Ionizing radiation effects such as neutron and gamma on conducting polyanilne have been studied for various doses varied from 6 to 504Gy and 15 to 41.9 kGy, respectively. Spectroscopic methods such as UV-Vis spectroscopy, X-ray diffraction, Raman spectroscopy and I-V measurements have been used to characterize the pristine and irradiated polyanilne samples. UV-visible spectroscopy shows a shift in the absorption edge towards visible region after irradiation, which can be correlated to the transition involved in these polymers and variation in the band gaps (Eg) using Tauc’s expression which indicate a decrease in band gap. XRD spectra revealed that crystallinity and particle size improve after irradiation, which could be attributed to cross-linking mechanism. The current voltage (I-V) characteristics have been carried out at room temperature using four probe set up and it has been found that polyaniline films show ohmic behaviour before and after irradiation. Moreover, conductivity improves after irradiation, which is due to enhancement in carrier concentration. Conducting polymers as a radiation sensor for gamma and neutron as well as for dosimetry aspects have been studied.

Polyaniline polyvinyl alcohol (PANI-PVA) composite films have been prepared chemically in inorganic acid medium at different ratios of their monomer units. A homogeneous blend can be obtained even using inorganic acid medium by terminating the reaction soon after the mixture attains homogeneous colour change. The SEM pictures show that the films have well formed grains with approximate sizes ranging from 0.3 to 1.2 m. The results show definite dependence of various parameters on the PANI-PVA ratio in the blend. The XRD spectra show increase in crystallinity in the films with increase of PVA concentration. The FTIR spectra show some peaks, which ascertain chemical interlinking of PANI and PVA in these blends. The studies of electrical conductivity of these films through measurement of current-voltage (I-V) characteristics show non-ohmic power law behaviour (I a Vn) with power (n) lying in the range 0.22 to 0.88. The conductivity value of these films is found to be between 1.80 to 0.9 S cm-1.

Temperature, T, dependence of the electrical
conductivity, s, of own-made polyaniline pellets, highly doped either by
HCl or by dodecylbenzenesulphonic acid, is discussed. For the both dopants, a
variable-range-hopping exponent 2/5 is found below T^* ˜ 200 -
250 K. This result can be understood on the basis of a recent theory of Fogler,
Teber and Shklovskii which takes into account Coulomb correlations in a
three-dimensional system of chain-like conductors, predicting a power-law
density of states for charge excitations around the Fermi energy. At T
> T ^*, the s(T) curves are steeper,
implying a tendency towards nearest-neighbour hopping by a reduction of the
average hopping length.

Abstract

Polyaniline (PAn) was prepared chemically in the presence of bronsted acid from aqueous solutions. Polyaniline- nylon 6 composite (termed as PAn/Ny6) prepared via solvent casting method. The preparation conditions were optimized with regard to the mechanical properties of the polymer composite. It was found that the molar ratio of PAn to nylon have the greatest effect in determining the mechanical properties of polymer composite. Electrical conductivity was measured using standard method of four point probe. Spectrophotometric analysis (UV-Vis) was used for investigation of the effect of thermal treatment on polyaniline and it’s composite

Abstract

Abstract

A novel enzyme immobilization platform was prepared on a platinum disk working
electrode by polymerizing aniline inside the interstitial pores of polyester
sulphonic acid sodium salt (PESA). Scanning electron microscopy study showed the
formation of homogeneous sulphonated polyaniline (PANI) nanotubes (~90 nm) and
thermogravimetric analysis (TGA) confirmed that the nanotubes were stable up to
230 °C. The PANI:PESA nanocomposite showed a quasi-reversible redox behaviour in
phosphate buffer saline. Horseradish peroxidase (HRP) was immobilized on to this
modified electrode for hydrogen peroxide detection. The biosensor gave a
sensitivity of 1.33 µA (µM)^-1 and a detection limit of 0.185 µM for
H₂O₂. Stability experiments showed that the biosensor
retained more than 64% of its initial sensitivity over four days of storage at 4
°C.