Polyaniline Coatings Research Articles

Functionalized Modified Ti4O7 Polyaniline Coating for 316SS Bipolar Plate in Proton-Exchange Membrane Fuel Cells.

In this paper, the PANI/PDA-Ti4O7 composite coating was prepared on 316L by constant current deposition with a current density of 2.8 mA·cm-2, in which the Ti4O7 powders were modified by PDA (polydopamine). The open-circuit potential of the obtained PANI/PDA-Ti4O7 composite coating is about 365 mVAg/AgCl, which is more positive than that of the bare 316L. During immersion in 1 M H2SO4 + 2 ppm HF for 200 h, the high stable corrosion potential and the lower Rf indicate that the composite coating has long-term corrosion resistance.

Enhancing corrosion resistance of 316L stainless steel through electrochemical deposition of polyaniline coatings in acidic environments

Stainless steel is widely used because of its excellent corrosion resistance in typical environments. However, it is susceptible to corrosion in acidic media, therefore, to address this issue, the electrochemical deposition of polyaniline coatings on 316L stainless steel was investigated using cyclic voltammetry at different potential windows and scan rates. The successful polymerization and surface morphology were analyzed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Moreover, thermal stability of the PANI coating was assessed through thermo gravimetric analysis while the corrosion behavior of bare and coated steels immersed in 1M H2SO4 was studied using electrochemical impedance spectroscopy (EIS). Based on the Nyquist plots obtained from the EIS revealed that the corrosion resistance of the PANI coating improved significantly with a decrease in scan rate and by limiting the upper potential, especially during longer exposure times up to 72 h. Results suggest that controlling the deposition parameters and optimizing the electrochemical conditions can lead to even greater improvements in the corrosion resistance of the stainless steel. These findings offer valuable insights for researchers and engineers in the field of materials science and corrosion protection, enabling them to develop more precise and efficient strategies for enhancing the durability and performance of stainless steel in acidic environments.

Smart Doped Polyaniline Coating for Wireless Anodic Protection of AISI 304 Stainless Steel in a Corrosive Medium Containing Sulfate and Chloride Ions: Electrochemical and DFT Evaluations.

Polyaniline (PANI) coatings have the capability of in situ anodic protection of stainless steels (SSs). However, these coatings have a high degradation rate in sulfuric acid. Also, the protection of SSs in a medium contaminated with chloride ions is an unsolved challenge. Therefore, the present work aims to modify the electrodeposited PANI coating with different dopants to find the optimal coating for the anodic protection of 304 SS in chloride-contaminated sulfuric acid. Thus, CH3COO-, HSO4-, NO3-, H2PO4-, and NaSO4- were doped electrochemically in PANI to determine the most effective corrosion depressor. Density functional theory (DF)T calculations determined that the lowest Gibbs free energy (more spontaneous doping) is for HSO4- doping by 24 kcal/mol. The band gap energy is <0.5 eV for the PANI/H2SO4 coating, indicating the very high conductivity of this coating. Monte Carlo simulation revealed that the highest deformation energy is related to PANI/H2SO4 at 1877 kcal/mol (stronger adsorption). Mott-Schottky and energy-dispersive spectroscopy (EDS) results showed that PANI doped with sulfuric acid creates a p-type semiconductor (Ni-rich), while the rest of the dopants lead to the formation of an n-type semiconductor passive film (Fe/Cr-rich). Despite the relatively low corrosion resistance of PANI/H2SO4 in the early days, its resistance improved over time by more than 1 order of magnitude. Therefore, this seems to be a more favorable option for long-term anodic protection. Thus, in this work, the corrosion behavior of the passive film formed at the interface of PANI and SS was comprehensively evaluated.

Engineering Carbon Nanotube Yarns with Polyaniline Coating toward Enhanced Thermoelectric Performance.

The growing demand for wearable electronics has driven the development of flexible thermoelectric (TE) generators which can harvest waste body heat as a renewable power source. Despite carbon nanotube (CNT) yarns have attracted significant attention as a promising candidate for TE materials, challenges still exist in improving their TE efficiency for commercial applications. Herein, we developed high performance CNT/polyaniline (PANI) yarns by engineering the coating of polyaniline emeraldine base (PANIeb), in which CNT yarns were firstly coated by PANIeb layer and further doped by HCl vapor treatment. With the incorporation of PANIeb, σ and S were simultaneously increased to 1796 S cm-1 and 74.8 μV K-1 for CNT/PANIeb 4-2d fibers, respectively. Further HCl vapor treatment induced greatly increased σ to 3194 S cm-1, but maintained be 83 % value before doping, giving rise to the highest power factor of 1224 μW m-1K-2, higher than pristine CNT yarns of 576 μW m-1K-2. Combining outstanding high TE performance and bending durability, a flexible TE generator was constructed to deliver high out power of 187 nW with temperature gradients of about 30 K. These results demonstrate the potential promise of high-performance CNT/PANI-HCl yarns to harvest waste body heat for sustainable power supply.

