer of cement mortar where the amount of EOGO of 0.10% by the cement weight is fixed for all mixtures. Also, four different interval times based on cement setting time are considered, namely immediately, 6 h, 12 h, and 1 day. Similar mixtures are prepared but without adding EOGO for comparison purposes. The results show that EOGO is capable of enhancing the contact surface of layered cement composites by strengthening the split strength of two different layers (between 12 and 29%). Moreover, casting the paste layer containing EOGO after 6 h of mortar layer seems to be the optimum interval time among others by improving compressive strength (by 29%) and residual strength (by 34%) and not affecting flexural strength and porosity percentage.

Cu enhances the photothermal effect of a TiN film for antibacterial applications

In recent years, diseases caused by the spread of hazardous microorganisms (e.g., bacteria) have become a growing global concern. Imparting antimicrobial properties to the surface of a material is critical for the prevention of bacterial disease transmission. In this study, titanium nitride/copper composite (TiN-CuX) films with excellent antibacterial properties were deposited on AISI 304 stainless steel (304ss) via magnetron sputtering. The TiN-CuX composite films exhibited excellent photothermal performance under near-infrared (NIR, 808 nm) irradiation: the temperature of a TiN-CuX composite film surface exposed to a bacterium-containing medium increased rapidly, resulting in the death of bacteria on the surface (∼100 %). The TiN–Cu600 film exhibited 70.8 % antibacterial activity owing to the release of Cu2+ in the absence of NIR irradiation. The TiN-CuX composite films prepared in this study demonstrated outstanding antibacterial capabilities owing to synergy between the photothermal effect and Cu2+ release. The TiN-CuX composite films prepared in this study are intended for use as photothermal antibacterial coatings and represent a new approach for the production of antibacterial coatings on material surfaces.

Bond strength of epoxy-based composites at the interface with surface deposited metal layer: A comparative study with different dimensional fillers

With the complexity of the working environment, pure epoxy resin can no longer meet the requirements, and the weak interfacial bonding between metal layer and epoxy-based composites limits its development. In this work, we propose a novel molecular grafting modification technique by using the active functional groups of polymers, which can apply to epoxy-based composites with various fillers to improve the adhesive strength of the interface between the metal film and matrix. 3D surface profile and surface wettability were used to characterize the effect of fillers on the surface of epoxy composites. Scanning electron microscope (SEM) and Raman spectroscopy were utilized to judge the interface failure modes of the composites. Peeling test and surface-enhanced Raman scattering (SERS) were conducted to examine how fillers affected adhesion. The results showed that silane grafting substantially improved the bonding between the epoxy-based composite matrix and the metal layer without the need for alkaline washing and palladium (Pd) activation steps on the substrate. The average adhesive strength can reach a maximum of 17.76 N/cm. The study also revealed the effect of filler size on the interfacial adhesive strength. The interfacial adhesive strength was increased by two dimensional lamellar materials, decreased by one-dimensional tubular materials, and remained unaffected by zero-dimensional spherical materials. This study may have positive implications for improving interfacial bonding between metal and polymer composite surfaces.

Synergizing metakaolin and waste-glass for sustainable and functional UHPCC– a central composite design and ecological footprint assessment

