Conductivity Of Composite Films Research Articles

A Silk Fibroin and Ultra-Long Silver Nanowires Based Transparent Conductive Composite Film for Nanosensor Devices

In addition to flexible touch screens, organic flexible photoelectric films have broad application prospects. In this paper, a transparent and conductive composite film was prepared by embedding a conductive network of ultra-long silver nanowires with silk fibroin as the substrate material. The ultra-long length can help minimize the number of junctions between the nanowires on the conductive grid, which can reduce greatly the resistance and optical shielding effect of the conductive layer. To tune the flexibility of the film, an appropriate amount of calcium ions (Ca2+) could be added to the silk fibroin solution. The conductivity, light transmittance, and temperature, stress and humidity sensitivity of the composite films were characterized and proved satisfactory. Its capability of self-healing was also demonstrated. With the natural biocompatibility and self-healing ability, this silk fibroin film may be applied in biomedical science, such as an electronic skin that can detect multiple human health indicators.

Dispersion of Nano-materials in Polymer Composite Materials

Polymer composites materials are the subject of extensive studies because of their novel properties compared with their constituent materials. Dispersion stability of sub-micron sized particles in the medium is important from the point of colloidal views. In the present study, dispersion of nano-materials in the matrix polymer is one of the most important problems to enhance their mechanical properties. We tackled this problem to carry out surface modification of the nano-materials, such as carbon nano tubes (CNTs), using amphiphilic polymers, polyNvinylacetamide (PNVA), synthesized thorough radical polymerization. Hydrogen bond worked between PNVA onto the modified nano-materials and hydrophilic matrix, such as polyvinyl alcohol (PVA), to enhance surface adhesions and dispersions of the nano-materials in the matrix. As a result, the mechanical properties of their composites materials were strengthened. When CNTs were used in PVA, the transparency of the composite was also increased due to improvement of their dispersions. In addition, if the CNTs formed the networks in the composites, the highly conductive and transparent polymer composite films were fabricated.

Adhesive, reflective, and conductive films comprised of graphene nanosheets decorated with Ag nanoparticles for flexible electronics

A highly adhesive, reflective and conductive graphene-silver composite film has been fabricated on the modified surface of polyethylene terephthalate (PET) substrate. Graphene nanosheets (GNS) were decorated with silver nanoparticles (AgNPs-GNS) by electroless plating and co-deposited onto the polymer surfaces by spray-spin-spray technique. Peel test results showed that peeling strength between composite films and substrate increased from 1.2 N/cm to 4.8 N/cm by grafting. The average reflectance of composite films was reached 98% from results of the spectrometer, which was much higher than commercial Ag films. Owing to the co-deposition with AgNPs-GNS, the composite films exhibited a sheet resistance of 40 mΩ/sq, which was 80.3% lower than pristine silver films. In addition, AgNPs-GNS/Ag composite films maintained their conductive stability even after over 1000 times of bending tests and several hours of salt spray environment, indicating the application possibility of flexible circuits. Meanwhile, these composite films were used to produce several electronic components integrating on target circuit and the composite films could maintain a good stability of electrical conductivity even after being bending compression and bending tension. These results indicate that these high-quality, highly conductive and flexible composite films prepared by the spray-spin-spray method could be applied to real flexible electronics.

Influence of nanostructured VO-acetylacetonate coordination system with 2-(pyridin-4-ylmethylene) hydrazine-1-carbothioamide in pseudocapacitance performance of p-type conductive polymer composite film

ABSTRACT In this work, first, VO-acetylacetonate coordination system with 2-(pyridin-4-ylmethylene) hydrazine-1-carbothioamide (VO(acac)2L) was synthesised via sonochemical routes. Then POAP/VO(acac)2L films were fabricated through electropolymerization of poly ortho aminophenol (POAP) in the presence of VO(acac)2L and used as the active electrode of an electrochemical supercapacitor (SC) with a significant electrochemical properties improvement. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) was applied to characterise the structural state of the prepared samples. Also, some electrochemical methods such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD) were carried out for the system performance investigation. This work may open an avenue to develop efficient and robust nanocomposite materials for an energy storage device in an acidic medium.

Conductive Polyaniline Doped with Dodecyl Benzene Sulfonic Acid: Synthesis, Characterization, and Antistatic Application.

