AgNWs Content Research Articles

Preparation and characterization of electrospun silver nanowires/ZnO/PVP composite transparent conductive film

In this study, a silver nanowires (AgNWs)/nano-zinc oxide (ZnO)/polyvinylpyrrolidone (PVP) film is fabricated as an alternative to indium tin oxide transparent conductive films (TCFs). AgNWs are prepared by the polyol method with PVP as a dispersant to prevent Ag nanoparticles agglomeration during AgNWs formation. Nano-ZnO is synthesized using sol–gel method. AgNWs/ZnO/PVP TCFs are prepared using the electrostatic spinning and spin coating methods for comparison. It is found that the best PVP/AgNO3 molar ratio is 3.5:1. FTIR and XRD analyses show that 500°C calcination leads to better crystallinity and purity of nano-ZnO. Four-point prober analysis indicates that the higher the AgNWs content, the lower the TCF sheet resistance. The best sheet resistance of AgNWs/ZnO/PVP TCF by the electrostatic spinning method is obtained as 81 [Formula: see text]/sq, and the light transmittance is 85.3%. Moreover, in the 5-week stability test, the sheet resistance of the electrospun TCF increases by 6.17%, much lower than 24.9% of the spin coated TCF. It is verified that the elecrospun AgNWs/ZnO/PVP composite TCF is a promising alternative to the traditional ITO TCFs.

Polyurethane/silver nanowire composites with Diels-Alder structure for self-healing and thermal conduction abilities

To meet the non-removable application scenarios of most integrated electronics, the development of polymer-based packaging materials possessing superior thermal conductivity and self-healing characteristics simultaneously is necessary. However, on account of the complexity of composite structure and composition, its self-heal remains a formidable challenge. Herein, we have designed a self-healing and thermally conductive bi-functional polyurethane composites with Diels-Alder structure (PUDA) and silver nanowires (AgNWs). The hydrogen-bonding network at the interface of AgNWs and PUDA facilitated the dispersion of AgNWs in the matrix, which endows the composites with desirable thermal conductivity. Incorporating 3, 6, 9, 12, and 15 wt% of AgNWs into PUDA leads to increases in thermal conductivity of 33%, 104%, 154%, 321%, and 371%, respectively. In particular, the novel composites incorporated 12 wt% AgNWs exhibited the most efficient balance between self-healing efficiency and thermal conductivity performance. The thermal conductivity of PUDA/AgNWs with 12% of AgNWs content is 1.01 W/mK, which is 4.8 times that of PUDA (0.21 W/mK). After two reconstitution cycles, the thermal conductivity of PUDA/AgNWs-12 was restored to 85%. This study demonstrates the successful preparation of composites possessing both desirable thermal conductivity and self-healing capabilities, rendering them suitable for use as thermal interface materials in thermal management systems and flexible electronics applications.

Asymmetric c-MWCNT/AgNWs/PANFs hybrid film constructed by tailoring conductive-blocks strategy for efficient EMI shielding

Currently, extensive utilization of wireless devices require human being tantamount to tackle electromagnetic wave pollution to avoid serious harm to health body and precision equipment. Herein, asymmetric structure hybrid film were developed from para-aramid nanofiber (PANFs), carboxylated multiwalled carbon nanotubes (c-MWCNT) and silver nanowire (AgNWs) through vacuum-assistant filtration and freeze drying route. The robust and high aspect ratio PANFs established matrix foundation for forming large scale hybrid film, which rendered feasible support for conductive building blocks c-MWCNT and AgNW. Thanks to the unique asymmetric porous structure, the as-prepared c-MWCNT/AgNWs/PANFs hybrid film with 8 wt% of c-MWCNT and 4 wt% of AgNW remained efficient EMI shielding performance, whose shielding effectiveness (SE) and specific effectiveness (SEE/t) reached 40.59 dB and 10678.17 dB cm2 g−1 at thickness of 0.061 mm in X band, respectively. Furthermore, the shielding effectiveness and absorption coefficient could be regulated by c-MWCNT content, AgNW content, and ratio of c-MWCNT and AgNW. With improving the conductive ratio, the c-MWCNT/AgNWs/PANFs hybrid film possessed tunable shielding effectiveness between 9.40～40.59 dB and absorption coefficient between 0.028～0.303. This work provided feasible avenue for controlling electromagnetic feature through tailoring conductive blocks strategy.

