Faiz Mohammad

Screening of some Indian medicinal plants for their antimicrobial properties

A total of 82 Indian medicinal plants traditionally used in medicines were subjected to preliminary antibacterial screening against several pathogenic and opportunistic microorganisms. Aqueous, hexane and alcoholic extracts of each plant were tested for their antibacterial activity using agar well diffusion method at sample concentration of 200 mg/ml. The results indicated that out of 82 plants, 56 exhibited antibacterial activity against one or more test pathogens. Interestingly, extracts of five plants showed strong and broad spectrum activity as compared to rest of 51 plant extracts which demonstrated moderate activity. On the whole the alcoholic extracts showed greater activity than their corresponding aqueous and hexane extracts. Among various extracts, only alcoholic extracts of Emblica officinalis, Terminalia chebula, Terminalia belerica, Plumbago zeylanica and Holarrhena antidysenterica were found to show potentially interesting activity against test bacteria. These active crude alcoholic extracts were also assayed for cellular toxicity to fresh sheep erythrocytes and found to have no cellular toxicity.

Comparative studies on diffusion behaviour of electrochemically prepared polythiophene and polypyrrole : effect of ionic size of dopant

Abstract In this paper, the diffusion measurements into and out of electrochemically prepared polythiophene films have been studied in electrochemical cells containing N(Bu) 4 BF 4 , NaClO 4 , LiAsF 6 and NaSbF 6 in propylene carbonate and the effect of the size of the diffusing ions on diffusion coefficients have been discussed. The diffusion behaviour of BF 4 − ions into and out of electrochemically prepared polypyrrole has also been studied for comparison. An increase in diffusion coefficients in the order of NaSbF 6 4 BF 4 4 6 at 273 K has been observed. It is proposed that the ionic size is a limiting factor. These results are discussed in terms of potential applications of these polymers.

Morphology and Thermal Stability of Electrically Conducting Nanocomposites Prepared by Sulfosalicylic Acid Micelles Assisted Polymerization of Aniline in Presence of ZrO2 Nanoparticles

Electrically conductive polyaniline (Pani)/zirconium oxide (ZrO2) nanocomposites were prepared by in-situ oxidative polymerization of aniline in the presence of sulfosalicylic acid (SSA), HCl and different amounts of ZrO2 nanoparticles. Pani/ZrO2 nanocomposites were characterized by Fourier Transform Infra-Red Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The stability of the nanocomposites in terms of DC electrical conductivity retention was also studied in ambient atmosphere by isothermal ageing and cyclic ageing techniques. Pani/ZrO2 nanocomposites were observed to be more conducting than Pani but showed poorer stability in terms of DC electrical conductivity retention under ambient environmental conditions.

Binary doped polypyrrole and polypyrrole/boron nitride nanocomposites: preparation, characterization and application in detection of liquefied petroleum gas leaks

We report an electrical conductivity based rapid response liquefied petroleum gas (LPG) sensor using binary doped polypyrrole and polypyrrole/boron nitride (PPy/BN) nanocomposites as the conductive material. Binary doped PPy and PPy/BN nanocomposites have been synthesized using a chemical oxidative in situ polymerization method using FeCl3 as an oxidant in the presence of camphorsulfonic acid (CSA). A PPy/BN nanocomposite has also been synthesized using a chemical oxidative in situ polymerization method using FeCl3 as an oxidant. PPy/FeCl3/CSA, PPy/BN/FeCl3 and PPy/BN/FeCl3/CSA were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and field emission scanning electron microscopy. On the basis of these results, the well-organized structural nanocomposites were successfully prepared owing to specific interactions between the PPy and the BN nanosheets. The results indicated that the morphology and electrical properties of the nanocomposites were significantly influenced by the BN nanosheet loading and CSA. Transformation of non-conducting PPy/BN/FeCl3 into conducting PPy/BN/FeCl3/CSA was also observed. Addition of CSA caused a significant increment in electrical conductivity due to binary doping of the nanocomposites. The as-prepared PPy/FeCl3/CSA and PPy/BN/FeCl3/CSA nanocomposites were studied for the change in their electrical conductivity on exposure to liquefied petroleum gas (LPG) and ambient air at room temperature with the possible use as a sensor for detection of LPG leaks.

Studies on Nanocomposites of Polyaniline and Zinc Oxide Nanoparticles with Supporting Matrix of Polycarbonate

Nanocomposites of polyaniline and zinc oxide nanoparticles using polycarbonate as supporting matrix were prepared by direct mixing process. These nanocomposites were studied for their DC electrical conductivity using four-in-line probe technique. Stability of DC electrical conductivity in terms of electrical conductivity retention was also studied using two slightly different techniques. The nanocomposites were also characterized using FTIR, SEM, TEM, and XRD. It was found that the electrical conductivity of the nanocomposites first increased with the increase in concentration of ZnO nanoparticles content, but then decreased on further increase in its content. Stability studies showed that the loss in electrical conductivity decreased with increase of ZnO content in nanocomposites. TEM and XRD results showed that nanoparticles are uniformly distributed in polymer matrix and also suggest that the direct solution mixing method may be adopted as an easy and efficient route for the preparation of nanocomposites.

