Langmuir monolayer properties of 4-methylbenzenethiol capped gold nanoparticles

Heriot, Sasha Y.; Pedrosa, José M.; Camacho, Luis; Richardson, T.

doi:10.1016/j.msec.2005.08.001

Cited by 7 publications

(7 citation statements)

References 29 publications

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“…Multilayer structures in nanoparticle LS films have been discussed e.g. by Heriot et al , They observed 3-dimensional structures in LS films of 4-methylbenzenethiol-stabilized Au nanoparticles and explained this by a localized film collapse taking place during film transfer onto a solid substrate. In our Co nanoparticle system we have observed darker areas on the subphase surface which we believe are bi- and multilayer structures formed already in the floating Langmuir film before the transfer step.…”

Section: Resultsmentioning

confidence: 99%

Cobalt Nanoparticle Langmuir−Schaefer Films on Ethylene Glycol Subphase

et al. 2010

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The Langmuir-Schaefer (LS) technique was applied to prepare two-dimensional films of tridodecylamine (TDA)-stabilized Co nanoparticles. Ethylene glycol was used as the subphase because the Co nanoparticles spread better on it than on water. Surface pressure-area isotherms provided very little information on the floating films, and Brewster angle microscopy (BAM) was needed to characterize the film formation in situ. In addition to the subphase, various other experimental factors were tested in the LS film preparation, including solvent and presence of free TDA ligands and poly(styrene-b-ethylene oxide) (PS-b-PEO) in the nanoparticle dispersion. LS films deposited from dispersions from which the excess TDA ligands had been removed by washing the Co nanoparticles with 2-propanol consisted of hexagonally organized particles in rafts that were organized in necklace structures. The addition of PS-b-PEO to the deposition dispersion resulted in small nanoparticle rafts evenly distributed over the substrate surface. The best Co-nanoparticle-PS-b-PEO films were obtained with a mass ratio of 20:1 between Co (9 nm) and block copolymer (38 200 g/mol, PEO content 22 mass %). These films were successfully transferred onto Formvar-coated TEM grids and characterized by transmission electron microscopy (TEM) and a superconducting quantum interference device (SQUID) magnetometer. At room temperature the films showed superparamagnetic behavior with a saturation magnetization M(s) of 100 emu/g (Co). Our work indicates that it is possible to obtain thin superparamagnetic LS films of TDA-stabilized Co nanoparticles. This is an important result as the TDA-stabilized Co nanoparticles show a very good resistance to corrosion.

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Section: Resultsmentioning

confidence: 99%

Cobalt Nanoparticle Langmuir−Schaefer Films on Ethylene Glycol Subphase

et al. 2010

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“…A síntese pode ser efectuada tanto em fase homogénea, Figura 8 Espectro de absorvância obtido por espectrofotometria de UV-visível para uma suspensão coloidal de citrato/Au-NPs com diâmetro de cerca de 14 nm; λ max. ≈ 516,5 nm pelos métodos introduzidos por Turkevich (meio aquoso) [105] e refi nado por outros autores [106,107] e Kimura et al [101] (meio orgânico), ou duas fases líquidas [108][109][110][111], inicialmente descrita por Brust et al [112]. Neste caso, a transferência do AuCl 4 da fase aquosa para a orgânica usa, por exemplo, halogenetos de tetralquilamónio; a redução do Au(III) ocorre na fase orgânica por adição do redutor.…”

Section: Estruturas Auto-montadas Envol-vendo Nanopartículas De Ouro Preparação De Suspensões Coloidais De Au-npsunclassified

“…A interacção estabilizador/Au-NPs, pode ser diversa, desde simples adsorção física a interacções químicas mais fortes (adsorção química). As Au-NPs podem ser estabilizadas por iões citrato [86,99,103,106,113,114], polímeros [102,115], dendrímeros [116], tióis [100][101][102]104,[107][108][109][110][111][112][113][114][117][118][119] e surfactantes [120]. Em certos casos, a espécie estabilizadora, que se adsorve na superfície das Au-NPs, pode ser o próprio redutor (como citrato de sódio) ou outra adicionada no passo de síntese (por ex.…”

Section: Estruturas Auto-montadas Envol-vendo Nanopartículas De Ouro Preparação De Suspensões Coloidais De Au-npsunclassified

“…Figura 7 (a) Imagem de STM de MC de decanotiol em Au e (b) representação esquemática do arranjo e orientação das moléculas adsorvidas na superfície Au(111). Reproduzida com permissão da referência[81].…”

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“…Zhong et al[41] sugerem que na desadsorção de alcanotiolatos de cadeia longa ocorre a formação de micelas ou agregados nas proximidades da superfície do eléctrodo (ou mesmo na superfície, como observado em imagens de STM por Esplandiu et al[48]). De uma maneira geral, os n-alcanotióis em superfícies monocristalinas puras Au(110), Au(111) e em Au/mica (tratado termicamente) e n-alcanotióis de cadeia curta (n < 11) em superfícies atomi-camente planas Au(111), apresentam um único pico de desadsorção redutiva. (Au/Si ≈ Au/vidro > Au/mica), a separação dos picos (200-300 mV) refl ecte as dissemelhantes energias de ligação do S ao substrato[10,21].…”

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