Sustainable antibacterial collagen composites with silver nanowires for resistive pressure sensor applications

Considering the circular economy and the increasing need of smart materials for the digitalization of society, it is essential that these materials are based on bio-resources. Thus, in order to replace synthetic by natural polymers in multifunctional composites, this work reports on the development of collagen/silver nanowires (Ag NWs) composites for resistive sensor applications. It is demonstrated the physical interactions of hydroxyl groups in collagen with the Ag NWs and that the Ag NWs are well dispersed within the collagen matrix. Further, the addition of Ag NWs to the collagen matrix increases the thermal stability of collagen and the Ag NW content does not affect the triple helix structure of the polymer matrix. The mechanical, electrical and antibacterial properties depend on Ag NW content and the best electric conductivity of 0.0515 S cm−1 is obtained for composites with 6 wt% of Ag NWs. This composite presents suitable resistance variations under pressure and bending allowing the development of sustainable multifunctional sensing composites with antibacterial activity that can be applied in next generation touch sensing electronic devices.

PEDOT:PSS and AgNW synergistically contributed high electromagnetic shielding performance for polyurethane-based composite coating

To meet the electromagnetic shielding requirements of complex shaped products, we prepared an environmentally friendly, efficient electromagnetic shielding coating on polyethylene terephthalate (PET) using water-based polyurethane, silver nanowire (AgNW), and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS). The addition of PEDOT:PSS not only notably improved the dispersion of AgNWs in the matrix and also acted as bridges between AgNWs, so the coating’s conductivity was greatly enhanced at a low AgNW content. The conductivity and EMI shielding effectiveness (EMI SE) of the coating with only 24.8 μm thickness and 30 wt% AgNWs reached 19,225 S/m and 68.8 dB, respectively. The EMI SE at such a thin thickness and low AgNW content is outstanding compared with previously reported literature. The coating also shows sufficient flexibility and adhesion stability, and mechanical robustness under sonication and chemical environments. Also, the coating can be attached to a variety of representative substrates, such as polypropylene, nylon, PET, glass, wood and metal.

A triboelectric nanogenerator coupled with internal and external friction for gesture recognition based on EHD printing technology

Surface charge density is a critical factor in determining the output performance of triboelectric nanogenerators (TENGs). However, enhancing the surface charge density is a relatively complex process characterized by high cost, fast charge dissipation, and inferior stability. Herein, a TENG with internal and external friction synergistic coupling enhancement that employed an electrohydrodynamic (EHD) printing technique for gesture recognition was proposed. Under the external force, the electrical performance of the triboelectric material could be improved via internal friction formed by the contact between the lines of silver nanowires (AgNWs) mixing with hydroxy propyl methyl cellulose (HPMC) (AgNWs (HPMC)) inside the tribolayer and the PDMS with microgrooves. The effects of dielectric layer thickness, micropore size, the number of micropore arrays, as well as the AgNWs content and the number of AgNWs (HPMC) lines on TENG output performance were analysed systematically. When the micropore arrays TENG (MA-TENG) size was 15 mm × 15 mm, the thickness of a dielectric layer was 240 µm, the number of micropore arrays was 36, and the number of AgNWs (HPMC) lines was 28, the charge transfer quantum of MA-TENG was 34.9 nC, which is about 5.8 times that of flat TENG. The peak power of the MA-TENG was 580 μW, which was about 10 times than that of the flat TENG. Finally, a self-powered gesture recognition was demonstrated successfully based on the developed MA-TENG and revealed its potential in the field of human-computer interaction. This work not only proposed a new method with the advantages of a simple process, low cost, and high output stability, to significantly increase the surface charge density, but also provided a new scheme for electronic skin and wearable devices.