Electropolymerized conducting polyaniline coating on nickel-aluminum bronze alloy for improved corrosion resistance in marine environment

Corrosion of metals in marine environments is a vital problem with significant negative economic impacts and coating is an effective measure of protection. In this work, polyaniline (PANI) conducting polymer was deposited as a protective layer on a nickel-aluminiumbronze (NAB) alloy using the galvanostatic electropolymerization method at different current densities. The deposited coating was characterized by various techniques such as FTIR and SEM. To evaluate its effectiveness in corrosion protection, the anticorrosion properties of different PANI coatings were evaluated in a 3.5 wt% NaCl solution by both potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The electrochemical results revealed that PANI coatings acted as a barrier towards the corrosive species and provided significant corrosion resistance to NAB degradation, with an inhibition efficiency of about 93% and a mixed-type inhibition behavior with cathodic predominance. Furthermore, corrosion protection was found to be dependent on the coated film properties and the optimum corrosion inhibition was achieved under the test conditions for films deposited at a current density of 5 mA cm-². Moreover, Raman spectroscopy confirmed the presence of the partially oxidized conductive polyaniline, the emeraldine form and its polaron structure, on the alloy surface. In addition, atomic force microscopy (AFM) was used to monitor the changes in the microstructure of the coating after exposure to the saline environment and demonstrated the formation of a robust coating with a significantly lower (5 times) surface roughness for the coated alloy than the uncoated surface after immersion. Overall results strongly support the potential of PANI for corrosion protection of the NAB alloy.

Study on Motion Sensing Using Textile Electrodes-Focusing on the Application of PANI Conductive Material

Abstract This study investigates the application of textile electrodes using PANI (Polyaniline) conductive material for motion sensing, specifically aimed at motion monitoring for the elderly. By depositing a PANI conductive layer on the base of warp-knitted fabric through in-situ polymerization and plasma treatment, a PCCWKF (Polyaniline Coated Conductive Warp-Knitted Fabric) with enhanced electrical conductivity and mechanical flexibility was developed. The research optimized the electrical resistivity and durability of PCCWKF by incorporating Polyvinyl Alcohol (PVA) as a toughening agent, improving the adhesion of the PANI conductive layer to the textile substrate. The sensor’s efficacy in accurately recording and monitoring motion amplitude and frequency in real-time was demonstrated through its application in smart clothing, focusing on respiratory, elbow, and knee motion monitoring. This study holds significant implications for the advancement of wearable technology and smart textiles in the health monitoring of the elderly.

Anionic Dye Removal with a Thin Cationic Polyaniline Coating on Cellulosic Biomaterial.

This paper reports the development of novel adsorbent materials using polyaniline (PANI) grafted onto Posidonia (POS) fibers, aimed at efficiently removing phenol red (PSP), an anionic dye, from aqueous solutions. The synthesis involved the copolymerization of aniline grafted on the surface of the POS and aniline monomer in solution, resulting in a chemically bound thin PANI layer on the POS bioadsorbent. Structural characteristics and binding affinities of these adsorbents with PANI under its emeraldine salt (POS@PANI-ES) or emeraldine base (POS@PANI-EB) forms are reported. The rapid adsorption kinetics observed are attributed to enhanced accessibility to PANI adsorption sites on the POS surface. The binding percentages of PSP to POS@PANI-ES and POS@PANI-EB materials were found to be 97 and 50%, respectively, after 15 min of contact time. The Langmuir model for localized adsorption sites and the Volmer model for nonlocalized adsorption as a mobile layer were fitted to the experimental adsorption isotherms of PSP to POS@PANI-EB and POS@PANI-ES, yielding the thermodynamic parameters of adsorption. The adsorption capacities of PSP on POS@PANI-EB and POS@PANI-ES were 37.8 and 71.5 μmol g-1, respectively. The adsorption of PSP remained above 80% at moderate salt concentrations of around 0.1 mol L-1; however, higher concentrations of NaCl and CaCl2 in PSP solutions significantly reduced the adsorption on POS@PANI-ES.

