Electroconductive Properties Research Articles

Investigating the Influence on the Electro-Conductive Properties of Leather as a Result of Natural Aging

Conductive leather and its use in smart products have found a lot of interest. Leather behaves as a good insulator, so it was treated with electrically conducting polypyrrole using a chemical polymerization technique to give it conductive characteristics. The electro-conductive properties are obtained by using the double in–situ oxidative polymerization of pyrrole. The electrical properties of conductive samples are studied using the Van Der Pauw method as a measuring method. The conductive leather transformation process was carried out during the 2018-2020 period, and the conductive leather samples were preserved in room conditions until the year 2023. The effect of natural ageing on the electro-conductive properties of conductive leather is the focus of this research. The results show that environmental factors influence polymer breakdown and stability, by causing an increase in electrical resistance. The changes in electrical surface resistance, as the effect of the ageing factor, vary from 39.8% to 129.9%. Those changes in electrical resistance indicate that ageing is one of the major concerns in the electrical properties and stability of conductive leather samples, so the performed measurements have importance in providing information for the researchers and designers regarding the conductivity changes over time as a result of natural ageing, which would like to work with conductive leather on smart products.

Investigating the Influence on the Electro-Conductive Properties of Leather as a Result of Natural Aging

Conductive leather and its use in smart products have found a lot of interest. Leather behaves as a good insulator, so it was treated with electrically conducting polypyrrole using a chemical polymerization technique to give it conductive characteristics. The electro-conductive properties are obtained by using the double in–situ oxidative polymerization of pyrrole. The electrical properties of conductive samples are studied using the Van Der Pauw method as a measuring method. The conductive leather transformation process was carried out during the 2018-2020 period, and the conductive leather samples were preserved in room conditions until the year 2023. The effect of natural ageing on the electro-conductive properties of conductive leather is the focus of this research. The results show that environmental factors influence polymer breakdown and stability, by causing an increase in electrical resistance. The changes in electrical surface resistance, as the effect of the ageing factor, vary from 39.8% to 129.9%. Those changes in electrical resistance indicate that ageing is one of the major concerns in the electrical properties and stability of conductive leather samples, so the performed measurements have importance in providing information for the researchers and designers regarding the conductivity changes over time as a result of natural ageing, which would like to work with conductive leather on smart products.

Characterization and piezo-resistivity studies on graphite-enabled self-sensing cementitious composites with high stress and strain sensitivity

Carbon-based conductive fillers have recently been incorporated into a cement matrix to develop an intrinsic self-sensing concrete for data monitoring without the need for embedded, attached, or remote sensors while maintaining or improving its mechanical properties and durability. This paper studies cementitious composites filled with graphite as a novel self-sensing construction material. Experiments were systematically conducted to investigate the dispersion, chemical, mechanical, electroconductivity and piezo-resistivity properties of the composites. Experimental results showed an effective mixing with uniform dispersion of the graphite which acted as an inert filler in the mix and did not alter the microstructure of cement hydration products. Isothermal calorimetry, TGA and rheology tests showed good hydration and adequate workability of the composites with low graphite concentration (≤ 10%), while the effect of adding graphite on the compressive strength is insignificant for graphite concentrations of up to 10%. Monotonic and cyclic compressive test results indicated a repeatable piezo-resistivity performance for low graphite concentration cementitious composites whose stress sensitivity values vary from 0.75 to 7.25%/MPa, and strain sensitivity/gauge factor (GF) 150–1250 with some hysteresis. These combinations showed a stable and reliable piezo-resistivity and the ability to detect damage upon failure.

