Etude de la synthèse par voie chimique de nanostructures de polyaniline et de nanocomposites de polyaniline particules métalliques : application à la détection d'ammoniac

Abstract

The ammonia absorption properties of polyaniline nanostructures are studied in terms of sensitivity, response and recovery times and stability. These characteristics are obtained by measuring, at room temperature, the absorbance variations at 632 nm. First, nanostructures are synthesized either by interfacial or rapid or dropwise polymerizations with the oxidant-to monomer mole ratio equals to 0.5 or 1. The influence of the deposition method as well as the nature of the dopant on the gas detection properties are also studied. The results show a strong dependence of the morphology on the deposition method, the in-situ technique leads to the best sensitivity and response time. For this deposition method, the nanostructures sensitivity, response time and regeneration rate depend on the synthesis method, the dopant and the mole ratio. The ageing effect after 8 months under ambient conditions and the mechanism of interaction between the polyaniline nanostructures and ammonia molecules are also presented. In a second step, we present a new method of metal incorporation into the polyaniline nanostructures based on the use of palladium/tin colloidal solutions. The preparation of the PANI/Pd nanocomposite has been done either with the in-situ method or the ex-situ one. The results show that the in-situ adding of colloids affects mainly the morphology of nanostructures, however the ex-situ adding of Pd/Sn affects mainly their doping level.