Desenvolvimento de nanobiocompósitos superparamagnéticos para aplicação em dispositivos eletrônicos

Abstract

The progress of electronics in recent years has increased the need for light, flexible, high efficiency/volume ratio materials that are also biodegradable. Natural polymers can be used for this purpose. Significant contributions to the miniaturization and performance of these materials are reported in the literature when a magneto-dielectric filler is dispersed in these matrices. This work presents different composites obtained with the dispersion of superparamagnetic nanoparticles (MNPs) in three biomolecules: chitosan, collagen and cellulose. Its thermal, morphological, structural, dielectric and magnetic properties, as well as its potential as substrate for microstrip antennas were evaluated. Fe3O4 MNPs were synthesized and functionalized in ultrasound with polyethylenimine, trisodium citrate and sodium polyacrylate, obtaining three different ferrofluids, which presented specific mass and viscosity with values close to, but higher than the base fluid, and lower surface tension than water. Fe3O4 functionalized polyethylenimine MNPs were chosen as the dispersed phase for the composites. Substrates with decreasing dielectric constant with frequency, but in range 2-12, and with good dispersion of MNPs in the matrix were obtained. Prototypes of microstrip antennas showed good bandwidths and return loss, besides frequency of operation directly dependent on the composition of the composites, between 4.63-5.55 GHz. Therefore, the obtained materials are suitable candidates for substrates in microstrip antennas operating in microwave, with cheap and eco-friendly processing, good dielectric properties, flexibility, lightness and biodegradability.