A novel method was conducted to synthesize conductive polyaniline (PANI) doped with dodecyl benzene sulfonic acid (DBSA) (PANDB) in xylene by using chemical oxidative polymerization at 25 °C. Meanwhile, the synthesis process was photographed. Results showed as the reaction time was increased, and the color of the product was gradually turned into dark green. The influence of different synthesis time on properties of synthesized PANDB was then examined by a Fourier transform infrared (FTIR) spectrometer, an ultraviolet-visible spectrophotometer (UV-vis), a four-point measurement method, and a Field-emittance scanning electron microscope (FE-SEM). The result indicated that the optimum reaction time was 24 h with conductivity at around 2.03 S/cm. FE-SEM images and the conductivity testing showed that the more needle-like shapes in resulted PANDB, the higher the conductivity. The synthesized PANDB solution was blended with UV curable coating firstly and then coated on polyethylene terephthalate (PET) sheet. The UV coating/PANDB conductive composite films displayed an impressive translucency along with an adequate flexibility at room temperature. The UV coating/PANDB conductive composite film on PET sheet was flexible, transparent, and with antistatic function.

Lightweight, flexible and superhydrophobic conductive composite films based on layer-by-layer self-assembly for high-performance electromagnetic interference shielding

With the rapid development of wearable devices, electromagnetic interference (EMI) shielding materials with good flexibility and high conductivity have been desired to eliminate resulting radiation pollution. Herein, a lightweight and flexible PAN@Ni@PPy@PFDT (PNP@PPy@PFDT) film with core-shell structure and self-cleaning property is constructed for EMI shielding application via layer-by-layer self-assembly strategy to realize oxidative polymerization of pyrrole under low-temperature environment. Polydopamine (PDA) is first decorated on the PN nanofiber to improve the interface compatibility and hence promote the uniform deposition of PPy nanoparticles (PPy-NPs). After further treatment with fluorine containing molecules, the conductive PNP@PPy film becomes superhydrophobic and self-cleaning. The contact angle of the composite films can reach 155°. The composite films show high conductivity up to 291S/m and high specific shielding effectiveness up to 4479 dB cm2g−1, which is attributed to the conductive core-shell structure and enhanced absorption with the hierarchical structure of the films. This strategy is of great significance for the manufacture of multifunctional composite films to achieve efficient EMI shielding performance and broaden the practical application of conductive materials.

Chitosan/Polyethylene Oxide (PEO) Filled Carbonized Wood Fiber Conductive Composite Film

Biopolymer-based conductive polymer composites (CPCs) would open up various possibilities in biomedical applications owing to ease of processing, renewable resource and environmentally friendly. However, low mechanical properties are a major issue for their applications. In this study, the investigated the conductivity of chitosan/ PEO blend films filled with carbonized wood fiber (CWF) prepared by solution casting. The effect of CWF was also investigated on tensile properties and their morphological surfaces. The tensile results from different ratios of chitosan/PEO blend films without CWF show that the tensile strength and modulus increased with the increase of chitosan content and chitosan/PEO blend film with 70/30 ratio exhibited the best combination of tensile strength and flexibility. However, a reduction of tensile strength was observed when CWF amount was increased while the modulus of the tensile shows an increment. The film also exhibited higher electrical conductivity as compared to low chitosan ratio. The addition of CWF greatly enhanced the conductivity three-fold from 10-10 to 10-6 S/cm. The electrical conductivity continued to increase with the increase of CWF up to 30wt%. The surface morphology by Scanning Electron Microscopy (SEM) exhibits the absence of phase separation for the blends indicating good miscibility between the PEO and chitosan. Incorporation of CWF into the blend films at 5wt% showed agglomeration. However, the increase of CWF created larger agglomerations that formed conductive pathways resulting in improved conductivity. FTIR analysis suggested that intermolecular interactions occurred between chitosan and PEO while CWF interacts more with the protons of PEO.

Highly Stretchable Conductive Nanocomposite Films Using Regenerated Cellulose Nanoparticles

Dip-coating or printing methods are often used to fabricate conductive composite films using organic polymeric conducting fillers to achieve high performance, but these approaches are prone to fric...

