Preparação e caracterização de filmes nanocompósitos de polianilina e nanofibras de celulose com híbridos de óxido de manganês (ii)/ferro (ii) e grafeno

Abstract

The search for materials from renewable sources has always aroused great interest from the scientific community. Cellulose-based materials have stood out due to their peculiar characteristics and their ability to interact with various materials, such as conducting polymers, magnetic nanoparticles, graphene, among others. Cellulose-based materials, such as cellulose nanofibers, are considered environmentally friendly and have stood out in the market for providing an increase in their physical and mechanical properties due to their nanometric structure. In this work, composite films were produced using cellulose nanofibers (CNF), polyaniline (PANI), magnetic nanoparticles (MNP) and oxidized and reduced graphene (RGO). PANI was synthesized in the presence of cellulose nanofibers and was thus deposited on the surface of the fibers. For the preparation of the final composites, the NPM and RGO were subsequently added, following a factorial design where the MNP and RGO content varied from 0.54% to 17.46%. The MPN used were manganese ferrite (MnFe2O4). The RGO was synthesized by the modified Hummers method, exfoliated in an ultrasonic processor and reduced with hydrazine. The composite films were obtained by vacuum filtration in a Büchner funnel, which was then taken to dry in metal sheets at 50 ° C under pressure of 1 ton. The thickness of the films remained around 0.166 mm. The main analyzes performed for the characterization of the compounds were SEM, RAMAN, conductivity analysis by the method of four ready-made and effective shielding against microwave radiation (EMI). In the SEM, the morphologies of the composite materials were observed, showing the way in which the RGO was deposited on the surface of the PANI-CNF forming clusters. The exfoliation suffered in graphite was also notorious, which was effectively reduced to RGO due to the various layers visualized in SEM,a fact also proven in RAMAN by the displacements of bands D and G. In the analysis of four tips, higher conductivity values were obtained for the composites with a higher RGO content in their composition, they were also more effective against EMI shielding obtaining better results. From the experimental results obtained, it was possible to make an analogy that PANI-CNF composites with RGO have excellent conductivity and are more efficient in EMI microwave shielding. Keywords: Cellulose nanofibers, polyaniline, graphene, magnetic nanoparticles.