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The conditions for processing and doping of blends of poly(o-alkoxyaniline)s and poly(vinylidene fluoride) were investigated. Flexible, free-standing and stretchable films of blends of various compositions were obtained by casting. A low percolation threshold was observed with the onset of conductivity at low polyalkoxyaniline contents (i.e. 5%). Interestingly, these blends displayed electrochromism...
Potentiometric and calorimetric measurements on aniline polymerized by persulfate reveal an induction period, which may be decreased or eliminated by the addition of ceric (Ce IV ) ion. The addition of the second oxidizer appears to promote nucleation. The molecular weight and electrical conductivity of the resulting polyaniline were measured. Substantial shortening of the reaction...
The doping of polyaniline has been achieved by introducing the dopant molecule into the solid, undoped polymer without the use of an auxiliary solvent. Complex formation in the solid phase occurs at elevated temperatures and results in the formation of a soluble and processable conducting complex. The complexation was followed by calorimetric studies during a heating scan and the exothermic heat...
Optically active polyaniline salts can be readily generated in solution via the enantioselective acid doping of the neutral emeraldine base form of aniline with either (+)- or (-)-camphorsulfonic acid in a variety of organic solvents (1-methyl-2-pyrrolidinone (NMP), dimethylformamide, dimethylsulfoxide, CHCl 3 ). Strong mirror-imaged circular dichroism (CD) spectra were observed for the deep...
Based on the analysis of the authors' own experimental data on the chemical oxidative polymerization of aniline (ANI), as well as on the results of other authors on the electrochemical oxidation of ANI and the electrochemical response of the polyaniline (PANI) film obtained, the conclusion has been drawn that the polymerization of ANI can be considered both as a cationic polymerization and as a normal...
The chemical oxidation of aniline to polyaniline has been monitored by colour and acidity changes during dispersion polymerization. A small amount of various p-phenylenediamines or benzidine was found to accelerate the formation of polyaniline. The ability of such compounds to form cation radicals upon oxidation allows them to act as mediators in electron-transfer processes. Related chemicals, e.g...
Polyaniline doped with poly(alkylene phosphates) has been studied by Fourier transform infra-red, X-ray photoelectron and ultraviolet/visible spectroscopies. The protonation of the polymer was indicated by the appearance of infra-red modes characteristic of polyaniline salts and by the bands typical of polyphosphates at ca. 1000 cm -1 . X-ray photoelectron spectra showed a decrease...
The oxidative polymerization of aniline gives rise to polyaniline which exists in a variety of forms, differing in electrical conductivity and in colour. A scheme of interrelated structures which accounts for all the spectroscopic and conductometric observations, is proposed, together with a set of equations summarizing the chemical transformations involved.
The changes in intrinsic oxidation state ([=N-] and [-NH-] content) and protonation level ([N + ] ratio) of emeraldine (EM) base powders as a function of protonic acid loadings resulting from the protonation-deprotonation cycle have been assessed quantitatively by X-ray photoelectron spectroscopy. A hysteresis effect was observed for the protonation-deprotonation cycle involving HCl, but...
A series of polyaniline films have been coated on electrodes by chemical and electrochemical means in order to investigate the thermal stability of the electroactivity in air and nitrogen atmospheres. Polyaniline was also synthesized chemically and cast as a membrane (thick film). It was found that the electroactivity and conductivity of the films was stable up to 150°C. Exposure to higher temperatures...
A miscible and electroactive polymer blend comprising polyaniline (PANI) as the conductive component and poly(vinyl acetate) (PVAc) as the thermoplastic component was prepared and characterized. The solution-processable conducting PANI was prepared by doping with p-phenolsulfonic acid (PSA), which also helps enhance its miscibility with PVAc through hydrogen-bonding interaction. Blends containing...
An interrelationship between the mechanism of aniline polymerization and the direction of redox processes with participation of polyaniline chains on the one hand, and the π-electron energy of oligoanilines with various numbers of units, degrees of oxidation and protonation on the other hand, has been found for the first time. Calculations performed using the Hueckel method revealed that the difference...
Polymer blend films of polyaniline and nylon 6 were prepared from homogeneous solutions in formic acid at various weight ratios of polyaniline and nylon 6. Free standing, lustrous and flexible films were obtained by casting. The maximum conductivity of the film was about 0.2 S cm -1 , corresponding to a weight ratio of 0.5 wt/wt polyaniline (PAni) and nylon 6. The film exhibits semiconducting...
A novel route to preparation of polyaniline (PANI) composites based on mixing of a solution of host polymer with preliminarily formed colloidal PANI dispersion of very fine particles (lower limit ca 5 nm) is reported. This colloidal PANI dispersion was formed by oxidative polymerization of aniline (ANI) in the presence of dodecylbenzenesulfonic acid in aqueous medium, and can be dried and redispersed...
The miscibility of polyaniline (PANI) salts, doped with p-phenol sulfonic acid (PSA) or 5-sulfosalicylic acid (SSA), with poly(2-ethyl-2-oxazoline) (PEOx) was studied by differential scanning calorimetry (d.s.c.) and Fourier-transform infra-red spectroscopy (FTi.r.). D.s.c. measurements show a single glass transition temperature (T g ) for each of the blends containing 5-60 wt% of PANI. ...
Films of polyaniline doped with (±)-camphor sulfonic acid, cast from m-cresol, exhibit considerable metallic properties. Such films are partially crystalline, but appear macroscopically disordered when probed by X-rays. Changing the X-ray geometry to probe molecular trajectories within the thickness of such films reveals considerable anisotropy; the molecules statistically adopt a chain direction...
Chemical oxidative polymerization of dodecylbenzenesulfonic acid aniline salt in water using ammonium peroxydisulfate as oxidant was found to give an homogeneous polyaniline suspension. An aqueous transparent and green uniform suspension containing polyaniline complexed and doped with dodecylbenzenesulfonic acid was obtained to show a typical emeraldine salt spectrum. The polyaniline suspension was...
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,...
Sharp changes in the transport and structural properties were noticed when a pH-dependent study of polyaniline (PAN) with monovalent (Cl - ) and multivalent (PO 4 ) 3- ions was carried out. Scanning electron micrographs (SEM) of these samples reveal that the sharp changes induced by doping are more prominent at the pH where the transformation of the PAN lattice takes...
The rate of aniline polymerization, measured by calorimetry, decreases when the hydrochloric acid concentration in the polymerization solution is increased from 2 to 6 M. The amount of chloride covalently bonded to the aromatic rings of the polymer backbone, estimated from the presence of new vibrational bands in the i.r. spectra, increases with an increment of hydrochloric acid concentration. The...
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