Flexible, robust, sandwich structure polyimide composite film with alternative MXene and Ag NWs layers for electromagnetic interference shielding

The design and fabrication of electromagnetic interference shielding films with a novel structure to eliminate undesirable electromagnetic pollution is an important research direction. However, it is still a challenge to combine and organize nanofillers in different dimensions into the structured network in polymer-based electromagnetic interference (EMI) shielding composites. In this work, a sandwich structure polyimide (PI) composite film with alternative 2D-MXene network and 1D-Silver nanowires (Ag NWs) network was prepared through the “electrospinning-immersion-hot pressing” method. With the increase of Ag NWs content, the EMI shielding effectiveness (SE) gradually increases while maintaining good flexibility and mechanical robustness. The EMI SE and the tensile strength of 150 μm thick sandwich composite film can reach up to 79.54 dB and 39.82 MPa, respectively. The prepared flexible and robust PI composite film with a sandwich structure has high EMI SE with less metal content, which can provide guidelines for the development of high-performance EMI polymeric films with potentials in wearable devices and equipment.

Asymmetric multilayered MXene-AgNWs/cellulose nanofiber composite films with antibacterial properties for high-efficiency electromagnetic interference shielding

• Multilayer films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. • The effects of different conductive layers order and different number of layers on electromagnetic shielding performance were investigated. • Due to the excellent layered structure, the MXene-AgNWs/cellulose nanofiber composite film exhibits excellent EMI shielding capability at an ultra-thin thickness. • Benefiting from the properties of silver nanowires, the multifunctional shielding composite exhibits excellent antibacterial properties and better environmental adaptability. Flexible, lightweight, robust and versatile properties are essential for the next generation of wearable as well as intelligent electromagnetic interference (EMI) shielding materials. In this work, multilayered films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. Compared with a uniformly mixed film, the resultant layered composite films that loaded with a low MXene and AgNWs content exhibit superior mechanical properties with a tensile strength of 137 MPa, a strain at break of 5.7%, excellent EMI shielding effectiveness (EMI SE) of 61.9 dB, and higher EMI SE/t of 20,653 dB cm −1 . This is attributed to the high-performance CNF substrate, the highly efficient layered structures, and extensive hydrogen-bonding interactions. In particular, a high degree of ohmic loss of multiple interfaces and polarization relaxation of local defects, as well as an abundance of terminal groups, favor the loss of electromagnetic waves (EMW) within the material. In addition, the prepared multifunctional layered composite films also show good antibacterial properties. As a result, the obtained new kind of flexible layered structure EMI shielding composite films with excellent EMI shielding performance, and mechanical properties present promising application prospects in the fields of EMI shielding and protection for aerospace, portable, and wearable flexible electronic devices.

Lightweight and Highly Compressible Expandable Polymer Microsphere/Silver Nanowire Composites for Wideband Electromagnetic Interference Shielding.

The exploration of lightweight and compressible electromagnetic interference (EMI) shielding materials with outstanding shielding effectiveness (SE) is still a tremendous challenge in the elimination of electromagnetic pollution. Lightweight and highly compressible expandable polymer microsphere/silver nanowire (EPM/AgNW) composites with micron-sized closed pores and an interfacial AgNW conductive network are fabricated via a facile thermal expansion process in an enclosed space. The EPM/AgNW composites with AgNW loading of 0.127 vol % show low density (0.061 g/cm3), high compressibility and compression strength (4.25 MPa at 92.6% of compressive strain), and high EMI SE (over 40 dB, 1 mm) at a wideband of 8-40 GHz. Their EMI SE can be improved to a record 111.5 dB by increasing the AgNW content to 0.340 vol %, which corresponds to the surface-specific SE (SSE/d; SE divided by density and thickness) up to 13433 dB·cm2/g. The EMI shielding mechanism is further discussed using the finite-element analysis software COMSOL Multiphysics, and the application of the EPM/AgNW composites is visually demonstrated via near-field shielding in a practical antenna radiation. The overall properties of light weight, high elasticity, excellent mechanical strength, and outstanding EMI shielding performance suggest that the as-prepared EPM/AgNW composites have a great potential for applications in modern electronics.

