Adhesion Of Films Research Articles

Natural Product-Based Pressure-Sensitive Adhesives via Carveol-Dithiothreitol Thiol-Ene Step-Growth Polymerization.

Pressure-sensitive adhesives occupy a large role in the commercial use of polymers; however, they are typically limited to nondegradable formulations using petroleum-based materials. As the plastic and environmental crises have intensified, the need for renewable starting materials and degradable designs has similarly deepened. With that goal, we endeavored to make adhesive films from renewable terpenes as a safer and more sustainable route to PSAs. Specifically, based on our previous report of the cross-linking ability of a carveol-based carbonate through thiol-ene chemistry, we report further exploration of the adhesive possibilities of this system. A carbonate monomer of dimerized carveol was linearly polymerized with dithiothreitol via UV-initiated thiol-ene chemistry and formed into adhesive coatings, with unmodified geraniol doped in as a tackifier. We obtained a range of adhesive properties based on the ratio of exo-methylene to thiol units and reported on the degradation of the adhesive coatings.

Injectable and photocurable precursors with their improved adhesive elastomeric films by nature-inspired marine mussels chemistry

Photocurable materials, capable of being delivered as liquids and rapidly cured in situ within seconds using UV light, are garnering increased interest in advanced minimally invasive procedures. Examining living organisms to extract novel principles and technologies, and subsequently applying them into synthetic materials to enhance their performances holds a central position in biomimetics (bioinspiration). In this exploration, we delve into the multifaceted world of marine mussel adhesion, emphasizing the pivotal role of 3,4-dihydroxy-L-phenylalanine (L-DOPA) in adhesive proteins. Simultaneously, we navigated the promising realm of elastomers derived from fatty acid dimers. 90° peeling test and fluorescence microscope indicate that the adhesiveness of the catechol-containing samples (5 % and 10 %) to the hydrophilic surface versus control samples were ∼ 4 and 8 times higher, respectively, as compared to within the tested group. Overall, our results suggest that the incorporation of methacrylated L-DOPA in the synthesis of photocured elastomeric networks leads to lower water contact angle and improved adhesiveness, creating new avenues for potential biomedical applications.

Development of Low-interference, Resistance to Moisturethermal Adhesion Film for Display Applications

Development of Low-interference, Resistance to Moisturethermal Adhesion Film for Display Applications

A novel mucoadhesive film containing probiotic extract for oral candidiasis treatment: Formulation and antifungal evaluation

Probiotic strains offer a novel and potentially effective approach to treat oral candidiasis. Buccal mucoadhesive films have attracted considerable attention in recent years due to their unique ability to adhere and persist on the oral mucosa, while gradually releasing their encapsulated drug content. Therefore, the aim of the study was to develop mucoadhesive films containing probiotic extract for treatment of oral candidiasis. Mucoadhesive films were fabricated with hydrophilic polymers, such as polyvinyl alcohol (PVA) and hydroxy propyl methyl cellulose (HPMC). Then, films were evaluated regarding their thickness, pH, tensile strength and elongation, swelling, in vitro release and antifungal activity. The type of polymer used had an impact on the mechanical properties, swelling and release of the films. Films prepared using PVA showed significantly higher tensile strength and elongation at break values compared to those prepared using HPMC. However, swelling index increased with enhancing HPMC concentration in the films. The release of probiotic extract from the film prepared with HPMC occurred slowly. Based on these results, films containing 54 % HPMC and 26 % PVA were selected as optimal formulation. Moreover, it was found that optimal film containing probiotic extract could inhibit the growth of Candida albicans. Regarding to the obtained results, probiotic oral adhesive mucoadhesive films can be considered as a promising alternative to traditional methods in the treatment of candidiasis.

