PREPARAÇÃO E CARACTERIZAÇÃO DE NANOPARTÍCULAS de Ag e ZnO E INCORPORAÇÃO EM FIBRAS DE TECIDOS DE ALGODÃO

Abstract

The fabrics are used for various applications in our daily life, and particularly natural fabrics such as cotton are susceptible to bacterial growth due to moisture that it can accumulate which facilitates this process and also the fibers themselves may serve as nutrients for the growth of microorganisms. In this work, the synthesis of silver and zinc oxide particles was carried out for their and corporation into cotton fibers by the Layer-by-layer method. The silver nanoparticles provide high biocidal activity when incorporated into fabrics textiles and zinc oxide particles promote a block against ultraviolet radiation and also provide the self-cleaning properties for the fabric by the oxidation of compounds on its surface. Therefore the aim of this work was to promote these characteristics in a cotton fabric. The synthesis of silver nanoparticles and zinc oxide were performed using polyelectrolytes as suspension stabilizers. The syntheses were carried out using four ratios related to the metal concentration and polyelectrolyte (1, 2, 5 and 10%). For silver nanoparticles, the 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl-) was used as stabilizer obtaining nanoparticles of 5 nm in diameter and for ZnO nanoparticles it was used the poly(dialildimethylamonium chloride) PDDA, obtaining in this case particles with sizes larger than 400 nm. These nanocomposites were used to obtain a thin coating on the cotton fibers. For the construction of the films on the cotton fibers, it was used the LbL technique, where it was necessary to perform a prior chemical treatment on the fabric in order to provide an interaction between the cotton fabric surface and the polyelectrolytes. The bilayers were grown in fabrics with the use of polystyrenesulfonate (PSS) as polyanion. Characterization of the fabrics coated with Ag/SiPy+Cl- nanocomposites was performed by varying the number of bilayers. From the SEM images, it was observed the LbL coating on the fabric surface and EDS analysis enabled to estimate the amount of AgNps adsorbed on fabrics. The antibacterial tests for these fabrics showed good results for E. coli and S. aureus bacteria indicating a bactericidal and bacteriostatic character. From the color analysis and UV- Vis spectra of cotton fabrics, it was possible to estimate its homogeneity. Studies of the release of silver nanoparticles were performed by atomic absorption analysis of the washing solution up to 15 washing cycles of the fabric, indicating a high stability of the nanocomposite coating. SEM characterization of the fabrics coated with the nanocomposite ZnO/PDDA showed the growth of the bilayers as well as increase of the ZnO amount on the cotton fiber by the EDS analysis. Through TEM images observed nanoparticles with sizes between 2-10 nm. The analysis of the UV protection factor of these fabrics showed a 60% blockage of UVA and UVB radiations. Studies of photocatalytic degradation of methylene blue dye showed good results degradando totalmente o corante em 8 horas para tecidos revestidos com poucas bicamadas, which increased with the number of bilayers in the fabric. It was observed that in presence of silver nanoparticles, the degradation of the dye becomes more pronounced. The analysis of the shedding of particles of zinc oxide was also performed by atomic absorption analysis of the wash solution until 15 washing cycles. The results for this nanocomposite coated on the fabric also showed satisfactory results.