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Doctoral Thesis
DOI
https://doi.org/10.11606/T.88.2011.tde-25092011-171004
Document
Author
Full name
Ritamara Isis de Mattos
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2011
Supervisor
Committee
Maule, Agnieszka Joanna Pawlicka (President)
Cavalheiro, Carla Cristina Schmitt
Magon, Claudio Jose
Oliveira, Adilson Jesus Aparecido de
Walmsley, Lygia Christina de Moura
Title in Portuguese
Estudo de condutores protônicos a base de macromoléculas naturais
Keywords in Portuguese
Blendas
Condutividade iônica
Condutor protônico
Eletrólitos poliméricos
Gelatina
Polímeros naturais
Quitosana
RMN
RPE
Abstract in Portuguese
Esta tese apresenta os resultados do estudo de eletrólitos poliméricos protônicos obtidos a base de gelatina e quitosana, modificadas através da adição de glicerol e formaldeído - ácidos acético ou clorídrico foram adicionados para promover a condutividade iônica dos filmes. Foram também preparadas blendas a partir de gelatina com quitosana, assim como filmes a base de gelatina e nanopartículas. Com exceção dos filmes com nanopartículas, todos eles possuem boa transparência, estabilidade térmica, maleabilidade, aderência ao vidro e apresentam uma superfície homogênea, sem trincas ou rachaduras. As temperaturas de transição vítrea (Tg) dos eletrólitos foram obtidas do estreitamento de linha de RMN. A taxa de relaxação spin-rede do 'ANTPOT. 1 H' em função da temperatura mostrou um máximo bem definido cuja posição depende da concentração de ácido no caso da gelatina e da quantidade de glicerol no caso da quitosana, refletindo a alta mobilidade do próton nestes eletrólitos. As técnicas de RPE, onda contínua e pulsada, foram utilizadas para o estudo de eletrólitos dopados com 'CU'CL'O IND.4'. Os valores de condutividade iônica dos eletrólitos são da ordem de '10 POT.-5' S/cm para os filmes de gelatina (com ácido acético ou clorídrico), quitosana e blendas e entre '10 POT.-6' a '10 POT.-8' para os eletrólitos de gelatina com nanopartículas. Estes estudos revelaram que a concentração de ácido acético ou clorídrico (na gelatina), influencia a condutividade iônica dos eletrólitos, mas, para o caso das blendas esta influência é pequena. No caso dos filmes de gelatina com nanopartículas, a condutividade diminui de forma significativa. Em relação aos eletrólitos de quitosana a condutividade iônica é influenciada pela quantidade de glicerol adicionado. Verificou-se que o aumento da temperatura até 80°C promove o aumento da condutividade iônica para todos os filmes estudados.
Title in English
Study of protonic conductors based on natural macromolecules
Keywords in English
Blends
Chitosan
EPR
Gelatin
Ionic conductivity
Natural polymer
NMR
Polymer electrolytes
Proton conductor
Abstract in English
This thesis shows the results from the study of protonic polymer electrolytes obtained from gelatin and chitosan, modified by the addition of glycerol and formaldehyde - acetic and hydrochloric acids are added to promote the ionic conductivity of the films. Blends based on chitosan and gelatin were also prepared, as well as films based on gelatin and nanoparticles. With the exception of the films with nanoparticles, all samples presented good transparency, thermal stability, flexibility, adhesion to glass and homogeneous surface without cracks. The glass transition temperature (Tg) of the electrolytes were obtained from the NMR line narrowing. The spin-lattice relaxation rate of the 'ANTPOT. 1 H' spin-network as a function of temperature showed a well-defined maximum whose position depends on the concentration of acid in the case of gelatin and on the glycerol content in the case of chitosan, reflecting the high mobility of the protons in the electrolytes. Continuous wave and pulsed EPR techniques were used to study the electrolytes doped with 'CU'CL'O IND.4'. The values of the ionic conductivity of the electrolytes are of the order of '10 POT.-5' S/cm for the films of gelatin (with acetic or hydrochloric acids), chitosan and blends and from '10 POT.-6' to '10 POT.-8' for the electrolytes of gelatin with nanoparticles. These studies revealed that the concentration of acetic or hydrochloric acids (in gelatin), influences the ionic conductivity of the electrolytes but, in the case of blends, this influence is small. In the case of the films based on gelatin with nanoparticles, the ionic conductivity decreases significantly. In relation to the electrolyte based on chitosan, the ionic conductivity is influenced by the amount of glycerol added. It was found that increasing the temperature to 80°C promotes the increase of ionic conductivity for all films studied.
 
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Publishing Date
2012-08-03
 
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