O uso do ultrassom como ferramenta para induzir modificações estruturais, térmicas e elétricas na polianilina: análise teórica e experimental

Abstract

This work investigates the effect of ultrasonic treatment on the structural and electronic properties of polyaniline (PAni) synthesized in aqueous and acidic media. FTIR and UV-Vis spectroscopy techniques were employed to analyze the degree of chain organization and the electronic transitions. The UV-Vis spectra revealed π-π* transitions and polaronic bands, whose intensities and shifts depend on the sonication power and the medium used. The application of the Tauc method allowed the estimation of the direct optical band gap values, while the analysis of the Urbach energy provided information about the structural disorder of the samples. The FTIR spectra confirmed the preservation of quinoid and benzenoid units and suggested the formation of cross-linking between chains, especially under acidic conditions. The cross-linking index, calculated from the Q/B ratio, revealed greater cross-linking in acidic medium, corroborating the conductivity results, which showed better electrical performance in the more cross-linked samples. These results highlight the relevance of controlling sonication and the chemical medium in modulating the structural and conductive properties of PAni, providing important insights for the development of functional conductive polymeric materials.