Development and Investigation of PEDOT:PSS Composition Coated Fabrics Intended for Microwave Shielding and Absorption

The Impact of Structural Variations and Coating Techniques on the Microwave Properties of Woven Fabrics Coated with PEDOT:PSS Composition

Minimizing the impact of electromagnetic radiation (EMR) holds paramount importance in safeguarding individuals who frequently utilize electrical and electronic devices. Electrically conductive textiles, which possess specialized EMR shielding features, present a promising solution to mitigate the risks related to EMR. Furthermore, these textile-based shielding materials could find application as radar-absorbing materials in stealth technology, emphasizing the need for substantial absorption capabilities in shielding mechanisms. In this study, various textile-based materials with an electrically conductive coating that contain the conjugated polymer system poly(3,4-ethylene-dioxythiophene)-polystyrene sulfonate (PEDOT:PSS) were prepared and investigated. The influence of the textile substrate structural parameters, coating deposit, and coating method on their microwave properties-transmission, reflection, and absorption-was investigated. Reflection and transmission measurements were conducted within a frequency range of 2 to 18 GHz. These measurements revealed that, for the tested samples, the shielding properties are determined by the combined effect of reflection and absorption. However, the role of these two parameters varies across the tested frequency range. It was defined that for fabrics coated on one side, better reflection reduction is obtained when the shielding effectiveness (SE) is below |20| dB. It was found that by controlling the coating deposition on the fabric, it is possible to fine-tune the electrical properties to a certain extent, thereby influencing the microwave properties of the coated fabrics. The studies of prepared samples have shown that reflection and transmission parameters depend not only on the type and quantity of conductive paste applied to the fabric but also on the fabric's construction parameters and the coating technique used. It was found that the denser the substrate used for coating, the more conductive paste solidifies on the surface, forming a thicker coat on the top. For conductive fabrics with the same substrate to achieve a particular SE value using the knife-over-roll coating technology, the required coating deposit amount is considerably lower as compared with the deposit necessary in the case of screen printing: for the knife-over-roll-coated sample to reach SE 15 dB, the required deposit is approximately 14 g/m2; meanwhile, for a sample coated via screen printing, this amount rises to 23 g/m2.

Processability of Thermoelectric Ultrafine Fibers via Electrospinning for Wearable Electronics

Polymer-based thermoelectric generators hold great appeal in the realm of wearable electronics as they enable the utilization of body heat for power generation. Fibers produced from conducting polymers for use in thermoelectric generators have high porosity and good flexibility, providing comfort-based performance advantages over thin films for wearable electronics. Some fiber processing techniques have been explored to produce textile-based thermoelectric generators; however, they fail to approach the conductivities of polymeric thin films. Ultrafine fibers solution processed through electrospinning yield fiber diameters on the nanoscale, allowing for high surface area to volume ratios and thus low thermal conductivity; however, a number of processing challenges in electrospinning conducting polymers limit the success of preparing high performing thermoelectric textiles. In this work, the specific processing challenges inherent to electrospinning conducting polymers are addressed for both n- and p-type materials. For the p-type polymer, 63 wt % PEDOT:PSS fibers are fabricated through solution formulation improvements yielding a conductivity of 3 S/cm and a power factor of 0.1 μW/mK2. The first of their kind n-type poly(NiETT)/PVA electrospun fibers were created yielding a conductivity of 0.11 S/cm and a power factor of 0.0036 μW/mK2. These nonwoven ultrafine fiber mats show progress toward achieving textile-based thermoelectric materials with equivalent performance of comparable polymeric thin films. This work shows the feasibility of creating ultrafine fibers for use in thermoelectric generators through electrospinning including the first demonstration of poly(NiETT)/PVA fibers.

