جستجوی مقالات مرتبط با کلیدواژه « polyaniline » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

In this study, to remove the acidic blue 92 during the heterogeneous electro-fenton process, the electrospinning method produced a nanofiber layer and used it as the cathode. Polyaniline/nylon66 nanofiber (PANI/PA66) was produced by the electrospinning method to produce such a nanofibrous electrode. Reduced graphene oxide nanoparticles were added to the polymeric solution to improve the conductivity of the nanofibrous electrode and the dye removal percentage. Magnetic iron nanoparticles were also used as fenton catalysts (PANI/PA66/rGO/Fe3O4). The optimal electrospinning conditions were determined by response surface methodology. Electro fenton process for dye removal was carried out in a two-electrode system using PANI/PA 66 / rGO 6 % / Fe3O4 as a cathode in 120 minutes, and the highest dye removal percentage achieved was 91.78 %. Also, the effect of selecting essential parameters on the dye removal efficiency, such as pH, initial dye concentration, and Fe3O4 dosage, was investigated.

Solar cells has gained a great attention as a green, renewable and cheap energy resources. To overcome the challenging technical problems and improve their competitiveness with silicone solar cells, the design, synthesis and development of new materials with engineered band gap energies has found an undeniable importance.

Herein, the synthesis of a polymer with donor-acceptor structure based on polyaniline grafted to ZnO nanoparticles at one end and naphthalene moiety at the other end of chains, and investigation of their chemical structure, composition, morphology, optical and electrochemical properties is reported. The chemical structure of the materials were analyzed by FT-IR and 1H NMR spectroscopy. The organic and inorganic contents of materials were determined by thermal gravimetric analysis (TGA) and atomic absorption spectroscopy (AAS) techniques. The morphology and size of nanoparticles were observed by scanning electron microscopy (SEM). The optical and electrical band gap energy of the samples were measured by ultraviolet visible-diffuse reflectance (UV-Vis-DRS) spectroscopy and cyclic voltammetry (CV) diagrams.

The chemical structure of designed materials has been successfully confirmed by the results of FT-IR and 1H NMR spectra. TGA and AAS analysis have indicated that the synthesized final material has contained about 10% of ZnO and 90% of organic parts including toluene-2,4-diisocyanate, 2,4-diaminotoluene, polyaniline and naphthalene groups. An almost highly uniform spherical nanoparticles with sizes about 70 nm has been observed by SEM images. UV-Vis-DRS spectroscopy and CV diagrams have revealed that by grafting ZnO nanoparticles and naphthalene moiety to the polyaniline chain ends, the optical and electrical band gap energy of the sample were lowered to 1.19 and 0.95 eV, respectively. It was concluded that the grafted groups to chain ends has increased the length of conjugated system, lowering the energy level of lowest unoccupied molecular orbital (LUMO) and increasing the energy level of highest occupied molecular orbital (HOMO). Detailed analysis of CV diagrams has indicated that the effect in lowering of LUMO has been a bit more pronounced than the increasing of HOMO energy level.

In this paper, mesoporous PAA/dextran-polyaniline core-shell nanofibers were prepared with the combination of electrospinning and in-situ polymerization methods and their heavy metal adsorption ability was investigated. The result showed that PAA and dextran can be fully crosslinked through the esterification reaction via a heat-treatment method. Polyaniline with flake-like structure was deposited on the nanofiber surface resulted in high surface area and mesoporous structure of nanofibers. The number of pores was increased by removing the calcium carbonate nanoparticles incorporated on the nanofiber surface during the polymerization process. Investigation of the variables affecting the adsorption process showed that the adsorption efficiency increased with increasing adsorbent and gradually reached a constant value. As the concentration of lead metal decreased, the percentage of removal decreased and the amount of removed metal varied at different pH values. HT-PAA / dextran nanofibers showed relatively high adsorption capacity for Pb, which increased to 951.1 mg / g after aniline polymerization on the surface of the nanofibers. The synthesized nanofibers showed a high maximum adsorption capacity of 1111.11 mg/g for Pb obtained from the Langmuir isotherm model.

