Polyaniline Layer Research Articles

Optical, structural, and morphological properties of PANI/CdSe(TPs) nanocomposite thin films

Polyaniline (PANI) thin films and cadmium selenide tetrapods (CdSe TPs) have been prepared by low-cost chemical bath deposition and solvothermal route, respectively. Hybrid PANI/CdSe(TPs) nanocomposite layers were obtained by dipping the PANI layers into the solution of CdSe(TPs) for various duration. The optical, structural, morphological and compositional properties of pristine PANI and nanocomposite layers are studied. The dipping time of PANI layer into CdSe(TPs) solution significantly affect onto the above properties. The absorption and PL intensities for PANI/CdSe(TPs) layers in visible to NIR region increases upon increasing the dipping time. CdSe TPs revealed hexagonal crystal structure by X-ray diffraction analysis. The inter-planer distance was measured about 0.352 nm corresponds to (002) plane of hexagonal CdSe with HRTEM. Growth of void free, granular, and densely packed PANI/CdSe(TPs) layers was confirmed from SEM images. Stoichiometric atomic percentage contents of Cd and Se were obtained by EDAX analyses in PANI/CdSe(TPs) thin film. FTIR results indicate the interaction between CdSe and the acid protonated N–H groups of PANI. The LO1 peak of CdSe and increased relative intensity of C–N+ band of PANI observed in the Raman spectra demonstrates the formation of PANI/CdSe nanocomposites. Thermogravimetric result reveals enhanced thermal stability of PANI/CdSe(TPs) nanocomposite compared to pristine PANI.

Graphene oxide-supported carbon nanofiber-like network derived from polyaniline: A novel composite for enhanced glucose oxidase bioelectrode performance

A three-dimensional architecture of PANI@GO hybrid was synthesized via in-situ polymerization of aniline monomers on the surface of graphene oxide (GO) and carbonized at 1600°C. The SEM images showed that surfaces of planar GO were covered by a compact nanofiber-like polyaniline (PANI) layer which presented an interconnected network. Nanofiber-like PANI on the GO surface was mostly preserved and became the carbon nanofibers (CNFs) after carbonization. The TEM images showed that the carbonized PANI grew seamlessly on the GO surface and served as conductive “network” between interlayers of GO. The carbonized PANI@GO hybrid was used to modify a glassy carbon electrode (GCE) based on GOx, resulting in efficient direct electron transfer (DET) and excellent bio-catalytic performance. In addition, a glucose/O2 fuel cell constructed using Nafion/GOx/PANI1600@GO/GCE as the anode and an E-TEK Pt/C modified GCE as the cathode generated a maximum power density of 0.756mWcm−2 at 0.42V. Findings in this study may be helpful for exploiting novel materials for immobilization of enzymes through carbonizing conducting polymers or their composites with inorganic materials at high temperature for applications in enzymatic biofuel cells or biosensors.

Synthesis of polyaniline shell on nickel oxide nanoflake arrays for enhanced lithium ion storage

Developing conducting polymer/oxide composites are of great importance to construct advanced electrochemical devices. In this work, we report a successive electrodeposition methods to fabricate polyaniline (PANI) on nickel oxide (NiO) nanoflake forming composite core-shell arrays. A thin layer of PANI of ∼10nm is successfully coated on the surface of NiO nanoflake core. High porosity and enhanced conductivity are obtained in this composite electrode. As anode materials for lithium ion batteries, the NiO/PANI core-shell arrays exhibit weaker polarization and better cycling performance as compared to the bare NiO film. The second discharge capacity of NiO/PANI composite arrays is about 780mAhg−1 at 0.1Ag−1, higher than that of the bare NiO film (679mAhg−1). The improvements of the electrochemical properties are attributed to the PANI, which forms a uniform conductive network leading to improved electrochemical performance.

Investigating mechanical, dielectric, and electromagnetic interference shielding properties of polymer blends and three component hybrid composites based on polyvinyl alcohol, polyaniline, and few layer graphene