Synthesis, Electrical, Electronic and Charge Transport Properties of Poly(aniline‐co‐p‐toluidine)

Copolymers of aniline with p‐toluidine were synthesized for different molar ratios of the respective monomers in acid medium. The electrical conductivity, charge transport and spectral characteristics upon incorporation of p‐toluidine units into the polyaniline backbone were investigated. The electrical conductivity of the copolymers showed frequency dependence which became more prominent with an increase in the number of p‐toluidine units in the polyaniline backbone. A direct relationship between the frequency dependence and electron localization was observed in the copolymers. Electronic spectra showed blue shifts in the π→π*and benzenoid→quinoid transitions revealing a decrease in the extent of conjugation in the copolymers. The protonated forms of the copolymers were soluble in DMSO giving polaron band around 400 nm. The decrease in electrical conductivity was attributed to the greater electron localizations as revealed from the broader ESR signals. Temperature dependence of electrical conductivity showed that charge transport was mainly through variable range hopping though a mixed conduction behavior was observed at higher temperature range.

Synergistic Effect of Polyaniline Modified Silica Gel for Highly Efficient Separation of Non Resolvable Amino Acids

Herein, we present a comparative study for the analysis of amino acids on silica gel (SIG) and polyaniline (Pani) modified SIG as stationary phases using 1% ethanolic solution of boric acid as mobile phase. The separation studies revealed that in the case of modified SIG, improved separations of two component mixtures of amino acids were achieved. Some new combinations of binary separations were achieved on Pani modified SIG layer, which were not efficiently separated in the case of pure SIG. Thus, by the modification of SIG surface with Pani, sorbent with enhanced chromatographic performance can be achieved.

Synthesis, Electrical Conductivity, Spectral and Thermal Stability Studies on Poly(aniline-co-o-nitroaniline)

o-Nitroaniline units were incorporated in the polyaniline backbone through copolymerization with aniline. The copolymers were synthesized for 1:3 and 1:1 molar ratios of aniline and o-nitroaniline in acidic medium using potassium persulphate as oxidant and their properties were compared with that of polyaniline. The polymers showed less electrical conductivity than polyaniline. Unlike polyaniline, the presence of nitro group caused higher frequency dependence of electrical conductivity. Electronic spectra showed a blue shift in both the band of the copolymers due to the decrease in the extent of conjugation leading to lower conductivity, which could also be explained in terms of a decrease of delocalization of electron as evinced from electron para magnetic resonance (EPR) data. Thermo gravimetric analysis (TGA) revealed that copolymer derived from 1:1 molar ratio showed comparable thermal stability with polyaniline and the one derived from 1:3 molar ratios is thermally less stable than polyaniline. Activation energies for thermal degradation were estimated using Broido equation. The temperature dependence of electrical conductivity suggested charge transport is mainly through variable range hopping.

Conducting nanocomposites of polyaniline/nylon 6,6/zinc oxide nanoparticles: preparation, characterization and electrical conductivity studies

Nanocomposites of polyaniline as a conducting polymer and main matrix, zinc oxide nanoparticles as inorganic filler and nylon 6,6 as supporting matrix were prepared by solution mixing process in a common solvent. DC electrical conductivity and its thermal stability at different temperatures under ambient atmospheric conditions were studied for the nanocomposites. The stability studies were carried out by two slightly different techniques, i.e., cyclic ageing and isothermal ageing. The results showed that the DC electrical conductivity of the nanocomposites decreased with increase in the content of zinc oxide nanoparticles whereas the thermal stability in terms of DC electrical conductivity retention was slightly improved in few cases but not for all samples. The advance analytical techniques such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and X-ray diffraction (XRD) were also used to characterize the selected samples. It was also observed that zinc oxide nanoparticles in the nanocomposites were homogeneously distributed; however, some clusters/aggregates were also present. The FTIR results showed the existence of some interaction between the individual components of the nanocomposites as evident from the little shift in the peaks of FTIR spectra. This result was also supported by XRD data.

Synthesis, Characterization and Electrical Properties of Polypyrrole/ Zirconia Nanocomposite and its Application as Ethene Gas Sensor

In this communication, we report the synthesis of polypyrrole (PPy) and polypyrrole/zirconia (PPy/ZrO2) nanocomposites by an in-situ chemical polymerisation method and their application as sensor for detection of ethene gas for the first time. The as-prepared PPy and PPy/ZrO2 nanocomposites were characterised by Fourier-transform infrared spectroscopy, thermogravimetric analysis, x-ray diffraction and scanning electron microscopy. The nanocomposite containing 20 wt.% of ZrO2 was found to possess higher DC (direct current) electrical conductivity than PPy and the other PPy/ZrO2 nanocomposites. Sensing response was calculated on the basis of change in DC electrical conductivity. The most conductive nanocomposite was found to be highly sensitive and reversible to ethene gas. This study indicates an effective approach to possible future sensing technology for the detection of ethene gas.