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Srinivasan Palaniappan - One of the best experts on this subject based on the ideXlab platform.
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mannich type reaction in solvent free condition using reusable Polyaniline catalyst
Journal of Molecular Catalysis A-chemical, 2004Co-Authors: Srinivasan Palaniappan, Chellachamy Anbalagan Amarnath, Amalraj John, Vaidya Jayathirtha RaoAbstract:Abstract Polyaniline salts are prepared by doping of Polyaniline base with different Bronsted acids (H 2 SO 4 , HCl, HClO 4 , and HBF 4 ) and organic acid [5-sulfosalicylic acid (SSA), p- toluene sulfonic acid (PTSA)]. Polyaniline complexes are also prepared by using Lewis acids (ZnI 2 and FeCl 3 ). Polyaniline salts and Polyaniline complexes are characterized by physical, electrical and spectral methods. Polyaniline salts and Polyaniline complexes are used as catalyst for the Mannich-type reaction under solvent free condition. β-Amino carbonyl compounds obtained in high yields with simple and more environmental benign procedure. The use of Polyaniline catalysts are feasible because of their easy preparation, easy handling, stability, easy recovery, reusability, good activity and eco-friendly.
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Polyaniline salts and complexes as catalyst in bisindole synthesis
Catalysis Letters, 2004Co-Authors: Srinivasan Palaniappan, Chandrasekaran Saravanan, Chellachamy Anbalagan Amarnath, Vaidya Jayathirtha RaoAbstract:Polyaniline salts are prepared by doping of Polyaniline base with different Bronsted acids (H2SO4, HNO3 and H3PO4), organic acid — p-toluene sulfonic acid (PTSA) and Iodine (I2). Polyaniline complexes are also prepared using Lewis acids (BF3, AlCl3 and SnCl2). Polyaniline salts and Polyaniline complexes are characterized by physical, electrical and spectral methods. Polyaniline salts and Polyaniline complexes are used as catalyst for the first time in bisindole synthesis. Bisindole (3,3′-bis(indolyl)phenylmethane) is obtained in excellent yields with simple and more environmental benign procedure. The use of Polyaniline catalysts are feasible because of their easy preparation, easy handling, stability, easy recovery, reusability, good activity and eco-friendly.
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Spectral and thermal characterization of Polyaniline–oxalic acid salt
Journal of Polymer Science Part A, 1995Co-Authors: Srinivasan PalaniappanAbstract:Polyaniline–oxalic acid salts were prepared at 5 and 30°C by chemical polymerization of aniline using different concentration of oxalic acid. Polyaniline base was obtained from the corresponding Polyaniline salt by dedoping using aqueous ammonium hydroxide solution. Conductivity measurements, elemental analysis, Infrared, electronic absorption, electron paramagnetic resonance spectral, and thermogravimetric analysis were performed on the Polyaniline salts and bases. Composition and the extent of dopant in Polyaniline salt systems where determined. The value of composition of Polyaniline: oxalic acid is 4: 1.6 and the polymer yield is around 66%. The value of conductivity, polymer yield and composition of Polyaniline–oxalic acid salt is independent of concentration of oxalic acid used and also the synthesis temperature. The results are compared with Polyaniline–hydrochloride salt prepared by chemical polymerization. The conductivity of Polyaniline–oxalic acid salt is three orders of magnitude lower than that of Polyaniline-hydrocholoride salt. © 1995 John Wiley & Sons, Inc.
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Composition and spectral studies of Polyaniline salts
Polymers for Advanced Technologies, 1994Co-Authors: Srinivasan Palaniappan, B. H. NarayanaAbstract:Five different Polyaniline salts have been prepared by chemical polymerization of aniline in aqueous solution of different acids. The Polyaniline base was obtained from the corresponding Polyaniline salt by dedoping using aqueous ammonium hydroxide solution. Electron paramagnetic, electronic absorption, infrared spectral and conductivity measurements have been performed on the Polyaniline salts and Polyaniline bases. This composition and the extent of dopant in Polyaniline salt systems have been determined. There is no definite correlation between the conductivity and the stoichiometric ratio between the Polyaniline base and the acid, and also the spin concentration.
Guewuu Hwang - One of the best experts on this subject based on the ideXlab platform.