Investigation of Electrical and Wearing Properties of Wool Fabric Coated with PEDOT:PSS

The way to improve the properties (resistance to washing, delamination, and rubbing off) of the PEDOT:PSS coating applied on wool fabric without reduction of its electrical conductivity by introducing a commercially available combination of low formaldehyde content melamine resins into the printing paste is presented in this paper. Primarily, to improve the hydrophilicity and dyeability of wool fabric, the samples were modified using low-pressure nitrogen (N₂) gas plasma. Two commercially available PEDOT:PSS dispersions were used to treat wool fabric by the exhaust dyeing and screen printing methods, respectively. Spectrophotometric measurements of the color difference (ΔE*_ab) and visual evaluation of woolen fabric dyed and printed with PEDOT:PSS in different shades of the blue color showed that the sample modified with N₂ plasma obtained a more intense color compared to the unmodified one. SEM was used to examine the surface morphology and a cross-sectional view of wool fabric that had undergone various modifications. SEM image shows that the dye penetrates deeper into the wool fabric after plasma modification using dyeing and coating methods with a PEDOT:PSS polymer. In addition, with a Tubicoat fixing agent, HT coating looks more homogeneous and uniform. The chemical structure spectra of wool fabrics coated with PEDOT:PSS were investigated using FTIR-ATR characterization. The influence of melamine formaldehyde resins on the electrical properties, resistance to washing, and mechanical effects of PEDOT:PSS treated wool fabric was also evaluated. The resistivity measurement of the samples containing melamine-formaldehyde resins as an additive did not show a significant decrease in electrical conductivity, while the electrical conductivity was maintained after the washing and rubbing test as well. The best results of electrical conductivity for investigated wool fabrics before and after washing and mechanical action were determined for samples subjected to the combined processing-surface modification by low-pressure N₂ plasma, dyeing by exhaust with PEDOT:PSS, and coating by the screen-printing method of PEDOT:PSS and a 3 wt.% melamine formaldehyde resins mixture.

Green Nanomaterials for Smart Textiles Dedicated to Environmental and Biomedical Applications

Smart textiles recently reaped significant attention owing to their potential applications in various fields, such as environmental and biomedical monitoring. Integrating green nanomaterials into smart textiles can enhance their functionality and sustainability. This review will outline recent advancements in smart textiles incorporating green nanomaterials for environmental and biomedical applications. The article highlights green nanomaterials' synthesis, characterization, and applications in smart textile development. We discuss the challenges and limitations of using green nanomaterials in smart textiles and future perspectives for developing environmentally friendly and biocompatible smart textiles.

Washable PEDOT:PSS Coated Polyester with Submicron Sized Fibers for Wearable Technologies

The use of non-metallic conductive yarns in wearable technologies like smart textiles requires compliant washable fibers that can withstand domestic washing without losing their conductive properties. A one-pot coating with PEDOT:PSS conductive polymers was applied to polyester submicron fibers, increasing the water resistance and washability under various domestic washing conditions. Plasma treatment of the untreated samples improved the anchoring of the coating to the fibers, producing smooth and homogeneous coatings. The primary doping of PEDOT:PSS with ethylene glycol (EG), dimethyl sulfoxide (DMSO), and a non-ionic surfactant as well as the secondary doping of the composite fibers improved the sheet resistance at room temperature. The as-obtained composite materials showed similar mechanical properties as the parent fibers, indicating that the coating and post-treatment do not affect the overall mechanical property of the composite. The performance of the composites under different temperature and humidity conditions and washability using the standardized ISO 6330:2012 procedure for domestic washing and drying showed that the obtained composites are good candidates for reliable washable wearable technologies, such as all-organic washable Joule heaters in functional textiles.

Review on PEDOT:PSS-Based Conductive Fabric

This article reviews conductive fabrics made with the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), their fabrication techniques, and their applications. PEDOT:PSS has attracted interest in smart textile technology due to its relatively high electrical conductivity, water dispersibility, ease of manufacturing, environmental stability, and commercial availability. Several methods apply PEDOT:PSS to textiles. They include polymerization of the monomer, coating, dyeing, and printing methods. In addition, several studies have shown the conductivity of fabrics with the addition of PEDOT:PSS. The electrical properties of conductive textiles with a certain sheet resistance can be reduced by several orders of magnitude using PEDOT:PSS and polar solvents as secondary dopants. In addition, several studies have shown that the flexibility and durability of textiles coated with PEDOT:PSS can be improved by creating a composite with other polymers, such as polyurethane, which has high flexibility and extensibility. This improvement is due to the stronger bonding of PEDOT:PSS to the fabrics. Sensors, actuators, antennas, interconnectors, energy harvesting, and storage devices have been developed with PEDOT:PSS-based conductive fabrics.