Optimizing ultra-high-performance cementitious composites (UHPCC) with sustainable materials often compromises certain properties due to the chemical nature of alternative binders used to replace standard UHPCC components like Portland cement (OPC) and microsilica (MS). In the context of Waste-Glass-UHPCC, the reduction in early strength, attributed to the varied pozzolanic reactivity of MS and recycled glass powder as cementitious materials, may reduce its application that requires high early strength. This study addresses the early strength deficiency of Waste-Glass-UHPCC by incorporating metakaolin (MK) and also aims to assess the impact of MK on 28-day compressive strength, durability, and carbon footprint. Research investigating the effects of MK on UHPCC with reduced OPC and MS content is currently limited. Specifically, this investigation explores the influence of MK on UHPCC characterized by a cement content of 620 kg/m3. By utilizing advanced statistical methods [i.e., the Central Composite Design (CCD) and Response Surface Methodology (RSM)], this study investigates the substitution of MK for OPC in formulations of Waste-Glass-UHPCC. The experimental design comprises 18 encoded mixtures, allowing for the development of second-order regression models for critical responses [slump flow and compressive strength at different ages]. Besides, visualization through RSM-3D graphs facilitates a comprehensive examination of the effects of various factors. For a deeper analysis, two of the CCD's points, i.e., SP-12 (Waste-Glass-UHPCC without metakaolin), and SP-10 (Waste-Glass-UHPCC with 65.77 kg of metakaolin per cubic meter) were further investigated along with a control dosage that represents a typical UHPCC formulation. The responses studied encompassed 1, 7, and 28 d compressive strength, chloride ion penetration, and carbon footprint measured by a systematic life cycle analysis (following ISO 15804), assessing the environmental impact of the UHPCC's making materials from raw extraction to disposal. Despite encountering challenges in meeting self-compacting concrete criteria due to MK's tendency to accelerate hydration, the enhanced early strength properties (61 % higher than those of the Waste-Glass-UHPCC) make the MK-based mixture appropriate for various applications such as bridge engineering or pavement rehabilitation. Additionally, the addition of MK in UHPCC formulation demonstrated superior resistance to chloride ion permeability even compared to the control mixture, attributed to MK's ability to enhance the concrete's microstructure and capture chloride ions, attributed to Friedel's salt formation. Noteworthy findings include a significant (27 %) reduction in carbon footprint with the incorporation of MK in Waste-Glass-UHPCC compared to the control counterparts. The current study highlights the durability and environmental advantages of MK-based UHPCC blends while emphasizing the critical requirements of workability and strength development of sustainable UHPCC.

Activation preference: A new descriptor to predict non-radical oxidation pathways

The peroxymonosulfate (PMS) activation was influenced strongly by active sites on a catalyst surface. To some extent, biochar characters, such as structure, elemental composition, and specific surface area (SSA), can reflect the composition of active sites. However, the understanding of active centers lacked accuracy in the structure–activity relationships of biochar-based catalysts (BBC) due to the consideration of one single feature. In this study, XGBoost (XGB), random forest regression (RF), and supporting vector regression (SVR) models were employed to construct descriptors to predict non-radical (NR) contribution in BBC/PMS systems. Consequently, the XGB model provided the best prediction with an R2 value of 0.81. Thereby, activation preference (γ), as a characteristic descriptor of BBC, was developed using the XGB model. Interestingly, the descriptor fully considered carbon content (C%), oxygen content (O%), defects (ID/IG), and SSA. Besides, O% played the most critical role in predicting NR contribution. Noticeably, the NR oxidation pathway could be promoted within the range of 50–60 % for C%, 30–50 % for O%, 0.4–1.2 for ID/IG, and 579–1259 m2/g for SSA in the BBC/PMS system. Herein, machine learning (ML) was applied to develop a comprehensive descriptor, further providing an innovative strategy for high-throughput screening of BBCs to activate PMS efficiently. The comprehensive descriptor offered a new perspective for elucidating the structure–activity relationship of BBC, facilitating the application of BBC/PMS systems in water treatment.

High-strength, flexible and self-lubricating wood-plastic composites based on synergistic reinforcement of "hard-soft" units

To further improve the mechanical and friction properties of polymer-based self-lubricating composites. Herein, regenerated lignocellulose (RLC) was used to assist in exfoliating MoS2 and blended with polydopamine functionalized polytetrafluoro-wax (PFW@PDA) to obtain precursor slurry containing "hard-soft" units. Introducing it into carbon fiber (CFs) reinforced epoxy resin (EP) composites to realize the uniformly transferred mechanical stresses and frictional shear force. The plastic deformation of PFW@PDA enhances the flexibility of the composites and endows it with strong variability capabilities. Importantly, the "hard-soft" synergistic slipping layer formed by MoS2 and PFW at the friction interface significantly reduces the friction coefficient and wear rate of the composites surface, giving it excellent self-lubricating properties.

Experimental and numerical study of a novel composite building wall U-value

The present study aims to minimize the overall heat transfer coefficient (U-value) and heat flux through building walls to improve indoor thermal comfort, using different bricks and insulating materials in building wall construction. The building walls of three different types of bricks (Type-1, Type-2, and Type-3) were tested to compare the U-value through the wall. The brick with the low U-value was used to build a composite wall with the addition of glass wool and air cavity. The experiment was conducted maintaining different hot chamber temperatures (40℃ to 65℃) to see the effect of hot chamber temperature on the U-value. The temperature of the cold fluid chamber is increased by 0.9℃ in 0 to 210 min of testing duration. The maximum heat flux using Type-3 brick in the composite wall is reduced by 3.37%, and the percentage reduction in indoor temperature is 40.83%. Steady-state numerical analysis was also performed to perceive the temperature distribution on the composite wall surface and found to be well-matched with the experimental model with a percentage deviation of 1.96%. The results suggested that using glass wool and air cavities with low thermal conductivity, low density, and high specific heat capacity effectively reduces the U-value throughout the building wall.