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structures and properties of the water soluble self acid doped conducting polymer blends sulfonic acid ring substituted Polyaniline poly vinyl alcohol and poly aniline co n propanesulfonic acid aniline poly vinyl alcohol
Polymer, 1997Co-Authors: Showan Chen, Guewuu HwangAbstract:Abstract Blends of the water-soluble self-acid-doped conducting Polyanilines, sulfonic acid ring-substituted Polyaniline (SPAN) and poly(aniline- co - N -propanesulfonic acid aniline) (PAPSAH), each with poly(vinyl alcohol) (PVA) were prepared and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, electronic spectroscopy, infra-red spectroscopy, thermogravimentric analysis, conductivity measurements, atomic force microscopy, and scanning tunnelling microscopy. It was found that the incorporation of PVA has no effect on the doping levels of SPAN and PAPSAH in the blends. This is due to the higher basicity of the N than OH, causing a more favourable interaction of the SO 3 H group with N. The strong interaction of these Polyanilines with PVA through hydrogen bonding between hydroxyl groups (of PVA) and amine and positively charged amine and imine sites (of SPAN and PAPSAH) leads to a decrease in hydrogen bonding among PVA subchains and to a partial miscibility. As the PVA content is higher than 70%, interconnected regions of PVA-rich phase and of SPAN-rich phase are formed such that the dilution effect of PVA on the conductivity is not large. Although SPAN has a much higher thermal undoping temperature (190°C) than PAPSAH (110°C), it reduces to 110°C in the blends due to the occurence of dehydration at this temperature, while for the blend of PAPSAH with PVA, its thermal undoping temperature remains unchanged.
Vaidya Jayathirtha Rao - One of the best experts on this subject based on the ideXlab platform.
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mannich type reaction in solvent free condition using reusable Polyaniline catalyst
Journal of Molecular Catalysis A-chemical, 2004Co-Authors: Srinivasan Palaniappan, Chellachamy Anbalagan Amarnath, Amalraj John, Vaidya Jayathirtha RaoAbstract:Abstract Polyaniline salts are prepared by doping of Polyaniline base with different Bronsted acids (H 2 SO 4 , HCl, HClO 4 , and HBF 4 ) and organic acid [5-sulfosalicylic acid (SSA), p- toluene sulfonic acid (PTSA)]. Polyaniline complexes are also prepared by using Lewis acids (ZnI 2 and FeCl 3 ). Polyaniline salts and Polyaniline complexes are characterized by physical, electrical and spectral methods. Polyaniline salts and Polyaniline complexes are used as catalyst for the Mannich-type reaction under solvent free condition. β-Amino carbonyl compounds obtained in high yields with simple and more environmental benign procedure. The use of Polyaniline catalysts are feasible because of their easy preparation, easy handling, stability, easy recovery, reusability, good activity and eco-friendly.
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Polyaniline salts and complexes as catalyst in bisindole synthesis
Catalysis Letters, 2004Co-Authors: Srinivasan Palaniappan, Chandrasekaran Saravanan, Chellachamy Anbalagan Amarnath, Vaidya Jayathirtha RaoAbstract:Polyaniline salts are prepared by doping of Polyaniline base with different Bronsted acids (H2SO4, HNO3 and H3PO4), organic acid — p-toluene sulfonic acid (PTSA) and Iodine (I2). Polyaniline complexes are also prepared using Lewis acids (BF3, AlCl3 and SnCl2). Polyaniline salts and Polyaniline complexes are characterized by physical, electrical and spectral methods. Polyaniline salts and Polyaniline complexes are used as catalyst for the first time in bisindole synthesis. Bisindole (3,3′-bis(indolyl)phenylmethane) is obtained in excellent yields with simple and more environmental benign procedure. The use of Polyaniline catalysts are feasible because of their easy preparation, easy handling, stability, easy recovery, reusability, good activity and eco-friendly.
Qi Wang - One of the best experts on this subject based on the ideXlab platform.
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ultrasonic irradiation a novel approach to prepare conductive Polyaniline nanocrystalline titanium oxide composites
Chemistry of Materials, 2002Co-Authors: Hesheng Xia, Qi WangAbstract:A novel approach, i.e., ultrasonic irradiation, was used to prepare Polyaniline/nanocrystalline TiO2 composite particles. Polymerization of aniline proceeded under ultrasonic irradiation in the presence of nanocrystalline TiO2. The aggregation of nano TiO2 can be reduced under ultrasonic irradiation, and the nanoparticles can be redispersed in the aqueous solution. The Polyaniline deposits on the surface of the nanoparticle, which leads to a core−shell structure. The resulting Polyaniline/nano TiO2 composite particles are spherical, and the sizes vary with the content of TiO2. The Polyaniline/nano TiO2 composite particles prepared by the conventional stirring method have a “raspberry” aggregate structure, which is different from that obtained through ultrasonic irradiation. The presence of nanocrystalline TiO2 strengthens the UV absorption of Polyaniline and leads to a blue shift of the π-polaron absorption of Polyaniline. Ultrasound can enhance the doping level. When Polyaniline deposits on the surface o...
Jaroslav Stejskal - One of the best experts on this subject based on the ideXlab platform.
