Nanocomposite Adhesives Research Articles

Fabrication of Ag nanowires and Ag-graphite nanocomposite conductive adhesives by one-step hydrothermal method

Fabrication of Ag nanowires and Ag-graphite nanocomposite conductive adhesives by one-step hydrothermal method

Development of biodegradable bioadhesive nanocomposites reinforced with quantum dots and functionalized carbon nanotubes

A series of photoluminescent nanocomposite polyurethane adhesives were elaborated from a chemoenzymatic prepared diol of caprolactone (PCL-diol) and ethylene glycol with an excess of two different isocyanates: i) hexamethylene (HDI) and (ii) isophorone (IPDI)) diisocyanates. Adhesive formulations were filled with functionalized poly(amido-amine) (PAMAM) carbon nanotubes (f-MWNTs) and carbon quantum dots (CQDTs). Dry swine gut was used as substrate and mechanical tests were performed to explore the performance of the adhesives. The obtained materials were characterized by infrared spectroscopy (FT-IR), energy surface by contact angle, differential scanning calorimetry (DSC), hydrolytic degradation, and mechanical testing under tension, lap shear, T-peel, wound closure, and burst pressure. Among the main results were the formation of covalent bonds between the substrate and the adhesive, and the fact that the mechanical strength of the nanocomposite adhesives was superior to that of the unfilled adhesives. Compatibility of nanocomposites with the substrate was achieved by increasing wettability by the incorporation of both nanofillers. Also, adhesives filled with only CQDTs and with MWNTs-CDQTs combined showed photoluminescence activity under ultraviolet light.

Engineering Wet-Resistant and Osteogenic Nanocomposite Adhesive to Control Bleeding and Infection after Median Sternotomy.

Median sternotomy surgery stands as one of the prevailing strategies in cardiac surgery. In this study, the cutting-edge bone adhesive is designed, inspired by the impressive adhesive properties found in mussels and sandcastle worms. This work has created an osteogenic nanocomposite coacervate adhesive by integrating a cellulose-polyphosphodopamide interpenetrating network, quaternized chitosan, and zinc, gallium-doped hydroxyapatite nanoparticles. This adhesive is characterized by robust catechol-metal coordination which effectively adheres to both hard and soft tissues with a maximum adhesive strength of 900 ± 38kPa on the sheep sternum bone, surpassing that of commercial bone adhesives. The release of zinc and gallium cations from nanocomposite adhesives and quaternized chitosan matrix imparts remarkable antibacterial properties and promotes rapid blood coagulation, in vitro and ex vivo. It is also proved that this nanocomposite adhesive exhibits significant in vitro bioactivity, stable degradability, biocompatibility, and osteogenic ability. Furthermore, the capacity of nanocomposite coacervate to adhere to bone tissue and support osteogenesis contributes to the successful healing of a sternum bone defect in a rabbit model in vivo. In summary, these nanocomposite coacervate adhesives with promising characteristics are expected to provide solutions to clinical issues faced during median sternotomy surgery.

Reversibly stable and highly stretchable transparent polymer nanocomposite adhesives using hierarchical spring-like molecular nanobridges

For the development of stretchable optoelectronic devices, optically transparent composite adhesives should afford reversible stretchability and high optical transmittance as well as strong interfacial adhesion. However, simultaneous achievement of these essential prerequisites for advanced stretchable optical composite adhesives remains challenging. Herein, we offer an unprecedented approach for the fabrication of reversibly stretchable and optically transparent polymer nanocomposite adhesives based on the construction of hierarchical elastic molecular nanobridges between rigid-flexible hybrid nanoparticles and matrix resin. Photoreactive flexible poly(propylene glycol) (meth)acrylate chains were chemically combined with a rigid nano-silica core to form rigid and flexible hybrid nanoparticles. Subsequently, multiple elastic molecular nanobridges between the embedded hybrid nanoparticles and acrylate resin matrix were constructed inside the polymer composite through UV curing, which results in a stretchable interconnection that allows efficient repeated stretching and recovery of stretchable polymer nanocomposite adhesives. The newly fabricated nanocomposite adhesive film with a low content of rigid-flexible hybrid nanoparticles afforded an excellent reversible stretchability and outstanding cyclic elastic durability, and simultaneously maintained high optical transparency (95.1%) and interfacial adhesion strength (21.5 N/25 mm) of the film compared to those of conventional optical adhesive film.