Radiation-induced synthesis, electrical and optical characterization of conducting polyaniline of PANI/ PVA composites

This study employs the gamma radiation technique to produce conducting polyaniline from an aqueous solution. The solution comprises four materials: ANI, PVA, CaCl2 and distilled H2O, which serve as a binder or film support, precursor, Cl ions provider, and a solvent. To obtain the conducting polyaniline (PANI/PVA) composite, a film of ANI/ PVA/ CaCl2 was subjected to gamma radiation under ambient conditions. Conducting polyaniline composite was seen to form once the colour began to change from white to green in accordance with the doses of radiation. The results demonstrated that the level of gamma radiation increased to 30 KGy, thereby confirming that the electrical insulation ANI/ PVA/ CaCl2 film was converted into electrically conductive polyaniline composite film. In addition, the measurements of UV–Visible spectrophotometer revealed an absorption band of 795 nm rises alongside the radiation dose which produced PANI/PVA with a green hue that increases in intensity in accordance with rises in the doses of radiation.

Design and fabrication of conductive composite films with high elasticity and strength using hybrid polymer matrix

ABSTRACT Flexible conductive polymer composites with good mechanical property play an important role in the modern electronic industry. In this study, aromatic poly(amide-imide) (PAI) and thermoplastic polyurethane (TPU), functionalized multi-wall carbon nanotube (FMWCNT) and reduced graphene oxide (RGO), were, respectively, used as polymer matrix and conductive filler to fabricate conductive polymer composites. Combing the advantages of PAI (high strength) and TPU (good elasticity), PAI-TPU/FMWCNT-RGO polymer composites exhibited a high tensile strength of 58.8 MPa and good elongation at break of 255%. On the other hand, the hybrid conductive filler of FMWCNT-RGO possessed a 3D structure, which is beneficial for improving conductive property, and thus a relative high conductivity of 35.9 S m−1 was achieved. The enhanced mechanical and conductive properties are mainly ascribed from the good compatibility between the polymer matrix and conductive fillers, which promotes the good dispersion of conductive filler into the polymer matrixes.

Dielectric, thermally conductive, and heat-resistant polyimide composite film filled with silver nanoparticle-modified hexagonal boron nitride

In this study, silver–polydopamine–hexagonal boron nitride (h-BN@Ag) particles were prepared using mussel chemistry and reducibility of catechol. The modified method was simple and eco-friendly. In addition, we prepared h-BN@Ag/polyimide (PI) composite films via in situ polymerization, the scraper method, and thermal imidization. Owing to the good dispersion of the h-BN@Ag filler particles in the PI matrix and the bridging role of the Ag nanoparticles, the thermal conductivities of the h-BN@Ag/PI composite films were higher than that of the pure PI film. The thermal conductivity of the h-BN@Ag/PI film with the filler content of 10 wt% was 0.382 W (m·K)−1, which was 108% higher than that of pure PI films (0.184 W (m·K) −1). Furthermore, the composite films presented extremely low dielectric permittivity and loss tangent. Moreover, the heat resistance index of the composite films (304.6°C) was higher than that of pure PI (294.3°C). Thus, h-BN@Ag/PI composite films could be promising electronic packaging materials.

Durable, Sensitive, and Wide‐Range Wearable Pressure Sensors Based on Wavy‐Structured Flexible Conductive Composite Film

AbstractFlexible pressure sensors have potential applications in human motion monitoring and electronic skins. To satisfy the practical applications, pressure sensors with a high sensitivity, a low detection limit, a broad response range, and an excellent stability are highly needed. Here, a piezoresistive pressure sensor based on wavy‐structured single‐walled carbon nanotube/graphite flake/thermoplastic polyurethane (SWCNT/GF/TPU) composite film is fabricated by a prestretching process. Due to the random wavy structure, high conductivity, and good flexibility, the prepared sensor displays a low detection limit of 2 Pa, a wide sensing range of 0–60 kPa, and a high sensitivity of 5.49 kPa−1 for 0–50 Pa. Furthermore, the sensor shows a remarkable repeatability of over 1.1 × 104, 9.0 × 103, and 2.0 × 103 pressure loading/unloading cycles at 50 Pa, 500 Pa, and 30 kPa, respectively, and a fast responsibility of 100–150 ms of loading response time and 400–600 ms of relaxation time. Therefore, the pressure sensor is successfully adopted to monitor both the large‐scale human activities (e.g., walk and jump) and the small‐scale signals (e.g., wrist pulse). Furthermore, a sensor array is assembled to map the weight and shape of an object, indicating its various potential applications including human–machine interactions, human health monitoring, and other wearable electronics.