Technologies based on microwave absorption are based on science of absorber materialsin this frequency range. The nature of microwave is an alternating electrical andmagnetic field that could be naturally absorbed in transmission through materials with nonzeroconductivity or imaginary part of permittivity (dielectric loss) and nonzero imaginarypart of magnetic permeability (magnetic loss). Meanwhile, microwave absorbing polymercomposites due to their light weight, low fabrication cost, and high performance havesignificant importance. Polymer matrix of these composites are generally nonconductivematerials that are host for microwave absorbing materials such as carbon nanotube, ferrite,and titanium dioxide, and so conductivity enhancement of polymer matrix could be effectiveon improvement of absorption mechanism especially in nonconductive magnetic absorbers.In this regard, polyaniline as a conductive polymer, has important role in improvementof quality of absorbing composites in microwave range. Also, improvement of variouscharacteristics of polyaniline has strong dependence on properties of other componentsand especially on synthesis method. Therefore, especial consideration on various kinds,components, and synthesis methods of such composites and key role of polyaniline intheir properties is critical for researchers in the field. In this paper, after introducing themechanism of electromagnetic wave absorption, we introduce different kinds of compositesincluding polyaniline with other organic and inorganic materials, synthesis methods, andproperties related to design of microwave absorbers.

The surface modification of polyvinylchloride-based heterogeneous cation exchange membranes was carried out using chitosan-co-polyaniline/graphene oxide nanocomposite layer for the application in electrodialysis process. The PANI/GO nanocomposites were prepared by in situ chemical oxidative polymerization of aniline in the presence of graphene oxide nanoplates. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), water content, flux and permeability, areal ionic resistance, water softening ability and fouling measurements were used to characterize the membrane. The FTIR analysis results and SEM images demonstrated successful formation of polyaniline on the graphene oxide nanoplates. The scanning electron microscope images of membranes also exhibited a uniform layer of chitosan-co-PANI/graphene oxide nanoplates on the membrane surface. The water content of modified membranes was higher than that of pristine membrane. The sodium flux and sodium permeability were improved about 20% by 0.1 %wt PANI/graphene oxide nanocomposite. The areal ionic resistance of modified membranes also showed a decreasing trend by utilizing composite nanoplates in the membrane matrix. The prepared membranes showed good ability for Ca and Mg removal from water. The removal efficiency of Ca and Mg by membrane containing 0.5 %wt PANI/graphene oxide composite nanoplates was, respectively, 61 and 79% during 15 min. Moreover, the pollutant and foulant formed on the membrane surface were totally removed by sonication technique. The modified membranes showed suitable electrochemical characteristics compared to membranes reported by other researchers and made by industries.

In this study, the effects of drying temperature and mechanical pressure on the surface structure and dynamical properties of polyaniline (PAni) were studied. PAni was synthesized through the aniline polymerization process in the presence of ammonium persulfate in acidic medium and normal methyl-2-pyrrolidine solution. The obtained solution was dipped on a substrate of quartz glass. Atomic force microscopy (AFM) analysis based on nano-indentation tests were used to determine the values of hardness, Young’s modulus and Poisson’s ratio of the films. The results of the analysis of the scanning electron microscope demonstrated that the surface morphology of the film is changed from a fiber-to-interconnected cross-linked networkby increasing the drying temperature. The transmission electron microscope analysis showed that the diameter of the fibers on the surfaces dried at 318 K and 418 K was 18 and 30 nm, respectively. AFM results showed that the mean surface roughness of PAni film at 318 K without mechanical pressure was 63 nm, while for the film pressed at 5 MPa was less than 35 nm. Thermo-mechanical analysis showed that the glass transition temperature of the PAni film prepared without mechanical pressure and the film pressed at 5 MPa were 386 K and 378 K, respectively. Investigating the temperature dependence and applied pressure on the film surface in determining the viscoelastic properties of the PAni nanostructured film can provide readers with appropriate information about the storage and loss modulus of the film and the activation energy of the polymer layer during the thermal decomposition process.

Conductive polymers, such as polyaniline, which have conjugate structure and electrical properties, are attractive compounds for using in the electronic industry, anti-static coatings and anti-corrosive coatings. Due to their perfect electrical properties, they are widely used for various applications, especially polymer nanocomposites. In this study, the introduction of conductive polymers and their synthesis methods, fabrication of polymer nanocomposites and their anti-corrosion performance in organic coatings are discussed. The results showed that the presence of polyaniline in the organic coating formulations cuased a thick and dense iron oxide layer formation on the metal surface so that this coating did not only improve the adhesion of the epoxy coating to the substrate and prevent the cathodic delamination, but also the development of corrosion products under the coating can be limited because of the active role of polyaniline.

