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Previous issue date: 2014-02-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / A associa??o entre pol?meros e sais i?nicos, por intera??o f?sica, ? uma forma eficiente
de prepara??o de filmes com interessantes propriedades mec?nica e el?trica. Embora a
combina??o f?sica entre os pol?meros e os sais e a obten??o de filme autossustent?vel pelo
m?todo de evapora??o possa ser facilmente conseguida, as propriedades desse novo composto
pode ser bem diferentes dos componentes separados. Este trabalho descreve as novas
propriedades el?tricas do comp?sito alginato de s?dio/poli(etileno glicol)/glicerol sem e com
modifica??o com os sais de tungstato de s?dio e tetrabut?xido de tit?nio atrav?s de intera??es
f?sicas entres eles. A prepara??o do filme se deu pelo m?todo sol-gel, tanto da matriz
polim?rica pura (alginato de s?dio/poli(etileno glicol)/glicerol) como da matriz polim?rica
dopada com diferentes al?quotas, 1, 2, 3 e 4 mL, da solu??o de tungstato de s?dio na
concentra??o de 1mmol/L e, 0,1, 0,2, 0,3 e 0,4 mL de tetrabut?xido de tit?nio, adicionadas
diretamente na matriz; em uma amostra da mistura polim?rica, tamb?m foi estudada a mistura
das maiores concentra??es dos dois sais associados. Os filmes foram caracterizados atrav?s da
reflex?o total atenuada (ATR), difratometria de raios X (DRX), microscopia eletr?nica de
varredura (MEV), espectroscopia de raios X por dispers?o de energia (EDS) e as
contribui??es dos sais nas propriedades el?tricas dos filmes foram analisadas atrav?s da
espectroscopia de imped?ncia eletroqu?mica (EIE). O filme de alginato de s?dio com o
poli(etileno glicol) apresenta rigidez mec?nica dificultando a trabalhabilidade do filme,
entretanto, a adi??o do glicerol reduz as for?as intermoleculares entre as cadeias polim?ricas
diminuindo essa fragilidade devido ao pequeno tamanho da cadeia, permitindo que seja
inserido com mais facilidade entre as cadeias polim?ricas e, consequentemente, exer?a maior
influ?ncia sobre as propriedades mec?nicas do que a maior mol?cula do poli(etileno glicol).
As intera??es f?sicas s?o comprovadas atrav?s dos espectros de ATR. As bandas
caracter?sticas do alginato n?o s?o deslocadas e ocorre aumento da ?rea das bandas e
favorecimento de vibra??es na presen?a do glicerol. Os difratogramas evidenciaram a
predomin?ncia do comportamento amorfo nos filmes. As an?lises de MEV mostraram a
predomin?ncia de uma superf?cie mais lisa quando o glicerol est? presente nos filme e, na
presen?a dos sais, as micrografias apresentam a exist?ncia de poros e irregularidade
superficiais, assim como, heterogeneidade. Quando os sais est?o associados no mesmo filme
h? a predomin?ncia de distribui??o de microestruturas. Atrav?s da EIE observou-se que a
associa??o do glicerol e PEG no filme de NaAlg produz um comportamento caracter?stico de
transporte de carga com uma condutividade na ordem de 10-4 ??1
.cm
-1. Quando o comp?sito
est? associado com o tungstato de s?dio apresenta um comportamento de armazenamento de
carga e, quando a associa??o ? com o tetrabut?xido de tit?nio o transporte de carga ?
favorecido, sendo esse comportamento observado tamb?m no filme com a mistura dos sais,
gerando valor de condutividade na ordem de 10-3 ??1
.cm
-1. A associa??o dos sais na matriz
polim?rica aumenta a mobilidade i?nica extr?nseca do comp?sito e melhora suas propriedades
condutoras. / The association between polymers and ionic salts by physical interaction, is an
efficient way of making films with interesting mechanical and electrical properties. Although
physical combination of polymers and salts and the obtaining of self-sustaining film by
evaporation method can be easily achieved, the properties of this new compound may be
different from the separate components. This work describes the electrical properties of new
composite sodium alginate/poly(ethylene glycol)/glycerol with and without modification with
the salts of sodium tungstate and titanium tetrabutoxide through physical interactions among
them. The preparation of the film made by the sol-gel method, both the pure polymer matrix
(sodium alginate/poly (ethylene glycol)/glycerol) and the polymeric matrix doped with
varying rates 1, 2, 3 and 4 mL solution of sodium tungstate at a concentration of 1 mmol/L,
and 0,1, 0,2, 0,3, and 0,4 ml of titanium tetrabutoxide in a sample of the polymer mixture, was
studied the mixture of higher concentrations of the two salts associated. The films were
characterized by attenuated total reflection (ATR), X-ray diffraction (XRD), scanning
electron microscopy (SEM), X-Ray Spectroscopy Energy Dispersive (EDS) and the
contributions of salts on the electrical properties of the films were analyzed by
electrochemical impedance spectroscopy (EIS). The film of sodium alginate with poly
(ethylene glycol) has mechanical rigidity making it difficult the workability of the film,
however, the addition of glycerol reduces the intermolecular forces between the polymer
chains reducing such fragility due to the small size of the chain, allowing it to be inserted
more easily in the polymer chain, and thus exert greater influence on the mechanical
properties of the poly(ethylene glycol) larger molecule. Physical interactions are proven
through the ATR spectra. The characteristics bands of alginate are not displaced, increasing
the area of the bands and favors of vibrations in the presence of glycerol occurs. The XRD
patterns showed the predominance of the behavior amorphous in films. SEM analyzes showed
the predominance of a smoother surface when glycerol is present in the film, and when the
salts are associated micrographs show the existence of pores and surface irregularities, as well
as heterogeneity. When salts are associated in the same film there is a predominant
distribution of microstructures. Through the EIS it was observed that the association of
glycerol and PEG in NaAlg film produces a characteristic behavior of charge transport with a
conductivity on the order of 10-4 ?-1
.cm
-1. When the composite is associated with sodium
tungstate presents a charge storage behavior, and when the association is with the titanium
tetrabutoxide charge transport is favored, and in the film with the mixture of the salts the
conductivity value is in the order 10-3 ?
-1
.cm
-1. The association of salts increases the extrinsic
ionic mobility of the composite and improvement in their conductive properties.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/19802 |
| Date | 28 February 2014 |
| Creators | Silva, C?ssia Miriam Lucas da |
| Contributors | 10843329491, http://lattes.cnpq.br/2069510469317474, Huitle, Carlos Alberto Martinez, 01139059980, http://lattes.cnpq.br/2485073932883264, Silva, Djalma Ribeiro da, 13893734449, http://lattes.cnpq.br/2791074318745945, Costa, Jos? Alzamir Pereira da, 16357671720, http://lattes.cnpq.br/5592146590288686, Castro, Suely Souza Leal de, 05705753896, http://lattes.cnpq.br/9860381828526444, Cavalcante, Maria Gorette |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM QU?MICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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