Enhanced Adhesion Strength Research Articles

Study on the Effect of Jute CNFs Addition on the Water Absorption and Mechanical Properties of Geopolymer Concrete

This study investigates the influence of thermoplastic polyurethane (TPU) reinforced with jute cellulose nanofibers (CNFs) on the water absorption and mechanical properties of geopolymer concrete. The integration of TPU/jute CNF nanocomposites into geopolymer concrete is explored as a strategy to enhance both its durability and mechanical performance. Geopolymer concrete, a sustainable alternative to traditional Portland cement concrete, is known for its low carbon footprint, but it suffers from high brittleness and water absorption. The water absorption behavior of the modified concrete was assessed, revealing a significant reduction in water uptake due to the hydrophobic nature of TPU and the reinforcing effect of jute CNFs. Additionally, the mechanical properties, including compressive and flexural strengths, were evaluated to understand the impact of the nanocomposites on the structural integrity of the concrete. The addition of TPU/jute CNFs notably enhanced the splitting tensile strength (63.5%), compressive strength (59%), and water absorption (0.59%) of the composite, indicating a promising route for developing high-performance construction materials. The integration of 6 wt% of TPU/jute CNF nanocomposites was found to be optimal, resulting in a uniform matrix, reduced micro-cracks, and improved compressive strength due to enhanced adhesion between the nanocomposites and the geopolymer matrix. Furthermore, a curing temperature of 100 °C was identified as ideal, minimizing unreacted fly ash and enhancing adhesion strength, while higher temperatures (140 °C) led to material deterioration due to rapid water loss. The findings demonstrate that the addition of TPU/jute CNF nanocomposites not only improves resistance to water penetration but also enhances overall mechanical performance. This supports the development of more sustainable and resilient construction materials, contributing to global efforts to reduce the environmental impact of the construction industry. Future research should focus on the long-term durability of these composites under various environmental conditions to validate their effectiveness in real-world applications.

Fabrication of versatile and durable superhydrophobic cotton fabrics using PTA-Ala adhesive

In recent years, the preparation of functional textiles based on polyphenols adhesion has received extensive attention and research. However, polyphenols are prone to peroxidation during oxidative polymerization, which can compromise the interfacial adhesion of their monomers. Reintroducing reactive functional groups after oxidative polymerization of polyphenols may potentially compensate for the lost interfacial adhesion while increasing cohesion. In this paper, L-alanine (Ala) is introduced into poly (tannic acid) (PTA) solution to generate the PTA-Ala via Michael addition and Schiff base reaction. Original cotton fabrics are modified with PTA-Ala solution to enhance adhesion strength between the fabrics and subsequent functional modifiers. A silver nanowire network is then incorporated to increase the surface roughness through tannic acid reduction. Finally, polydimethylsiloxane is applied to reduce fabric surface energy, resulting in superhydrophobic multifunctional OH-PDMS/Ag/PTA-Ala/cotton fabrics. The finished cotton fabric exhibits a water contact angle of 166.7 ± 1.9° and a rolling angle of 5 ± 0.5°. Moreover, the fabric features diverse functionalities such as oil-water separation, photothermal conversion, antimicrobial properties, water collection, and anti-icing capabilities, alongside excellent durability and self-healing properties that extend its service life. This finished cotton fabric demonstrates promising applications in oil pollution control, outdoor clothing and medical protection, highlighting its broad across various industries.

Adhesion Strength Enhancement of Butyl Rubber and Aluminum Using Nanoscale Self-Assembled Monolayers of Various Silane Coupling Agents for Vibration Damping Plates.

In this paper, we enhance the adhesion strength of butyl rubber-based vibrational damping plates using nanoscale self-assembled monolayers of various silane coupling agents. The silane coupling agents used to chemically modify the plate's aluminum surface include 3-aminopropyltriethoxysilane (APTES), (3-glycidyloxypropyl) triethoxysilane (GPTES), 3-mercaptopropyltrimethoxysilane (MPTMS), and 3-(triethoxysilyl)propyl isocyanate (ICPTES). The modified surfaces were analyzed using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the enhancement in adhesion strength between the rubber and aluminum was estimated through T-Peel tests. As a result, MPTMS showed the highest enhancement in adhesion strength, of approximately 220% compared to the untreated sample, while GPTES, ICPTES, and APTES resulted in adhesion strength enhancements of approximately 200%, 150%, and 130%, respectively.

