Aashis S. Roy

Surface Modified

Polyaniline-CaTiO3 nanocomposites with their various weight percentages were prepared by chemical oxidative in situ polymerization technique. The prepared composites were characterized by Fourier transform infrared spectroscopy, scanning electronic microscope, and X-ray diffraction. The temperature-dependent dc conductivity of polyaniline-CaTiO3 nanocomposite was studied within the range of 40-200°C and found that 50 wt% shows high conductivity compared to other composites. Humidity sensor properties of polyaniline-CaTiO3 nanocomposite show better sensing properties and exhibit good linearity in sensing response curve, which discuss the implications of distortions and nonstoichiometry on their physical properties. Among all composites, 50 wt% of polyaniline-CaTiO3 nanocomposites show high sensitivity up to ~ 90% and their response-recovery times are 500 and 453 s, respectively.

{\rm CaTiO}_{3}

Polyaniline- (PANI) praseodymium Oxide (Pr2O3) composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α) behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors.

Loaded in Polyaniline by Sodium Dodecyl Benzene Sulphonic Acid for Humidity Sensor

The frequency dependent conductivity and dielectric behavior of PANI/CdO polymer nanocomposites based on polyaniline/CdO with SDBSA have been studied. The formation of nanocomposites and changes in the structural and microstructural properties of the materials were investigated by X-ray diffraction (XRD), FTIR and SEM techniques. The variation of ac conductivity with frequency obeys Jonscher power law except a small deviation in the low frequency region due to electrode polarization effect. The dc conductivity increases with increase in CdO concentration. Studies of dielectric properties at lower frequencies show that the relaxation contribution is superimposed by electrode polarization effect. The appearance of peak for each concentration in the loss tangent suggests the presence of relaxing dipoles in the polymer nanocomposite. On addition of CdO, the peak shifts towards higher frequency side indicating the speed up the relaxation time. Analysis of frequency dependence of dielectric and modulus formalism suggests that the electronic and polymer segmental motions are strongly coupled.

Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites

The polyaniline-PbO composites of various mass fractions were prepared by in situ polymerisation. The prepared samples were characterised by FTIR, and the dominant peaks confirmed the formation of polyaniline-PbO composites. The SEM study shows a granular agglomerated morphology, and increases with an increase in the lead oxide mass % in polyaniline. Direct current (DC) conductivity (σDC) was studied as a function of temperature (T). From these studies, it was found that conductivity increased at higher temperatures due to the polarons hopping from one localised state to another. DSC studies reveal, the decrease in peak temperature from 273°C (pure PANI) to 169.2°C, 193.5°C, 218.4°C, 235.2°C, and 224.2°C, respectively for the various mass fractions (10 %, 30 %, 20 %, 40 %, and 50 %) of polyaniline-PbO composites.

Impedance Spectroscopic Studies on Nanometric Polyaniline/CdO Composites

In situ polymerization of aniline was carried out in the presence of nickel zinc oxide to synthesize polyaniline/NiZnO3 composites (PANI/NiZnO3) by chemical oxidation method. The composites have been synthesized with various compositions (10, 20, 30, 40 and 50 wt%) of nickel zinc oxides in PANI. From the infrared spectroscopy (FTIR) studies on polyaniline/NiZnO3 composites, the peak at 1140 cm−1 is considered to be the measure of the degree of electron delocalization. The surface morphology of these composites was studied with the scanning electron micrograph (SEM). The dc conductivity was studied in the temperature range from 40–160°C and supports the one-dimensional variable range hopping (1DVRH) model proposed by Mott. The results obtained for these composites are of scientific and technological interest.

Synthesis, characterisation, and DC conductivity of polyaniline-lead oxide composites

Purpose – The purpose of this paper is to study the sensitivity and selectivity properties of polyaniline/tantalum pentoxide (PANI/Ta2O5) composite to liquid petroleum gas (LPG).Design/methodology/approach – Polyaniline/tantalum pentaoxide (PANI/Ta2O5) composites were synthesized by in situ chemical polymerization method using ammonium persulphate as an oxidizing agent. This is the novel polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The composites were characterized by FTIR, XRD and SEM. Temperature dependence conductivity of the composites shows thermally activated behaviour. Sensitivity and selectivity of the composites are studied.Findings – The PANI/ Ta2O5 composites of 20 wt% and 30 wt% are showing maximum change in resistance against time when compared to pure PANI and other polyaniline composites when exposed to LPG. The 20 wt % composites show maximum sensitivity of 83% to LPG. The selectivity studies reveals that LPG could be sensed better when compared ...