Hydrophobic Conductive Coatings for Fuel Cell Gas Diffusion Layers

Mass transfer of the reactant gases, water management, thermal and electrical conductivity are all highly depending on the properties of the gas diffusion layer (GDL) in polymer electrolyte fuel cells (PEFCs). GDLs are produced in complex and energy demanding processes including high temperature graphitization and are modified using polytetrafluoroethylene (PTFE) to introduce the hydrophobicity needed to efficiently remove water [1]. PTFE is, however, negatively impacts the required electrical conductivity and is facing an uncertain future with the pending restrictions on the use of perfluoroalkyl substances (PFAS) [2], [3]. Therefore, we have investigated the use of electrically conductive polyaniline (PANI) coatings on carbon fiber substrates with modifications to increase hydrophobicity. As substrate, AvCarb carbon paper EP40 was used and PTFE treated EP40T was used as state-of-the-art reference. EP40 was coated through dip-coating or electro-coating using PANI modified with sodium dodecylbenzenesulphonate as additive to adjust hydrophobicity [4]. With this approach, we have been able to show comparable pore volumes and pore surface areas (Figure 1) through mercury porosimetry as well as comparable hydrophobic properties.

Negatively Charging Nonprecious Metal Phosphides/Selenides via General Polyaniline Coating for Improved Alkaline H2 Evolution

Negatively Charging Nonprecious Metal Phosphides/Selenides via General Polyaniline Coating for Improved Alkaline H₂ Evolution

New insight into degradation mechanisms of conductive and thermally resistant polyaniline films

Conductive polyaniline (PANI) coatings find application in various fields, such as electrostatic dissipation, anticorrosion coatings, actives delivery, batteries, and solar control. Improving the thermal and electrical stability of PANI coatings at high temperatures and challenging environments is of growing interest. In this study, a novel polymer blend formulation was developed by adding polyurethane (PU) and sulfonyldiphenol (SDP) to a dinonylnaphthalene sulfonic acid (DNNSA)-doped PANI matrix. Films of the PANI-PU/SDP formulation and unmodified PANI control films were prepared on ITO glass substrates using spin coating, followed by thermal treatment. Characterization of the films was performed using thermogravimetric analysis-mass spectrometry (TGA-MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) with depth profiling. Results showed that unmodified PANI films aged at 150 °C exhibited rapid thermo-oxidative degradation, resulting in a significant loss in electrical conductivity after 24 h. The inclusion of PU and SDP remarkably improved the thermal stability of the films, maintaining desirable conductivity levels over a week. ToF-SIMS depth profiling helped identify potential degradation mechanisms and monitor changes in chemical composition throughout the film thickness. This study provides insights into the functionality, optimization, and deployment of these new film types.

Preparation and performance of PANI/CNTs composite coating on 316 stainless steel bipolar plates by pulsed electrodeposition

Compact polyaniline (PANI) coating and polyaniline/carbon nanotubes (PANI/CNTs) composite coating are prepared on the surface of 316 stainless steel bipolar plate for proton exchange membrane fuel cells by a new method of pulse electrodeposition. The micro morphology shows that the PANI coating prepared by pulse electrodeposition is more uniform and compact than that by direct current electrodeposition. The compactness, corrosion resistance and electrical conductivity of PANI coating are further increased after CNTs are compounded. The results show that compared with PANI coating, the corrosion potential of PANI/CNTs coating is increased by about 78 mV, and the corrosion current density is reduced by an order of magnitude. Under the working potential of 0.6 V (vs. SCE), the current density of PANI/CNTs coating is reduced to about 1.9 μA·cm−2. After potentiostatic test for 5 h, there was no obvious corrosion on the surface of the coating. The interfacial contact resistance (ICR) contact resistance of PANI/CNTs coating is reduced by 35 % compared with PANI coating, and after the polarization process, PANI/CNTs coating has lower contact resistance than PANI coatings. The improved corrosion resistance and electrical conductivity of PANI/CNTs coating can be better applied in the protection of bipolar plates.