A cleaner and eco-friendly approach to simultaneous extraction and characterization of essential oil and pectin from Assam lemon peel and its application for energy generation through TENG devices

Scientists have been working on developing a green bio-TENG for portable remote devices, including wearables in the biomedical sector. The process involves obtaining pectin, a green material with anti-microbial properties, as a Triboelectric material. This study focuses on the extraction of essential oil (EO) and pectin from Assam lemon peel simultaneously. A single-step strategy was optimized using a central composite design-based response surface approach. The extracted pectin yielded 4.19 ± 0.31 % and 11.53 ± 0.11 %, respectively. GC-MS analysis revealed 52 volatile components in the Assam lemon EOs, with limonin being 94.47 % and β-Bisabolene being 1.26 %. Only khusilal was found in the EOs, a rare discovery in the scientific domain. The extracted pectin showed good purity and antimicrobial properties. The in vitro activities of the citrus EO against microbial cultures revealed its activity in controlling and eradicating bacterial and fungal growth. Hydro distillation followed by enzyme treatment is a promising approach that combines two separate extraction procedures. The produced biopolymer showed the generation of electrical signals under minimal pressure and stretching and prevented microbial degeneration when applied to a nanogenerator.

Preparation of superhydrophobic carbon fiber composite surface with excellent durability

AbstractSuper‐hydrophobic surface has excellent waterproof, self‐cleaning and delayed icing properties, and is widely used in various fields, but its lack of durability restricts its large‐scale use. In this paper, carbon fiber composite material with excellent mechanical properties is selected as the substrate, PTFE nanoparticles with excellent hydrophobicity are used as the surface energy substance, and metal screen is selected as the template, combined with hot pressing molding process, a super‐hydrophobic surface with multi‐level micro‐nano structure is successfully constructed. The test shows that the water contact angle of the surface is 169°, and the rolling angle is about 2°. The contact angle of the surface is also over 150° for other liquids, and it bounces off the external water droplets for three times, so it can easily take away pollutants and keep the surface dry and clean under the action of water flow. In the same icing environment, compared with the original surface, it can prolong the freezing time of droplets by 5 times. After repeated rubbing, the surface still has superhydrophobic properties until the whole surface is completely destroyed. The preparation method used in this study is simple, and the prepared superhydrophobic surface has excellent performance, which is expected to promote the application of superhydrophobic surface in practical working conditions.Highlights The preparation method is fast, efficient, low‐energy and environment‐friendly, and the used materials are simple and economical, and can be reused. The prepared surface has excellent hydrophobic performance for different media. The prepared superhydrophobic surface has low adhesion and droplet rebound performance. The prepared superhydrophobic surface has excellent delayed icing performance. The prepared superhydrophobic surface has excellent wear resistance.

Two-step printing bionic self-lubricating composite surface fabricated by selective laser melting ink-printed metal nanoparticles

The combination of self-lubricating materials and surface texture was a promising strategy to improve tribology performance. The designed parameters and manufacturing methods of the textured composite surface were pivotal in fully harnessing this synergistic effect. Inspired by natural structures such as the scapharca subcrenata shell, trimeresurus stejnegeri snakeskin, crocodile, and tree frog toe pad surface, bionic self-lubricating composite surfaces (BSCSs) with different textures were prepared on AISI 4140 steel substrate to enhance tribological properties. These BSCSs combined self-lubricating composite material (SLCM) with copper (Cu) material in bionic patterns using the selective laser melting ink-printing metal nanoparticles manufacturing method. Tribological properties and worn surfaces of the BSCSs with various design parameters were analyzed under dry sliding conditions. Results indicated that the synergy effects of printed Cu and SLCM texture effectively reduced friction coefficient and improved wear resistance of the BSCSs. The SLCM texture density and the size of array element in the BSCSs were found to influence the types of lubricating film formed during the sliding process, thereby affecting the tribological performance. This investigation provided a potential surface design strategy and a more flexible manufacturing method for surface engineering.