Branched Oligomer-Based Reversible Adhesives Enabled by Controllable Self-Aggregation.

Supramolecular adhesion material systems based on small molecules have shown great potential to unite the great contradiction between strong adhesion and reversibility. However, these material systems suffer from low adhesion strength/narrow adhesion span, limited designability, and single interaction due to fewer covalent bond content and action sites in small molecules. Herein, an ultrahigh-strength and large-span reversible adhesive enabled by a branched oligomer controllable self-aggregation strategy is developed. The dense covalent bonds present in the branched oligomers greatly enhance adhesion strength without compromising reversibility. The resulting adhesive exhibits a large-span reversible adhesion of ≈140 times, switching between ultra-strong and tough adhesion strength (5.58MPa and 5093.92Nm-1) and ultralow adhesion (0.04MPa and 87.656Nm-1) with alternating temperature. Moreover, reversible dynamic double cross-linking endows the adhesive with stable reversible adhesion transitions even after 100 cycles. This reversible adhesion property can also be remotely controlled via a voltage of 8V, with a loading voltage duration of 45s. This work paves the way for the design of reversible adhesives with long-span outstanding properties using covalent polymers and offers a pathway for the rational design of high-performance adhesives featuring both robust toughness and exceptional reversibility.

Enhanced adhesion strength of copper metallization on silicon heterojunction solar cell due to improved electrochemical reduction uniformity of ITO

Copper electroplating is an ideal technique for the metallization of highly efficient silicon heterojunction (SHJ) solar cells due to the unique advantage in the low cost, strong adhesion, and low contact resistance. Achieving these characteristics depends strongly on the seed layer before Cu electroplating. This work reports a potential economical and effective route for electrochemically reducing ITO to assist electroplating of Ni seed layer and increase the adhesion of the metallization grids. Good wettability of electrolyte solution to ITO and the low temperature account for the reduction uniformity. A uniform In,Sn/SnO mixed metal layer is formed on ITO surface after electrochemical reduction. With the assistance of the uniform reduction the adhesion strength of the metallization grid reaches to 9.9 N mm⁻1. Although it is conducted on a small-size ITO-coating Si plate, the present plating is convenient and low-cost for the metallization, which is expected to be suitable for the large-scale commercialization of SHJ solar cells.

Selective extraction of lithium from salt lake brine by in situ crosslinked stable three-dimensional network film electrodes

Water-soluble binders for electrode preparation offer advantages over traditional PVDF, including environmental benefits, improved electrochemical performance, and improved mechanical properties. The trend is to find environmentally friendly binders that are compatible with water-based processes. In this context, we designed and synthesized aqueous binders with three-dimensional crosslinked structures. These structures are based on highly branched, hydrophilic polyvinyl alcohol and lithium carboxymethyl cellulose, which facilitates Li+ transport. Furthermore, LiMn2O4/C/PVA-c-CMCLi film electrodes were prepared through covalent crosslinking. The film electrode was superior to the LiMn2O4/C/PVDF film electrode in terms of adsorption capacity (25.53 mg·g−1), but comparable to the LiMn2O4/C/PVDF film electrode in terms of cyclic stability (96.38 % capacity retention after 50 CV cycles). They also showed a shorter time to reach the adsorption equilibrium (2 h) and high selectivity for Li+ in simulated brine with a high Mg2+/Li+ ratio (40) from East Taijiner. This is attributed to the synergistic effects of the improved electrolyte wettability, enhanced adhesion strength through covalent crosslinking, and increased Li+ transport rate facilitated by -COOLi in CMCLi. These results indicate that this binder has the potential to replace PVDF in the preparation of film electrodes for extracting Li+ from brine with high Mg2+/Li+ ratios.