Static and Dynamic Mechanical Behavior of Carbon Fiber Reinforced Plastic (CFRP) Single-Lap Shear Joints Joule-Bonded with Conductive Epoxy Nanocomposites

The potential of electrically conductive graphene nanoplatelets (GNPs)/epoxy, multi-walled carbon nanotubes (MWNCTs)/epoxy and hybrid GNPs-MWCNTs/epoxy nanocomposites as adhesives for out-of-autoclave (OoA) and in-the-field CFRP repair via Joule heat curing was investigated. Scanning electron microscopy revealed a good dispersion of the nanoparticles in the matrix in all the nanocomposite adhesives above their percolation thresholds, which led to a homogeneous distribution of the heat generated during Joule CFRP repair. The joints bonded with neat epoxy and the nanocomposites showed similar lap shear strengths, with the addition of nanoparticles enhancing the fatigue performance of the adhesively bonded joints relative to when neat epoxy was used as an adhesive and oven-cured. The interfacial and cohesive failure mechanisms were found to coexist in all the cases, with an increasing dominance of the cohesive when nanofillers were embedded into the adhesive. No effect of the specific type of nanofiller incorporated into the epoxy as the conductive component was observed on the mechanical performance of the bonded joints, with the adhesives containing MWCNTs showing similar results to those filled with GNPs at considerably lower loadings due to their lower percolation thresholds. The independence of the properties regardless of the curing method highlights the promise of these Joule-cured adhesives for industrial applications.

Effect of nanoparticle type and processing technique on the performance of lap shear joint of epoxy nanocomposite adhesives

Effect of nanoparticle type and processing technique on the performance of lap shear joint of epoxy nanocomposite adhesives

Piezoelectric Nanocomposite‐Based Multifunctional Wearable Bioelectronics for Mental Stress Analysis Utilizing Physiological Signals

AbstractThis study multifunctional wearable bioelectronics (MWBs) integrated with a piezoelectric sensor and a micropatterned temperature sensor for accurate detection of human physiological signals. Piezoelectric nanocomposite uniformity, stretchability, and adhesion is improved through the functionalization of nanoparticles with glycidyl silane and nonionic surfactants dispersion in the organic polymer matrix. Additionally, crack‐free nanometal layers are deposited on the nanocomposite interface with high adhesion by thiol silane functionalization and oxygen plasma treatment. The MWBs exhibit a temperature sensitivity of 7.1 Ω °C−1 (R2 of 0.999) between 30 °C to 40 °C, a pressure sensitivity of 72 mV kPa−1 (R2 of 0.998) within 0.5 kPa to 10 kPa, and a stable mechanical durability. MWBs have demonstrated to detect subtle pulse waveforms at an arm‐mimicking phantom and human skin, respectively. Furthermore, MWBs are applied to analyze physiological signal characteristics caused by human stress, demonstrating its potential for use in healthcare electronics in various medical applications.

DLP printing of BT/HA nanocomposite ceramic scaffolds using low refractive index BT crystals

Biological piezoelectric materials have significant potential for bone repair and energy harvesting owing to their excellent biocompatibility and piezoelectric effect. The BaTiO3/Ca10(PO4)6(OH)2 (BT/HA) composite material is an outstanding representative of biological piezoelectric materials, which has not been individually designed using digital light processing (DLP) 3D printing because of the large difference in the refractive index of its components. Therefore, in this work, double-sided-tooth plate-like BT crystals with high curvature were prepared via a hydrothermal process, and BT/HA ceramic slurries were grinded out using dispersed intermittent ball milling scheme, and BT/HA nanocomposite ceramic scaffolds were fabricated by DLP 3D printing technology. The nanostructure, dielectric properties, and piezoelectric energy harvesting performance of the BT/HA nanocomposite ceramic scaffolds were evaluated. The influences of different morphologies and contents for BT on the piezoelectric potential and stress distribution were analyzed based on a multi-physics coupling finite element simulation. The cell proliferation and adhesion abilities were investigated also. The BT/HA nanocomposite ceramic scaffolds present excellent dielectric properties, cell proliferation and adhesion abilities, and an open circuit voltage of 8 V during piezoelectric energy harvesting. The material properties and multi-physics coupling finite element analysis imply that the double-sided-tooth plate-like BT plays an important role for the fastness structure and electric field distribution in the BT/HA nanocomposite. Thus, this work provides a strategy for the application of the customized BT/HA nanocomposite ceramic scaffolds in new-generation orthopedic implants and biological energy harvesting.

