Synthesis and characterization of conducting polyaniline nanotubes in the presence of colloidal TiO2 nanoparticles

Conducting polyaniline nanotubes were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in water, in the presence of colloidal TiO2 nanoparticles of an average diameter ~5 nm. Polyaniline-TiO2 nanocomposite has been characterized by the electrical conductivity measurements, thermogravimetric analysis, FTIR spectroscopy, scanning and transmission electron microscopies. The electrical conductivity of synthesized nanocomposite was 1.1 × 10–3 S cm–1, slightly higher than that of pure polyaniline prepared under the same conditions. Polyaniline nanotubes have an outer diameter of 45–230 nm nm, an inner diameter of 15–130 nm, and a length extending from 0.5 to 2.0 μm.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Struktura i stereohemija poli-(1-naftilamina) elektrohemijski sintetisanog u neutralnom acetonitrilnom rastvoru

Poly-(1-naphthylamine) films were synthesized potentiodinamically and potentiostatically from 1-naphthylamine in neutral acetonitrile medium using a platinum electrode. These polymer films were investigated by infrared spectroscopy. Contrary to earlier published results neglecting the stereochemistry of the poly-(1-naphthylamine), we predict on the basis of quantum stereochemical analysis of the possible structural subunits of the polymer, that the ordinary N–C(4) coupled product is not predominant in the polymer because it is far removed from the expected planarity. Based on the results of IR investigations and semiempirical quantum chemical calculations, it is proposed that the polymer products are formed via mixed N–C(4), N–C(5) and N–C(7) coupling routes. The heats of formation of the oxidized 1-naphthylamine dimers and hexamers were calculated.Poli-(1-naftilaminski) filmovi sintetisani su potenciostatski i potenciodinamički iz neutralnog acetonitrilnog rastvora 1-naftilamina na platinskoj elektrodi. Ovi polimerni filmovi ispitivani su IR spektroskopijom. Za razliku od ranije publikovanih rezultata koji su zanemarivali stereohemiju poli-1(-naftilamina), u ovom radu se predviđa na osnovu kvantne stereohemijske analize mogućih strukturnih jedinica polimera da uobičajeni N–C(4) kuplovani produkt nije predominantan u polimeru, jer njegova struktura nije planarna. Na osnovu rezultata IR ispitivanja i semiempirijskih kvantno-hemijskih proračuna mi pretpostavljeno je da se polimerni produkti formiraju kombinovanim N–C(4), N–C(5) i N–C(7) načinima vezivanja 1-naftilamina. U ovom radu su takođe izračunate toplote nastajanja oksidovanih dimera i heksamera 1-naftilamina

Ferromagnetic response of nanocomposites based on polyaniline and TiO2 nanocrystals of different shape

Ferromagnetic polyaniline (PANI)/TiO2 nanocomposites were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate (APS), in the presence of colloidal TiO2 nanoparticles and TiO2 nanotubes, without added acid. The morphological, magnetic and structural properties of the PANI/TiO2 nanocomposites were studied by SEM microscopy, SQUID magnetometer and FTIR spectroscopy. The electrical conductivity of synthesized nanocomposites was ~10-3 Scm-1. The room temperature ferromagnetic response significantly depends on shape of TiO2 nanoparticles

Photocatalytic properties of polyaniline/TiO2 nanocomposite

Polyaniline/TiO2 (PANI/TiO2) nanocomposite was synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate (APS) in water, in the presence of colloidal TiO2 nanoparticles of an average diameter ~5 nm. The resulting PANI/TiO2 composite powder was used for photocatalytic degradation of methylene blue (MB). Its photocatalytic activity has been compared with activity of neat colloidal TiO2 nanoparticles

Electrocatalityc application of gold-polyaniline nanocomposite

Gold‒polyaniline (AuPANI) nanocomposite, with granular morphology of PANI and rod‒like Au nanoparticles (NPs) as dominate structure distributed in it, was prepared by interfacial polymerization method in an immiscible water/toluene biphasic system. Simultaneously with the aniline polymerization to polyaniline (PANI) by HAuCl4, as an oxidant, AuNPs are formed. AuPANI composite as green precipitate is collected from aqueous phase. Polyaniline in the composite is in the conductive emeraldine salt form (PANIES), with high amount of Au (28.85 wt %). Nanocomposite showed great electrocatalytic activity towards the electrochemical O2reduction reaction (ORR), with high ORR onset potential and high selectivity for O2reduction to water. This makes it a good candidate for a new class of Pt‒free ORR catalyst.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 2016