Conductive polymers such as polypyrrole (PPy), polyaniline and polythiophene have foreseeable use in various products such as chemical-sensors, transducers, antistatic coatings, conductive fibers and smart textiles. Supercritical carbon dioxide (SC-CO2) is a ‘green’ solvent that can be used in chemical processes. Although, none of the aforementioned polymers are soluble in SC-CO2, but precipitations take place during the polymerization. Given the fluorophilicity of SC-CO2 and the strong interaction between SC-CO2 and carbonyl groups, the unique combination of fluoroalkyl groups and carbonyl groups makes the polymers highly soluble in CO2 at moderate pressure and temperature. The blends of conductive polymers with another polymer, which are often referred to as conductive composites, are generally produced conductive fibers. As a non-toxic and environmentally acceptable solvent, SC-CO2 may also be beneficial in tailoring the properties of the composites by control of sorption and desorption processes.

Carbon materials and specially graphene, due to their unique electrical, thermal, mechanical, optical and electrochemical properties have been very popular to combine with other materials and formation of nanocomposites in recent years. Graphene-based polymer nanocomposites are one of the most common polymer-based nanocomposites. They have much better thermal, electrical, mechanical, optical and electrochemical properties than pure substances i.e., polymer and graphene. Polyaniline is a useful conducting polymer that has been widely used in electronic devices, optical and electrochemical applications owing to its low cost, good environmental stability, interesting electroactivity, good electrical conductivity and easy preparation. Carbon-based polyaniline nanocomposites have attracted a great deal of interest due to their new properties or enhanced performance during the past few years. In recent years, synthesis and application of polyaniline/graphene nanocomposites is one of the most important strategies to improve organic solar cell functions. In this review, after a brief introduction on organic solar cells, the properties of polyaniline, carbon materials and graphene, references have been made to the most common types of carbon-based polyaniline nanocomposites, specially polyaniline/graphene. Some of the research done in the last few years is with the aim of designing organic solar cell in order to improve their performance in the past few years.

A novel nanocomposite of graphene (G), Polyvinylpyrrolidone (PVP) and Polyaniline (PANI) has been prepared and this nanocomposite used for the modification of paper – based biosensors for determination of cholesterol. The droplet–like nanostructures of G/PVP/PANI-modified electrodes were obtained with an average size of 160±1.02 nm. Presence of Polyvinyl pyrrolidone (~ 2mg/ml) in this nanocomposite can be improving the dispersibility of graphene, furthermore increase the electrochemical conductivity of electrodes that leading to enhanced sensitivity of the biosensor. This modified electrode also shows high electrocatalytic activity towards the oxidation of hydrogen peroxide. Moreover, cholesterol oxidase (ChOx) Connected to graphene/ Polyvinyl pyrrolidone/ Polyaniline (G/PVP/PANI) - modified electrode for the amperometric determination of cholesterol. Under favorable conditions, a linear range of 50 µM to 10 mM of cholesterol is achieved and the limit of detection designated to be 1 µM for cholesterol. Eventually, the recommended system can be applied for the determination of cholesterol in a complex biological fluid.

Polyaniline/graphene oxide composites of different morphologies were synthesized by oxidation polymerization method without using conventional oxidants. By changing the type of acid (doping agent) and its concentration, two different morphologies including worm-like morphology and flaky- or scalelike morphology were obtained. Morphology of these composites was studied by scanning electron microscopy (SEM). In order to achieve a better characterization of the polyaniline/graphene oxide composite, they were also investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). XRD analysis showed that, unlike in worm-like composite, crystallization was induced in flaky- or scale-like composite and the graphene oxide sheets were well exfoliated. To study electrochemical properties of the composites, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used. The synthesized polyaniline/graphene oxide composites were evaluated by measuring their electrochemical properties, and it was observed that only the worm-like composite was electrochemically active. The worm-like composite also showed a higher current density in the cyclic voltammetry test, due to its higher electrochemically active surface. Degree of conversion for composites was calculated and the kinetic data demonstrated that the composites were not polymerized completely, and therefore they did not show high electrochemical properties. The synthesized composites are suitable pre-polymers and their polymerization reaction can be completed by conventional oxidants, such as ammonium persulfate (APS) or by electrochemical method for high conversion of aniline monomer and improving the electrochemical properties of composite properties.