Laponite nanoparticle-crosslinked carboxymethyl cellulose-based injectable hydrogels with efficient underwater-specific adhesion for rapid hemostasis

Tissue adhesives have attracted intense and increasing interest due to their multiple biomedical applications. Despite the rapid development of adhesive hydrogels, huge challenges remain for materials that can ensure strong adhesion and seal hemostasis in aqueous and blood environments. To address this issue, we have developed an innovative design of PAA-based coacervate hydrogel with strong wet adhesion capability through a simple mixture of PAA copolymers with oxidized-carboxymethylcellulose (OCMC), and tannic acid (TA) as the main components, and structurally enhanced with natural clays (Laponite XLG). The absorbed TA provides solid adhesion to dry and wet substrates via multiple interactions, which endows the XLG-enhanced coacervate with the desired underwater adhesive strength. More importantly, the dielectric constant is introduced to evaluate the polarity of the tested samples, which may be used as guidance for the design of mussel-inspired adhesives with even better underwater adhesive properties. In vivo hemorrhage experiments further confirmed that the hydrogel adhesive dramatically shortened the hemostatic time to tens of seconds. Overall, the persistent adhesion and acceptable cytocompatibility of the hydrogel nanocomposite make it a promising alternative suture-free approach for rapid hemostasis at different length scales and is expected to be extended to clinical application for other organ injuries.

Prediction of lap shear strength of GNP and TiO2/epoxy nanocomposite adhesives

Abstract In this study, graphene nanoplatelets (GNPs) and titanium dioxide nanofillers were added to epoxy resin P-5005 at five different weight percentages (wt%), viz., 1, 5, 10, 15, and 20 wt%. The tensile properties of the nanocomposites were experimentally tested following ASTM D638-14. Then, the above-mentioned nanocomposites were applied as adhesives for an overlap joint of two A5055 aluminum sheets. The apparent shear strength behavior of joints was tested following ASTM D1002-01. Moreover, experimentally obtained results were applied to train and test machine learning and deep learning models, i.e., adaptive neuro-fuzzy inference system, support vector machine, multiple linear regression, and artificial neural network (ANN). The peak tensile strength (TS) and joint failure load (FL) values were observed in epoxy/GNP samples. The ANN model exhibited the least error in predicting the TS and FL of the considered nanocomposites. The epoxy/GNP nanocomposites exhibited the highest TS of 28.49 MPa at 1 wt%, and the peak overlap joints exhibited an FL of 3.69 kN at 15 wt%.

Design of interface dynamic cross-linked hybrid network with highly improved mechanical, recycling and adhesive performance

Engineering interface dynamic crosslinking is particularly favorable for nanocomposite to acquire intriguing properties such as energy dissipation, recyclability and adhesion, yet it still remains a formidable task. Herein, we report a robust and recyclable nanocomposite hot melt adhesives (HMAs) enabled by employing noncovalent interactions at the interface between core–shell structured silica nanoparticles (T-SiO2 NPs) and carboxylated ethylene vinyl acetate copolymer (EVA-COOH). Through elaborate architecture by hydrogen bonds and Fe-based coordination bonds assembly of interface crosslinking network, the resultant hybrid network exhibits excellent mechanical properties, with tensile strength of 11.34 MPa, modulus of 2.64 MPa and toughness of 104.4 MJ m−3, which are 2.89 times, 1.77 times and 1.80 times that of the neat EVA, respectively. Furthermore, due to the dynamic nature of the network, its mechanical properties could be well maintained (∼100 %) even after multiple generations of recycling. More strikingly, the as-prepared HMAs displayed an outstanding ability to bond diverse substrates tightly. In addition, stable adhesion performance is realized on the aluminum (Al) surface under air and harsh conditions. This inorganic–organic interface crosslinking strategy shows great significance for fabricating low-cost and environmentally adaptive functional materials.

