Obtenção e caracterização de filmes de polianilina com dióxido de estanho

Abstract

Composite materials have attracted large interest for research in the development of new materials with specific properties. Several classifications of materials may be utilized to the production of composites, as the formed by organic and inorganic phases. The materials of this research were polyaniline and tin dioxide for composites obtaining for future application in sensors. PANI is a conducting polymer which has the following properties: high electrical conductivity (10 3 S=cm), chemical stability and easy obtaining for chemical synthesis. SnO 2 is a semiconductor of wide bandgap which has the following properties: high electrical conductivity if doped; transparency in the visible region; thermal, mechanical and chemical stability. This semiconductor has been used in several applications, such as gas sensors, electrodes in lithiumion batteries, etc. PANI and the composite ware obtained by chemical polymerization, where different concentrations of SnO 2 were tested. PANI and PANI/SnO2 films were obtained by casting technique. The precursor material was characterized by infrared spectroscopy (FTIR) and the films were characterized by scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD) and Hall effect. FTIR spectroscopy presented functional groups of PANI and Sn-O bonds, however, it was not observed peaks of chemical bonds between the polymer and the oxide. SEM of SnO 2 showed a decrease of grain size for the oxide passed by the grinder, but there was no homogeneity for grains sizes. Besides, SEM of the films presented that the increase of oxide concentration leads to the increase of the surface roughness in the composites. The oxide structure was tetragonal rutile according to Raman spectroscopy. The presence of oxygen vacancy and structural disorder were also identified. Raman spectroscopies of the composites films do not identify chemical bonds between the materials, as confirmed by FTIR. PANI presented amorphous structure by the XRD results. The composites confirm the presence of SnO 2 in tetragonal rutile structure. Finally, for the sheet resistance (R S ), PANI showed values similar to those found in literature and composites with the lower concentration of oxide revealed lower values of R S .