Synthesis and characterization of a new semiconductor nanocomposite based on polyaniline and graphene and investigating its electrochemical and electroconductivity properties

The purpose of this study is to investigate the magnetic and electrochemical properties of the new GO/Pani-CeO2/CoFe2O4 nanocomposite. This nanocomposite was synthesized through two routes and the results of the investigations show interesting cases. The interaction between CeO2-Pani and the presence of Ce-O was confirmed by FTIR spectroscopy and the XRD data showed the successful formation of the magnetite nanoparticles with the presence of CeO2 anchored onto polyaniline within the GO matrix. X-ray photoelectron spectroscopy (XPS) showed well the presence of Ce+3 (in addition to Ce+4) and its percentage. The products were identified by other methods such as VSM, FE-SEM, and EDX. Electrochemical studies such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS) to evaluate the effect of changes in the accumulation type of the synthesized nanocomposite were recorded in 0.5 M H3PO4 vs. Ag/AgCl. The stability test also shows that the desired compound has relatively good stability as a supercapacitor.

Reversibility of Swelling, pH Sensitivity, Electroconductivity, and Mechanical Properties of Composites Based on Polyacrylic Acid Hydrogels and Conducting Polymers

Composites based on polyacrylic acid gels as matrices and conducting polymers (polyaniline and polypyrrole) as functional components have been obtained. It has been shown that the dependence of the equilibrium degree of swelling on the pH medium for the matrices demonstrates its pronounced maximum at pH = 11. The reversibility of the processes of swelling/contraction for the matrices and composites over a wide variation of swelling medium acidities was studied and analyzed. The effect of the crosslinking degree of the matrix on the content of the conducting components in the composites was determined. The electric conductivity of the composites depended on the degree of crosslinking of the matrices, and the content of the conducting component was measured. Deformational characteristics at compression were measured for the matrices and composites prepared in block-shaped cylinders. It was proven that the formation of a rigid-chain conducting polymer phase in the composites led to an increase in the elastic modulus as compared with the one for the matrix gel, but it did not cause a noticeable decrease in elasticity. It was observed that the new composites were characterized by a combination of swelling capacity, pH sensitivity, and electroconductivity.

Mobile oxygen in layered nickelates of perovskite-type

The influence of the different types of oxygen on the structure and electrical conductivity of the perovskite-type nickelates were investigated. The nickelates La2NiO4+δ, La0,6Sr1,4NiO4–δ, Sr3Al0,75Ni1,25O7–δ were synthesised using the solidstate reaction route. Phase composition was determined by X-ray powder diffraction analysis. The iodometric titration technique was used to specify the oxygen content of the powders. Oxygen desorption and absorption, including oxygen index variation, were investigated by oxygen solid electrolyte coulometry (OSEC). Electroconductive properties of samples were studied by a standard DC four-point method. Utilizing OSEC technique, three mobile and one regular type of oxygen were observed in the perovskite layered nickelates with P/RS and 2P/RS structure. These four types of mobile oxygen differ in the binding energy to the crystal lattice and crystallographic positions. The desorption-sorption processes of various types of mobile oxygen have different effects on the thermal expansion of crystal lattice parameters. The regular oxygen, occupying the apex of octahedron, affects the lattice parameters most prominently. This type of oxygen changes the character of the temperature dependence of specific resistivity sufficiently. Interstitial oxygen does not yield such anomalies.

Design and Optimization of Microbial Fuel Cells and Evaluation of a New Air-Breathing Cathode Based on Carbon Felt Modified with a Hydrogel—Ion Jelly®

The increased demand for alternative sustainable energy sources has boosted research in the field of fuel cells (FC). Among these, microbial fuel cells (MFC), based on microbial anodes and different types of cathodes, have been the subject of renewed interest due to their ability to simultaneously perform wastewater treatment and bioelectricity generation. Several different MFCs have been proposed in this work using different conditions and configurations, namely cathode materials, membranes, external resistances, and microbial composition, among other factors. This work reports the design and optimization of MFC performance and evaluates a hydrogel (Ion Jelly®) modified air-breathing cathode, with and without an immobilized laccase enzyme. This MFC configuration was also compared with other MFC configuration performances, namely abiotic and biocathodes, concerning wastewater treatment and electricity generation. Similar efficiencies in COD reduction, voltage (375 mV), PD (48 mW/m2), CD (130 mA/m2), and OCP (534 mV) were obtained. The results point out the important role of Ion Jelly® in improving the MFC air-breathing cathode performance as it has the advantage that its electroconductivity properties can be designed before modifying the cathode electrodes. The biofilm on MFC anodic electrodes presented a lower microbial diversity than the wastewater treatment effluent used as inocula, and inclusively Geobacteracea was also identified due to the high microbial selective niches constituted by MFC systems.

