Géis nanoestruturados por hidróxidos e óxidos metálicos: uma otimização de sistemas binários de solventes
Data
2023-02-28
Autores
Tabuti, Thiago Galeote 
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
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Resumo
Uma nova metodologia para obtenção de NPs de ZnO baseada em um sistema Glicerol-Ureia (GU) foi criada na EEL-USP e vem sendo otimizada. No presente trabalho foi proposta a troca da ureia por isopropanol e avaliada a influência da proporção molar dos solventes e da temperatura. O resultado dessa substituição foi a obtenção de um gel nanoestruturado com ZnO. No método GU, explorou-se a inflência da quantidade molar dos reagentes sal de zinco:base hidroxílica e da temperatura, onde algumas condições foram determinantes para a formação total de ZnO ou para a obtenção do intermediário Zn(OH)2. Também foi testada uma nova abordagem com um sistema de borbulhamento de amônia em glicerol, que resultou na formação de ZnO com morfologia de agulhas. O método GI foi replicado para o precursor de magnésio, que resultou em um gel formado por Mg(OH)2, que posteriormente gerou novas possibilidades de calcinação (do gel ou do xerogel), resultando em conformações diferentes. A estrutura do gel permite amplas possibilidades de funcionalização a partir da utilização de aditivos para a formação de materiais híbridos e compósitos para determinadas aplicações. Nesse sentido, os géis contendo Zn(OH)2 e Mg(OH)2 foram misturados para formar um material hibrido com ZnO e MgO após a calcinação, o que resultou em morfologias diferentes das esperadas. Os materiais obtidos foram caracterizados por DRX, MEV, MET. Por fim, o ZnO obtido pelo método GU foi aplicado no recobrimento de arcabouços biomédicos e foi avaliada a sua atividade antimicrobiana, gerando resultados promissores.
A new methodology for obtaining ZnO NPs based on a Glycerol-Urea (GU) system was created at EEL-USP and is being optimized. In the present work, the replacement of urea by isopropanol was proposed, and the influence of the molar proportion of solvents and temperature was evaluated. The result of this substitution was to obtain a nanostructured gel with ZnO. In the GU method, the influence of the molar amount of the zinc salt:hydroxyl base reagents and the temperature is explored, where some conditions were determinant for the total formation of ZnO or for obtaining the Zn(OH)2 stage. Also a novel approach with an ammonia-glycerol bubbling system was done, which resulted in the formation of ZnO with needle-like morphology. The GI method was replicated for the magnesium precursor, which resulted in a gel formed by Mg(OH)2, which later generated new calcination possibilities (of the gel or of the xerogel), generating different conformations. The gel structure allows wide functionalization possibilities from the use of additives for the formation of hybrid materials and compounds for certain applications. In this sense, the gels containing Zn(OH)2 and Mg(OH)2 were mixed to form a hybrid material with ZnO and MgO after calcination, which resulted in morphologies different from those expected. The obtained materials were characterized by XRD, SEM, TEM. Finally, the ZnO obtained by the GU method was applied in the coating of biomedical scaffolds and its antimicrobial activity was evaluated, generating promising results.
A new methodology for obtaining ZnO NPs based on a Glycerol-Urea (GU) system was created at EEL-USP and is being optimized. In the present work, the replacement of urea by isopropanol was proposed, and the influence of the molar proportion of solvents and temperature was evaluated. The result of this substitution was to obtain a nanostructured gel with ZnO. In the GU method, the influence of the molar amount of the zinc salt:hydroxyl base reagents and the temperature is explored, where some conditions were determinant for the total formation of ZnO or for obtaining the Zn(OH)2 stage. Also a novel approach with an ammonia-glycerol bubbling system was done, which resulted in the formation of ZnO with needle-like morphology. The GI method was replicated for the magnesium precursor, which resulted in a gel formed by Mg(OH)2, which later generated new calcination possibilities (of the gel or of the xerogel), generating different conformations. The gel structure allows wide functionalization possibilities from the use of additives for the formation of hybrid materials and compounds for certain applications. In this sense, the gels containing Zn(OH)2 and Mg(OH)2 were mixed to form a hybrid material with ZnO and MgO after calcination, which resulted in morphologies different from those expected. The obtained materials were characterized by XRD, SEM, TEM. Finally, the ZnO obtained by the GU method was applied in the coating of biomedical scaffolds and its antimicrobial activity was evaluated, generating promising results.