Enhancement of adhesion strength in viscoelastic unsteady contacts

We present a general energy approach to study the unsteady adhesive contact of viscoelastic materials. Under the assumption of infinitely short-range adhesive interactions, we exploit the principle of virtual work to generalize Griffith’s local energy balance at contact edges to the case of a non-conservative (viscoelastic) material, subjected to a generic contact time–history. We apply the proposed energy balance criterion to study the approach–retraction motion of a rigid sphere in contact with a viscoelastic half-space. A strong interplay between adhesion and viscoelastic hysteretic losses is reported which can lead to strongly increased adhesion strength, depending on the loading history. Specifically, two different mechanisms are found to govern the increase of pull-off force during either approach–retraction cycles and approach – full relaxation – retraction tests. In the former case, hysteretic losses occurring close to the circular perimeter of the contact play a major role, significantly enhancing the energy release rate. In the latter case, instead, the pull-off enhancement mostly depends on the glassy response of the whole (bulk) material which, triggered by the fast retraction after relaxation, leads to a sort of ‘frozen’ state and results in a flat-punch-like detachment mechanism (i.e., constant contact area). In this case, the JKR theory of adhesive contact cannot be invoked to relate the observed pull-off force to the effective adhesion energy, i.e. the energy release rate G, and strongly overestimates it. Therefore, a rigorous mathematical procedure is also proposed to correctly calculate the energy release rate in viscoelastic dissipative contacts.

Controlling Hybrid Polyhydroxyurethane Adhesive and Rheological Properties by Partial Carbonation of Biobased Epoxy Monomer.

Controlling hybrid material properties by simple monomer design offers an elegant pathway to prepare thermoset adhesives with tunable properties. Herein, biobased hybrid polyhydroxyurethane/polyepoxy is prepared starting from partially carbonated cashew nut shell epoxy derivatives (NC514) and m-xylene diamine (MXDA). The curing reactions, that is, epoxy-amine and cyclic carbonate aminolysis, monitored by ATR-IR spectroscopy at 50°C are found to be concomitant yielding highly homogeneous materials. Hybrid networks are extensively characterized by swelling tests, TGA, DMA, DSC, tensile tests, rheology, and lap-shear-test on aluminum substrates. The introduction of hydroxyurethane moieties within the epoxy-amine networks enhanced the adhesion properties (up to 20% compare to neat epoxy resins) by combining hydrogen bonding capability and vitrimeric properties (thermoset able to flow). Rheological characterizations and reprocessing tests demonstrated that hybrid adhesives with up to 47 mol% of cyclic carbonate groups are capable of covalent exchange (internally catalyzed by tertiary amine) while keeping similar thermomechanical properties and enhanced adhesion strength compare to the permanent epoxy network.

A novel strategy for constructing active anti-corrosive coatings by embedding three-dimensional fiber networks

The corrosion protection effectiveness of micro/nanocontainer-based intelligent coatings significantly depends on their dispersion within the coating matrix. Inspired by the bionic concept of a ‘vascular network’ we designed a polylactic acid (PLA) three-dimensional fiber network incorporating the pH-responsive TiO2-8-hydroxyquinoline (TiO2-8HQ) nanotubes using electrospinning technology. These TiO2-8HQ@PLA networks are crosslinked and evenly dispersed on the Mg alloy surface, responsive to local pH variations. The encapsulated 8HQ inhibitors release rapidly in alkaline conditions, transporting through the network to enable continuous self-healing in multi-defect areas. An epoxy coating applied over the network forms a novel vascular network intelligent coating. Electrochemical and surface analysis tests reveal that 2 %TiO2-8HQ@PLA-EP provides the most enduring corrosion resistance over 50 days in a 3.5 wt% NaCl solution, with a coating resistance of 2.33 × 106 Ω cm2 and charge transfer resistance of 4.81 × 106 Ω cm2. Additionally, the network enhances adhesion strength (38.01 MPa) and surface wettability (104.25° ± 0.15°), significantly improving the coating’s physical barrier performance. The combination of the micro/nanocontainers technology and vascular network innovative design provides a unique insight into active corrosion control on diverse metals.