Flash ablation metallization of conductive thermoplastics

Fused filament fabrication (FFF) is the most widely available 3D printing technology. Recently, a variety of conductive thermoplastic filaments have become commercially available, allowing printing of electronic structures using the technology. However, the contact interface and conductivity of these filaments after printing remains relatively poor, the latter of which is typically at least four orders of magnitude lower than bulk metal conductors. While several post-processing approaches exist to enhance conductivity, they are either user-intensive, time consuming, or cannot easily be integrated in-line with the rest of the printing process. In this work, we demonstrate that exposing conductive composite thermoplastic films (3D printed or solution-cast) to high-intensity pulsed light increases their conductance by up to two orders of magnitude in a manner that is fast, non-contact, and potentially in-line. This process, referred to as flash ablation metallization (FAM), is found to vaporize the thermoplastic matrix on the top surface of a composite film, leaving behind a metal-dense surface layer. The technique was found to be effective for a variety of commercial and custom-made conductive thermoplastic composites, with the largest response found in Electrifi, a commercial filament consisting of copper particle loading in a biodegradable polyester. 3D-printed circuit boards were constructed with and without FAM exposure, with exposed circuits exhibiting reduced operating voltages as well as improvements in reliability.

Perpendicular and In‐Plane Conductivity of Poly(methyl methacrylate) Composite Films Filled with Carbon‐Based Fillers Prepared from Solution Casting Process

AbstractIn this study, poly(methyl methacrylate) (PMMA)/carbon black (CB), PMMA/carbon fiber (CF), and PMMA/carbon nanotube (CNT) conductive composite films with different filler concentrations are prepared using the solution casting technique. Both perpendicular and in‐plane direction conductivity of all the binary composite films are investigated, percolation thresholds (ϕc) of both directions of PMMA/CB, PMMA/CF, and PMMA/CNT composite films are investigated and the experimental data are fitted using McLachlan’s equation. For all the three investigated films, the perpendicular ϕc,⊥ and in‐plane ϕc,∥ with different fillers show totally different behaviors. Pristine CB, CF, and CNT as well as PMMA/CB, PMMA/CF, and PMMA/CNT composite films are discussed. The gravity effect of the fillers is found to be most significant in the PMMA/CB system. A schematic diagram of PMMA composite films with CB, CF, and CNT as filler prepared from solution casting process is presented to explain the distribution gradient of the fillers in the perpendicular direction of the film after solution casting. A power law behavior is revealed for different filler types (CB, CF, CNT) correlating the exponent t for McLachlan’s equation and corresponding ϕc for in‐plane and perpendicular directions.

In‐situ sol–gel synthesis of zirconia networks in flexible and conductive composite films

AbstractThe conductive and stretchable films with improved hardness are suitable for the fabrication of flexible electronic devices. This study describes the sol–gel technique to prepare a novel conductive and flexible film consisting of epoxidized natural rubber (ENR), doped polyaniline (PD) and zirconia. The zirconia networks were directly synthesized in‐situ in ENR/PD solution and flexible conductive composite film with improved hardness was obtained. The morphology study revealed the size of PD decreased significantly from 77.89 ± 43.95 nm to 4.32 ± 1.13 nm and highest electrical conductivity of 1.9 × 10−3 S/cm was achieved with 10 wt.% percolation threshold of zirconia precursor. The binding energy of Zr3d5/2 and Zr3d3/2 decreased, suggesting that zirconia was converted to the lower oxidation state. Furthermore, the shape of PD changed from spherical to rod‐like structure with root mean square value of 2 nm, while the hardness and reduced modulus improved to 1.72 MPa and 36.7 MPa, respectively.

Facile Preparation of an Excellent Mechanical Property Electroactive Biopolymer-Based Conductive Composite Film and Self-Enhancing Cellulose Hydrogel to Construct a High-Performance Wearable Supercapacitor

Wearable supercapacitors, as one of the most important power supplies for wearable electronics, require excellent flexibility and deformability and a structure that is not easily delaminated. In th...