High-performance epoxy nanocomposite adhesives with enhanced mechanical, thermal and adhesion properties based on new nanoscale ionic materials

Epoxy (EP) adhesives as high-shear strength permanent adhesives have been used in various engineering applications, particularly aerospace and automotive. However, these adhesives suffer from disadvantages such as high fragility, poor tensile strength, and toughness, which limits adhesion efficiency in structural bonding. Here, a novel EP nanocomposite adhesive-based SiO2-nanoscale ionic materials (SiO2-NIMs) with excellent adhesives strength, transparency, thermal stability, and mechanical properties was prepared via a solvent-free process. To prepare SiO2-NIMs, the sulfonated-SiO2 nanoparticles (SiO2-SO3H) were ionically tethered as a core-corona with Jeffamine-ED-2003 chains as a canopy. Then, SiO2-NIMs/EP nanocomposites with various SiO2-NIMs contents were fabricated. We demonstrate that SiO2-NIMs as high-performance additives, unlike conventional additives, via an exclusive mechanism can simultaneously improve interfacial bond strength, stiffness, and toughness of EP adhesive. The RMS and DMTA tests averred the liquid-like SiO2-NIMs played a magnificent multi-functional role that acts as nonvolatile solvents, reinforcing-agent particles, and toughening agents, causing improved shear strength and resistance to crack growth of epoxy adhesives. The core-corona-canopy parts of SiO2-NIMs make hydrogen bonds and ionic-electrostatic interactions between the adhesive and adherent layers. The single lap shear under different temperatures, TGA, tensile, and SEM tests were applied to investigate adhesion strength, thermal and mechanical properties, and fracture surface morphology of EP adhesives, respectively. For example, the 5 phr SiO2-NIMs/EP showed increased lap shear strength at RT, tensile toughness, tensile strength, stiffness, elongation% and char-yield% by 54%, 240%, 92%, 36%, 91%, and 50% compared to neat EP, respectively. This study introduces SiO2-NIMs as promising additives for high-performance EP adhesives.

Strong Biopolymer-Based Nanocomposite Hydrogel Adhesives with Removability and Reusability for Damaged Tissue Closure and Healing.

Bioadhesives are widely used in a variety of medical settings due to their ease of use and efficient wound closure and repair. However, achieving both strong adhesion and removability/reusability is highly needed but challenging. Here, we reported an injectable mesoporous bioactive glass nanoparticle (MBGN)-incorporated biopolymer hydrogel bioadhesive that demonstrates a strong adhesion strength (up to 107.55 kPa) at physiological temperatures that is also removable and reusable. The incorporation of MBGNs in the biopolymer hydrogel significantly enhances the tissue adhesive strength due to an increased cohesive and adhesive property compared to the hydrogel adhesive alone. The detachment of bioadhesive results from temperature-induced weakening of interfacial adhesive strength. Moreover, the bioadhesive displays injectability, self-healing, and excellent biocompatibility. We demonstrate potential applications of the bioadhesive in vitro, ex vivo, and in vivo for hemostasis and intestinal leakage closure and accelerated skin wound healing compared to surgical wound closures. This work provides a novel design of strong and removable bioadhesives.

High-performance carbon nanofiber reinforced epoxy-based nanocomposite adhesive materials modified with novel functionalization method and triblock copolymer