Chitosan-polyaniline-TiO2 ternary nanocomposite coating as effective anti-corrosion material for low carbon steel in 3.5 wt% NaCl solution

The coating materials Polyaniline (PANi), Polyaniline-TiO2, and Chitosan-Polyaniline-TiO2 ternary nanocomposite (CPT) were separately synthesized by chemical oxidative polymerization with ammonium persulphate as an oxidant in a hydrochloride aqueous medium. The synthesized materials were characterized by FT-IR, XRD, SEM, and TEM. The FT-IR and XRD result adequately established the interaction between chitosan, PANi, and TiO2 NPs. Microstructural studies revealed significant variation in the morphologies of PANi, PANi-TiO2, and chitosan-polyaniline-TiO2 nanocomposite and embedment of TiO2 NPs in the polymer matrix. The coating materials PANi, PANi-TiO2, and CPT were mixed with epoxy resin (10%) and subsequently, cast on low carbon steel (LCS) using NMP as solvent and triethyl tetra amine as curing agent. The anti-corrosion properties of coated specimens in 3.5 wt.% NaCl solution was evaluated using EIS studies, PDP, Salt spray test, water uptake test, immersion test, and SEM. Results of corrosion tests revealed superior corrosion protection offered by CPT ternary nanocomposite coating to LCS in 3.5 wt % NaCl solution compared to PANi and PANi-TiO2 nanocomposite coatings.

Robust, Versatile Access to Quasi-Monodispersed Phase Change Sub-Microcapsules via Ab Initio Emulsion Polymerization

The phase change sub-microcapsules (PCMCs) with the particle size of 100 nm to 1 μm have a great application potential in the field of hybrid materials for solar energy storage, while the preparation of PCMCs remains challenging without ultrasonic treatment and high-speed (>1000 rpm) homogenization. Herein, PCMCs with readily tunable phase change properties are prepared via facile, robust ab initio emulsion polymerization. The PCMCs present the quasi-monodispersed particle morphologies with the tunable particle size from 159 to 383 nm depending on the loading content of acrylic acid and the free surfactant. The latent heat density and phase change temperature of the PCMCs can be tuned from 66.6 to 115.2 J/g and from 20.8 to 65.4 °C, respectively, depending on the loading content and the type of phase change cores. The PCMCs confirm the latent heat efficiency of about 1, the high thermal reliability, and the high shape stability. The PCMCs can be functionalized by polyaniline coatings with an efficient photothermal effect. The robust, versatile approach to functionalized PCMCs can provide an alternative opportunity for the development of the next-generation smart thermal energy materials.

Surfactant doped polyaniline coatings for functionalized gas diffusion layers in low temperature fuel cells

Gas diffusion layers (GDLs) are essential for the proper distribution of the reaction gases, the removal of excess water as well as electrical contact in polymer electrolyte fuel cells (PEFCs).

The Atrazine Removal with the Polyaniline Coated Rice Husk as a Cheap Adsorbent

In this study, a composite of rice husk (RH) modified with polyaniline (PANI) was produced and its potential as an adsorbent in removal of atrazine was investigated.&#x0D; Within the scope of the study, the effects of contact time (0-480 min), initial pH (3.5-&#x0D; 9.5), initial atrazine concentration (2-25 mg/L), and PANI/RH amount (0-1.6 g) on&#x0D; treatment efficiency were examined. The optimum treatment efficiency for atrazine&#x0D; (25 mg/L) was found as 58.3% under 120 min., 5.4 of pH, and 1.0 g/50 ml of&#x0D; adsorbent dosage, and at this condition, adsorption capacities (qt) was calculated as&#x0D; 0.58 mg/g. Furthermore, when the initial atrazine concentration was raised from 2 to&#x0D; 25 mg/L, the removal efficiencies decreased from 81.1 to 60.4 %, but the adsorption&#x0D; capacities (qt) increased from 0.067 to 0.629 mg/g. In addition, the efficiency of the&#x0D; adsorption process was evaluated by applying Langmuir and Freundlich isotherm&#x0D; models. Among the performed isotherm models, Freundlich isotherm provided the&#x0D; best correlation for atrazine and the Freundlich constant related to the sorption&#x0D; capacity was calculated as 2.02 mg/g at an initial pH of 5.4 for the 2.0-25 mg/L&#x0D; atrazine at 25 oC. Raw-PANI/RH and used-PANI/RH composites were characterized&#x0D; with FTIR, XRD, and SEM analysis.

