Síntese de partículas ocas de óxido de alumínio e funcionalização de superfície para incorporação em matriz de PVA

• Ano de defesa: 2023
• Autor(a) principal: Arcanto, João Pedro Massaria de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Química; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Química
• Palavras-chave em Português: Óxido metálico; Alumina; Partículas ocas; Hard template; Álcool polivinílico; Compósitos; subject.br-rjbn; Química
• Link de acesso: http://repositorio.ufes.br/handle/10/17100

The addition of metal oxides to polymer matrices creates composites with superior mechanical properties, such as increased rigidity and toughness. Inorganic fillers, in general, can also be used to increase these properties. The use of nanoparticulate fillers is studied for the synthesis and characterization of nanostructured materials, including the recently classified "hollow nanoparticles", which have interesting properties such as lower density and greater specific surface area. The hard template synthesis method is highlighted by its versatility and low cost, making it possible to obtain hollow particles of metal oxides. In this work the synthesis of hollow Al2O3 particles was conducted through a hydrothermal route, using glucose as a precursor for a carbonaceous mold. This mold is spherical, approximately 700 nm in diameter, and are composed of polycondensed aromatic rings and oligosaccharides remaining from the hydrothermal decomposition of glucose. The Al2O3 particles were characterized by FTIR, which indicated that the surface has adsorbed water molecules, and X-ray diffraction indicated that the composition is mostly γ- Al2O3 (HALO). SEM images show that morphology of HALO is spherical, approximately 398 nm mean diameter, composed of wrinkled hollow shells. The HALOs were solvothermally functionalized with terephthalic acid in a bench top reactor, and the surface binding was confirmed by FTIR analysis (HALO-T). PVA films were prepared by adding a plasticizing agent (glucose) and varying fillers of HALO (APC) and HALO-T (ATC). Universal testing machine tests showed that films with 1% (w/w) HALO-T are 340% stiffer and require 2 times more energy to rupture, than films additivated with 1% HALO. Atomic force microscopy images corroborate this result, showing that the average surface roughness is higher for ATC and that such films have higher specific surface area, compared to the APC film.