New high-performance epoxy-based nanocomposite adhesive materials were developed with the innovative use of nanomaterials to enhance the bond strength, especially at elevated temperatures. A tetraglycidyl diaminodiphenylmethane (TGDDM) based aerospace-grade epoxy adhesive (EA9396) with a high glass transition temperature and viscosity was combined with functionalized CNFs and a phase-separated poly(styrene)-poly(butadiene)-poly(methyl methacrylate) triblock copolymer (SBM). The ozone-treated CNFs (OZ-CNFs) were functionalized with polyethyleneimine dendrimer (PEI + OZ-CNFs), or a polyamine hardener (H + OZ-CNFs) and characterized using X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) to confirm the chemical reaction of the amine functional groups. Room temperature mechanical testing revealed the optimized nanocomposite adhesives containing SBM and CNFs functionalized with either PEI or hardener resulted in a 40% increase in lap shear strength (50 MPa) when compared to the unmodified epoxy (35.6 MPa). At the elevated temperature of 90 °C, a strength improvement of 35% and 38% (29.5 MPa and 30 MPa) was observed for the adhesives containing SBM and CNFs functionalized using PEI or hardener, respectively. SEM images showed that CNF functionalization provided a more uniform distribution in the adhesive and enhanced the SBM plastic deformation during crack propagation. The PEI and hardener functionalization also significantly reduced the level of CNF pull-out, which was believed to enhance the energy dissipation mechanisms responsible for the significant increase in the lap shear strength.

Enhanced mechanical, thermal and adhesion properties of addition cured polydimethylsiloxane nanocomposite adhesives

The reinforcement of elastomeric polydimethylsiloxanes (PDMS) with carbon-based fillers and silica has gained much attention over the last few decades due to the inherent stability of the fillers which improves the physical and mechanical properties of the polymer nanocomposites. We report herein the preparation of an addition cured V-PDMS (vinyl-terminated PDMS) nanocomposite using CNT (carbon nanotube) and Aerosil COK 84 (mixed silica and alumina) as fillers. The influence of the fillers on the morphology, mechanical properties, thermal stability, thermal conductivity, and adhesive strength of these addition cured PDMS nanocomposites was studied in detail. It was observed that the tensile strength and thermal stability of the nanocomposites were enhanced upon the addition of fillers. The higher thermal conductivity of the CNT reinforced nanocomposites has potential application in heat sealing materials. The adhesive strength was studied by conducting a lap shear test on both mild steel and aluminum substrates and the adhesive strength was found to be higher for the mild steel substrate.

Evaluation of a gold nanocomposite hyaluronic acid-based adhesion barrier with antibacterial properties in an animal model

Objectives: In this study, the effects of a gold nanocomposite hyaluronic acid-based adhesion barrier were evaluated in an animal model. Materials and methods: In our study, a total of 42 rats in seven groups, with six rats in each group, were evaluated. The groups were established according to the application of an adhesion barrier. In the first, second, and third groups, an adhesion barrier was applied by standard median laparotomy in the first, second, and fourth weeks, respectively. The fourth, fifth, and sixth groups underwent the same procedure in the first, second, and fourth weeks; however, no adhesion barrier was applied to these groups. The seventh group was the control group, and no treatment was performed in this group. Results: There was no significant difference in the formation of inflammatory cells and fibrous tissue between the groups that underwent laparotomy in the first and second weeks with and without the adhesion barrier (p>0.05). However, both low inflammatory cells (p<0.05) and low fibrous tissue (p<0.05) were evaluated in favor of the adhesion barrier group operated at the fourth week. Conclusion: A gold nanocomposite hyaluronic acid-based adhesion barrier prevents adhesion, particularly in the long term. However, the results need to be supported by clinical studies.

Ozone functionalized graphene nanoplatelets and triblock copolymer hybrids as nanoscale modifiers to enhance the mechanical performance of epoxy adhesives

In the present work, the mechanical and fracture performance of a newly developed high-performance nanocomposite adhesive was characterized experimentally. The nanocomposite adhesive was based on an epoxy resin, which was modified with 10 wt% of triblock copolymers (BCPs) including styrene-butadiene-methylmethacrylate (SBM) and methylmethacrylate-butylacrylate-methylmethacrylate (MAM), and ozone-functionalized graphene nanoplatelets (OZ-GNPs). The mechanical properties of the adhesive joints were systematically evaluated using lap shear, tensile-butt, and Mode-I fracture toughness tests. The lap shear strength and the ultimate shear strain of the 1.0 wt% OZ-GNP + SBM ternary nanocomposite epoxy adhesives obtained 91% and 97%, while 1.0 wt% OZ-GNP + MAM adhesives attained 64% and 63% improvement, respectively, compared to that of the pure epoxy. Consequently, the potential load capacity was improved by about 93% (1.0 wt% OZ-GNP + SBM) and 62% (1.0 wt% OZ-GNP + MAM) compared to that of pure epoxy joints. However, the tensile butt joint strength of the nanocomposite adhesives was slightly reduced due to the lower stiffness of the BCPs. The mode-I fracture toughness results for the 1.0 wt% OZ-GNP + SBM and 1.0 wt% OZ-GNP + MAM increased significantly by approximately 1000% and 200%, respectively, compared to the unmodified epoxy adhesive. Fractography using scanning electron microscopy showed the formation of BCP nanostructures, plastic deformation, crack deflection, debonding of the BCP, and subsequent plastic void growth, which all contributed to the increase in the fracture toughness of the nanocomposite adhesives. The extent of the plastic deformation zone was enhanced by the addition of OZ-GNPs.