Enzymatic oligomerization and polymerization of arylamines: state of the art and perspectives

The literature concerning the oxidative oligomerization and polymerization of various arylamines, e.g., aniline, substituted anilines, aminonaphthalene and its derivatives, catalyzed by oxidoreductases, such as laccases and peroxidases, in aqueous, organic, and mixed aqueous organic monophasic or biphasic media, is reviewed. An overview of template-free as well as template-assisted enzymatic syntheses of oligomers and polymers of arylamines is given. Special attention is paid to mechanistic aspects of these biocatalytic processes. Because of the nontoxicity of oxidoreductases and their high catalytic efficiency, as well as high selectivity of enzymatic oligomerizations/polymerizations under mild conditions-using mainly water as a solvent and often resulting in minimal byproduct formation-enzymatic oligomerizations and polymerizations of arylamines are environmentally friendly and significantly contribute to a "green'' chemistry of conducting and redox-active oligomers and polymers. Current and potential future applications of enzymatic polymerization processes and enzymatically synthesized oligo/polyarylamines are discussed

Novel microporous composites of MOF-5 and polyaniline with high specific surface area

Composites of metal organic framework MOF-5 and conjugated polymer polyaniline (PANI) were synthesized for the first time. Two procedures, which avoid humidity during the synthesis in order to preserve the structure of MOF-5, were applied. In the first one, dissolved part of nonconducting emeraldine base form of PANI (PANI-EB) in N,N΄-dimethylformamide was mixed with MOF-5 in different mass ratios. In the second one, the composites were prepared mechano-chemically, by using powdered conducting emeraldine salt form of PANI (PANI-ES) and solid MOF-5, mixed in chloroform in different mass ratios. The composites were characterized by various techniques: scanning electron microscopy (SEM), FTIR spectroscopy, nitrogen sorption and electrical conductivity measurements, XRD, and flame atomic absorption spectroscopy (FAAS). The procedure which used PANI-EB led to microporous PANI/MOF-5 composites with very high BET specific surface area, SBET (the highest value SBET of c.a. 2700 m2 g−1, even higher than SBET of starting pure MOF-5, showed the composite which contains 89 wt.% of MOF-5) and low conductivity (∼10-7 S cm−1). The second procedure which used PANI-ES gave microporous PANI/MOF-5 composites which showed moderate conductivities (the highest conductivity of 1.0 ⋅ 10−3 S cm-1 exhibited the composite which contains 25 wt.% of MOF-5) and also high SBET values, but lower than those measured for the composites with PANI-EB (the highest SBET of c.a. 850 m2 g-1 showed the composite of PANI doped with HCl which contains c.a. 77 wt.% of MOF-5). XRD measurements confirmed that predominately cubic crystalline structure of MOF-5 was present in almost all composites. © 2020 Elsevier B.V

Self-assembled polyaniline nanotubes and nanoribbons/titanium dioxide nanocomposites

Self-assembled polyaniline (PANI) nanotubes, accompanied with nanoribbons, were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous medium, in the presence of colloidal titanium dioxide (TiO(2)) nanoparticles of 4.5 nm size, without added acid. The morphology, structure, and physicochemical properties of the PANI/TiO(2) nanocomposites. prepared at various initial aniline/TiO(2) mole ratios, were studied by scanning (SEM) and transmission (TEM) electron microscopies, FTIR, Raman and inductively coupled plasma optical emission (ICP-OES) spectroscopies, elemental analysis, X-ray powder diffraction (XRPD), conductivity measurements, and thermogravimetric analysis (TGA). The electrical conductivity of PANI/TiO(2) nanocomposites increases in the range 3.8 x 10(-4) to 1.1 x 10(-3) S cm(-1) by increasing aniline/TiO(2) mole ratio from 1 to 10. The morphology of PANI/TiO(2) nanocomposites significantly depends on the initial aniline/TiO(2) mole ratio. In the morphology of the nanocomposite synthesized using aniline/TiO(2) mole ratio 10, nanotubes accompanied with nanosheets prevail. The nanocomposite synthesized at aniline/TiO(2) mole ratio 5 consists of the network of nanotubes (an outer diameter 30-40 nm, an inner diameter 4-7 nm) and nanorods (diameter 50-90 nm), accompanied with nanoribbons (a thickness, width, and length in the range of 50-70 nm, 160-350 nm, and similar to 1-3 mu m, respectively). The PANI/TiO(2) nanocomposite synthesized at aniline/TiO(2) mole ratio 2 contains polyhedral submicrometre particles accompanied with nanotubes, while the nanocomposite prepared at aniline/TiO(2) mole ratio 1 consists of agglomerated nanofibers, submicrometre and nanoparticles. The presence of emeraldine salt form of PANI, linear and branched PANI chains, and phenazine units in PANI/TiO(2) nanocomposites was proved by FTIR and Raman spectroscopies. The improved thermal stability of PANI matrix in all PANI/TiO(2) nanocomposites was observed. (C) 2010 Elsevier B.V. All rights reserved