Studying the Stability and Conductivity of the Composite Films via Electrospinning/Spray Process

The electrospinning/spray technique is a promising approach to fabricate composite films for many applications in flexible electronic devices. In this study, an elastic film with remarkable conductivity is synthesized by electrospinning TPU (thermoplastic polyurethanes) fibers and electrospraying graphene nanosheets into the single collector. This technique allows the graphene nanosheets to adhere uniformly to a carbon textile matrix for promoting its conductivity. But the graphene is possible to be oxidized into graphene oxide during electrospray, which is attributed to the high-voltage field, the rapid evaporation of the solvent and the full exposure to air. And the spinning fibers have the potential to induce the behavior as well. The instability of graphene during the process can make an impact on the overall conductivity and uniformity of composite films. So, we set up a series of experiments on the study of oxidization behavior of graphene and its influence on the performance of composite films. With different parameters, some samples are synthesized to conduct Raman spectroscopy analysis as well as take the measurements of overall conductivity through a 4-point probe electrical conductivity device. The oxidization behavior of graphene during the electrospinning/spray process can be well characterized by the results from the Raman spectrums. And the results of electrical conductivity measurements can provide powerful evidence to ensure the great conductivity of composite films via electrospinning/spray process.

Effect of SWCNT Filler on Mechanical Properties and Electrical Conductivity of PVA/CS/GA/SWCNT Nanocomposite Thin Film

This study aims to investigate the effect of SWCNT nanofiller on mechanical properties and electrical conductivity of PVA/CS/GA nanocomposite film. Polyvinyl alcohol (PVA) and chitosan (CS) are used as polymer matrix that crosslinked by glutaraldehyde (GA). Nanofiller SWCNT was inserted in a polymer composite matrix at different composition. The thin films were characterized using FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), TG/DTA (Thermal Gravimetric/Differential Thermal Analysis), sheet resistance, and tensile strength measurements. The results revealed that the addition of SWCNT notably increased the electrical conductivity of composite film from 1.2 x 10‒4 S.cm‒1 to 9 x10‒3 S cm‒1 as well as tensile strength and elongation 43 MPa to 62 MPa, 68% to 84%, respectively. The cross-sectional SEM images indicated that the conductive thin films have a layered structure where the insertion of SWCNT did not change their morphological structure significantly. Additionally, SWCNT improved the thermal stability of PVA/CS/GA nanocomposites thin film. These finding can be promising for the development of optoelectronic devices i.e. photovoltaic, emitting diodes, etc.

Electrical and Thermal and Self-Healing Properties of Graphene-Thermopolyurethane Flexible Conductive Films.

We fabricated graphene-thermopolyurethane (G-TPU) flexible conductive film by a blending method and systematically investigated the electrical, thermal and self-healing properties of the G-TPU flexible conductive film by infrared light and electricity. The experimental results demonstrate that the G-TPU composite films have good conductivity and thermal conductivity in the appropriate mass content of graphene in the composite film. The composite films have the good electro-thermal and infrared light thermal response performances and electro-thermal response performance is closely related to the mass content of graphene in the composite film, but the infrared light thermal response performance is not. The scratch on the composite film can be completely healed, using electricity or infrared light. The healing efficiency of the composite film healed using infrared light is higher than that of using the electricity, while the healing time of the composite film is shorter. Regardless of the self-healing method, the temperature of the self-healing is a very important factor. The self-healing conductive composite film still exhibits a good conductivity.

Fabricating robust soft-hard network of self-healable polyvinyl alcohol composite films with functionalized cellulose nanocrystals

In this study, conductive cellulose nanocrystals (CNCs) were coated with polypyrrole (PPy) using in situ chemical polymerization to form CNC-PPy conductive nano-network. The one-pot polymerization of “hard” segment methyl methacrylate (MMA) was continued onto above functionalized CNCs, then blended with “soft” molecular segment polyvinyl alcohol (PVA) to contain self-healing and conductive composite film (CPMV) fabricated by soft-hard network. In addition, the tensile strength of CPMV films with 2 wt% CNC-PPy was enhanced by 47.1%. Also, CPMV films exhibited self-healing properties due to the presence of hydrogen bonding dynamic network and showed sensitive resistance changes under external stimuli, which could be used to monitor various actions of the human body. Thus, the CPMV films present potential applications in electronic devices such as flexible electrodes, biosensors, and implantable devices.