Improved Sheet Resistance of Nanofiber-Based Transparent Conducting Electrodes Using Silver Nanowires.

There is an increased need for research on flexible transparent electrodes (FTEs) because they are critical to next-generation electronic devices, such as wearable computers. In this study, highly conductive transparent conducting electrodes, based on polyvinylidene fluoride (PVDF) nanofiber webs treated with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and silver nanowires (AgNWs), were successfully fabricated. Transparent conducting electrodes (TCEs) were obtained by a brush-painting process using different weight ratios of a AgNWs to PEDOT:PSS solution, and the surface, electrical, optical, and chemical properties, as well as the tensile strength of the samples, were determined. It was found that the electrical conductivity of the samples improved as the AgNW content increased, but the light transmittance decreased. In this work, there was a slight decrease in the optical properties and a considerable increase in the electrical properties due to the hybridization of AgNWs and PEDOT:PSS, compared to using only PEDOT:PSS. When considering both transparency and electrical conductivity, which are essential parameters of TCEs, sample PA2, which was treated by mixing AgNWs and PEDOT:PSS/dimethyl sulfoxide (DMSO) in a ratio of 1:5 (16.67 wt% of AgNWs), was found to be the best sample, with a sheet resistance of 905 Ω/cm2 and light transmittance of 79%.

Anti-Fogging, Frost-Resistant transparent and flexible silver Nanowire-Ti3C2Tx MXene based composite films for excellent electromagnetic interference shielding ability

The development of electronics proposes higher requirements for flexible, transparent, and conductive materials with high electromagnetic shielding performance in viewing windows. Flexible transparent films have been fabricated by collaborating one-dimensional silver nanowires (AgNWs) and novel two-dimensional Ti3C2Tx MXene sheets on PET films with an external polymeric coating consisting of poly (vinyl alcohol) (PVA) and poly(styrene sulfonate) (PSS). Especially, the combination of different dimensional nanomaterials effectively establishes a conductive network that exhibits a synergistic effect on excellent electromagnetic interference (EMI) shielding performance, which is superior to that of pure AgNW network or Ti3C2Tx network to some extent. By optimizing the AgNWs content (0.05 mg/cm2) and Ti3C2Tx sheets content (0.01 mg/cm2), the PET/AgNW/Ti3C2Tx/PVA-PSS film exhibits a transmittance of 81% and a desirable EMI SE value of 30.5 dB. In addition, the film shows outstanding anti-fogging and frost-resistant properties due to the remarkable water absorption capacity of PVA and PSS on the external surface. Considering its efficiency and simplicity, this transparent conductive film has promising applications in flexible transparent electronic devices and optical related fields.

Superhydrophobic and Flexible Silver Nanowire-Coated Cellulose Filter Papers with Sputter-Deposited Nickel Nanoparticles for Ultrahigh Electromagnetic Interference Shielding.

Superhydrophobic, flexible, and ultrahigh-performance electromagnetic interference (EMI) shielding papers are of paramount importance to safety and long-term service under external mechanical deformations or other harsh service environments because they fulfill the growing demand for multipurpose materials. Herein, we fabricated multifunctional papers by incorporating sputter-deposited nickel nanoparticles (NiNPs) and a fluorine-containing coating onto cellulose filter papers coated with silver nanowires (AgNWs). AgNW networks with sputter-deposited NiNPs provide outstanding magnetic properties, electrical conductivity, and EMI shielding performance. At an AgNW content of 0.109 vol % and a NiNP content of 0.013 mg/cm2, the resultant papers exhibit a superior EMI shielding effectiveness (SE) of 88.4 dB. Additionally, the fluorine-containing coating endows the resultant papers with a high contact angle of 149.7°. Remarkably, the obtained papers still maintain a high EMI SE even after 1500 bending cycles or immersion in water, salt, or strong alkaline solutions for 2 h, indicating their outstanding mechanical robustness and chemical durability. This work opens a new window for designing and implementing ultrahigh-performance EMI shielding materials.

