Preparação e caracterização de compósitos de poli(metacrilato de metila) e óxido de titânio
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2020-02-14
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Universidade Estadual Paulista (Unesp)
Resumo
As aplicações usando óxidos de metais de transição são cada vez mais estudadas. O óxido de titânio é um material de baixo custo, abundante na natureza e possui ótimas propriedades físico-químicas na área de fotocatálise e luminescência, podendo assim participar do processo de fotocromismo. O poli(metacrilato de metila) é um polímero rígido e transparente, com aplicações em diversos setores. Neste presente trabalho, ambos os materiais foram usados para produzir compósitos, tendo como matriz o poli(metilmetacrilato) introduzido ou o óxido de titânio (TiO2). Os compósitos foram preparados por deposição (casting), segundo a metodologia desenvolvida anteriormente pelo Grupo de Vidros de Cerâmicos (GVC) da UNESP de Ilha Solteira. Foram produzidos compósitos com diferentes concentrações de TiO2 (10%, 20%, 30% e 40%) em relação à massa do polímero. Caracterizações por meio de Microscopia Eletrônica de Varredura (MEV), Ultravioleta e Visível (UV-Vis), Difração de Raios X (DRX), Espectro de Luminescência e Termogravimetria (TG) foram realizadas. A partir das análises das micrografias, foi possível observar que os compósitos não apresentaram homogeneidade de acordo com a técnica de preparo usada. Pelas análises por espectroscopia por energia dispersiva (EDS), foi possível detectar uma pequena quantidade do dopante disperso na matriz. A banda proibida (band gap) do material demonstrou uma diferença de valor com o aumento da concentração de TiO2. A partir das medidas de DRX, foi possível verificar que a matriz é predominantemente amorfa e que, com a adição do dopante, não houve formação de regiões cristalinas. Os resultados obtidos foram decorrentes das baixas concentrações de TiO2 utilizadas ou então pela heterogeneidade da amostra. Os espectros de luminescência indicaram que o material apresentou uma capacidade de emissão e excitação favorável e que 20% de TiO2 na matriz leva a uma melhora na luminescência, quando se compara com as demais concentrações de agente dopante que foram testadas. Com isso, conclui-se que à medida que se aumenta a porcentagem de TiO2 há uma supressão do efeito luminescente. Já as análises termogravimétricas foram importantes para determinar a estabilidade térmica do material, uma vez que conhecer tal propriedade é de extrema importância para o processamento e aplicação desse tipo de material. Por fim, ressalta-se que foi possível obter compósitos de poli(metacrilato de metila) com TiO2 e caracterizá-los quanto às suas propriedades físico-químicas, e que, embora tais compósitos não tenham apresentados um efeito fotocrômico imediato, o presente estudo ajudará em trabalhos futuros, como por exemplo, na otimização do método que aqui foi proposto para a obtenção dos compósitos.
Applications that use transition metal oxides are increasingly studied. Titanium oxide is a low-cost material, abundant in nature, and has excellent physical-chemical characteristics in the area of photocatalysis and luminescence, thus being able to participate in the photochromism process. Poly (methyl methacrylate) is a rigid and transparent polymer, with applications in several sectors. In this work, both materials were used to produce compounds, having as matrix or introduced poly (methylmethacrylate) or titanium oxide (TiO2). The compounds were prepared by deposition (casting), according to the method previously developed by the Ceramics Glass Group (GVC) at UNESP in Ilha Solteira. Compounds with different types of TiO2 (10%, 20%, 30% and 40%) in relation to the polymer mass were used. Characterizations by Scanning Electron Microscopy (SEM), Ultraviolet and Visible (UV-Vis), X-Ray Diffraction (XRD), Luminescence Spectrum and Thermogravimetry (TG) were submitted. From the analysis of the micrographs, it was possible to observe that the compounds were not homogenized, according to the preparation technique used. The lamps analyzed by dispersive energy spectroscopy (EDS), were possible to detect a small amount of dispersed dopant in the matrix. A prohibited band (band gap) of the material showed a difference in value with the increase in the concentration of TiO2. From the XRD measurements, it was possible to verify whether the matrix is predominantly amorphous and, with the addition of dopant, there was no training of crystalline regions. The results obtained were low in TiO2 used or else due to the heterogeneity of the sample. The luminescence spectra indicates that the material has a favorable emission and excitation capacity, and 20% of TiO2 in the matrix leads to an improvement in luminescence when compared with the other items of the agent that were tested. Thus, it is concluded that as the percentage of TiO2 increases, it suppresses the luminescent effect. Since thermogravimetry was important to determine the thermal stability of the material, once you know the property it is extremely important for the processing and application of this type of material. Finally, it should be noted that it was possible to obtain poly (methyl methacrylate) composites doped with TiO2 and including how much their chemical-physical products are, and that, although these compounds were not affected by the immediate photochromic effect, the present study will help in future work, for example, in the optimization of the method proposed here to use the compounds.
Applications that use transition metal oxides are increasingly studied. Titanium oxide is a low-cost material, abundant in nature, and has excellent physical-chemical characteristics in the area of photocatalysis and luminescence, thus being able to participate in the photochromism process. Poly (methyl methacrylate) is a rigid and transparent polymer, with applications in several sectors. In this work, both materials were used to produce compounds, having as matrix or introduced poly (methylmethacrylate) or titanium oxide (TiO2). The compounds were prepared by deposition (casting), according to the method previously developed by the Ceramics Glass Group (GVC) at UNESP in Ilha Solteira. Compounds with different types of TiO2 (10%, 20%, 30% and 40%) in relation to the polymer mass were used. Characterizations by Scanning Electron Microscopy (SEM), Ultraviolet and Visible (UV-Vis), X-Ray Diffraction (XRD), Luminescence Spectrum and Thermogravimetry (TG) were submitted. From the analysis of the micrographs, it was possible to observe that the compounds were not homogenized, according to the preparation technique used. The lamps analyzed by dispersive energy spectroscopy (EDS), were possible to detect a small amount of dispersed dopant in the matrix. A prohibited band (band gap) of the material showed a difference in value with the increase in the concentration of TiO2. From the XRD measurements, it was possible to verify whether the matrix is predominantly amorphous and, with the addition of dopant, there was no training of crystalline regions. The results obtained were low in TiO2 used or else due to the heterogeneity of the sample. The luminescence spectra indicates that the material has a favorable emission and excitation capacity, and 20% of TiO2 in the matrix leads to an improvement in luminescence when compared with the other items of the agent that were tested. Thus, it is concluded that as the percentage of TiO2 increases, it suppresses the luminescent effect. Since thermogravimetry was important to determine the thermal stability of the material, once you know the property it is extremely important for the processing and application of this type of material. Finally, it should be noted that it was possible to obtain poly (methyl methacrylate) composites doped with TiO2 and including how much their chemical-physical products are, and that, although these compounds were not affected by the immediate photochromic effect, the present study will help in future work, for example, in the optimization of the method proposed here to use the compounds.
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Palavras-chave
Polímeros, Deposição (Casting), Óxidos de metais de transição, Oxides of transition metals, Polymers, Casting