Conductive and antibacterial films by loading reduced graphene oxide/silver nanoparticles on cellulose nanofiber films

The development of sustainable high-performance materials based on nanocellulose has received great attention in recent years. Herein, nanocellulose based composite films with highly electro-conductive and antibacterial properties have been developed by loading reduced graphene oxide (rGO)/silver nanoparticles (AgNPs) on cellulose nanofiber films via vacuum filtration process. The reduction effect of gallic acid on the chemical structure and electrical conductivity of rGO/AgNP composites was studied. Due to the strong reducibility of gallic acid, the obtained rGO/AgNPs exhibited a high electrical conductivity of 1549.2 S·m−1. Furthermore, the electrical conductivity, mechanical properties and antibacterial properties of the prepared rGO/AgNP-cellulose nanofiber films as a function of various proportions were investigated. The prepared composite film with a specific ratio of rGO/AgNPs to cellulose nanofibers as 7:3 exhibited the superior tensile strength of 28.0 MPa and the electrical conductivity of 1199.3 S·m−1. Meanwhile, compared with pure cellulose nanofiber films, rGO/AgNP-cellulose nanofiber films displayed strong antibacterial effect against Escherichia coli and Staphylococcus aureus. Therefore, this work demonstrated an effective approach for imparting structural and functional properties to cellulose nanofiber based films, which could hold great application prospects for flexible and wearable electronics.

Electroconductive Materials Based on Polylactide and Polypyrrole for Biomedical Applications

Electroconductive scaffolds of different shape for tissue engineering have been obtained on the basis of two biocompatible polymers: polylactide and polypyrrole. The composite scaffolds have been based on porous permeable films or tubes of polylactides prepared via electrospinning. A layer of electroconductive polypyrrole has been applied at the developed surface of the scaffolds consisting of the chaotically interwoven fibers of micron-scale thickness. The structure of the tissue engineering scaffolds as well as their mechanical, redox, and electroconductive properties have been investigated. It has been found that the scaffolds are stable during electrical stimulation via prolonged application of the cyclic potentials.

Polypyrrole-modified multi-functional coatings for improved electro-conductive, hydrophilic and flame-retardant properties of polyamide 66 textiles

Polypyrrole-modified multi-functional coatings for improved electro-conductive, hydrophilic and flame-retardant properties of polyamide 66 textiles

Template-Directed Polymerization Strategy for Producing rGO/UHMWPE Composite Aerogels with Tunable Properties.

In this paper, we suggest a previously unknown template-directed polymerization strategy for producing graphene/polymer aerogels with elevated mechanical properties, preservation of the nanoscale pore structure, an extraordinary crystallite structure, as well as tunable electrical and hydrophobic properties. The suggested approach is studied using the reduced graphene oxide (rGO)/ultrahigh molecular weight polyethylene (UHMWPE) system as an example. We also develop a novel method of ethylene polymerization with formation of UHMWPE directly on the surface of rGO sheets prestructured as the aerogel template. At a UHMWPE content smaller than 20 wt %, composite materials demonstrate completely reversible deformation and good conductivity. An ultrahigh polymer content (more than 80 wt %) results in materials with pronounced plasticity, improved hydrophobic properties, and a Young's modulus that is more than 200 times larger than that of pure rGO aerogel. Variation of the polymer content makes it possible to tune the electro-conductive properties of the aerogel in the range from 4.8 × 10-6 to 4.9 × 10-1 S/m and adjust its hydrophobic properties. The developed approach would make it possible to create composite materials with highly developed nanostructural morphology and advanced properties controlled by the thickness of the polymer layer on the surface of graphene sheets.