Absorption of electromagnetic radiation in the microwave region is one of the most important cases which, today, is used in commercial purposes and many application fields including communications equipment, civil, military and various electronic systems and technologies. Therefore, with development of wireless electronic devices, we need to have knowledge on some devices that should absorb harmful radiation. According to the nature and position of the wave absorbing materials, the synthesis of these materials and study of their properties are considered important. Since waves constitute both electric field and magnetic field, an ideal wave absorption material should be able to absorb electrical and magnetic waves simultaneously. The nanocomposites containing an electrically conductive material are best candidates as waves absorbents. In using these nanocomposites the wave electric part can be absorbed and converted into heat, in order to dampen the waves. The magnetic property of waves is also another aspect which constitutes waves. Magnetic nanoparticles can absorb the waves by creating small magnetic fields. Therefore, those nanocomposites containing inorganic magnetic nanoparticles as well as conjugated polymers with semi-conductive properties are recently considered as new wave absorbing materials. These light-weight composites can be synthesized easily. Because of the special position of wave absorbent composites in today’s life, study on their varieties, method of preparation and specific features is considered as the topic of this article.

The novel conductive nanocomposite and composite from polyaniline (PANI) were prepared. The composites were synthesized by in situ oxidative chemical polymerization of aniline on silica- and nanosilica-supported sulfuric acid. The reaction was carried out in a mortar and ammonium persulfate was used as oxidant under solvent-free condition at room temperature. Structure, size and morphology of the synthesized nanocomposite and composite were determined by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Conductivity was measured by four-probe technique and revealed that the samples not only had the conductivity in the range of conductive polymers (~ 0.4 S/cm) but also they showed high conductivity as composites and blends of polyaniline reported by others. Synthesis of composites (nanocomposites) and formation of polarons were confirmed by FTIR and UV-Vis. SEM images showed that silica particles were thoroughly coated by PANI and all were amorphous. According to the TEM and AFM images, particle size in composite and nanocomposite was in the range of 1-5 μm and 35-49 nm, respectively. Furthermore, the surface morphology, shape and dimensions of particles obtained by AFM strongly supported the SEM and TEM observations related to polymer deposition on the silica particles. The key benefits of the approach used in this research are the preparation of novel conductive composite and nanocomposites with the polaron structure under green chemistry condition of dopant solid acids including silica- and nanosilica-supported sulfuric acid.

Chitosan (Chito) as a biopolymer with high antibacterial, biocompatibility and biodegradability and polyaniline (PANI) as a conductive polymer and silver (Ag) nanoparticles to enhance antibacterial property were used to prepare polyanilin-chitosan-silver (PANI-Chito-Ag) nanocomposites. The synthesis of PANIChito composite and PANI-Chito-Ag nanocomposite was performed through aniline polymerization in the presence of Chito and Ag. In order to evaluate the physicochemical and antibacterial properties of synthesized composite and nanocomposites, several combinations of components with different weight ratios were used. Antibacterial tests were performed using two different types of bacteria: Escherichia coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria) to determine the antibacterial capability of the PANI-Chito-Ag nanocomposite. The obtained results showed that higher Chito and silver contents produced stronger antibacterial property. The biodegradability test results confirmed that,the biodegradability increased as the content of Chito increased. Also, by increasing Streptomyces (gram-positive bacteria) concentration in natural soil, the biodegradability rate of nanocomposite was enhanced. The results obtained from thermogravimetric analysis (TGA) tests also indicated improvement in thermal stability of PANI-Chito-Ag nanocomposite compared to that of pure Chito. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to analyze and characterize the composition and structure of PANIChito-Ag triple hybrid nanocomposite. The results confirmed uniform distribution of Ag nanoparticles within the polymer matrix.

