Effect of metal phthalocyanines on the synthesis and physicochemical properties of polyaniline

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Cerate oxidimetry : Oxidation of maleic,fumaric, benzoic,salicylic and phthalic acids

1. It has been shown that maleic, fumaric, benzoic, phthalic and salicylic acids can be oxidized completely to carbon dioxide and water by ceric sulphate in the presence of concentrated sulphuric acid. 2. These acids can be estimated quantitatively by the use of ceric sulphate. 3. Acetic and succinic acids are not oxidized by ceric sulphate even in the presence of high concentrations of sulphuric acid.     

Electrochemical properties of rhodium- and gold-containing polyaniline films

Graphite-supported polyaniline films (PANI) containing rhodium particles were obtained by two procedures: metal electrodeposition on a prepared PANI film and electropolymerization. The adsorption/desorption and electrowinning of hydrogen on these films were observed for both types of synthesized composite films. PANI/Au composites were synthesized using the PANI films deposited onto a gold electrode. High anode potentials were further applied to the electrode in the presence of chloride ions, leading to a dissolution of gold and its transfer to the films during subsequent electroreduction. The amounts of the chloride complexes of gold formed in this procedure were determined by cyclic voltammetry of their electroreduction.     

Structure and properties of plasma-polymerized thin films of polyaniline

Plasma polymerization of aniline and in-situ doping of polvaniline with iodine was carried out using radio frequency glow discharge. Thin films of polyaniline were deposited on platinum and glass. The infrared spectrum shows that the aromatic ring is retained under the plasma conditions. The electrical conductivity measurements indicate that the conductivity increases by more than seven orders of magnitude when the polyaniline is doped by iodine. The scanning electron microscopic studies reveal the formation of irregular pentagons on glass substrate while on platinum, polvaniline forms a fibrillar network. In both the cases a continuous film is obtained.     

Nanomechanical properties of polyaniline and azo polyelectrolyte multilayer films

<正>Nanomechanical properties of multilayer films constructed of polyaniline(PANI) and azobeneze-containing polyelectrolytes(PNACN and PPAPE) were studied by using nanoindentation method.The multilayer films were prepared by the electrostatic layer-by-layer self-assembly through alternately dipping in the polymer solutions.The multilayer films deposited onto the glass slides after proper dry were used for the nanomechanical property testing.The nanomechanical measurement indicated that the PANI/PNACN and PANI/PPAPE multilayers possessed the mean elastic modulus of 5.42 GPa and 4.35 GPa,and hardness of 0.26 GPa and 0.18 GPa,respectively.The nanoscratch properties of the PANI/PNACN and PANI/PPAPE multilayer films were also measured.The critical loads of PANI/PNACN and PANI/PPAPE films were 103.52 mN and 100.59 mN.The degree of electrostatic cross-linking in the multilayers could be altered by exposing the films to aqueous solutions with different pH values.As a result,the modulus and hardness of the multilayer films were changed through the solvent treatment.Both modulus and hardness of the PANI/PNACN films obviously increased after dipping the multilayer films in solutions with pH in a range from 9 to 11.     

Electrophysical properties of polyaniline doped with heteropoly acids

Composites of polyaniline with phosphotungstic and phosphomolybdic heteropoly acids of Keggin type were studied by impedance spectroscopy. Doping of polyaniline with these acids allows the proton conductivity of the polymer in the composites to be increased by six orders of magnitude.     

Doping of polyaniline films with organic sulfonic acids in aqueous media and the effect of water on these doped films

Polyaniline (PANI) films in the form of emeraldine salt (ES) doped with aqueous organic sulfonic acids such as camphorsulfonic acid (CSA), p-toluenesulfonic acid (p-TSA) and dodecylbenzenesulfonic acid (DBSA) were studied. The ES films were obtained by treating the PANI in the form of emeraldine base (EB) with the aqueous solution of the acids. The dopant weight fraction (w), which is related to the mass gain during the redoping of EB, was in situ determined using a quartz crystal microbalance (QCM). The behaviour of PANI doping with different acids indicates that the uptake shows a slow diffusion process. The kinetics of the doping reaction is dominated by Fickian diffusion kinetics. The diffusion coefficients (D) of the dopant ions into the PANI chains were determined and were found to vary within the range of (1.6-18) × 10⁻¹⁵ cm² s⁻¹. Moreover, the effect of water on these doped ES films was studied. The starting point is the fact that PANI-coated the electrode of QCM shows significant frequency shifts on exposure to water. The changes in the frequency as a function of treatment time in water were quantitatively measured. The response of the device suggests that the mass decrease under water exposure is due to dopant ions release. The latter films were dedoped by exposure to ammonia solution to obtain the EB film form. A further decrease in the mass of the films was observed. The percentage of the mass loss due to water exposure is found to be less than w determined during the dedoping process.     