Methodology for the Experimental Evaluation of the Conductive Properties of Concrete Structures for Sustainable Transport Development

In the process of development of a new composition of electroconductive concrete for sustainable transport development, the problem arose of the lack of methodology for determining the electrical conductivity of concrete structures. The article presents the developed technique of experimental evaluation of electroconductive properties of concrete structures in laboratory conditions, the circuit of the installation for measuring electroconductive characteristics of concrete structures and experimental results for the developed new type of electroconductive concrete for reinforced concrete contact-line supporting structures «ElBetTrans». The paper reflects the main aspects and conditions of the experiment, technological processes, the order of fixing the results, and the requirements for the equipment and materials used. The presented methodology of experimental evaluation of conductive properties of concrete structures is suitable for objective evaluation and analysis of conductive characteristics of tested samples.

Reinforced conductive polyester based on itaconic acids, glycerol and polypyrrole with potential for electroconductive tissue restoration

Modified chemically crosslinked polyesters as soft and electroconductive materials have investigated for tissue engineering applications. In this work, electroconductivity, thermal stability, and mechanical properties of synthesized Poly (glycerol-sebacate-itaconic) (PGSIT) by the solvent-free method was studied by incorporating polypyrrole (PPy) and clay within the PGSIT matrix. Hydrogen bonds between PGSIT and PPy lead to a homogeneous dispersion of clay and PPy within the PGSIT matrix. The evaluations indicated that PPy and clay could raise the conductivity of PGSIT from 5.9 × 10−11 S/cm to 1.4 × 10−4 S/cm, Young’s modulus from 0.19 MPa to 0.9 MPa, tensile strain to 0.91 MPa from 0.25 MPa, and improved the thermal stability and hydrophilicity of the matrix. The PGSIT-PPy-clay composite might have the potential as electroconductive bio-elastomer in tissue engineering applications.

First-principles study of the structural and electronic properties of LiFePO4 by graphene and N-doped graphene modification

Using first-principles calculations within the DFT + U framework, the structural and electronic properties of LiFePO4 (010) surface modified by graphene and N-doped graphene have been investigated. The calculated formation energy indicates that the graphene and N-doped graphene doped on the (010) surface of the LiFePO4(LFP) is energetically favored. N-substitution can significantly increase the impurity bands between the valence-band maximum and the conduction-band minimum, indicating better electro-conductive properties. Atomic Populations indicates that Li+ is more independent in olivine-type LFP crystal and can be embedded and exited in skeleton relatively freely after graphene and N modification.

Effect of optical illumination and magnetic field on the electroconductive and polarization properties of clathrate GaSe<CS(NH 2) 2<C 14H 10>>, synthesized under lighting

Effect of optical illumination and magnetic field on the electroconductive and polarization properties of clathrate GaSe<CS(NH 2) 2<C 14H 10>>, synthesized under lighting

Injectable, adhesive, self-healing and conductive hydrogels based on MXene nanosheets for spinal cord injury repair

In situ reconstruction of the micro-environment through multifunctional hydrogel verified to be an efficient strategy to accelerate spinal cord injury (SCI) repair. However, it remains great challenges to prepare hydrogel simultaneously possessing injectable, electroconductive, adhesive, and self-healing properties for the traumatic SCI repair. Herein, a novel polyvinylpyrrolidone/phytic acid/Mxenes (PVP/PA/Mxenes, PPM) hydrogel was developed for SCI repair. PVP, PA and Mxenes with appropriate content were uniformly mixed and resulted in a fast and facile gelation process. Benefiting from the reversible noncovalent interaction between PVP and PA, the obtained PPM hydrogels showed excellent shear-thinning and self-healing property, which could be implant into the irregular injured region through injection and fill the cavity without invasiveness. The incorporation of MXenes endowed the hydrogel with good electroconductive. Moreover, the PPM hydrogels exhibited good adhesion to various substrates owing to the abundant active groups distributed in the hydrogel. In vitro study further confirmed that the PPM hydrogel showed good biocompatibility. In the rat spinal cord completely truncation model, the hydrogel could significantly accelerate spinal cord regeneration by accelerating the angiogenesis, remyelination, axon regeneration and calcium channel activation, which may be through the activation of MEK/ERK signaling pathway in the regenerated spinal cord tissues. Overall, the resultant hydrogels developed in the presented work are favorable biomaterials for the repairment of traumatic SCI.

