Bulk PANI Research Articles

Highly Capacitive Mesoporous Polyaniline Spheres as Scalable and High Electrochemical Performance Supercapacitor Electrode

AbstractThis article demonstrates morphological based fabrication of Polyaniline mesopores (PANIMS) via the standard polymerization approach using Triton as an additive and 0.1 M H2SO4 as an electrolyte to achieve improved specific capacity (736 F g−1) in contrast to reported bulk PANI as well as PANI sphere morphologies. PANIMS1 exhibit long cyclic stability and capacitive retention ∼83 % in 0.1 M H2SO4 electrolyte after 5000 cycles. This easy and low‐cost fabrication of PANIMS was conducted by varying minimal amount of Triton in 0.1 M H2SO4 electrolyte solution to form mesopores. The adsorption and desorption isotherm of the mesopores suggests a specific surface area of 50.9 m2 g−1with a pore diameter of 2.2 nm. The protocol followed to form these PANIMS involves the variation of surfactant Triton to achieve sphere morphology thereby enhancing the charge storage property of PANI. These spheres also possess an enhanced electrical conductivity to be around ∼23 S/m than their bulk counterpart. The electrochemical assays show that there is excellent electrolyte ion penetration in the H2SO4 electrolyte which promotes a rapid ion transport to the PANIMS active sites. Also, a low value of Rct ∼2.17 Ω helps in giving a good capacitive performance of the PANIMS1 electrode. The electrochemical impedance spectroscopy (EIS) analysis shows a phase degree at 68°, response frequency at 0.38 Hz and time constant at 2.63 s. The study shows the present mesopores morphology of PANI projects to be one of the good electrode candidates for supercapacitor applications.

Nanorods and nanoblocks of polyaniline and their solvent resistance

The PANI crystals have been produced through a novel simple one-step method in which bulk PANI self-crystallize in mixture solvent. Nanorods have better solvent resistance and stability than any other morphologies of PANI. The nanorods could be useful for next generation organic electronics such as nanotransistors. The crystallization method will be readily scalable to produce bulk quantities of PANI crystals with high-quality and low-cost.

Electric-field-induced metastable state of electrical conductivity in polyaniline nanoparticles polymerized in nanopores of a MIL-101 dielectric matrix

Conducting polyaniline PANI has been obtained inside dielectric nanoporous coordination polymer MIL-101. The application of an electric field transforms both bulk PANI and nanocomposite PANI@MIL to a metastable high-conductive state. After a decrease in the applied electric field, PANI and PANI@MIL relax toward a state low-conductive stable by the law ln[σ(t)/σ(τ)] = −(t/τ)n, which is typical of disordered systems with the characteristic time τ of about six hours for PANI and with three times larger time for composite PANI@MIL. The temperature dependences of the electrical conductivity σ(T) of the samples in both high- and low-ohmic states are described by the fluctuation-induced conductivity model. Significant changes in relaxation processes and in the parameters of the fluctuation-induced tunneling conduction in nanocomposite PANI@MIL are due to a decrease in the sizes of polyaniline particles in the MIL-101 matrix to nanometers.

Spherical Polyelectrolyte Brushes as Templates for Stable Dispersions of Polyaniline Based Conducting Particles

AbstractWe prepare stable conducting core‐shell particles using spherical polyelectrolyte brushes (SPB) as microreactor‐templates. The polymerization of aniline is guided within the SPB shell so that no bulk polymerization proceeds up to 20% polyaniline (PANi) content in the resulting composite. The dispersions are electrostatically stabilized in a wide range of the ionic strength. The conductivity of the composite material reaches 0.1 S/cm which is comparable with the conductivity of bulk PANI obtained under comparable conditions.

One-pot synthesis of a polyaniline–silver nanocomposite prepared in ionic liquid

A mixture of aniline and a silver salt in ionic liquid has afforded a composite of PANI, in its more conducting form, and silver nanoparticles through a single-step direct reaction, without addition of any acid species or template. An ionic liquid acted as the solvent and template for the nanostructured material. The silver salt (AgTf2N) used in this work is soluble in the chosen ionic liquid, which is not an usual characteristic. TEM analysis of the obtained composite showed the presence of rounded silver nanoparticles with average diameter size around 10–20 nm uniformly dispersed in the polymeric matrix. XRD corroborates the size of the metallic particles at the nanoscale. FTIR and UV-vis confirmed that PANI was obtained in emeraldine salt form. The composite is slightly soluble in DMSO, an unusual feature for bulk conducting polyaniline. The composite shows electrical conductivity 100 times higher than bulk PANI prepared by usual procedures and its electroactivity was studied by cyclic voltammetry. Therefore, in this study it was shown that Ag+, in ionic liquid, is able to quickly oxidize the aniline to PANI, which is not observed in another media.