The quest for optimal water quantity in the synthesis of metal-organic framework MOF-5

Efficient and simple room temperature synthesis of pure phase metal-organic framework MOF-5 has been developed, based on the use of anhydrous zinc acetate, Zn(OAc)2, as a precursor, instead of zinc acetate dihydrate. Crucial influence of water on a reaction pathway was revealed. In order to obtain MOF-5, different amounts of water have been added into the solutions of Zn(OAc)2 in N,N-dimethylformamide (DMF) to prepare in situ zinc acetate hydrates with 0.25, 0.5, and 1.0 mol of water. Commercially available zinc acetate dihydrate was also used as a precursor for comparison. These solutions were mixed at room temperature with the solution of 1,4-benzenedicarboxylic acid in DMF in the absence of any base. Based on XRD, FTIR, and SEM measurements, it was shown that the optimal amount of water for the synthesis of completely pure, crystalline phase MOF-5 is 0.25–0.5 mol of water per one mole of Zn. The reaction systems with 1.0 and 2.0 mol of water per one mole of Zn also led to solids with MOF-5 as the dominant phase, but they also contain small amounts of another phase, formed due to the decomposition (hydrolysis) and/or distortion of the MOF-5 framework in the presence of excess amounts of water. The product synthesized in the system without any added water contains MOF-5 phase in a very small amount, while main phase is zinc 1,4-benzenedicarboxylate and/or zinc hydrogen 1,4-benzenedicarboxylate. Regular cubic submicro/microcrystal morphology exhibited the samples synthesized using 0.5 and 0.25 mol water per one mole of Zn (pure MOF-5), while for the samples synthesized at mole ratios H2O/Zn2+ = 1.0 and 2.0 other particle shapes are also seen. By nitrogen sorption measurements it was found that the highest values of BET specific surface area (1937 m2 g−1), micropore volume (0.83 cm3 g−1), and micropore area (1590 m2 g−1) showed MOF-5 prepared at mole ratio H2O/Zn2+ = 0.5, while the highest yield of MOF-5 is obtained with the theoretical mole ratio H2O/Zn2+ = 0.25. Thermal stability of synthesized materials was investigated by TGA. © 2018 Elsevier Inc

Ferromagnetic polyaniline/TiO2 nanocomposites

Novel ferromagnetic semiconducting polyaniline PANI/TiO2 nanocomposites were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous medium, in the presence of colloidal TiO2 nanoparticles (d similar to 4.5 nm), without added acid. The morphological, magnetic, structural, and optical properties of the PANI/TiO2 nanocomposites prepared at initial aniline/TiO2 mole ratios 80, 40, and 20 were studied by scanning electron microscopy, superconducting quantum interference device, X-ray powder diffraction, FTIR, Raman, and UV-Vis spectroscopies. The emeraldine salt form of linear PANI chains as well as the presence of phenazine units, branched PANI chains, and anatase crystalline structure of TiO2 in PANI/TiO2 nanocomposites was confirmed by FTIR and Raman spectroscopies. The electrical conductivity of synthesized composites was similar to 10-3 S cm-1. The room temperature ferromagnetic response with coercive field of Hc similar to 300 Oe and the remanent magnetization of Mr similar to 4.35 x 10-4 emu/g was detected in all investigated PANI/TiO2 nanocomposites. POLYM. COMPOS., 2012. (c) 2012 Society of Plastics Engineer