Synthesis of V2O5·nH2O nanobelts@polyaniline core–shell structures with highly efficient Zn2+ storage

Aqueous zinc-ion batteries (AZIBs) are regarded as attractive candidates for next-generation energy storage devices. Among various cathode materials, V2O5·nH2O (VOH) possesses a high theoretical capacity but poor cycle stability due to the susceptibility of its open structure to damage by the quick shuttling of Zn2+. Herein, the structural stability of VOH is directly improved by wrapping polyaniline (PANI) on the VOH nanobelts (VOH@PANI). As a cathode material for AZIBs, the VOH nanobelts@PANI core–shell structures exhibit an outstanding cycle stability of 98% after 2000 cycles at 2 A g−1. The improved conductivity and additional energy storage contribution of the PANI endow VOH@PANI with a specific capacity as high as 440 mAh g−1 at 0.1 A g−1, substantially higher than pure VOH (291 mAh g−1). At the same time, high energy and power densities of 349 Wh kg−1 and 3347 W kg−1 are achieved. This work not only demonstrates that p-type doped PANI coatings on VOH can boost the Zn2+ storage of VOH, but also provides a novel method to enhance cathode materials for high electrochemical performance.

Electrodeposition of Cu-Reinforced Polyaniline Coating for Protection of AH36 Steel in Natural Seawater

The marine environment is highly corrosive for mild and low alloy steels. This study aimed to enhance the corrosion resistance of the AH36 steel in a saline medium by coating it with a copper particles reinforced polyaniline (PANI) layer. PANI and Cu particles were grown on the steel surface by electrodepositing methods. Firstly, PANI was electropolymerized in the presence of oxalic acid, followed by the electrodeposition of Cu particles at different deposition times. The coating showed a well-distribution of Cu particles in the polymer matrix and excellent adhesion. Furthermore, the Cu particles and PANI-coated steels exhibited corrosion resistance significantly in the saline medium compared to the bare substrate and pristine PANI-coated samples. The improved corrosion protection of a Cu@PANI coating on the AH36 steel could contribute to forming a physical barrier by filling Cu particles on the PANI pores.

Hierarchical conducting polymer coated conjugated polyimide anode towards durable lithium-ion batteries

Organic polymer materials attract lots of attention as promising anode materials for lithium ion batteries (LIBs) due to the superior lithium ion storage capability and low cost. However, the inherent insulativity of the polymer anodes results in the unsatisfactory electrochemical performance. Herein, we design and construct a hierarchical flowers-like polyaniline-coated (PANI) pyromellitic dianhydride-based polyimide (PPI) composite (PANI-PPI-9). Benefiting from the core-shell structure, the PPI presents an improved electrochemical performance, especially the remarkable cycling life (503 mAh g−1 at 1.5 A g−1 after 2400 cycles). Ex-situ characterizations and kinetics analyses also verify that the PANI shell serves as the electronic transport highway without obstructing the Li storage of PPI. This work highlights the potential application of the multifarious polymer-based composite electrodes for the lithium ion batteries.

PANI-Based Stacked Ferromagnetic Systems: Electrochemical Preparation and Characterization

In this work, the electropolymerization of polyaniline (PANI) is explored for its action as either a suitable coating or as a substrate for Nickel (Ni) and Magnetite (Fe3O4) surfaces. PANI electropolymerization has been achieved through cyclic voltammetry (CV), potentiostatic and galvanostatic electrochemical methods. The interaction between the obtained surfaces and the ferromagnetic layers (Ni and Fe3O4) has been investigated as a function of the pH of the electrolytic PANI solution, and also a variety of experimental parameters have been optimized in order to achieve the synthesis of PANI coatings (solvent, substrate, concentrations, and cell set-up). Thus, we obtained stable and consistent PANI thick films at the interface of both the nickel and the magnetite ferromagnetic materials.

Galvanostatic optimization of polyaniline coating on mild steel in tartrate medium for corrosion protection

Optimization of polyaniline (PANI) coating on mild steel (MS) surface has been studied in 0.3 M aniline + 0.2 M sodium potassium tartrate (Na-K Tartrate) by galvanostatic polarization. The current densities of 0.5, 0.75. 1 and 2 mA cm-2 are used for the electrodeposition of PANI on MS. The obtained PANI coatings have been characterized for its morphology using an optical microscope and corrosion performance by using potentiodynamic polarization in 0.4 M Na2SO3 solution simulating an industrial environment. The results reveal a sequential process of dissolution of MS, passivation of MS by forming tartrate salt followed by oxidation of aniline monomer and subsequential nucleation and growth of PANI coating. It is found that the PANI coating obtained at 0.5 mA cm-2 results in better coating producing corrosion inhibition efficiency (IE) of approximately 90% compared to IE of about 75% for coating obtained at 2 mA cm-2.