Synthesis of polyaniline nanostructures in micellar solutions

AbstractPolymerization of aniline nanoparticles was carried out in aqueous micellar solutions of surfactants, including anionic (sodium dodecyl sulfate), nonionic (nonyl phenol ethoxylate), and cationic (cetyltrimethyl ammonium bromide) surfactants. The size and morphology of these synthesized PANI nanoparticles strongly depended on the structure of the surfactants used in the formation of micelles, as shown by transmission electron microscopy. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction were used in the characterization of the synthesized PANI nanoparticles. The PANI nanoparticles revealed enhanced conductivity compared to conventional bulk PANI. In addition PANI–poly(methyl methacrylate) (PMMA) nanocomposites were synthesized. The results revealed that the PMMA nanoparticles retarded thermal decomposition and enhanced the conductivities compared with pristine PANI nanoparticles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Photocatalytic activity of polyaniline-TiO2 nanocomposites

The characteristics of the UV illumination-assisted degradation of Malachite green (MG) on highly active nanostructured-anatase TiO2, bulk Polyaniline (PAni), PAni nanoparticles and PAni-TiO2 nanocomposites have been studied. Dodecylbenzene sulphonic acid doped PAni-TiO2 nanocomposites were synthesized by a water-assisted self-assembly method. Samples were characterized using transmission electron microscopy, X-ray diffraction studies, Fourier Transform Infra red spectroscopy and photoluminescence studies. Photoluminescence intensity of TiO2 nanoparticles was found to decrease with the increase of PAni in the nanocomposite which can be attributed to the reduction of electron-hole pair recombination at the interface of PAni and TiO2 due to electron transfer from TiO2 to PAni. Exposure to UV light brought about the photocatalytic oxidation of MG in contact with bulk PAni, PAni and TiO2 nanoparticles, and PAni-TiO2 nanocomposites. The decrease in absorbance was measured, and its kinetics was analyzed using the Langmuir-Hinshelwood kinetic model. PAni-TiO2 nanocomposites exhibit higher photocatalytic activity than pure TiO2 nanoparticles, bulk PAni and PAni nanoparticles under the same degradation condition for MG. The enhanced photocatalytic activity of nanocomposites is attributed to the electron transfer from TiO2 to PAni resulting in enhancing the oxidative property of the TiO2 nanoparticles.

Self-Assembled Nano-Needles of Polyaniline, Efficient Structures in Controlling Electrical Conductivity

ABSTRACTPolyaniline (PANI) is one of the most interesting conducting polymers with a wide and controllable conductivity range, synthesized easily via chemical or electrical route, stable chemically and environmentally, having high absorption in the visible range and high mobility of charge carriers. Under different conditions, PANI morphology can be controlled yielding to the creation of nano-tubes, belts, rods, fibers and particles.In this study, the chemical oxidative polymerization which consists of mixing aniline hydrochloride (A-HCl) with ammonium peroxydisulfate (APS) was used to synthesize HCl doped PANI. Fixing the weight ratio A-HCl/APS defined by the IUPAC while varying their quantities leads to the formation of PANI nanoparticles with variable diameters. In addition, PANI nano-needles of 60 nm average diameter at the center are also obtained. Different methods are used to investigate of 1-D morphologies. The electrical conductivity of bulk PANI pellets is measured using the four-point probe technique. The absorption in the visible range of PANI particles and nano-needles is determined by UV-Vis spectroscopy. XRD analysis was performed to study the effect of PANI particle size and morphology on the crystallinity of the powder. Such structures could be used in hybrid solar cells for higher conversion efficiencies.

Polyaniline nanocomposites via chemical oxidative polymerization in the presence of functional MCM-48 as in situ dopant

Functional MCM-48 (F-MCM-48), prepared by anchoring the organic sulfonic acid on the surface of the 3D cubic ( Ia3d) structural MCM-48, was used as both the inorganic substrate and the in situ dopant for the in situ chemical oxidative polymerization of aniline to obtain the PANI/F-MCM-48 nanocomposite material. The morphology of the resultant composite was characterized by SEM and a raspberry-like morphology was observed. The results of spectral analyses showed that there was a strong interaction between PANI chains and F-MCM-48, and the doping degree of PANI was high. Small-angle X-ray diffraction (XRD) analysis confirmed that the main peaks of the PANI/F-MCM-48 composite was similar to the pristine MCM-48, which revealed that the structure of MCM-48 was well-maintained after the polymerization and the resultant composite is more ordered and uniform than bulk PANI. Thermal gravimetric analysis (TGA) displayed that the thermal stability of the PANI/F-MCM-48 composite was enhanced, which could be attributed to the effect of F-MCM-48 acting as the shelter for the degradation of polyaniline chains. Moreover, the PANI/F-MCM-48 composite was possessed of good conductivity in magnitude up to 10 −2 S/cm at room temperature without external additives.

Study on electrical conductivity of single polyaniline microtube

The PANI microtubes with diameter of 200 nm were synthesized by the template synthesis technique. The electrical conductivity of individual PANI microtube was measured directly in the template channel using scanning probe microscope (SPM). The average conductivity of the microtube is 5.81 S/cm, which is higher than that of bulk PANI (1.75 S/cm). The higher average conductivity is due to the enhancement of electrical conductivity caused by the confined environment and ordered structure of the template channels. Moreover, most of the conductivities of the microtubes are in the range of 10 0 S/cm magnitude, which suggests that the SPM method possesses good reproducibility and feasibility for conductivity measurement of individual microtubes.