Green recycling of end-of-life photovoltaic modules via Deep-Eutectic solvents

Sustainable End-of-life (EOL) photovoltaic (PV) modules recycling is essential for achieving resource conservation and alleviating environmental issues. Ethylene vinyle acetate (EVA) adhesive films separation is a prerequisite for the realization of valuable component recovery of PV modules. However, the conventional wet chemical separation processes are usually accompanied by the challenges of low separation efficiency, high toxicity and difficult multiple recycling. Herein, a green, biodegradable, low-cost and recyclable deep eutectic solvent (DES) is firstly developed to efficiently separate EVA films in EOL PV modules. The high temperature stability and the acidic characteristic of DES can facilitate the separation of EVA film between component layers. At 175 ℃, the warping effect caused by the differential thermal contraction between the module component layers creates favorable conditions for the efficient reaction and separation by the DES. Additionally, the acidic medium reacts with the aluminum electrode layer of PV cells, which further enhances the separation efficiency of EVA films. The EVA separation rate reached 100%, the separation rate of the EVA containing aluminum (Al) up to 98.4% after 12.5 h at 175 ℃. Moreover, the developed DES exhibits excellent recyclable performance, the EVA separation rate remained 100% after 10 cycles. Compared to the traditional solvent toluene, DES has advantages in terms of economics, environmental impact, and efficiency. This strategy of design a green, biodegradable, low-cost and recyclable solvent to replace traditional solvents, and provides a promising route to efficiently separate EVA films in EOL PV modules.

Enhanced adhesion and corrosion resistance through the modulation of a metallic Ti underlayer thickness

In this investigation, TiCN/TiN thin solid film was selected as a protective coating and deposited onto AZ31 alloy through reactive magnetron sputtering. To mitigate the potential failure resulting from the significant physical disparity between the ceramic film and the metal substrate, a Ti thin film was employed as a base layer. Following the deposition process, an analysis was conducted on the structural features, residual stress, fracture morphology, adhesion strength, and corrosion characteristics of the film/substrate system utilizing X-ray diffraction, scanning electron microscopy, scratch testing, and electrochemical workstation. The findings indicate that the incorporation of a Ti metallic underlayer significantly improves the adhesion and corrosion resistance of the TiCN film. However, when the thickness of the Ti layer surpasses 0.37 μm (deposition of 15 min), it leads to the formation of a distinct columnar crystal microstructure, increased residual stress, and diminished adhesion and corrosion resistance. Additionally, this study delves into the corrosion failure mechanisms in a chloride environment and explains the principles of residual stress measurement through XRD.

Investigating the mechanism of enhancing interfacial adhesion of SiOx films on GaAs substrates through process optimization

In the manufacturing of GaAs-based quantum well (QW) lasers, the adhesion between the Silicon dioxide (SiOx) film layer and the Gallium arsenide (GaAs) substrate is crucial for the performance and durability of semiconductor devices. This study focused on depositing SiOx films on GaAs substrates using plasma-enhanced chemical vapor deposition (PECVD). The research aimed to investigate the impact of different coating processes on the deposition rate, properties, and composition of the coatings. The interfacial adhesion of various samples was assessed using nano-scratch tests. The results revealed that samples with lower SiH4 gas flow and RF power, or higher process pressure exhibited stronger adhesion strength. It's further observed that optimizing the process parameters reduced residual stresses in the film, thereby enhancing the GaAs-SiOx interfacial bonding. This work has the potential to significantly reduce the possibility of QW lasers malfunctions, improve the reliability of semiconductor devices and provide valuable insights for future studies on enhancing film-substrate adhesion.

A Study on the Influence of Functionalized Graphene on the Mechanical and Biocompatibility Performance of Electrospun Polyvinyl Alcohol Nanocomposites

Polyvinyl alcohol (PVA), a synthetic polymer produced by polymerizing vinyl acetate and subjecting it to alkaline hydrolysis, exhibits properties such as film formation, emulsification, and adhesion. However, pure PVA’s biocompatibility and mechanical properties are limited. Its hydrophilicity also causes it to dissolve in water and blood, rendering it less suitable for drug delivery applications. To address these limitations, PVA was crosslinked with glutaraldehyde (GA) to enhance toughness and resistance to water and blood dissolution. Additionally, carboxyl (COOH) and hydroxyl (OH) functionalized graphene were incorporated into electrospun PVA nanocomposites to further improve their mechanical properties. The results show that adding COOH- and OH-functionalized graphene in four different concentrations (0.5, 1.0, 1.5, and 2.0 wt.%) significantly enhanced the mechanical characteristics of PVA nanocomposites. Tensile strength and Young's modulus increased substantially, with OH-functionalized graphene increasing tensile strength and Young's modulus by 224% and 338.3%, respectively, and COOH-functionalized graphene increasing these properties by 245.6% and 371.4%. Morphological characterization using FT-IR and FESEM confirmed the successful incorporation of graphene into the PVA matrix. Biocompatibility testing through APTT and PT assays showed both nanocomposites are biocompatible, suggesting their potential for biomedical applications. The optimal filler concentration for both graphene types was 1.5 wt.%. This research demonstrates the promising potential of innovative materials for healthcare and biomedical engineering applications.

