Conducting Form Of Polyaniline Research Articles

Synthesis and Characterization of Bacterial Cellulose-Polyaniline Composite with Variation of Dopant Concentration

Polyaniline is a type of conductive polymer. Bacterial cellulose has high mechanical properties, so it can be made into polyaniline base composite materials. A stable form of polyaniline oxidation at room temperature is emeraldine base. The emeraldine base has a conductivity value of 10-6 S/cm. Dopants can change the shape of emeraldine base to emeraldine salt by protonation process. Emeraldine salt is a conductive form of polyaniline. The conductivity value of emeraldine salt is 0,03-0,07 S/cm. The addition of dopan in synthesis of polymer was carried out to determine its effect on the conductivity value. The disadvantage of polyaniline is that its mechanical properties are weak and easily brittle. Modifications are needed to improve the mechanical properties of polyaniline, one of which is the manufacture of composite. Bacterial celluloce has high mechanical properties so it can be made into polyaniline base composite materials. Synthesis of bacterial cellulose-polyaniline composites by in situ chemical polymerization methods. Syntehsis is started with BC membrane was dipped into aniline solution for about 2h with stirring at room temperature. The BC was immersed into ammonium peroxydisulfate solution for about 30m with stirring. The bacterial cellulose-polyaniline compositions obtained are black color which is characteristic of the emeraldine salt. The highest conductivity value of composite was obtained from the addition of 3,5M HCl dopant which was 4,70x10-4 S/cm. FTIR analysis of composite obtained peak of the characteristic polyanilin was conductive at 1565,92 cm-1 as C=C quinoid ring and 1442,95 cm-1 as C=C benzoid ring.

One-step polymerization leading to conducting polyaniline

Conducting form of polyaniline can be obtained by one-step polymerization of aniline in the presence of organic acids such as sulfonic acids, phosphonic acids, carboxylic acids or other organic compounds showing acidic character and at the same time very well soluble in water. Using these water soluble acids leads to the creation of appropriate polyaniline salts which show very high affinity to water. The polymerization is analogical to the well known precipitation polymerization in the presence of HCl, but leads directly to a final conducting form of polyaniline with conductivity of several S/cm.

Polyaniline composite coatings interrogated by a nulling optical-transmittance bridge for sensing low concentrations of ammonia gas

Polyaniline (PANI) is a π-conjugated polymer that shows electric and optical property changes, when it is in contact with oxidant/reductor chemicals. In particular, the interaction between the conductive form of PANI, the emeraldine salt (ES), and the NH 3 gas results in a decrease of the polaron densities inside the band gap of the organic material. In this work, the optical-transmittance changes detected in PANI coatings as a function of the sensing ammonia gas concentrations are studied by using a nulling optical-transmittance bridge with a 632 nm laser (He–Ne) source, which allows a sensitive monitoring of optical property changes. It is observed that the conductive PANI–polymethyl methacrylate (PMMA) composite coatings are sensitive for very low concentrations of HN 3 (from ∼10 to 4000 ppm, depending on the PANI films’ electrical conductivity), and their optical response is reversible as the reduction gas is removed by N 2.

A complete optical study of the conductive form of polyaniline: the emeraldine salt

We present a complete optical study of the emeraldine salt. We propose an extensive experimental Raman investigation of the primary doping and of the doping by the action of a protonic acid/solvent system, completed by a vibrational analysis. This work has been achieved while taking into account the non planar geometry of the emeraldine salt in order to put in evidence conformational modifications and the doping influence on out-of-plane vibrations. Complementary experiments of time-resolved fluorescence are reported in the picosecond time domain.

Synthesis and characterization of malonic acid-doped polyaniline

The conductive form of polyaniline was synthesized by the anodic and chemical oxidation of aniline in malonic acid medium. The conductivity of polyaniline doped with malonic acid changed from 1.62×10−6 to 2.5×10−5Scm−1 depending on the way it was synthesized. The polymer growth rate was observed to be very slow in malonic acid compared with H2SO4. Thermogravimetric data revealed that the maximum thermal reaction rate of PANI doped with malonic acid was at 200°C and 520°C compared with 290°C and 530°C of the polymer doped with H2SO4.

Phonon studies of intercalated conductive polymers

The phonon density-of-states of FeOCl, the conductive form of polyaniline and the intercalation compound (polyaniline) 0.20 FeOCl( I) have been measured by the neutron time-of-flight technique. The results are discussed in the light of the conducting and structural properties of the materials. Compound I is oxidised by standing in air and the neutron measurements reveal substantial changes in the inorganic host skeleton.