Dependence of the strengthening degree of nanocomposites “polymethyl methacrylate — functionalized carbon nanotubes” on the structure of the nanofiller

Using the example of nanocomposites formed from polymethyl methacrylate and carbon nanotubes, it is shown that the functionalization of a nanofiller changes the structure of carbon nanotubes and increases the radius of their annular formations. Theoretical and experimental data are presented, confirming that this significantly increases the level of interfacial adhesion in nanocomposites and the efficiency of transfer of applied mechanical stress between the polymer matrix and the nanofiller.

Synthesis of waterborne polyurethane nanocomposite adhesives of bio‐based polyol from rapeseed cake residual and cellulose nanowhisker

AbstractIn this research work, we synthesize a series of waterborne polyurethane (WPU) bio‐nanocomposite adhesives from bio‐based polyols, extracted from rapeseed cake residual (RCR) by oxypropylation procedure, and cellulose nanowhisker (CNW). The hydroxyl‐ (OH) number of the polyols, as the first variable parameter, is controlled through tuning oxypropylation degree by changing propylene oxide (PO) to RCR ratio. From the four prepared polyols, WPU of Polyol‐2 (WPU2) shows the most significant shear strength for wood and glass adhesion substrates. Polyurethane nanocomposites of CNW, with three different weight contents of 0.25, 0.50, and 1.0%, are prepared from WPU2, as the optimum WPU, and the WPU2 nanocomposite of WPU2‐0.50 wt% show the highest shear strength for all types of the substrates. For the WPU2 and WPU2‐0.50 wt% adhesives, the wood‐wood substrate show a high shear strength of 12.8 and 15.1 MPa, respectively. This work revealed that the shear strength of the adhesives and their failure mechanisms are affected by the structural parameters, OH‐number, and CNW content.

Designing of desired nanocomposite pressure-sensitive adhesives through tailoring the structural characteristics of polysilsesquioxane-acrylic core-shell nanoparticles

A series of novel nanocomposite pressure-sensitive adhesives (PSAs) made of core-shell nanoparticles has been designed with a diverse range of adhesion properties from general-purpose to high-shear adhesives. The PSAs were prepared by synthesis of polymethacryloxypropylsilsesquioxane (PSQ) nanoparticles and their encapsulation with an acrylic shell via semi-continuous emulsion polymerization. The effects of structural characteristics of the core-shell nanoparticles, i.e. composition of acrylic comonomers in the shell, shell thickness, and grafting density, on peel and shear strengths of the PSAs were scrutinized. Grafting of acrylic chains on the surface of PSQ nanoparticles led to an improvement in the peel and shear strengths due to enhancement in the dynamic mechanical moduli. Increase in the cohesive energy density of the PSAs through raising the methyl methacrylate content in the shell enabled designing of high peel and shear PSAs. Increasing the number of segments of the grafted chains present in the semi-dilute polymer brush (SDPB) region through 40% enlargement in the shell thickness of the nanoparticles decreased the peel and shear strengths. However, increasing the grafting density through a 4.5-fold rise in the core size and thus extension of the concentrated polymer brush region and elimination of SDPB region led to an extraordinary 1400-fold improvement in the shear strength. • Grafting of acrylic chains on PSQ enhanced peel and shear strengths simultaneously. • Optimization of cohesive energy density of shell enhanced peel and shear strengths. • Extension of semi-dilute polymer brush region deteriorated the shear strength. • Increase in grafting density led to an extraordinary improvement in shear strength.