Creating highly efficient stretchable OLEDs with nanowavy structures for angle-independent narrow band emission

Stretchable organic light-emitting diodes (SOLEDs) have been the challenging class of OLEDs as they have limited processability to fabricate a design that can withstand external deformation. Herein, we demonstrated the highly efficient top-emitting geometrical stretchable OLED (GSOLED) by incorporating the prestretched elastomer with optical adhesive film. The experimental and theoretical characterizations verified the enhancement of device efficiencies with the light extraction phenomenon brought by nanowavy corrugated structures. Furthermore, GSOLED shows stability in stretchable conditions and displays narrower emission spectrum with improved color purity. The full width at half maximum (FWHM) of 21 nm shows narrowband emission with a high current efficiency and EQE of 221 cd A−1 and 39.50%. This work marks a significant step forward, providing unprecedented insights into the factors influencing device performance in current and future material systems for stretchable organic light-emitting diodes.

90-degree peeling of elastic thin films from elastic soft substrates: Theoretical solutions and experimental verification

Peeling of thin films has been widely used in adhesion measurement, film transfer and bio-inspired design. Most previous studies focused on the peeling of thin films from rigid substrates, but soft substrates are common in practical applications. Herein, we propose a two-dimensional model based on the bilinear cohesive law to characterize the 90-degree peeling of elastic thin films from elastic soft substrates, and obtain theoretical solutions expressed in terms of the Chebyshev series. The theoretical solutions match well with the finite element method results, including the load-displacement curves and the bulging deformation of soft substrates. We find that with decreasing substrate modulus, the maximum peeling force (Pmax) decreases but the steady-state peeling force remains unchanged. With the present solutions, the interfacial strength and fracture energy can be extracted simultaneously from the 90-degree peeling experiments of thin film/soft substrate systems, and then the experimentally measured Pmax for different film thicknesses can be well predicted. Furthermore, we obtain a new power scaling law of Pmax, where the scaling exponent depends on substrate elasticity. These results can help us measure the interfacial properties of thin film/soft substrate systems via peel tests, and regulate their peeling behaviors by interface design.

Application of microscale methods to study the heat-induced delamination in engineered wood products bonded with one-component polyurethane adhesives

One-component polyurethanes (1-c-PUR) are commonly used adhesives for the manufacture of cross-laminated timber (CLT). Typically, these adhesives do not govern the mechanical response of CLT under normal service temperatures. However, when subjected to heating from a fire, failures may transition from within the timber to the bond line interphase zones. CLT bonded with 1-c-PUR has been shown to be prone to heat induced delamination (HID), which may compromise its structural performance at elevated temperatures. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic thermo-mechanical analysis (DTMA) were used to study the thermal and thermo-mechanical responses of engineered wood products and components (i.e. adhesives and timber) and their interphase (i.e. bond line). Two commercially available 1-c-PUR adhesive films from the same manufacturer, two timber species (Norway Spruce and Radiata Pine, as sawdust or as veneers), and four different veneer shear lap combinations, were studied. Shear lap specimens bonded with a conventional 1-c-PUR adhesive consistently experienced bond line mechanical failure in DTMA at about 220–240 °C. The same adhesive films tested via DSC and TGA softened at 240–260 °C. Conversely, a different 1-c-PUR adhesive, formulated specifically for enhanced performance at elevated temperature, displayed no detectable softening in DSC and TGA, and shear lap specimens in DTMA consistently failed within the timber; even at elevated temperatures. The presented thermo-mechanical methods allow identification of failure modes and temperatures, whilst the thermal microscale methods (i.e. TGA, DSC, DTMA) assist in understanding the various factors contributing to failures.