In this research polyaniline/Graphene nano-compoite has been prepared through in situ polymerization and was used as a photocatalist to degrade acid red 14 dye under visible light irradiation. SEM and XRD tests were used to characterize the morphological properties of nano-composite. The effect of different parameters such as initial dye concentration, nano-composite dosage, pH and temperature on the activity of the nano-composite towards the degradation process was investigated. The optimum efficiency of 98 percent and breaking of the main bonds of dye molecule was happened under dye concentration of 80 mg/L, PANI/Gr dosage of 0.6 gr/L, pH=7 and T= 25 oC after 150 min irradiation time. Over 95 percent of COD was also removed after 300 minutes.

Despite the widespread applications of conductive polymers, their usage has been limited due to their poor processability. Emulsion polymerization to produce stable nanoparticles in water, solve to some extent the difficult process of these polymers. In this study, synthesis of polyaniline by inverse emulsion polymerization method along with chemical, physical and structural aspects is discussed. Synthesize of conductive polyaniline is carried out using oxidizing agent of benzoyl peroxide in a non-polar solvent, a functionalized protonic acid as dopant/ emulsifier and hydrochloric acid to improve the product conductivity. In order to optimize efficiency and conductivity of synthesized polyaniline, the effect of synthesis conditions such as reaction time, type and concentration of reactants were investigated. Synthesizing in optimum condition, minimum resistance value for a produced polyaniline was about 8.29 Ω. Beside conductivity, morphology and other properties of polyaniline has been investigated by FT-IR, SEM, DSC and DLS analysis.

Polyaniline-montmorillonite (PANI-MMT) nanocomposite was synthesized by chemical polymerization of aniline in the presence of montmorillonite (MMT) nanostructures. The triple hybrid of polyaniline-polyvinylchloridemontmorillonite (PANI-PVC-MMT) was prepared by mixing of the synthesized PANIMMT nanocomposite with a solution of polyvinylchloride (PVC) in tetrahydrofurane (THF). In addition، PANI-PVC composite was prepared by mixing of pure synthesized PANI and PVC solution in THF. To investigate the mechanical properties، the PANIPVC composite and PANI- PVC-MMT nanocomposite films were prepared with 5، 10 and 15 wt% of pure PANI and PANI-MMT nanocomposite، respectively. The results showed that the PANI- PVC-MMT nanocomposite film having 10 wt% of PANIMMT nanocomposite displayed the best mechanical properties. Therefore، it was chosen as optimum film and its physico-chemical properties were characterized. The cyclic voltammetry (CV) technique confirmed that the triple hybrid of PANI-PVCMMT nanocomposite was electroactive. Also، Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques were used to characterize the composition and structure of the PANI-PVC-MMT triple hybrid nanocomposite. X- Ray diffraction (XRD) technique showed an intercalated structure for the PANI-PVC-MMT nanocomposite. The thermal stability improvement of the PANI-PVC-MMT nanocomposite in comparison with the pure PVC was established by thermogravimetric analysis (TGA).

Polyaniline (PANI) is one of the most interesting conducting polymers due to its low cost and easy availability of raw materials، easy synthesis، good environmental stability and controllable electrical conductivity and redox properties. In recent years it has been shown that electrically conducting polymers such as polyaniline in integrated coating applications are able to protect steel from corrosion due to formation of passive oxide layer on the metal surface. In this report، a nanocomposite of polyaniline–nanoSiO2 (PSC) has been prepared by using poly (vinyl alcohol) (PVA) as surfactant and ammonium persulfate as an oxidant in the aqueous media. The prepared materials were characterized and compared by Fourier transformation infrared (FTIR) spectroscopy، transmission electron microscopy (TEM) and X-ray diffraction (XRD). In this method different concentrations (1، 3 and 5wt%) of emulsion nanocomposite were each mixed with polyvinyl acetate (PVAc) binder. SEM image showed good distribution of nanocomposite in the polyvinyl acetate matrix. The anti-corrosive properties of this blend on carbon steel in 3. 5% NaCl and HCl (1M) were evaluated by Tafel slope analysis. The corrosion inhibition performance study was carried out at room temperature in aqueous solution of 1. 0 M HCl and 3. 5 % NaCl by using Tafel method. Experiments were carried out in a conventional three electrode cell assembly using Autolab Potentiostat/Galvanostat. The results showed that addition of nanocomposite to PVAc decreased the corrosion rate and corrosion current density. According to the results، the blend of 3 wt% of this nanocomposite with polyvinyl acetate has the best corrosion protection for steel St37 in both media.