To achieve the suitable set of synergistic mechanical, dielectric, and electromagnetic interference shielding properties, polymer blends based on varying the concentration of conductive polymer polyaniline (PANI) in insulative matrix of polyvinyl alcohol (PVA) as well as hybrid composites by adding few layer graphene (FLG) in PVA/PANI polymer blends are prepared using solution casting method. In PVA/PANI blends, by increasing the concentration of PANI, dielectric constant (ε′), dielectric loss (ε″), and total shielding efficiency (SET) of PVA are enhanced from 4 to 80, 0.72 to 164, and 2.5 to 30 dB at 100 Hz, respectively, at the considerable loss of its mechanical properties particularly the tensile strength from 23.9 to 8.5 MPa. For hybrid composites of PVA/PANI/FLG, mechanical as well as dielectric and EMI shielding properties are remarkably enhanced at very low loading levels of FLG. The incorporation of small amounts of FLG in PVA/PANI‐10 wt%, the ε′, ε″, and SETare increased from 4 to 7,907, 0.5 to 406,947.5 and 2.5 to 99 dB at 100 Hz, respectively, along with the considerable increase in the mechanical properties such as tensile strength from 15.7 to 36.3 MPa and modulus from 0.1 to 0.96 GPa at the loss of strain. In comparison to PVA/PANI blends, hybrid composites of PVA/PANI/FLG become a promising system for microwave absorption applications. POLYM. COMPOS., 39:3686–3695, 2018. © 2017 Society of Plastics Engineers

Synthesis of coaxial nanotubes of polyaniline and poly(hydroxyethyl methacrylate) by oxidative/initiated chemical vapor deposition

Vapor-phase synthesis techniques of polymeric nanostructures offer unique advantages over conventional, solution-based techniques because of their solventless nature. In this work, we report the fabrication of coaxial polymer nanotubes using two different chemical vapor deposition methods. The fabrication process involves the deposition of an outer layer of the conductive polyaniline (PANI) by oxidative chemical vapor deposition, followed by the deposition of the inner layer of poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel by initiated chemical vapor deposition. The vapor-phase techniques allowed for fine-tuning of the thickness of the individual layers, keeping the functionalities of the polymers intact. The response of the single components and the coaxial nanotubes to changes in humidity was investigated for potential humidity sensor applications. For single-component conductive PANI nanotubes, the resistance changed parabolically with relative humidity because of competing effects of doping and swelling of the PANI polymer under humid conditions. Introducing a hydrogel inner layer increased the overall resistance, and enhanced swelling, which caused the resistance to continuously increase with relative humidity.

THE TREATMENT OF WASTEWATER FROM DYES, USING MODIFIED MICROFILTRATION MEMBRANES

The urgent task is the issues of wastewater treatment from dyes, formed as a result of textile, chemical, leather, painting and other types of activities. In these days, the method of membrane separation is widely used for the purification of wastewater from dyes. The methods of water purification from dyes, by means of initial and modified microfiltration membranes, based on a nylon substrate, with a surface layer of polyaniline and gelatin, prepared by the methods of polymerization, suspension and dynamic coating, are considered in the work. It was found, that the degree of water purification from the model dye methylene blue with the initial membrane was no more than 47%, and after modification of the membrane, depending on the method, the degree of purification from the dye increased to 94%. At the same time, the specific productivity of membranes decreased after chemical treatment, depending on the processing method, from 3 to 12%. The particle size of the dye model solution is in the range 82 - 7100 nm, that corresponds to the working range of microfiltration membranes. After membrane separation, there is the reduction of dye particles size in the suspension, but after the separation of suspension with the nylon-polyaniline membrane, it is observed an increase of particle sizes up to 10 μm.

Efficient spin transport through polyaniline

By using the spin pumping process, we show that it is possible to transport a pure spin current across layers of conducting polyaniline (PANI) with several hundred nanometers sandwiched between a film of the ferrimagnetic insulator yttrium iron garnet (YIG) and a thin layer of platinum. The spin current generated by microwave-driven ferromagnetic resonance of the YIG film, injected through the YIG/PANI interface, crosses the whole PANI layer and then is injected into the Pt layer. By means of the inverse spin Hall effect in the Pt, the spin current is converted into charge current and electrically detected as a dc voltage. We measured a spin diffusion length in PANI of 590 \ifmmode\pm\else\textpm\fi{} 40 nm, which is very large compared with normal metals, demonstrating that PANI can be used as an efficient spin current conductor and poor charge current conductor, opening the path towards spintronics applications based in this very attractive material.

Thickness dependent semiconductor-to-metal transition of two-dimensional polyaniline with unique work functions.