1,4,7,10-Tetraazacyclododecane incorporating salicylic acid moieties synthesis and properties

The synthesis of salicylic acid derivatives of 1,4,7,10-tetraazacyclododecane has been described. The complexing properties of these compounds towards metal cations were investigated by absorption and emission spectroscopy, and ¹H NMR. The X-ray structure of L-2 nitrate is reported.     

The chemical synthesis of conductive polyaniline doped with dicarboxylic acids

The chemical polymerization of aniline was carried out in media containing different linear dicarboxylic acids with the use of oxidants such as K₂Cr₂O₇, KMnO₄, K₂S₂O₈, KIO₃ and FeCl₃. The highest yield and the conductivity were observed with K₂Cr₂O₇. The yield and the conductivity of the polyaniline (PAn) synthesized were observed to decrease in the order of oxalic acid > malonic acid > succinic acid > glutaric acid > adipic acid > phthalic acid. The solubility tests carried out in solvents such as DMF, DMSO and NMP showed that the larger the dopant molecule, the higher is the solubility of polyaniline. The PAn synthesized was characterized by measurements of conductivity, intrinsic viscosity, density and FTIR, UV-VIS and TGA techniques.     

Characterization of nanostructure and cell compatibility of polyaniline films with different dopant acids

Polyaniline (PANi) films were prepared by direct polymerizing deposition with four different kinds of acids as dopants or were prepared by a casting method on the surface of a polytetrafluoroethylene substrate. The properties of PANi films were characterized using atomic force microscopy, electrical conductivity measurements, and water contact angle measurements. Unlike the casting PANi film, experimental results indicated that the synthesized PANi films had a similar nanostructure as that of average nanoparticles (approximate diameter of 30-50 nm). To investigate the potential usefulness of PANi films in biomedical applications, we also studied their biocompatibility through the adhesion and proliferation properties of PC-12 pheochromocytoma cells. All the films were found to be biocompatible and allowed cell attachment and proliferation. However, the synthesized films have a much higher ability for cell adhesion than the casting film. After 4 days of culture on different PANi films, the cells formed more confluent monolayers on the synthesized PANi films than on the casting films. These results demonstrate that the PANi films could be used to culture neurotic cells and that their surface architecture on the nanoscale may affect cell function such as attachment and proliferation.     

Morphology and thermal properties of conductive polyaniline/polyamide composite films

Polyaniline (PANI) in an emeraldine‐base form, synthesized by chemical oxidation polymerization, was doped with camphor sulfonic acid (CSA). The conducting complex (PANI–CSA) and a matrix, polyamide‐66, polyamide‐11, or polyamide‐1010, were dissolved in a mixed solvent, and the blend solution was dropped onto glass and dried for the preparation of PANI/polyamide composite films. The conductivity of the films ranged from 10^?7 to 10⁰ S/cm when the weight fraction of PANI–CSA in the matrices changed from 0.01 to 0.09, and the percolation threshold was about 2 wt %. The morphology of the composite films before and after etching was studied with scanning electron microscopy, and the thermal properties of the composite films were monitored with differential scanning calorimetry. The results indicated that the morphology of the blend systems was in a globular form. The addition of PANI–CSA to the films resulted in a decrease in the melting temperature of the composite films and also affected the crystallinity of the blend systems. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2531–2538, 2002     

Controllable synthesis of novel sandwiched polyaniline/ZnO/polyaniline free‐standing nanocomposite films

