0000000000026078
AUTHOR
E.s. Matveeva
Residual water and electrical properties of polyaniline
Summary form only given. The work aims to study the mechanism of interaction between water molecules and polyaniline (PANI) backbone as an important constituent of acid-base transformations ensuring good conductive properties of PANI. Experiments have been made using chemically synthesized emeraldine base subjected to different chemical treatments and aging procedures. Thermogravimetric measurement have shown that water content in polymeric matrices may amount up to 20-25 wt.% with two distinguished reversible absorbance states of water molecules. Weakly bond water (3-5 kcal/mol) is incorporated into PANI from ambient atmosphere and could be eliminated by drying at room temperature in vacuu…
Thermogravimetric and calorimetric studies of water absorbed in polyaniline
Abstract Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the behavior of residual water absorbed by an emeraldine base and a salt of chemically synthesized polyaniline (PANI—EB, PANI-ES). The matrix of PANI is shown to contain water molecules participating in both reversible and irreversible absorption. In its turn, the reversibly absorbed water consists of two components. The first component (WD 1 ) amounts to 5–7 wt.% and is removable from PANI-EB in a flow of dry nitrogen at room temperature. The second one (6–8 wt.%) of more strongly bonded water (WD 2 ) can be withdrawn from PANI-EB at temperatures from 70 to 150 °C depending on the measu…
Growth of polyaniline films on porous silicon layers
Abstract The electrochemical deposition of electrically active polyaniline films (PANI) onto the surface of porous silicon (PS) layers formed at p- and n-type silicon wafers has been studied using cyclic voltammetry measurements and infrared spectroscopy. The process of PANI deposition is easier on the PS layers formed at n-Si wafers and essentially retarded at PS/p-Si samples, presumably due to a parallel reaction of oxygen evolution. The polymerization reaction starts at the pore bottoms and propagates towards the external surface of the PS layer. Electric conduction of PS/PANI composites is lower than of uncovered PS layers.
Structure of doped polyaniline - dielectric spectroscopy measurements
The role of doping reagents (residual water and acid anions) in determining the electric properties of a chemically synthesized polyaniline (PANI) was studied using a dielectric spectroscopy method. Dependencies of dielectric losses and susceptibility of PANI as the functions of temperature (-100÷+100°C) and electric field frequency (0.3÷30000 Hz) were examined at it was shown the role of water acts as a doping impurity similar to acid anions. The model is proposed to explain the role of water in terms of adsorption of H 2 O molecules at nitrogen sites of PANI chain and their dissociation
Direct involvement of acid centers of polyaniline in charge transfer on organic acceptor
Abstract Electrochemical behavior of hydroquinone and 4F-hydroquinone has been studied on Pt/polyaniline (PANI) electrodes in 1 M H 2 SO 4 solution. Redox transformation of quinone/hydroquinone systems takes place on PANI practically without overpotential and, probably, the two-electron charge transfer processes are realized in such systems. Reaction currents depend on PANI quantities deposited on the Pt electrode and the molecular complex is formed. There exists a great electronic exchange between acid centers of PANI and quinone/hydroquinone molecules, resulting in electronic conjugation of this surface state (adsorbed molecule) with the polymer. Existence of such complexes was confirmed …