Searching for two-dimensional (2D) layered materials with diverse electronic conductivities is one of the leading topics in materials science. Herein, from first-principles calculations, we report the thickness-dependent conductivity of layered 2D polyaniline (PANI) structures. When PANI is thinned down to a monolayer, it behaves as a p-type semiconductor with an indirect bandgap of 1.04 eV from the HSE functional, which is the closest to that of bulk silicon among all the known monolayer 2D materials. When two PANI monolayers are stacked together to form a bilayer, the bandgap is reduced to only 0.12 eV. From trilayer to bulk, the characteristic of the metal is realized with both intra- and inter-layer conductivities. Notably, the semiconducting and metallic PANI can form a seamless contact with low contact resistance that greatly benefits the carrier injection and facilitates carrier transport. Electronic structure and density of state analyses reveal the importance of the 2pz orbital in contributing to the metallic conductance through crossing the system Fermi level. The binding between PANI layers is 61.68 meV per atom, indicating that the interlayer interaction within PANI stacks is mostly van der Waals attraction. This striking semiconductor-to-metal transition realized in one homogeneous 2D nanomaterial only through thickness control should open up new opportunities for the design of seamless electronic contacts and constitute the ultimate functional unit for future nano-electronic devices.

Bio-inspired Artificial Muscle Based on Chemical Sensors

In this work, we have investigated the modeling, design and fabrication of bio-inspired artificial muscle unit capable of contracting according to the directives sent in form of chemical messengers. This new technology has the potential to revolutionize current robotics, because it could permit a paradigm shift in robots: from electro-mechanical devices to electro-chemical devices. The bio-inspired artificial muscle will be based on basic contractile units coupled to electrochemical sensors, with the purpose of allowing adaptive and flexible control similar to that in animal locomotion. An artificial nerve termination, able to modify the chemical characteristics of the inner environment, will generate directives in form of chemical messengers. Electro-chemical sensors have been used in order to detect the presence of the chemical messengers and transform them into electronic signals to be used in conventional control electronics. This study has been focused on the development and optimization of sensing materials for inorganic ions such as hydrogen ions. Among various conducting polymers studied, polyaniline (PANI) has attracted much attention due to its unique and controllable chemical and electrical properties. PANI layer has been electrochemically deposited on the gold arrays surface by cyclic voltammetry. Preliminary experiments on PANI-modified sensors in order to obtain the better sensitivity as chemical sensing used in artificial muscle unit have been carried out. To allow diffusion of chemical messages, the system has been immersed in wet environment. Using this approach, we study the effective possibility to control, assessing the performance in terms of accuracy of the control of the contraction, the impact of the delay due to the transmission time of the chemicals, precision and stability of control.

Electrosynthesis of Polyaniline on Carbon Fiber Felt: Influence of Voltammetric Cycles on Electroactivity

The carbon materials and conducting polymers are known by application in electronic devices. This work aims to study the initial steps parameters of polyaniline electrosynthesis on carbon felts annealed at 1600 K by changing the number of voltammetry cycles in aniline acid solution. The characterization was performed by Field Emission Gun – Scanning Electron Microscopy, X-ray Diffraction, Infrared Fourier Transform Spectroscopy, Raman Spectroscopy and Electrochemical Impedance Spectroscopy. Under increasing number of cycles, the growth was more intense and it was easy to observe the pores clogging. Besides, it was noticed that emeraldine formation occurred progressively, from structures less to more oxidized: the polyaniline less cycled resulted closest that leucoemeraldine; polyaniline from nine cycles resulted closest to emeraldine, but all of them showed electroactive defects related to electrical charge (polarons) and conductivity (bipolarons). It was also observed that prime layers of polyaniline, formed until three cycles, followed more intense attraction of charges in solution to layer surface. This effect was emphasized from 3rd to 6th cycles.

Polyaniline coated Fe3O4 hollow nanospheres as anode materials for lithium ion batteries

Polyaniline layer coated hollow Fe3O4 nanospheres show enhanced lithium storage properties as compared to hollow and solid Fe3O4 nanospheres.

Effective Suppression of Polysulfide Dissolution by Uniformly Transfer-Printed Conducting Polymer on Sulfur Cathode for Li-S Batteries

The lithium-sulfur battery has received much attention in recent years owing to its high gravimetric capacity, far beyond that of current Li-ion batteries. Overcoming the shuttling effect caused by the dissolution of polysulfides during the charge-discharge process is a major challenge for the realization of Li-S cells. Here we report transfer-printing of a conductive polymer to cover and securely passivate the surface of sulfur electrodes to prevent the dissolution of polysulfides and, simultaneously, to provide high electronic conductivity of sulfur cathodes. Highly uniform polyaniline film can be controllably formed on sulfur cathodes via the transfer printing method, and a sulfur cathode with the printed polyaniline layer showed improved cycle performance (capacity retention of 96.4% and an average Coulombic efficiency of 99.6% for 200 cycles) compared to conventional sulfur cathodes. In situ measurement of transmittance during discharge demonstrated that the dissolution of sulfur in electrolytes is considerably suppressed by the printed polyaniline layer, substantiating that transfer-printed polyaniline film can provide robust protection as well as supplement electrical conductivity to the sulfur cathode. This strategy could be extensively applied to sulfur cathodes of diverse morphology and further extended to large-scale production.

