Filmes de Langmuir-Blodgett de nanopartículas de prata
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Data
2016-02-19
Autores
Assis, Douglas Ricardo de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A auto-organização é uma das ferramentas mais versáteis e mais poderosas para a estruturação de nanopartículas em duas ou três dimensões. A técnica de Langmuir - Blodgett é o método mais promissor para a produção de filmes bidimensionais organizados de tensoativos, polímeros e nanopartículas (NPs), porque proporciona um bom controle da espessura e a homogeneidade da monocamada e de multicamadas. Esse trabalho visa sintetizar nanopartículas de Ag na interface ar-água utilizando filmes de Langmuir-Blodgett de surfactantes como suportes. A síntese das NPs de Ag na interface ar/água foi realizada de acordo com a metodologia de Khomutov e colaboradores. Foi possível sintetizar as NPs de Ag através do espalhamento da mistura das soluções de sulfadiazina de prata e ácido esteárico com razão molar de 1:1. As imagens de microscopia eletrônica de varredura de alta resolução mostram que a ausência de ácido esteárico melhorou a organização das NPs durante a síntese na interface ar/água. A composição química das NPs de prata foi determinada através da espectroscopia de energia dispersiva de raios X acoplada ao microscópio eletrônico operando no modo de varredura. Um estudo comparativo foi feito preparando-se filmes de NPs de Ag. As nanopartículas de Ag recobertas com dodecil sulfato de sódio foram sintetizadas de acordo com o método descrito por Song. As nanopartículas de Ag recobertas com polietilenoglicol (MM ≈ 3400 g.mol-1) e com ácido oléico/oleilamina foram sintetizadas pelo método poliol. Os difratogramas de raios X confirmaram a composição e a fase obtida em cada amostra. Foi estudada a composição do recobrimento das NPs através da espectroscopia na região do infravermelho e quantificado através das análises termogravimétricas. A preparação dos filmes LB de todas as amostras foi feita de acordo com o método descrito por Shin. Através das imagens de microscopia eletrônica de varredura de alta resolução observa-se que somente os filmes LB das nanopartículas de Ag recobertas com ácido oléico e oleilamina apresentam uma organização a longo alcance. Durante a formação dos filmes das amostras recobertas com SDS e com PEG3400 as nanopartículas agregaram prejudicando a organização do sistema. Esse processo de agregação pode ser atribuído a falta de surfactante na superfície das NPs ou ao excesso de polímero que aprisiona as nanopartículas no meio de suas cadeias carbônicas interferindo na organização de NPs.
Self-assembly is one of the most powerful and versatile tools for structuring nanoparticles in two or three dimensions. The Langmuir–Blodgett (LB) technique is the most promising method for production of organized surfactants, polymers, and nanoparticles (NPs) two-dimensional films, because it provides good control of the thickness and homogeneity of the mono and multilayer. This paper aims to synthesize silver nanoparticles in the air-water interface using surfactants Langmuir-Blodgett films such as “templates”. The synthesis of Ag NPs in the air / water interface was performed according the Khomutov methodology [1] it was possible to synthesize Ag NPs by spreading the mixture of silver sulfadiazine solutions and stearic acid molar ratio 1: 1. Field emission gun scanning electron microscope (FEG-SEM) images show that the absence of stearic acid improved the arrangement of NPs during synthesis in the air / water interface. The chemical composition of silver NPs was determined by energy dispersive X-ray spectroscopy attached to the electron microscope operating in scan mode. A comparative study was made preparing Ag NPs films. The Ag nanoparticles coated with sodium dodecyl sulfate were synthesized according to the method described by Song. The Ag nanoparticles coated with polyethylene glycol (MW ≈ 3400 g / mol) and oleic acid / oleylamine was synthesized by the polyol method. The X-ray diffraction confirmed the composition and phase obtained in each sample. It studied the composition of the coating of NPs through spectroscopy in the infrared region and quantified through thermogravimetric analysis. The preparation of LB films of a silver nanoparticles covered with oleic acid and olelamine (Ag@AO/OL) was done according to the methodology described by Shin et al. The images obtained by electron microscopy high resolution scan can be observed that only the LB films of Ag nanoparticles coated with oleic acid and oleylamine have an organization-reaching. During the formation of the films of the other samples the aggregated nanoparticles damaging the system organization. This aggregation process may be attributed to the lack of surfactant on the surface of the NPs or excess polymer which entraps the nanoparticles in the middle of their carbon chains interfering with NPs organization.
Self-assembly is one of the most powerful and versatile tools for structuring nanoparticles in two or three dimensions. The Langmuir–Blodgett (LB) technique is the most promising method for production of organized surfactants, polymers, and nanoparticles (NPs) two-dimensional films, because it provides good control of the thickness and homogeneity of the mono and multilayer. This paper aims to synthesize silver nanoparticles in the air-water interface using surfactants Langmuir-Blodgett films such as “templates”. The synthesis of Ag NPs in the air / water interface was performed according the Khomutov methodology [1] it was possible to synthesize Ag NPs by spreading the mixture of silver sulfadiazine solutions and stearic acid molar ratio 1: 1. Field emission gun scanning electron microscope (FEG-SEM) images show that the absence of stearic acid improved the arrangement of NPs during synthesis in the air / water interface. The chemical composition of silver NPs was determined by energy dispersive X-ray spectroscopy attached to the electron microscope operating in scan mode. A comparative study was made preparing Ag NPs films. The Ag nanoparticles coated with sodium dodecyl sulfate were synthesized according to the method described by Song. The Ag nanoparticles coated with polyethylene glycol (MW ≈ 3400 g / mol) and oleic acid / oleylamine was synthesized by the polyol method. The X-ray diffraction confirmed the composition and phase obtained in each sample. It studied the composition of the coating of NPs through spectroscopy in the infrared region and quantified through thermogravimetric analysis. The preparation of LB films of a silver nanoparticles covered with oleic acid and olelamine (Ag@AO/OL) was done according to the methodology described by Shin et al. The images obtained by electron microscopy high resolution scan can be observed that only the LB films of Ag nanoparticles coated with oleic acid and oleylamine have an organization-reaching. During the formation of the films of the other samples the aggregated nanoparticles damaging the system organization. This aggregation process may be attributed to the lack of surfactant on the surface of the NPs or excess polymer which entraps the nanoparticles in the middle of their carbon chains interfering with NPs organization.
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Palavras-chave
Filmes de Langmuir-Blodgett, Nanopartículas de prata, Sulfadiazina de prata, Langmuir-Blodgett films, Silver nanoparticles, Silver sulfadiazine, Interface ar-água, Air-water interface