Electrical Conductivity of Polyaniline/NiZnO3 Composites: A Solid State Electrolyte

The graphene, a monolayer of carbon atoms arranged in two dimensional lattices has attracted greater research interests due to its exceptional electrical and optical properties. The properties of conducting polymer can be tailored to a large extent with a suitable formation of nanocomposites using graphene material. In this paper we report on the preparation and characterization of transparent conductive graphene nanoplatelets/polyaniline (GNPs–PANI) composite coatings. The structural features of the nanocompositeswere investigated using Fourier transform infrared spectra (FTIR) and micro Raman analysis. FTIR spectra of GNP–PANI coating clearly reveal the presence of characteristic peaks of both PANI and GNP indicating the formation of a composite film. The micro Raman spectra reveal the presence of characteristic D and G modes of vibrations in composite film (GNP–PANI) with intensity of G mode greater than the D mode due to the composite formation. The optical Raman images confirm the uniform dispersion of GNP in PANI. The transport properties of the composite film were studied through AC/DC conductivity measurement, dielectric behavior is analyzed with respect to dielectric constant, loss tangent, and Cole–Cole plots characteristics. The study of transport properties of the composite film reveals that the presence of GNPin the PANI significantly tailors the electrical properties of pure PANI. Due to its transparent nature and excellent electrical properties, these GNP–PANI nanocomposites can find wide technological applications in the fabrication of optoelectronic devices.

Influence of Ta2O5 on polyaniline surface for liquid petroleum gas sensing applications

Abstract Polypyrrole/molybdenum trioxide (MoO3) composites have been prepared by the in situ polymerization technique. The prepared composites were characterized by Fourier transform infrared spectroscopy and surface morphology by employing scanning electron microscopy. It was observed that the grains are highly agglomerated and its average size is 2–4 mm. Furthermore, the dielectric study was carried out at microwave frequency. It was observed that the variations in MoO3 to polypyrrole cause the interface polarization and multiple scattering, which is useful for the absorption of large number of microwaves. Among all the composites, 50 wt% polypyrrole/MoO3 composites show the lowest real and imaginary permittivity values (i.e., 3.57 and 5.51, respectively), and for other composites, real values vary from 5.51 to 16.57. Therefore, these composites can be used as microwave application.

Micro-Raman spectroscopy and effective conductivity studies of graphene nanoplatelets/polyaniline composites

Highly crystalline polyaniline (PANI) with elongated chain-like nanostructures 20–35 nm in diameter and 60–80 nm in length were prepared using sodium dodecylbenzenesulfonic acid (SDBSA) in ice medium without stirring. The synthesized polyanilines were characterized by SEM, FTIR, and UV-Visible spectroscopy and XRD measurements. The formation of polyaniline/SDBSA salts insoluble in reaction system without stirring is found to be favourable for the formation of this clustered chain-like nanostructure. The temperature dependent conductivity measurement shows a thermally activated exponential behaviour of the chain-like polyaniline nanostructure. The melting point of the nanostructured polyaniline was found to be 253 °C.

Synthesis, characterization, and microwave properties of polypyrrole/molybdenum trioxide composites

Abstract: This work proposes a technique for isolation of bacteria using magnetic nanoparticles. The magnetic nanoparticles that are prepared by a sol-gel method using citric acid and nano-ferrites are characterized for structural and morphology by X-ray diffraction (XRD) and Transmission electron microscope (TEM), respectively. The prepared nano-ferrites coated with poly vinyl alcohol (PVA) over platinum electrode are used for detection of Bacillus Cereus. The isolated bacterial cells from colloidal solution are treated with zinc ferrite for 12 h, and it is observed that the cells are coagulated with the nanoparticle when allowed to settle down. This is further filtered by different size of filter paper to get less than 0.1% of cells in water. Various electrochemical parameters like cyclovoltammetry (CV), sweep step function, Tafel plot, AC impedance are studied employing the modified platinum electrode. It is observed through CV graph that the peaks are formed at -0.25 V due to the oxidation of bacterial cells, which is further supported by sweep step function graph. Therefore, this is one of the economically efficient techniques to detect and isolate the Bacillus cereus from a colloidal solution.