1, 3, 6, 8-pyrene sulfonic acid tetrasodium fluorescent pigment synthesis and security ink production

Colorants used in security inks are special pigments that radiate in the UV region or IR region. Obtained pigments can be from valuable rare earth elements or they can be organic based. Organic-based pigments are generally insoluble in water, which limits their use. For this purpose, an organic-based UV-radiating pigment was synthesized and made water-soluble by forming its salt. With the obtained salt-formed pigment, inkjet ink that can be used in counterfeiting was applied and its printability and resistance properties were determined. In this study, 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was synthesized and water-based inkjet inks with hydroxy ethyl cellulose binder were produced. The prepared inks were printed on the paper surface. The color and gloss of the prints obtained were measured both in the visible region and in the UV region. Its optical properties were detected by UV spectroscopy. Strength properties such as light fastness, nitro resistance, alkali resistance, acid resistance, rub resistance, drying time, adhesion and dry film weight of the prints were determined. As a result; Inkjet ink with 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was produced and it was concluded that it has good resistance properties.

Enhancement of effluent degradation by zinc oxide, carbon nitride, and carbon xerogel trifecta on brass monoliths.

In recent years, heterogeneous photocatalysis has emerged as a promising alternative for the treatment of organic pollutants. This technique offers several advantages, such as low cost and ease of operation. However, finding a semiconductor material that is both operationally viable and highly active under solar irradiation remains a challenge, often requiring materials of nanometric size. Furthermore, in many processes, photocatalysts are suspended in the solution, requiring additional steps to remove them. This can render the technique economically unviable, especially for nanosized catalysts. This work demonstrated the feasibility of using a structured photocatalyst (ZnO, g-C3N4, and carbon xerogel) optimized for this photodegradation process. The synthesized materials were characterized by nitrogen adsorption and desorption, X-ray diffraction (XRD), and diffuse reflectance spectroscopy (DRS). Adhesion testing demonstrated the efficiency of the deposition technique, with film adhesion exceeding 90%. The photocatalytic evaluation was performed using a mixture of three textile dyes in a recycle photoreactor, varying pH (4.7 and 10), recycle flow rate (2, 4, and 6 L h-1), immobilized mass (1, 2, and 3mgcm-2), monolith height (1.5, 3.0, and 4.5cm), and type of radiation (solar and visible artificials; and natural solar). The structured photocatalyst degraded over 99% of the dye mixture under artificial radiation. The solar energy results are highly promising, achieving a degradation efficiency of approximately 74%. Furthermore, it was possible to regenerate the structured photocatalyst up to seven consecutive times using exclusively natural solar light and maintain a degradation rate of around 70%. These results reinforce the feasibility and potential application of this system in photocatalytic reactions, highlighting its effectiveness and sustainability.

Deposition of a low-stress diamond film on stainless steel with a Mo/Mo-N interlayer

Depositing an adhering diamond film on stainless steel is still challenging. In this work, Mo/Mo-N film is used as an interlayer to solve the problem. The results show that diamond film with good adhesion is obtained when the interlayer with the N2/Ar ratios of 50 %–100 % is used. It is ascribed to the formation of Mo2N phase in the interlayer through which it is more difficult for carbon atoms to diffuse than Mo phase. On the Mo/Mo-N interlayer, carbon atoms are easily gathered and a new phase MoC appeared as well as Mo2C phase at the interface of diamond/interlayer. Thermal expansion of MoC is obviously lower than that of Mo2C, resulting in the lower stress of diamond film. And MoC offers higher bond strength between the diamond and the interlayer compared to Mo2C phase. As a result, the diamond film presents good adhesion.

Measurement of the water vapor transmission rate at temperatures above 100 °C

ABSTRACT Water vapor transmission rate (WVTR) and water vapor permeability coefficient were measured at temperatures between 110 and 138°C using the modified cup method. The cup, placed in a Highly Accelerated Stress Test chamber, allowed water vapor to permeate the sample film attached to the cup. The WVTR was determined based on the increase in mass of the cup. To prevent sample damage during measurement, a cup with a pressure adjustment mechanism was utilized. Carrier-incorporated phosphorus pentoxide was used as the desiccant instead of anhydrous calcium chloride to ensure a consistent moisture absorption rate, especially at high temperatures. The water vapor permeability coefficients for the polycarbonate, polyimide, and adhesive films were distributed on an approximately straight line in the Arrhenius plot. Additionally, the Arrhenius plots for the polyethylene terephthalate and polyethylene naphthalate films captured the permeability bending point near the glass transition temperature. To accurately measure the high-temperatureWVTR, upper and lower limits were established for the weighing interval, cup mass gain, and WVTR measurement range.

