Síntese, caracterização e estudo de nanocompósitos com matriz polimérica de PMMA e nanopartículas de CeO2
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Data
2022-08-29
Autores
Palazzo, Ana Eliza Castro Sobreira
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Universidade Estadual Paulista (Unesp)
Resumo
A nanotecnologia possui grande potencial de aplicação para melhoria de propriedades de matrizes poliméricas. Especificamente, neste trabalho, foram desenvolvidos nanocompósitos tendo como base a matriz polimérica de poli[1-(metoxicarbonil)-1-metil etileno] (PMMA) e enchimento de nanopartículas de óxido de cério (CeO2), de característica semicondutora. Para a realização deste trabalho, as nanopartículas de CeO2 foram sintetizadas a partir do método de precipitação química. Para este processo foram testadas duas diferentes metodologias de funcionalização superficial utilizando-se ou o surfactante aniônico dodecil sulfato de sódio (DSS) ou o ácido hexadecanóico (C16H32O2), também conhecido como ácido palmítico, um representante de cadeia longa do grupo dos ácidos carboxílicos, como ligantes modificadores da superfície das nanopartículas, de forma a propiciar o processo de incorporação na matriz polimérica. Para a síntese dos filmes de nanocompósitos, utilizou-se o método da mistura direta e evaporação do solvente, em diferentes protocolos de incorporação das nanopartículas na matriz. Para a caracterização das propriedades das amostras produzidas foram realizados estudos de termogravimetria (TGA), de calorimetria exploratória diferencial (DSC), de microscopia eletrônica de varredura (MEV), de espectroscopia de absorção na região do infravermelho (FTIR), espectroscopia RAMAN e difratometria de raios-X pelo método de pó (DRX). Os filmes de nanocompósitos de PMMA/CeO2 foram comparados com filmes de PMMA puro, indicando que, termicamente, o nanocompósito mantém as características principais da matriz de PMMA. A temperatura de transição vítrea dos nanocompósitos varia conforme o método de síntese e a funcionalização da superfície aplicada às nanopartículas. Por DRX, quando há adequada incorporação e dispersão das nanopartículas, observa-se os picos característicos dos planos cristalinos do CeO2 no nanocompósito e, por MEV, são avaliadas as suas microestruturas, analisando-se a dispersão. Os resultados obtidos mostraram que os protocolos testados de síntese do nanocompósito pretendido, com funcionalização tanto in-situ quanto ex-situ, foram adequados, porém, especificamente, para o protocolo ex-situ por transferência de fase com ácido palmítico, há ainda certa incerteza quanto à dispersão adequada das nanopartículas de CeO2 no PMMA, tendo a funcionalização in-situ, com DSS, apresentado-se mais promissora.
Nanotechnology has great application potential for improving the properties of polymeric matrices. Specifically, in this work, nanocomposites were developed based on the Poly(methyl 2-methylpropenoate), PMMA, polymer matrix and filled with cerium oxide (CeO2) nanoparticles, which has semiconductor characteristic. CeO2 nanoparticles were synthesized by the chemical precipitation method and two different methodologies of surface functionalization were tested using either anionic surfactant (DSS) or hexadecanoic acid (C16H32O2), also known as palmitic acid, a long-chain representative of the carboxylic acid group, as nanoparticle surface modifying ligands, in order to provide the process of incorporation into the polymer matrix. For the synthesis of the nanocomposite films, the method of direct mixing and solvent evaporation (casting) were used in different protocols of nanoparticles incorporation on polymer matrix. To characterize the properties of the produced samples, thermogravimetry (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), infrared absorption spectrum (FTIR), RAMAN spectroscopy and powder X-ray diffraction (XRD) studies were carried out. The PMMA/CeO2 nanocomposite films were compared with pure PMMA films, indicating that, thermally, the nanocomposite maintains the main characteristics of the PMMA matrix. The glass transition temperature of nanocomposites varies according to the synthesis method and surface functionalization applied to the nanoparticles. By XRD, when there is adequate incorporation and dispersion of the nanoparticles, the characteristic peaks of the CeO2 crystalline planes are observed in the nanocomposites and, by SEM, their microstructures are evaluated, intending to verify the dispersion. The obtained results showed that the tested synthesis protocols for the intended nanocomposite, with either in-situ or ex-situ functionalization, were satisfactory, however, specifically, for the ex-situ protocol by phase transfer with palmitic acid, there is some uncertainty as to the adequate dispersion of CeO2 nanoparticles in PMMA, being DSS ex-situ functionalization the most promising one.
Nanotechnology has great application potential for improving the properties of polymeric matrices. Specifically, in this work, nanocomposites were developed based on the Poly(methyl 2-methylpropenoate), PMMA, polymer matrix and filled with cerium oxide (CeO2) nanoparticles, which has semiconductor characteristic. CeO2 nanoparticles were synthesized by the chemical precipitation method and two different methodologies of surface functionalization were tested using either anionic surfactant (DSS) or hexadecanoic acid (C16H32O2), also known as palmitic acid, a long-chain representative of the carboxylic acid group, as nanoparticle surface modifying ligands, in order to provide the process of incorporation into the polymer matrix. For the synthesis of the nanocomposite films, the method of direct mixing and solvent evaporation (casting) were used in different protocols of nanoparticles incorporation on polymer matrix. To characterize the properties of the produced samples, thermogravimetry (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), infrared absorption spectrum (FTIR), RAMAN spectroscopy and powder X-ray diffraction (XRD) studies were carried out. The PMMA/CeO2 nanocomposite films were compared with pure PMMA films, indicating that, thermally, the nanocomposite maintains the main characteristics of the PMMA matrix. The glass transition temperature of nanocomposites varies according to the synthesis method and surface functionalization applied to the nanoparticles. By XRD, when there is adequate incorporation and dispersion of the nanoparticles, the characteristic peaks of the CeO2 crystalline planes are observed in the nanocomposites and, by SEM, their microstructures are evaluated, intending to verify the dispersion. The obtained results showed that the tested synthesis protocols for the intended nanocomposite, with either in-situ or ex-situ functionalization, were satisfactory, however, specifically, for the ex-situ protocol by phase transfer with palmitic acid, there is some uncertainty as to the adequate dispersion of CeO2 nanoparticles in PMMA, being DSS ex-situ functionalization the most promising one.
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Palavras-chave
Nanocompósito, PMMA, CeO2, Funcionalização superficial, Transferência de fase, Revestimento funcional, Nanocomposite, Surface Functionalization, Phase Transfer, Functional Coating, Nanocompósitos (Materiais), Materiais compostos, Compósitos poliméricos, Nanotecnologia