A ceria/calcium-phosphate functional composite coating on magnesium alloy for enhanced adhesion strength, corrosion resistance, and biocompatibility

Magnesium (Mg) and its alloys have been regarded as potential orthopedic implant materials due to their suitable properties but face challenges due to rapid biocorrosion and insufficient bio-functionality, necessitating surface treatment to mitigate dysfunction. In this work, a two-step electrodeposition was employed to construct a ceria/calcium-phosphate (Ce/Ca-P) composite coating on Mg alloys. This construction approach endows multi-functions of the coating. The ceria interlayer ameliorates adhesion strength. The pin-like structure on the outer layer of the Ce/Ca-P coating enhances the antibacterial capabilities of the coating in the early stages of the implantation. The calcium-phosphate outer layer and the ceria interlayer induce the deposition of calcium and phosphate ions promoting bone healing in the mid-term. The introduction of the ceria interlayer significantly reduces the corrosion rate of the Mg alloy by 86.7% improving the corrosion resistance of the alloy, which is of great significance to maintain the service reliability of the device during the long-term service period. The results indicate that the Ce/Ca-P coating exhibits good hemocompatibility and cytocompatibility. This type of developed coating with anti-corrosive and bio-functionalized capability helpfully advances the application of Mg-based bone implants.

Interlayer design for strong adhesion in the double-layer flexible copper clad laminate via HiPIMS deposition

By designing different interlayers (Al, Si/SixNy and Cr interlayer) and oxygen plasma pretreatment of the substrate, strong adhesion was realized for the double-layer flexible copper clad laminate on polyimide (PI) substrate via high power impulse magnetron sputtering (HiPIMS) technology. The microstructures and properties of Cu films on PI substrate were characterized by an X-ray powder diffractometer (XRD), X-ray photoelectron spectroscope (XPS), atom force microscopy (AFM), scanning electron microscope (SEM), nano-scratch test, scotch tape test and four-probe detector. With the introduction of interlayer and oxygen plasma pretreatment, the critical load of Cu film (300 nm thick) peaked at 43.5 mN and the sheet resistance ranged from 124 to 227 mΩ/sq. The oxygen plasma pretreatment resulted in the drastic oxidation to generate functional groups on the PI substrate surface, which contributed to the improvement of adhesion strength by chemical interaction in terms of the film with Si/SixNy or Cr interlayer. Besides, for the Cu film with Si/SixNy interlayer, the resistance against copper diffusion by the SixNy layer can also promote the enhancement of adhesion strength.

Multi-layer structured AlN/Er2O3 coating: Enhanced thermal stability and hydrogen isotope permeation resistance

AlN/Er2O3 multi-layer coatings, as a novel hydrogen isotope permeation barrier for nuclear reactor and hydrogen energy field, were prepared by magnetron sputtering coupled with metal-organic decomposition on the surface of reduced activation ferrite/martensitic steel. The thickness of the Er2O3 layers was adjusted by spin coating several times, the adhesion of the layers was tested with a micron scratch tester, and the microstructure and surface composition of the layers were analyzed by TEM and XPS. The results indicate the absence of evident crack holes on the coating surface, uniform distribution of elements without segregation, and satisfactory densification. In comparison with the individual Er2O3 coating, the multi-layer coating incorporating AlN as the interlayer exhibits enhanced adhesion strength, which could effectively mitigate the thermal mismatch phenomenon of Er2O3 under high temperature conditions. Electrochemical hydrogen permeation and high temperature gas pressure driven deuterium permeation tests demonstrated that the permeability resistance of the AlN/Er2O3 coating does not linearly increase with its thickness. The hydrogen permeation reduced factor of the coating reaches its maximum value when the thickness of the Er2O3 coating is 1500 nm.

A rationally designed polymer brush/lubricant coating system for effective static and dynamic marine antifouling

Bioinspired slippery surfaces have garnered significant attention as promising solutions to mitigate biofouling. Unlike traditional lubricant-infused porous surfaces, recent research has focused on the integration of lubricants within polymer brush-grafted surfaces. The combination of polydimethylsiloxane (PDMS) polymer brush and silicone oil has gradually become the most prevalent choice due to their outstanding chemical affinity. However, this conventional coating system also has the potential for improvement to meet the needs of long-lasting and efficient marine antifouling, including i) precisely designing the polymer brush’s chemical structure to match the polarity of a specific lubricant enhances their chemical affinity, and ii) appropriately reduce the coating system’s surface energy to improve the fouling desorption performance. Here, we introduce a systematically engineered polymer brush/lubricant coating system that incorporates fluorinated polysiloxane and perfluoropolyether fluid. This novel coating system exhibits enhanced adhesion strength coupled with reduced surface energy, resulting in superior stability and omniphobic properties. Additionally, it showcases excellent corrosion resistance and significantly deters marine microorganism adhesion, achieving reductions of 98.8 % for P. tricornutum and 99.8 % for Bacillus sp.. Marine field trials, conducted over a 90-day static immersion period, confirm the remarkable antifouling performance, which surpasses most existing slippery coatings. Moreover, under dynamic conditions, organisms adhering for 150 days are readily dislodged by shear force. These findings underscore the pivotal role of systematic design in polymer brush/lubricant coating systems for the advancement of high-performance slippery surfaces tailored for marine antifouling applications.