A nanofibrous membrane loaded with doxycycline and printed with conductive hydrogel strips promotes diabetic wound healing in vivo

Patients with diabetes suffer from a variety of complications and easily develop diabetic chronic wounds. The microenvironment of diabetic wounds is characterized by an excessive amount of reactive oxygen species (ROS) and an imbalance of proinflammatory and anti-inflammatory cells/factors, which hinder the regeneration of chronic wounds. In the present study, a wound dressing with immunomodulation and electroconductivity properties was prepared and assayed in vitro and in vivo. [2-(acryloyloxy) ethyl] Trimethylammonium chloride (Bio-IL) and gelatin methacrylate (GelMA) were 3D printed onto a doxycycline hydrochloride (DOXH)-loaded and ROS-degradable polyurethane (PFKU) nanofibrous membrane, followed by UV irradiation to obtain conductive hydrogel strips. DOXH was released more rapidly under a high ROS environment. The dressing promoted migration of endothelial cells and polarization of macrophages to the anti-inflammatory phenotype (M2) in vitro. In a diabetic rat wound healing test, the combination of conductivity and DOXH was most effective in accelerating wound healing, collagen deposition, revascularization, and re-epithelialization by downregulating ROS and inflammatory factor levels as well as by upregulating the M2 macrophage ratio. Statement of significanceThe microenvironment of diabetic wounds is characterized by an excessive amount of reactive oxygen species (ROS) and an imbalance of proinflammatory and anti-inflammatory cells/factors, which hinder the regeneration of chronic wounds. Herein, a wound dressing composed of a DOXH-loaded ROS-responsive polyurethane membrane and 3D-printed conductive hydrogel strips was prepared, which effectively accelerated skin regeneration in diabetic wounds in vivo with better epithelialization, angiogenesis, and collagen deposition. DOXH regulated the dysfunctional wound microenvironment by ROS scavenging and polarizing macrophages to M2 phenotype, thereby playing a dominant role in diabetic wound regeneration. This design may have great potential for preparing other similar materials for the therapy of other diseases with excessive inflammation or damage to electrophysiological organs, such as nerve defect and myocardial infarction.

Hyaluronic acid/gelatin microcapsule functionalized with carbon nanotube through laccase-catalyzed crosslinking for fabrication of cardiac microtissue.

Carbon nanotube (CNT) and gelatin (Gela) molecules are effective substrates in promoting engineered cardiac tissue functions. This study developed a microfluidic-based encapsulation process for biomimetic hydrogel microcapsule fabrication. The hydrogel microcapsule was produced through a coaxial double orifice microfluidic technique and a water-in-oil emulsion system in two sequential processes. The phenol (Ph) substituted Gela (Gela-Ph) and CNT (CNT-Ph), respectively as cell-adhesive and electrically conductive substrates were incorporated in hyaluronic acid (HA)-based hydrogel through laccase-mediated crosslinking. The Cardiomyocyte-enclosing microcapsule fabricated and cellular survival, function, and possible difference in the biological activity of encapsulated cells within micro vehicles were investigated. The coaxial microfluidic method and Lac-mediated crosslinking reaction resulted in spherical vehicle production in 183 μm diameter at 500 capsules/min speed. The encapsulation process did not affect cellular viability and harvested cells from microcapsule proliferated well likewise subcultured cells in tissue culture plate. The biophysical properties of the designed hydrogel, including mechanical strength, swelling, biodegradability and electroconductivity upregulated significantly for hydrogels decorated covalently with Gela-Ph and CNT-Ph. The tendency of the microcapsule for the spheroid formation of cardiomyocytes inside the proposed microcapsule occurred 3 days after encapsulation. Interestingly, immobilized Gela-Ph and CNT-Ph promote cellular growth and specific cardiac markers. Overall, the microfluidic-based encapsulation technology and synthesized biomimetic substrates with electroconductive properties demonstrate desirable cellular adhesion, proliferation, and cardiac functions for engineering cardiac tissue.

