Preparation And Properties Of Silver / Polyaniline Nanocomposites

Ag/polymer nanocomposites combine the electrical characteristics of silver and the mechanical and processing properties of polyaniline, the synergetic effects between silver nanoparticles and polyaniline may result in good electrical and thermal conductivities, catalytic and electrocatalytic properties. In this paper, nano-silver colloid have been prepared by using aniline as stabilizer and via the micro-emulsion method, base on this colloid, Ag/polyaniline nanocomposites were synthesized with ammonium perfulfate (APS) as oxidizing agents. The structure and morphology of the products were charactered by UV-visible spectra, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectra, scanning electron microscopy and transmission electron microscopy. The conductive performance, thermal stability property and electrochemical behaviour of the Ag/Polyaniline nanocomposite were investigated by conductivity test, thermogravimetric analysis, cyclic voltammetry, electrochemical impedance spectroscopy and polarization curves. The following results can be summarized.(1)The prepared Ag/polyaniline nanocomposites possess the core-shell structure with the Nano-silver particles as the core. The effects of the concentration of An and SDS on the structure and morphology of the products were studied, the results indicated that in the high concentration of An and SDS, the size and distribution of the nanocomposites will be effectively improved. There are bonding effect during Ag and polyaniline in the nanocomposites, this bonding effect led to the higher thermal property of the material, and the degradation temperature of the Ag/polyaniline nanocomposites reach 350℃.(2)As the Ag content increased, the prepared Ag/polyaniline nanocomposites possess higher electrical conductivity. When the ratio of An and AgNO3 was 1:3, the maximum electrical conductivity of the product is 65.98 S/cm. In the micro-emulsion pathway, the maximum electrical conductivity of the conduct is 38.53 S/cm under the 5 mM/L concentration of SDS. Both in the condition of low concentration, there were agglomeration between the prepared Ag/polyaniline nanocomposites, and the composites did not possess core-shell structure, thus the products possess high electrical conductivity.(3)In the preparing process of Ag/polyaniline nanocomposites, the products possess the highest electrical conductivity when using the HNO3 concentration of 0.2 M/L. The benzene units in the molecular chains of Polyaniline will be oxidized when using high concentration of HNO3. The electrical conductivity of the products decreased as the increasing amount of APS during the preparing process. The main molecular chains of Polyaniline will be oxidized by the excess amount of APS, therefore, the conjugate structure of the molecular chains will be disrupted so that the electrical conductivity of the Ag/polyaniline nanocomposites decrease sharply.(4)Compared with PANI, The cyclic voltammetry, electrochemical impedance spectroscopy results and the polarization curves showed that the Ag/polyaniline nanocomposites exhibit considerably higher electroactivity.