Integrating Bioinspired Natural Adhesion Mechanisms into Modified Polyacrylate Latex Pressure-Sensitive Adhesives.

For polyacrylate latex pressure-sensitive adhesives (PSAs), high peel strength is of crucial significance. It is not only a key factor for ensuring the long-lasting and effective adhesive force of polyacrylate latex PSAs but also can significantly expand their application scope in many vital fields, such as packaging, electronics, and medical high-performance composite materials. High peel strength can guarantee that the products maintain stable and reliable adhesive performance under complex and variable environmental conditions. However, at present, the peel strength capacity of polyacrylate latex PSAs is conspicuously insufficient, making it difficult to fully meet the urgent market demand for high peel strength, and severely restricting their application in many cutting-edge fields. Therefore, based on previous experimental studies, and deeply inspired by the adhesion mechanism of natural marine mussels, in this study, a traditional polyacrylate latex PSA was ingeniously graft-modified with 3,4-dihydroxybenzaldehyde (DHBA) through the method of monomer-starved seeded semi-continuous emulsion polymerization, successfully synthesizing novel high-peel-strength polyacrylate latex pressure-sensitive adhesives (HPSAs) with outstanding strong adhesion properties, and the influence of DHBA content on the properties of the HPSAs was comprehensively studied. The research results indicated that the properties of the modified HPSAs were comprehensively enhanced. Regarding the water resistance of the adhesive film, the minimum water absorption rate was 4.33%. In terms of the heat resistance of the adhesive tape, it could withstand heat at 90 °C for 1 h without leaving residue upon tape peeling. Notably, the adhesive properties were significantly improved, and when the DHBA content reached 4.0%, the loop tack and 180° peel strength of HPSA4 significantly increased to 5.75 N and 825.4 gf/25 mm, respectively, which were 2.5 times and 2 times those of the unmodified PSA, respectively. Such superior adhesive performance of HPSAs, on the one hand, should be attributed to the introduction of the bonding functional monomer DHBA with a rich polyphenol structure; on the other hand, the acetal structure formed by the grafting reaction of DHBA with the PSA effectively enhanced the spatial network and crosslink density of the HPSAs. In summary, in this study, the natural biological adhesion phenomenon was ingeniously utilized to increase the peel strength of pressure-sensitive adhesives, providing a highly forward-looking and feasible direct strategy for the development of environmentally friendly polyacrylate latex pressure-sensitive adhesives.

Anticorrosion properties of flavonoids for rust-free building materials: a review

Abstract Rust-free building materials are crucial for ensuring the durability and structural stability of constructions. Corrosion, a widespread issue affecting metals like steel, copper, and concrete, can be effectively managed with the help of corrosion inhibitors. One effective method for corrosion inhibition involves the application of corrosion-inhibiting coatings, which form resilient and tightly adherent films on metal surfaces. Flavonoids, renowned for their diverse biological activities, demonstrate significant anticorrosive properties. They contain beneficial compounds such as antioxidants and chelating agents. The efficacy of plant extracts as corrosion inhibitors is influenced by their organic constituents, particularly phenols and flavonoids. Flavonoids act by creating a protective film that serves as a barrier, shielding the metal surface from corrosive agents and limiting their access to the metal. This contributes to the prevention of corrosion. The integration of flavonoids into building materials has the potential to transform corrosion prevention practices, leading to improved durability, reduced maintenance costs, and a more environmentally friendly built environment. This article explores the promising prospects of flavonoids as an innovative and sustainable approach to corrosion prevention in building materials. Additionally, it aims to stimulate further research endeavors, fostering the development of effective and eco-friendly corrosion protection strategies for the construction industry.

