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Estudo de Dinâmicas de Criação de Birrefringência em Materiais com Azobenzenos
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Neste trabalho estudou-se as dinâmicas de criação e relaxação de birrefringência em ma-
teriais contendo azobenzenos, em função de parâmetros como o comprimento de onda e
a potência do laser de escrita, a criação de birrefringência em ciclos sucessivos e o trata-
mento térmico das amostras.
Nesse sentido, foram preparados filmes finos camada sobre camada a partir dos poli-
eletrólitos Poli[1-[4-(3-carboxi-4-hidroxifenilazo) - benzenesulfonamida)-1,2-etanodiil]
. sal de sódio] (PAZO) e Poli(cloreto de alilamina) (PAH) e filmes de derramamento de
PAZO. O crescimento de filmes camada sobre camada foi analisado através da medição da
sua absorvância, que foi medida com recurso a espetrofotometria de ultravioleta-visível.
As medições das dinâmicas de escrita e relaxação de birrefringência dos filmes foram
efetuadas com recurso a uma montagem experimental de criação de birrefringência com
lasers de escrita de 532, 450 e 405nm e um laser de medida de 633nm.
Os resultados experimentais mostram que o crescimento de filmes camada sobre
camada depende do aumento da concentração de PAZO, do número de bicamadas e do
tempo de exposição a PAZO. Quanto ao crescimento da birrefringência, este é afetado
tanto pelo comprimento de onda do laser de escrita como pela sua potência. Os efeitos
térmicos são muito atenuados após o primeiro ciclo de escrita. O valor de birrefringência
máximo calculado é de 0.155.
In this project, birefringence creation and relaxation dynamics in azobenzene containing materials were studied, as a function of parameters such as the wavelength and power of the writing laser, the creation of birefringence in successive cycles and the thermal treatment of the samples. In this regard, layer-by-layer thin films were prepared from Poly[1-[4-(3-carboxy-4- hydroxyphenylazo)-benzenesulfonamide)-1,2-ethanediyl] polyelectrolytes. sodium salt] (PAZO) and Poly(allylamine chloride) (PAH) and casting thin films were prepared using PAZO. The growth of layer-by-layer films was analyzed by measuring their absorbance, which was measured using ultraviolet-visible spectrophotometry. Measurements of the birefringence creation and relaxation dynamics of the films were performed using an experimental setup of birefringence creation with 532, 450 and 405nm writing lasers and a 633nm measuring laser. The experimental results show that the growth of layer-by-layer films depends on the increase in PAZO concentration, the number of bilayers and the time of exposure to PAZO. As for the growth of birefringence, it is affected both by the wavelength of the writing laser and by its power. Thermal effects are greatly mitigated after the first writing cycle. The maximum calculated birefringence value is 0.155.
In this project, birefringence creation and relaxation dynamics in azobenzene containing materials were studied, as a function of parameters such as the wavelength and power of the writing laser, the creation of birefringence in successive cycles and the thermal treatment of the samples. In this regard, layer-by-layer thin films were prepared from Poly[1-[4-(3-carboxy-4- hydroxyphenylazo)-benzenesulfonamide)-1,2-ethanediyl] polyelectrolytes. sodium salt] (PAZO) and Poly(allylamine chloride) (PAH) and casting thin films were prepared using PAZO. The growth of layer-by-layer films was analyzed by measuring their absorbance, which was measured using ultraviolet-visible spectrophotometry. Measurements of the birefringence creation and relaxation dynamics of the films were performed using an experimental setup of birefringence creation with 532, 450 and 405nm writing lasers and a 633nm measuring laser. The experimental results show that the growth of layer-by-layer films depends on the increase in PAZO concentration, the number of bilayers and the time of exposure to PAZO. As for the growth of birefringence, it is affected both by the wavelength of the writing laser and by its power. Thermal effects are greatly mitigated after the first writing cycle. The maximum calculated birefringence value is 0.155.