Thermally welded honeycomb-like silver nanowires aerogel backfilled with polydimethylsiloxane for electromagnetic interference shielding

Honeycomb-like silver nanowires (AgNWs) aerogel is constructed via a convenient ice template method and further thermally welded, followed by backfilling with polydimethylsiloxane (PDMS) to obtain AgNWs/PMDS elastomer. A high electromagnetic interference (EMI) shielding effectiveness (SE) of 74.7 dB (8.2 GHz) can be achieved in the elastomer with a low AgNWs content of 3.08 wt% and a thin thickness of 1 mm owing to welding and well-aligned pores structure of AgNWs skeleton. Also, the shielding performance of the elastomer displays negligible change after 1000 bending and stretching cycles. These traits underscore the great potential of the AgNWs/PMDS elastomer in today’s flexible electronics.

High conductive free-written thermoplastic polyurethane composite fibers utilized as weight-strain sensors

Many stretchable conductive composite fibers exhibit high elongation at break, but most of them do not have a large workable strain range towing to the low conductivity when used as strain sensors. In this paper, we fabricated a highly conductive silver nanowire (Ag NW)/multi-walled carbon nanotube (MWCNT)/thermoplastic polyurethane (TPU) fiber via a wet-spinning process to improve the workable strain range of composite fibers. TPU was used as a matrix material to introduce superior stretchability. MWCNTs act as sensing elements and Ag NWs were used to increase conductivity. We investigated the effect of Ag NW content on the mechanical, electrical, and strain-sensing performance of the fiber-type strain sensors. The optimal content of Ag NWs extended the workable strain range as higher as 254% with an electrical conductivity of 0.803 S/cm. A weight-to-strain cloth sensor was assembled by writing Ag NW/MWCNT/TPU fibers in the coagulation solution. Furthermore, such composite fiber can be free-written into any designed pattern, which can be used to prepare fiber-based devices.

Highly conductive, stretchable, and breathable epidermal electrode based on hierarchically interactive nano-network.

Stretchable electrodes have a crucial impact on the development of flexible electronic systems. Most conventionally blended nanocomposite electrodes are incapable of achieving high stretchability, breathability, or durability. In this work, a highly conductive, breathable, and stretchable epidermal electrode (SEE) is demonstrated by designing a hierarchically interactive nano-network that is composed of elastic polymer nano-fibers and multi-level silver nano-wires (AgNWs). The elastic polymer nano-fibers act as a continuous scaffold, and multi-level AgNWs embedded in the nano-fibers form branched conductive pathways. This structure enables high conductivity of the SEE at 4800 S cm-1 (at a significantly low AgNW content of 1.59 vt%), with high stretchability and excellent durability. For example, the SEE remained conductive even at a high strain of 500%, and it also maintained its initial resistance even after 30 000 cycles of strain at 50% or being washed with water for 100 000 cycles. The SEE was prepared by a facile in situ nonequilibrium fabrication process, and can easily be produced into an elastic circuit on a large scale, which provides a foundation for integrated and multifunctional electronic skins. The SEE possesses superior mechanical conformability and permeability of gas and liquid, and therefore, it was successfully applied in measuring electrocardiogram signals and thermal therapy, and exhibited highly robust and comfortable performances even while being washed with water or undergoing complex deformations.

Conductive sizing for improving electrical conductivity of carbon fiber/polyaryl ether ketone/AgNWs composites

ABSTRACTThe aim of this work is to enhance the electrical conductivity of PAEK/continuous carbon fiber (CF) composites while maintaining their mechanical properties. A conductive sizing was elaborated by mixing polyetherimide (PEI) with silver nanoplates (AgNpts) in suspension in dichloromethane. An aqueous PEI formulation was used as insulating sizing reference. The presence of AgNpts into the sizing enhances electrical conductivity up to 0.2 S.m−1 for a silver content ∼ 0.2 vol % without any modification of mechanical properties. The influence of conductive sizing on PAEK–AgNWs/CF was observed. For low AgNWs content lower (<1 vol %); the conductive sizing increases the electrical conductivity of the composite by one decade. This result shows that both types of Ag particles participate to the conductive path. For higher AgNWs content, electrical conductivity (200 S.m−1) is independent from the AgNpts content: the conductive path is only constituted by AgNWs. Mechanical properties of such composites show that the value of the conservative modulus is almost the same, while the dissipative modulus slightly increases. The global mechanical properties of the composite are preserved despite the addition of the CF, AgNWs, and AgNpts. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47872.