ТЕХНОЛОГИЧЕСКИЕ ПОДХОДЫ ПОВЫШЕНИЯ КАЧЕСТВА МЕЛКОЗЕРНИСТОГО БЕТОНА

The production of high quality and reliable fine-grained concrete using resource-saving technologies is a current and important task. The popularity of fine-grained concrete is determined by the possibility of eliminating coarse aggregate. It is expensive and in short supply in many regions of the country, and the ability to regulate within a wide range the structure and technical properties of the concrete mixture and concrete, by the quality of concreting of densely reinforced structures of complex configuration, increasing the impact strength of reinforced concrete elements. In this regard, to increase the demand for this product, research is carried out on the production of fine-grained concrete using locally available technogenic materials and technical methods based on established patterns of influence of recipe and technological parameters on physical, mechanical and operational characteristics. The lack of high-quality coarse sands in the region was a prerequisite for the search for new solutions to control the processes of contact formation between cement particles and fine aggregate. The recipe-technological method proposed in the work, which consists in the complex use of fractionated filler surface activated by the cationic additive of alkyldimethylbenzylammonium chloride, modified with microsilica binder, contributed to the enhancement of adhesive strength in the contact zone “cement stone-aggregate” and the formation of a dense structure composed of high-strength and poorly soluble formations. The proposed technology for producing fine-grained concrete will make it possible to create high-quality composites using technogenic raw materials, thereby solving the problem of the shortage of coarse natural sands suitable for construction.

Improvements in bioactivity, blood compatibility, and wear resistance of thermally sprayed carbon nanotube reinforced hydroxyapatite-based orthopedic implants

Titanium implants often fail due to aseptic loosening and non-hemocompatibility, necessitating costly revision surgeries. This study investigated the wear performance and biocompatibility of high-velocity oxy-fuel (HVOF) sprayed-hydroxyapatite (HA) and HA/alumina-19 wt%/carbon nanotube (CNT)− 1 wt% (HAC1) coatings. The novel heterocoagulation colloidal technique effectively dispersed CNTs, enhancing adhesion strength by ∼120 %, hardness by ∼45 %, and wear resistance by ∼32 % in simulated body fluid (SBF) and 17 % in dry conditions versus HA coatings, attributed to the low coefficient of friction (CoF) (1.16–1.48 times than HA) due to lubrication offered by peeled-off graphite layers from the CNT surface. Additionally, HAC1 implants exhibited superior apatite growth (∼52 % than HA), excellent non-hemolytic behavior (∼0.2 %), and no platelet activation, making it highly promising for orthopedic applications.

Fabrication of a novel bone adhesive (crosslinked phytic acid-gelatin coordinated with magnesium phosphate and calcined dolomite, and montmorillonite) for enhancing adhesion strength and biocompatibility

Fabrication of a novel bone adhesive (crosslinked phytic acid-gelatin coordinated with magnesium phosphate and calcined dolomite, and montmorillonite) for enhancing adhesion strength and biocompatibility

Inspired square micro-texture structures designed by nanosecond laser sculpture for enhancing adhesion strength of plasma spraying Si-HfO2 bond coat on SiC substrates

In order to enhance the adhesion strength between the Si-HfO2 bond coat and substrate, square micro-textures inspired by straw-checkered sand fixation are fabricated using nanosecond laser sculpture. The adhesion strength of the laser surface texture (LST) sample is up to 27.31 ± 3.34 MPa, which is more than 200 % higher than the conventional grit-blasted one (8.12 ± 0.70 MPa). The promoted interface bonding is attributed to the following three aspects: First, the mechanical anchoring established by micro-texture positively improves the adhesion strength. Second, the LST diminishes the contact angle to 16.5 ± 1.7°, improving the wetting of the SiC substrate. Third, the high-pressure plasma is implemented to produce enormous compressive stress (205.6 ± 14.6 MPa) on the SiC substrate surface, greatly aiding substrate/coating adhesion. The above three mechanisms work synergistically to enable the LST treatment to exhibit better adhesion than the conventional grit-blasted treatment on SiC substrate.