Planar and 3D fibrous polyaniline-based materials for memristive elements.

The memristive elements constructed using polymers - polyaniline (PANI) and polyethyleneoxide (PEO) - could be assembled on planar thin films or on 3D fibrous materials. Planar conductive PANI-based materials were made using the Langmuir-Schaefer (LS) method, and the 3D materials - using the electrospinning method which is a scalable technique. We have analyzed the influence of PANI molar mass, natures of solvent and subphase on the crystalline structure, thickness and conductivity of planar LS films, and the influence of PANI molar mass and the PANI-PEO ratio on the morphological and structural characteristics of 3D fibrous materials.

Flexible diode of polyaniline/ITO heterojunction on PET substrate

Hybrid organic-inorganic heterojunction between polyaniline and ITO film coated on flexible polyethylene terephthalate (PET) substrate has been prepared through vapor phase polymerization process. Polaron and bipolaron like defect states induced hole transport and exceptional mobility makes polyaniline a noble hole transport layer. Thus a p-n junction has been obtained between the hole transport layer of polyaniline and highly conductive n-type layer of ITO film. The synthesis process was carried out using FeCl3 as polymerizing agent in the oxidative chemical polymerization process. The prepared polyaniline has been found to be crystalline on characterization through X-ray diffraction measurement. X-ray photoelectron spectroscopic measurements were done for compositional analysis of the prepared film. The UV–vis-NIR absorbance spectra obtained for polyaniline shows the characteristics absorbance as observed for highly conductive polyaniline and confirms the occurrence of partially oxidized emeraldine form of polyaniline. The energy band gap of the polyaniline has been obtained as 2.52eV, by analyzing the optical transmittance spectra. A rectifying behavior has been observed in the electrical J-V plot, which is of great significance in designing polymer based flexible electronic devices.

Highly Stable Carbon Nanotube/Polyaniline Porous Network for Multifunctional Applications

Three-dimensional carbon nanotube (CNT) networks with high porosity and electrical conductivity have many potential applications in energy and environmental areas, but the network structure is not very stable due to weak inter-CNT interactions. Here, we coat a thin polyaniline (PANI) layer on as-synthesized CNT sponge to obtain a mechanically and electrically stable network, and enable multifunctional applications. The resulting CNT/PANI network serves as stable strain sensors, highly compressible supercapacitor electrode with enhanced volume-normalized capacitance (632 F/cm3), and reinforced nanocomposites with the PANI as intermediate layer between the CNT fillers and polymeric matrix. Our results provide a simple and controllable method for achieving high-stability porous networks composed of CNTs, graphene, or other nanostructures.

Effects of Contents of Multiwall Carbon Nanotubes in Polyaniline Films on Optical and Electrical Properties of Polyaniline

We investigate the effects of different contents of multiwall carbon nanotubes (MWCNTs) on optical and electrical properties of polyaniline (PANI). The MWCNTs/PANI composites are deposited on glass substrates coated with indium tin oxide (ITO) by the spin-coating technique. The scanning electron microscopy shows that nanotubes are coated with the PANI layer and x-ray diffraction patterns show that all deposited composite films have an amorphous character. The analysis of a UV-vis spectrophotometer indicates the blue shift of the absorbance peak and a decrease in optical band gap value by the enhancement of the CNT content in the PANI matrix while the Urbach energy increases. The Raman spectrum shows the blue shift 1404→1417 cm−1 and photoluminescence spectra show an increase in the intensity of characteristic PANI peak at 436 nm with the increasing CNT content.

