Estudo da influência do tamanho de cadeias poliméricas nas propriedades óticas e térmicas de polímeros conjugados
Arquivos
Data
2022-11-23
Autores
Custodio, Marina Carvalho 
Orientadores
Philadelphi, Laura Oliveira Péres
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Atualmente, existe uma grande quantidade de trabalhos científicos envolvendo polímeros conjugados, sendo estes materiais sintetizados por diferentes rotas. Conhecer as particularidades moleculares de um material como estrutura, composição e conformação é imprescindível para a determinação de suas aplicações. Polímeros conjugados são polímeros que possuem ligações duplas e simples alternadas em sua cadeia. Portanto, a caracterização de polímeros é demasiado significante, posto que a massa molar média, as ramificações e até mesmo os grupos terminais influenciam nas propriedades de cada material. Desta forma, o presente trabalho apresenta a relação entre a massa molar de polímeros conjugados (polifluorenos e politiofenos) com suas propriedades térmicas e ópticas. Esse estudo foi realizado utilizando-se técnicas analíticas como a Espectroscopia do UV-Visível e a Termogravimetria, além da obtenção da massa molar média (Mw) obtida via Cromatografia de Permeação em Gel (GPC), técnica essa que possui limitações que acabaram apontando resultados divergentes. Os resultados obtidos indicam que existe uma dependência das propriedades ópticas e térmicas com a massa molar. Espectros de absorção no UV-Visível demonstraram deslocamentos dos máximos de absorção para maiores comprimentos de onda à medida que se tem o aumento da massa molar do polímero, além da influência da polidispersividade. A partir das curvas de termodegradação observa-se que além da influência das massas molares, tem-se a influência da estrutura polimérica nos valores de Tonset atingidos.
Many scientific works have been written about organic conducting polymers and the many ways They can be employed and synthesized. Knowing the molecular particularities of a given material such as its structure, composition and conformation is indispensable when trying to determine its possible applications. Therefore, Polymer Characterization is of utmost importance, given that the molar mass, ramifications and even end-groups influence the properties of any material. In the present work we studied the correlation between the molar mass of conducting polymers (polyfluorenes and polythiophenes) and their thermal and optical properties. This work was conducted using simple and easily accessible techniques, such as Visible UV Spectroscopy and Thermogravimetric Analysis, as well as Gel Permeation Chromatography (GPC) which was used to find the weight averaged molecular weight (Mw) of the samples but due to its limitations ended up presenting controversial results. The results indicate that there is a correlation between the molar mass of a material and its thermal and optical properties. The Visible UV Spectroscopy data demonstrated an increase in the maximum absorption of higher wavelengths as the molar mass of the polymer increased, it also revealed the influence of polydispersity. Analyzing the thermal degradation curves we also observed that in addition to the influence of molar mass the polymeric structure also plays a role in the Tonset values obtained.
Many scientific works have been written about organic conducting polymers and the many ways They can be employed and synthesized. Knowing the molecular particularities of a given material such as its structure, composition and conformation is indispensable when trying to determine its possible applications. Therefore, Polymer Characterization is of utmost importance, given that the molar mass, ramifications and even end-groups influence the properties of any material. In the present work we studied the correlation between the molar mass of conducting polymers (polyfluorenes and polythiophenes) and their thermal and optical properties. This work was conducted using simple and easily accessible techniques, such as Visible UV Spectroscopy and Thermogravimetric Analysis, as well as Gel Permeation Chromatography (GPC) which was used to find the weight averaged molecular weight (Mw) of the samples but due to its limitations ended up presenting controversial results. The results indicate that there is a correlation between the molar mass of a material and its thermal and optical properties. The Visible UV Spectroscopy data demonstrated an increase in the maximum absorption of higher wavelengths as the molar mass of the polymer increased, it also revealed the influence of polydispersity. Analyzing the thermal degradation curves we also observed that in addition to the influence of molar mass the polymeric structure also plays a role in the Tonset values obtained.