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Formation of bacterial and fungal biofilm on conducting Polyaniline
Chemical Papers, 2017Co-Authors: Nikola Mikušová, Jaroslav Stejskal, Petr Humpolíček, Jan Růžička, Zdenka Capáková, Kristýna Janů, Věra Kašpárková, Patrycja Bober, Marek Koutný, Katerina FilatováAbstract:Polyaniline is an important conducting polymer with numerous applications and its surface properties, and consequently functionality, can be significantly influenced by bacterial biofilm. This paper represents the first ever study of biofilm formation on surface of Polyaniline salt, Polyaniline base and Polyaniline doped with biologically active poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) and phosphotungstic acid. The surface energy and conductivity of the films were measured and correlated to capability of selected strains of biofilm-positive bacteria and filamentous fungi to form a biofilm thereon. It was observed that Polyaniline salt did not inhibit the growth of microorganisms, whereas Polyaniline doped with PAMPSA exhibited a notable effect against growth of biofilm for all the bacterial strains used. The results advance present knowledge of biofilm formation on Polyaniline.
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Reprotonated Polyanilines: The stability of conductivity at elevated temperature
Polymer Degradation and Stability, 2014Co-Authors: Jaroslav Stejskal, Jan Prokeš, Miroslava TrchovaAbstract:Abstract Reprotonation of Polyaniline base with various acids opens a way to conducting materials widely differing in physical properties. The thermal stability of the resulting Polyaniline salts was tested by measurements of the conductivity at 125 °C for up to 500 h. Polyaniline sulfate was the most stable and its resistivity increased only by 3.6 times after that time. The stability differed considerably depending on the acid used for reprotonation. The room-temperature conductivity of Polyaniline salt is determined by the strength of the acid and its ionic bond with the imine nitrogen in Polyaniline. The thermal stability of conductivity, however, is controlled by the ability of the acid to constitute hydrogen bonds with the secondary amine nitrogens in Polyaniline. For that reason, oxygen-containing counter-ions, such as sulfates or sulfonates, produce more stable salts with Polyaniline, compared with Polyaniline protonated with, e.g., hydrochloric acid. The presence of hydroxyl group in the counter-ions also enhances the thermal stability of the Polyaniline salt. These conclusions are supported by the analysis of FTIR spectra.
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Biocompatibility of Polyaniline
Synthetic Metals, 2012Co-Authors: Petr Humpolíček, Vera Kasparkova, Petr Saha, Jaroslav StejskalAbstract:Abstract Both the non-conducting Polyaniline, emeraldine base, and its conducting form, Polyaniline hydrochloride, were tested for their biocompatibility in terms of skin irritation, sensitization and cytotoxicity performed on human immortalized non-tumorigenic keratinocyte and human hepatocellular carcinoma cell lines. The testing was carried out on extracts of Polyaniline powders in agreement with requirements of international standards applicable for testing of medical devices. The results can be hence generally employed in all types of materials and devices containing Polyaniline in various concentrations. The study confirmed that Polyaniline has not induced any sensitization and skin irritation either. In contrast, both Polyaniline forms showed considerable cytotoxicity, which was higher for Polyaniline hydrochloride compared to Polyaniline base and was observed on both cell lines. Differences between cytotoxicity found on human immortalized non-tumorigenic keratinocyte cell line and human hepatocellular carcinoma cell line were attributed to variability in specific metabolic capabilities of the respective cell lines. Significant reduction of cytotoxicity was achieved through deprotonation and reprotonation procedure, used as an additional purification step after polymer synthesis. Accordingly, the cytotoxicity is thus caused rather by the reaction by-products and residues than by Polyaniline itself.
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flame retardant effect of Polyaniline coating deposited on cellulose fibers
Journal of Applied Polymer Science, 2005Co-Authors: Jaroslav Stejskal, Miroslava Trchova, Irina SapurinaAbstract:Filtration paper was coated with a thin Polyaniline film. The content of conducting polymer was 8.2 and 6.3 wt % for Polyaniline hydrochloride and Polyaniline base, respectively. After burning, the coated material retains the original fibrilar morphology of cellulose. The Polyaniline coating converts to solid carbonaceous products. The resulting structure prevents the formation of gaseous carbon oxides by restricting the access of oxygen to cellulose. While the ash from the uncoated paper after burning is 0.005 wt %, the microtubular residue of Polyaniline-coated paper is 16–24 wt % of the original mass. The flame-retardant performance of Polyaniline and poly(1,4-phenylenediamine) coatings was comparable both for the protonated forms and the corresponding bases. The conversion of Polyaniline-coated cellulose fibers to solid pyrolytic products was characterized by FTIR and Raman spectroscopies. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2347–2354, 2005
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Polyaniline composites with fullerene C60
Physics of the Solid State, 2002Co-Authors: Irina Sapurina, Miroslava Trchova, A. V. Gribanov, M. V. Mokeev, V. N. Zgonnik, Jaroslav StejskalAbstract:Polyaniline-fullerene composites were prepared by the introduction of fullerene during polymerization of aniline. An investigation of the composites using FTIR and 13C NMR spectroscopy indicated interaction between fullerene and the imine groups of Polyaniline. The formation of a Polyaniline-fullerene complex with a structure corresponding to a doped Polyaniline was proved by wide-angle x-ray scattering analysis. The conductivity of composites is more than four orders of magnitude higher than that of undoped Polyaniline and that of fullerene. Improvement in the thermal stability of composites was evaluated using TGA.