A chemiresistive glucose sensor fabricated by inkjet printing

This paper proposes a simple and rapid fabrication of a glucose sensor based on inkjet printing method. A commercially available inkjet printer is used to print carbon nanotubes and polyaniline nanowires for patterning low sheet resistance electrodes and a chemiresistive glucose sensing area, respectively. Enzyme glucose oxidase, in conjunction with platinum nanoparticles were also incorporated into the chemiresistive sensor to generate a two-step catalytic process: in the first step, glucose is catalyzed by the oxidase to produce hydrogen peroxide as a byproduct, and in the second step, platinum nanoparticles catalyze hydrogen peroxide to produce hydroxide ions which causes a local pH change near the site of reaction. Since the conductivity of polyaniline is known to be pH-responsive, the polyaniline layer serves as a chemiresistive sensor to detect the H2O2 concentration which subsequently leads to the quantification of the glucose concentration. The developed inkjet-printed glucose sensor was able to achieve a detection limit of 2 mM and a good linear relationship between current measurements and glucose concentration was obtained. The results indicate that the proposed method to print a simple, rapid, and disposable glucose sensing device can lead to the development of an on-demand printable point-of-care diagnostic kit for glucose measurement.

Fabrication of ternary hierarchical nanofibers MnO2/PANI/CNT and theirs application in electrochemical supercapacitors

In this article, ternary coaxial hierarchical nanofibers are prepared by a simple, repeatable, and scalable method. Polyaniline (PANI) is in-situ polymerized on multiwalled carbon nanotubes (MWCNT) to form PANI/MWCNT. Subsequently, manganese dioxide (MnO2) in-situ grows on PANI/MWCNT nanofibers to form ternary hierarchical nanofibers MnO2/PANI/MWCNT. The electrochemical performance of MnO2/PANI/MWCNT is investigated using cyclic voltammetry (CV), galvanostatic charge-discharge measurement, and electrochemical impedance spectroscopy. The results show that as-prepared ternary hierarchical nanofibers are all typical pseudo-capacitance capacitors. Compared with MWCNT, PANI nanofibers, and PANI/MWCNT composite nanofibers, the specific capacitance of MnO2/PANI/MWCNT composites exhibits the highest capacitance of 348.5Fg−1 at 1Ag−1, and 88.2% of which can still be maintained after 2000 consecutive cycles. The electrochemical measurements demonstrate that PANI layer and nanoflaky MnO2 can increase the specific capacitance of MWCNT. More important, MnO2 in-situ growth on PANI layer can effectively retain the structure of composites and improve the long-term cycle stability, which is conducive to obtain the new-type portable energy storage devices.

Thorium (IV) phosphate‐polyaniline composite‐based hydrophilic membranes for bending actuator application

In the present study, ionic polymer metal composite (IPMC) membrane actuator based on triple‐layered thorium(IV) phosphate/polyaniline/Pt (ThP‐PANI‐Pt) was prepared via consecutive solution recasting and electroless plating methods. The triple‐layered membrane is composed of thorium(IV) phosphate (ThP) inorganic cation exchanger layer in the middle section, two layers of polyaniline deposited through in situ polymerization and finally Pt electrode layers on both the surfaces on the outer section. The water uptake capacity of the ThP‐PANI composite polymer membrane was found to be 95.40% at 45ºC for 10 h of immersion time. The ion exchange capacity and proton conductivity was found to be 1.6 meq g−1of dry membrane and 1.12 × 10−3 S cm−1, respectively. Maximum water loss from IPMC was 38% at 4 V for a time period of 12 min. Scanning electron micrographs shows the smooth and uniform coating of Pt on both side of composite polymer membrane surfaces. Cyclic voltammetry, linear sweep voltammetry, transmission electron microscopy, Fourier transforms infrared spectroscopy, thermal gravimetric analysis, X‐ray diffraction, and tip displacement of ThP‐PANI‐Pt IPMC membrane actuator was also examined. POLYM. ENG. SCI., 57:258–267, 2017. © 2016 Society of Plastics Engineers

Supercritical Carbon Dioxide-Assisted Process for Well-Dispersed Silicon/Graphene Composite as a Li ion Battery Anode.

The silicon (Si)/graphene composite has been touted as one of the most promising anode materials for lithium ion batteries. However, the optimal fabrication method for this composite remains a challenge. Here, we developed a novel method using supercritical carbon dioxide (scCO2) to intercalate Si nanoparticles into graphene nanosheets. Silicon was modified with a thin layer of polyaniline, which assisted the dispersion of graphene sheets by introducing π-π interaction. Using scCO2, well-dispersed Si/graphene composite was successfully obtained in a short time under mild temperature. The composite showed high cycle performance (1,789 mAh/g after 250 cycles) and rate capability (1,690 mAh/g at a current density of 4,000 mA/g). This study provides a new approach for cost-effective and scalable preparation of a Si/graphene composite using scCO2 for a highly stable lithium battery anode material.