Conductive Collagen-Based Hydrogel Combined With Electrical Stimulation to Promote Neural Stem Cell Proliferation and Differentiation.

Injectable biomimetic hydrogels are a promising strategy for enhancing tissue repair after spinal cord injury (SCI) by restoring electrical signals and increasing stem cell differentiation. However, fabricating hydrogels that simultaneously exhibit high electrical conductivities, excellent mechanical properties, and biocompatibility remains a great challenge. In the present study, a collagen-based self-assembling cross-linking polymer network (SCPN) hydrogel containing poly-pyrrole (PPy), which imparted electroconductive properties, is developed for potential application in SCI repair. The prepared collagen/polypyrrole (Col/PPy)-based hydrogel exhibited a continuous and porous structure with pore sizes ranging from 50 to 200 μm. Mechanical test results indicated that the Young’s moduli of the prepared hydrogels were remarkably enhanced with PPy content in the range 0–40 mM. The conductivity of Col/PPy40 hydrogel was 0.176 ± 0.07 S/cm, which was beneficial for mediating electrical signals between tissues and accelerating the rate of nerve repair. The investigations of swelling and degradation of the hydrogels indicated that PPy chains interpenetrated and entangled with the collagen, thereby tightening the network structure of the hydrogel and improving its stability. The cell count kit-8 (CCK-8) assay and live/dead staining assay demonstrated that Col/PPy40 coupled with electrical simulation promoted the proliferation and survival of neural stem cells (NSCs). Compared with the other groups, the immunocytochemical analysis, qPCR, and Western blot studies suggested that Col/PPy40 coupled with ES maximally induced the differentiation of NSCs into neurons and inhibited the differentiation of NSCs into astrocytes. The results also indicated that the neurons in ES-treated Col/PPy40 hydrogel have longer neurites (170.8 ± 37.2 μm) and greater numbers of branch points (4.7 ± 1.2). Therefore, the prepared hydrogel system coupled with ES has potential prospects in the field of SCI treatment.

Electroconductive properties of carbon biocomposites formed by the deposition method

The temperature-frequency dependences of the electrical conductivity for biocomposite formed systems are obtained, and the influence of the carbon temperature type on the changes of the electrically conductive systems is observed. It has been established that the electrical conductivity at a direct current of 1.2 Ohm-1 • m-1 is formed for CNT/aspartate biocomposites. Such electrical conductivity is weakly dependent on frequency. The temperature dependence of the conductivity of CNT/aspartate allowed to set the activation energy at the level of Eg=0,037 eV, which indicates the predominant role of the mechanism of translucency. For biocomposites, TEG / aspartate obtained by ultrasonic dispersion of components in an aqueous medium, the nature of the frequency dependences of the electrical conductivity reflects the combination of the inputs in the material of two component components with different types of mechanisms. Namely: electronic for the carbon temperature and semiconductor for the organic component. This type of dependence at lower temperatures is due to the desorption of water molecules from the surface, through which the charge is transferred by the migration of the proton to the hydroxyl groups. The next increase in temperature causes the activation of electrons and their contribution to the electrical conductivity of the biocomposite. For the TEG / aspartate biocomposite, the calculated value of activation energy will be 0.170 eV.