Exploring the potential of Gigantochloa levis and Gigantochloa scortechinii bamboo species for plybamboo production

Gigantochloa levis and G. scortechinii bamboo species were evaluated as material for plybamboo production. Plybamboo was composed of three layers with 12 mm thickness and used phenol formaldehyde (PF) as their binder. Representative samples were cut and tested for bonding, physical, mechanical, and finishing properties. Results indicated that G. levis plybamboo exhibited higher bending strength property compared to G. scortechinii plybamboo, as indicated by its higher modulus of rupture (121 N/mm2) and modulus of elasticity (16300 N/mm2). The G. levis plybamboo also displayed higher bond shear strength and was dimensionally stable compared to G. scortechinii plybamboo. The finishing properties revealed that all coatings performed well in the cross-cut tape and pull-off tests. Notably, plybamboo from both bamboo species showed excellent coating film adhesion. Based on minimum standard requirement, results revealed that both bamboo species were suitable to be used in plybamboo production for general use. The findings showed that those species are valuable renewable natural resources for plybamboo production and had potential to be utilized as a substitute for wood in board production.

Liquid microlens compound structure for enhanced sub-micron resolution imaging and accelerated reconfigurable deformation manipulation

The optical observation of sub-micron structures encounters significant challenges due to the inadequate spatial shape matching of optical devices and the limitations imposed by diffraction. These factors result in suboptimal imaging resolution and the introduction of defocus distortion. One approach to mitigating these limitations involves utilizing a liquid microlens (LML) assisted microscope, which offers real-time and localized control capabilities. However, the dynamic tuning of LML is subject to volatility and instability, adversely affecting sub-micron resolution imaging. To address this issue, a contour-following coating inspired by the natural cornea is applied to the droplet's surface, resulting in the formation of liquid microlens compound structures (LMLCS). Firstly, photoresist microholes are fabricated on the optical disc. Then, liquid self-assembly technology is used to fill glycerol in the microholes. At last, a conformal spreading method of UV-curable adhesive precursor film is developed to ensure the combination of the microlens bilayer structure. Through the application of optical information transmission theory, finite difference time domain (FDTD) method, and the principle of Abbe microscopic imaging, the imaging magnification process and sub-micron resolution characteristic of the LMLCS are revealed. Remarkably, the obtained focal width at half maximum (FWHM) of 1.54 μm is smaller than the theoretical value, enabling reconfigurable sub-micron resolution observation and 1.63 times imaging magnification of 226 nm grating lines under the optical microscope. Compared with unencapsulated LML, this compound structure exhibits better sub-micron resolution capability, greater imaging magnification, and faster adaptive dynamic response characteristics. Consequently, the LMLCS introduces exciting prospects for exploring optical sub-micron measurement and sensing devices with exceptional performance.

Shape-stabilized flexible thermochromic films with one-sided adhesion via gradient crosslinking strategy for temperature indicating

Thermochromic dyes (TCDs) based on a three-component color change system suffer from solid rigidity and liquid leakage issues because of the intrinsic solid–liquid phase change performance, resulting in difficulty in temperature visualization applications for smart wearable fields. Despite considerable efforts in microencapsulation of thermochromic dyes, designing and fabricating essentially flexible thermochromic phase change films still need to be explored. Herein, a one-sided adhesive gradient-crosslinked thermochromic film is reported to address these issues to make a trade-off between stability and flexibility, excellent thermochromic performance, and temperature visualization. The thermochromic wearable films have been fabricated exploiting tea polyphenol thermochromic dyes, vinyl dimethylsiloxane, and hydrosilicone oil via the salt-template-assisted method and gradient crosslinking strategy, which have porous structures with an average pore size of 12.8 μm and a porosity of 28 %. Due to the spatial limiting threshold effect of the porosity structure, interconnected 3D polysiloxane porous networks can provide ample support for tea polyphenol thermochromic dyes and effectively prevent liquid leakage. Upon heating, the thermochromic film changes from blue to white with the K/S value decreasing from 7.69 to 0.78 and the ΔE* increasing from 2.7 to 16.1 at 610 nm, and the color-changing temperature is 42 °C. Gradient crosslinked thermochromic films exhibit excellent temperature-responsive color change properties, desirable one-side adhesion, and thermal energy storage, enabling multicolor temperature displays and temperature-controlled multilevel information transfer.