Wearable and Recyclable Water-Toleration Sensor Derived from Lipoic Acid.

Flexible wearable sensors recently have made significant progress in human motion detection and health monitoring. However, most sensors still face challenges in terms of single detection targets, single application environments, and non-recyclability. Lipoic acid (LA) shows a great application prospect in soft materials due to its unique properties. Herein, ionic conducting elastomers (ICEs) based on polymerizable deep eutectic solvents consisting of LA and choline chloride are prepared. In addition to the good mechanical strength, high transparency, ionic conductivity, and self-healing efficiency, the ICEs exhibit swelling-strengthening behavior and enhanced adhesion strength in underwater environments due to the moisture-induced association of poly(LA) hydrophobic chains, thus making it possible for underwater sensing applications, such as underwater communication. As a strain sensor, it exhibits highly sensitive strain response with repeatability and durability, enabling the monitoring of both large and fine human motions, including joint movements, facial expressions, and pulse waves. Furthermore, due to the enhancement of ion mobility at higher temperatures, it also possesses excellent temperature-sensing performance. Notably, the ICEs can be fully recycled and reused as a new strain/temperature sensor through heating. This study provides a novel strategy for enhancing the mechanical strength of poly(LA) and the fabrication of multifunctional sensors.

Enhanced adhesion strength between electroplated Cu and ABF substrate with isothermal annealing treatment

This study aimed to enhance the adhesion strength between electroplated Cu and a low-profile Ajinomoto build-up film (ABF) substrate through isothermal annealing treatment. We examined the electroplated Cu microstructure evolution (including grain size, orientation, and texture) and elemental distribution at the Cu/ABF interface after annealing at 180 °C and 210 °C by means of electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and transmission electron microscopy (TEM) in conjunction with energy dispersive X-ray spectroscopy (EDS). Furthermore, the adhesion strength of the Cu/ABF structure after isothermal annealing for different times was investigated through a peeling test based on the IPC-TM-650 test methods. The chemical bond and atomic concentration depth profiles of the fracture surface (ABF side) after the peeling test were characterized by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). These investigations demonstrated that the adhesion strength of the Cu/ABF structure can be greatly enhanced by the electroplated Cu microstructure modification and Cu/ABF interdiffusion through appropriate isothermal annealing treatment.

Robust aortic media adhesion using hydrophobically modified Alaska pollock gelatin-based adhesive for aortic dissections.

Type-A aortic dissection is an acute injury involving the delamination of the aorta at the parts of the aortic media. Aldehyde crosslinker-containing glues have been used to adhere to the media of the dissected aorta before joining an artificial graft. These glues effectively adhere to the aortic media; however, they show low biocompatibility due to the release of aldehyde compounds. In this study, we report innovative adhesives based on hydrophobically modified Alaska pollock gelatin (hm-ApGltn) with different alkyl or cholesteryl (Chol) groups that adhere to the media of the dissected aorta by combining hm-ApGltns with a biocompatible crosslinker, pentaerythritol poly(ethylene glycol) ether tetrasuccinimidyl glutarate. The modification of alkyl or Chol groups contributed to enhanced adhesion strength between porcine aortic media. The adhesion strength increased with increasing modification ratios of alkyl groups from propanoyl to dodecanoyl groups and then decreased at a modification ratio of ~20 mol %. Porcine aortic media adhered using 7.5Chol-ApGltn adhesive showed stretchability even when expanded and shrunk vertically by 25% at least five times. Hm-ApGltn adhesives subcutaneously injected into the backs of mice showed no severe inflammation and were degraded during the implantation period. These results indicated that hm-ApGltn adhesives have potential applications in type-A aortic dissection.