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Master's Dissertation
DOI
10.11606/D.46.2006.tde-16092006-145739
Document
Author
Full name
Leonardo da Silva Bonifácio
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2006
Supervisor
Committee
Toma, Henrique Eisi (President)
Corio, Paola
Winnischofer, Herbert
Title in Portuguese
Processos de agregação e fusão de nanopartículas de ouro: Uma abordagem química
Keywords in Portuguese
Nanopartículas
Teoria de Mie
Abstract in Portuguese
Sob o olhar nanotecnológico, a dimensionalidade passa a ser um fator preponderante nas propriedades dos materiais. O ouro metálico com dimensões reduzidas para a escala nanométrica passa a exibir um comportamento peculiar em termos de sua estrutura eletrônica e reatividade. No trabalho realizado busca-se um melhor entendimento das propriedades das nanopartículas de ouro através de um abordagem química, com foco nas interações superficiais e suas correlações com fenômenos de agregação. No campo mais fundamental, foram realizados estudos visando entender a influência de ligantes de diferentes comprimentos de cadeia nos processos de agregação e de fusão de nanopartículas, utilizando-se para tal ligantes de interesse para a química supramolecular: pirazina, 4,4'-bipiridina, 1,2-bis (4-piridil)etano e 1,4-bis[(4-piridil)etenil]benzeno. Além disso, foram realizados estudos que permitiram a obtenção de nanopartículas de ouro passivadas com o complexo [Fe(CN)5(4-pySH)]3-,gerando um bloco de contrução interessante para a geração de materiais nanoestruturados a partir de ligações do tipo azul da Prússia. Por fim, estudos da interação de nanopartículas de ouro como o suporte inorgânico hidrotalcita foram realizados, possibilitando a geração de um material colorido composto de nanopartículas de ouro suportadas na superfície da matriz inorgânica. O material exibe ainda efeitos de mudança de coloração com o aumento da temperatura, correlacionados com o estado de agregação das nanopartículas metálicas.
Title in English
Fusion and Aggregation of Gold Nanoparticles: A Chemical Approach
Keywords in English
Nanoparticles
Theory of Mie
Abstract in English
Under the nanotechnological point of view, the dimensionality comes into play when one is dealing with many properties from the materials. Bulk gold with dimensions reduced to the nanometric scale shows singular reactivity and electronic properties. In the present work a further knowledge of the gold nanoparticles properties is sought from a chemical approach, through the investigation of surface interactions and their correlations with aggregation phenomena. Studies aiming a further understanding on the influence of different length ligands in the aggregation and fusional processes were performed with the ligands: pyrazine, 4,4'-bipyridine, 1,2-bis(4-pyridyl)ethane and 1,4-bis[(4- pyridyl)ethenyl]benzene. Furthermore, the investigation of nanoparticles surface interaction with the ligands 2 and 4-mercaptopyridine and their complexes with pentacianoferrate was also investigated allowing the obtainment of building block potentially useful for the generation of nanostructured materials through Prussian blue-like bonds. Finally, the obtainment of a new material based on surface interactions of gold nanoparticles on the inorganic support hydrotalcite was possible. The material exhibits peculiar thermochromic properties with colors dependent on the aggregation state of the nanoparticles.
 
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Publishing Date
2007-01-03
 
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