High-Resolution and Large-Area Patterning of Highly Conductive Silver Nanowire Electrodes by Reverse Offset Printing and Intense Pulsed Light Irradiation.

Conventional printing technologies such as inkjet, screen, and gravure printing have been used to fabricate patterns of silver nanowire (AgNW) transparent conducting electrodes (TCEs) for a variety of electronic devices. However, they have critical limitations in achieving micrometer-scale fine line width, uniform thickness, sharp line edge, and pattering of various shapes. Moreover, the optical and electrical properties of printed AgNW patterns do not satisfy the performance required by flexible integrated electronic devices. Here, we report a high-resolution and large-area patterning of highly conductive AgNW TCEs by reverse offset printing and intense pulsed light (IPL) irradiation for flexible integrated electronic devices. A conductive AgNW ink for reverse offset printing is prepared by carefully adjusting the composition of AgNW content, solvents, surface energy modifiers, and organic binders for the first time. High-quality and high-resolution AgNW micropatterns with various shapes and line widths are successfully achieved on a large-area plastic substrate (120 × 100 mm2) by optimizing the process parameters of reverse offset printing. The reverse offset printed AgNW micropatterns exhibit superior fine line widths (up to 6 μm) and excellent pattern quality such as sharp line edge, fine line spacing, effective wire junction connection, and smooth film roughness. They are post-processed with IPL irradiation, thereby realizing excellent optical, electrical, and mechanical properties. Furthermore, flexible OLEDs and heaters based on reverse offset printed AgNW micropatterns are successfully fabricated and characterized, demonstrating the potential use of the reverse offset printing for the conductive AgNW ink.

Silver-nanowire-modified fabrics for wide-spectrum antimicrobial applications

Abstract

AZO/silver nanowire stacked films deposited by RF magnetron sputtering for transparent antenna

This study aims to prepare an aluminum doped zinc oxide (AZO)/silver nanowire (AgNWs) composite transparent conducting film on a glass substrate via radio-frequency (RF) magnetron sputtering and spin-coating. The effects of AgNWs content and AZO deposition temperature and pressure on the structural, electrical, and optical properties were investigated. Under the optimal conditions, the resistivity and transmittance of the AZO/AgNWs stacked films were 2.15 × 10−4 Ω·cm and 80.28%, respectively, in the 400–800 nm range. Finally, a wide-band transparent antenna with an operational frequency of 2.4 GHz was built from AZO/AgNWs stacked films. This antenna is useful for Bluetooth communication.

Stretchable and magneto-sensitive strain sensor based on silver nanowire-polyurethane sponge enhanced magnetorheological elastomer

This work reported a stretchable, compressible and magneto-sensitive strain sensor based on conductive magnetorheological elastomer (MRE) containing silver nanowires (AgNWs) dip-coated polyurethane sponge, carbonyl iron particles and polydimethylsiloxane (PDMS) matrix. The mechanic-electric-magnetic coupling properties of conductive MRE were investigated and they were significantly influenced by mechanical properties of PDMS matrix and the AgNWs content. By increasing curing agent weight ratio, the cross-linking density of the PDMS increased thus the magneto-induced modulus decreased. The MRE was able to be used in the strain sensors, because its relative resistance variation reached 91.8% and 67.6% when 20% tensile strain and 10% compressive strain were applied. By applying a 428 mT magnetic field, the relative resistance of MRE sensor increased to 200%. Based on the experimental results, a possible mechanism was proposed to investigate the mechanic-electric-magnetic coupling sensing characteristics. Finally, the MRE sensors can be integrated on a shoe to detect the foot motion, demonstrated this material was promising in the intelligent devices like artificial skin, composite electrodes and soft sensor.