Impact of Low-Pressure Plasma Treatment of Wool Fabric for Dyeing with PEDOT: PSS

This study presents the effect of non-thermal plasma modification on the changes of surface morphology, color characteristics and electrical conductivity of wool fabric dyed with intrinsically conductive polymer (ICP) poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). The wool fabric was treated with an aqueous dispersion of PEDOT: PSS, Clevios F ET, providing electrically conductive properties to textiles. The wool fabric, containing basic groups of amines (NH₂), was pre-activated with low-pressure plasma of non-polymer forming nitrogen (N₂) gas before exhaust dyeing with PEDOT: PSS at 90 °C was applied. This treatment imparted hydrophilicity, reduced felting, increased adhesion, improved dye ability and ensured that more PEDOT: PSS negatively charged sulfonate (−SO3−) counter ions would be electrostatically bounded with the cationic protonated amine groups of the wool fiber. Initially, before (N₂) plasma treatment and after fabrics were evaluated according to the test method for aqueous liquid repellency, the surface morphology of the plasma-modified and -unmodified wool dyed fabric was observed with scanning electron microscopy (SEM). The functional groups introduced onto the surface after N₂ gas plasma treatment of wool fabric were characterized by X-ray photoelectron and FTIR-ATR spectroscopy. The results of color difference measurements show that N₂ gas plasma treatments provide more intense color on Clevios F ET dyed wool fabric and retain its electrical conductivity.

Synthesis and Characterization of a Conductive Polymer Blend Based on PEDOT:PSS and Its Electromagnetic Applications

The purpose of this study is to prepare a resistive lossy material using conducting polymers for electromagnetic wave absorbers. This paper presents a conductive paste largely composed of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) with a polyurethane binder. The various secondary compounds are added in small amounts to an aqueous blended solution in order to enhance the electrical and mechanical properties of the conductive thin film. The synthesized conductive paste is characterized through electrical, chemical, and morphological analyses. The electrical conductivity of the thin film is measured using a four-point probe and surface profiler. The chemical and morphological changes are studied in various experiments using a Raman microscope, X-ray photoelectron spectroscopy, a scanning electron microscope, and an atomic force microscope. In order to verify the applicability of the synthesized conductive paste, which is composed of 70 wt% PEDOT:PSS, 30 wt% polyurethane, and secondary additives (DMAE 0.4 wt%, A-187 0.5 wt%, DMSO 7 wt%, Dynol 604 0.1 wt%, PUR 40 2.5 wt%), the Salisbury screen absorber is fabricated and evaluated in the X-band. According to the results, the absorber resonates at 9.7 GHz, the reflection loss is −38.6 dB, and the 90% absorption bandwidth is 3.4 GHz (8.2 to 11.6 GHz). Through this experiment, the applicability of the PEDOT:PSS-based conductive paste is sufficiently verified and it is found that excellent radar-absorbing performance can be realized.

EMI Shielding and Absorption of Electroconductive Textiles with PANI and PPy Conductive Polymers and Numerical Model Approach

The paper presents the results and analysis of interdisciplinary research concerning electromagnetic field shielding, conductive polymers printed on textiles and numerical simulation using the finite element method (FEM). The use of conductive, layered textiles for shielding electromagnetic interference (EMI) has been proposed. After establishing the optimal conditions for deposition of polyaniline (PANI) and polypyrrole (PPy) on polyacrylonitrile (PAN) fabric, conductive composites were made by means of reactive inkjet printing. For this purpose, polyacrylonitrile (PAN) fabrics were coated with polyaniline or polypyrrole, obtained by chemical oxidation of aniline hydrochloride and pyrrole by ammonium peroxydisulfate. The morphology of the obtained coatings was observed using a scanning electron microscope (SEM). The conductive properties (surface resistance) of the fabrics were measured using the four-wire method, and the tests of the effectiveness of electromagnetic shielding were carried out using the waveguide method in the frequency range from 2.5 to 18 GHz. The results of experimental shielding effectiveness (SE) tests and numerical simulation showed that the composites of polyacrylonitrile with polyaniline PAN/PANI and polyacrylonitrile with polypyrrole PAN/PPy achieved very good and good EMI shielding efficiency, respectively. Moreover, the obtained measurement results were verified by numerical modeling with the use of FEM–ANSYS HFFS software.