Controllable synthesis of novel sandwiched polyaniline (PANI)/ZnO/PANI free‐standing nanocomposite films is reported via spin coating of ZnO quantum‐dot interlayer on PANI base layer and then PANI surface layer on the ZnO interlayer. The thickness of the ZnO interlayer and the PANI surface layer can be easily controlled by adjusting spin time and spin speed, respectively. The effects of the ZnO interlayer thickness and the PANI surface layer thickness are examined in detail on the photoluminescence (PL) property. It is worth noting that coverage of the PANI surface layer on the ZnO interlayer can not only lead to great enhancement in the PL property but also to a maximum PL intensity at a medium PANI surface layer thickness. This maximum PL property is caused by the combined ZnO/PANI carrier transportation and PANI shielding effects. In addition, the nanocomposite films show reasonably good conductivity. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Dielectric properties of conducting polyaniline films by THz time-domain spectroscopy

The dielectric function of composite polyaniline (PANI)/polyurethane (PU) is studied in the terahertz range. Different free-standing films of composite PANI-CSA/PU with different PANI concentrations are measured by terahertz time-domain spectroscopy (THz-TDS). The Fourier transmission spectrum, the permittivity and conductivity are then precisely obtained between 0.1 and 4 THz. The behaviour of the dielectric function does not follow Drude theory and the extracted data are well fitted by Jonscher’s universal dielectric response. Furthermore, the percolation threshold is also deduced from the insulating to conducting transition extracted for several doping level at very high frequency.     

Electrochemical template synthesis of adherent polyaniline thin films with tubular structure

The synthesis of nano and microstructured thin polyaniline (PANI) films by a simple and very efficient template-assisted method is presented. This work shows the synthesis and characterization of acoustically rigid thin films structured at nanotubular shape by using methyl orange (MO) as a template-assisted system. The amount of the tubes can be easily controlled by the charge passed. The morphology for different films growth was characterized by field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM), and quartz crystal microbalance with dissipation mode (QCM-D). Raman spectroscopy results show important changes in the conformational PANI chain of the tubular material compare with a non-tubular one that provokes the increase of bipolarons population. This should be responsible by some changes in the electrochemical behavior of tubular film compared with the granular material, due to the higher conductivity when the emeraldine form starts to be formed.     

Effect of solution acidity on the electrochemical behavior of Nafion—polyaniline films

Electrochemical behavior of Nafion–polyaniline films in acidic and neutral media is studied. Doping and degradation of the films are considered.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 224–227.Original Russian Text Copyright © 2005 by Andreev.This revised version was published online in April 2005 with corrections to the article note and article title and cover date.     

Effect of water release on thermal properties of polyaniline

Conducting polyaniline (PANI) was studied by thermal expansion measurement, thermogravimetric analysis and by electrical conductivity measurement. Relative elongation and coefficient of thermal expansion (CTE) were determined from room temperature to 60 °C. Various temperature profiles were used. During heating, the treatment of samples at a constant temperature higher than the room temperature, or evacuation, water was released from the samples. Water release was detected by mass and thermogravimetric analysis. Water release was connected with shrinkage of the PANI samples and apparent negative CTE in the first thermal cycle. In the following thermal cycles, it increased and reached a positive value. CTE of PANI attained values in the range of ?30 × 10^?6 K^?1 up to 20 × 10^?6 K^?1 in dependence on water content in the sample before measurement and on experimental conditions of measurement. Irreversible shrinkage of the polymer was the largest in the first thermal cycle. Water release exhibited a strong time and temperature dependence, and it was only partially reversible. The electrical conductivity was measured by a four-point van der Pauw method. Relative electrical conductivity decreased with amounts of water release. Relative decrease of electrical conductivity reached as far as 20% after evacuation 7 h at the room temperature.     

Effect of aromatic substitution in aniline on the properties of polyaniline

Substitution in aniline has tremendous effect in the synthesis of poly(substituted anilines) as well as in their properties. In this investigation polyaniline (PANI), poly(m-nitro aniline) (PMNA), poly(m-amino phenol) (PMAP) and poly(o-ethyl aniline) (POEA) were synthesized by oxidative polymerization under identical conditions. Different properties were measured and compared with PANI to find out the presence of electron donating -OH group, electron withdrawing -NO₂ group and less effecting ethyl group on the properties of poly(substituted anilines). It was found that presence of any type of substitution in the benzene ring of aniline increases the solubility of the resulted polymer but reduces the yield, degree of polymerization, thermal stability, electrical and thermal conductivity. The colors, bulk density, particle size, percentage of crystallinity vary considerably depending on the nature of substitution.