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The Preparation, Characterization and Morphology Controlling of Hydrophobic Gold Nanoparticles

Author: YaoYuFeng
Tutor: ShenMing
School: Yangzhou University
Course: Physical and chemical
Keywords: Gold nanoparticles Hydrophobic Octadecylamine Gold nanoparticles Molar ratio Mixed surfactant Reverse microemulsion N-heptane N-butanol New surfactant
CLC: TB383.1
Type: Master's thesis
Year: 2008
Downloads: 443
Quote: 0
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Abstract


Metal nanocrystals are an important part of the field of nano-materials, preparation Techologies recent decades has been a hot topic in the IT sector. Especially for precious metals, organic combination of its unique physical and chemical properties of nanostructures special properties reached, it has the unusual surface chemical properties, optical, magnetic, catalytic, energy, microelectronics and biology and other fields has broad application prospects, attention has been paid more and more widely, the hydrophobic metal nanoparticles may be more important in nanoelectronics, bionic device manufacturing. In this thesis, the reverse microemulsion method, by changing the experimental parameters of the protective agent, reducing agents and their dosages are combined with microwave radiation and other means to achieve the controlled synthesis of gold nanoparticles of different size and morphology of the hydrophobic. Hydrophobic gold nanoparticles obtained were characterized by a variety of testing methods and the use of UV-vis, TEM, XPS, ED, XRD and CA (contact angle). To sum up, the main contents include: 1. By simple heating means, the amount of NaOH promote, the use of CTAB, octadecylamine (the C 18 the NH 2 ) and CTAB / the C 18 NH 2 as a surfactant and n-heptane, ethanol and HAuCl 4 · 4H 2 O consisting of W / O microemulsion by ethanol restore HAuCl 4 respectively had CTAB, the C 18 NH 2 and CTAB / C 18 NH 2 wrapped with different morphologies hydrophobic gold nanoparticles. It was found that with CTAB / C 18 NH 2 mixed surfactant instead of a single surfactant CTAB, can greatly weaken the CTAB-oriented control of the synthesis of the morphology of the gold particles the role reduce CTAB / C 18 NH 2 molar ratio in favor obtained spherical, better dispersion of the hydrophobic nature of gold nanoparticles. (2) under microwave irradiation using octadecylamine / n-butanol / n-heptane / propionaldehyde / the HAuCl 4 ,? 4H2O reverse microemulsion system as a template, propionaldehyde as a reducing agent, the successful synthesis of ten eight amine-protected gold nanoparticles. Experimental results show that the With the the amine / Jinmo Er ratio decreases, the size of the resulting gold particles gradually increases from the spherical morphology of the particles gradually change to the polygon. 18 NH 2 mixed surfactant CTAB / C instead of single surfactant C 18 NH 2 with CTAB / C 18 NH 2 mole ratio increases, successful implementation of the morphology of gold nanoparticles from spherical to triangular, hexagonal transition, continue to increase CTAB content have relatively large shaft diameter gold nanorods. Conditions of alkali promotion C 18 NH 2 / n-butanol / n-heptane / HAuCl 4 (aq) W / O microemulsion at room temperature by n-butanol situ reduction the HAuCl 4 synthetic octadecylamine wrapped hydrophobic gold nanoparticles. The experimental results show that the hydrophobic monodisperse gold nanoparticles with the the C 18 NH 2 / HAuCl 4 mole ratio increased with the increase, The particle size decreases. When the the amine / Jin Moer high, the gold nanoparticles obtained octadecylamine spherical structure and narrow particle size distribution in 6 8 nm range. Studies have shown that the slow reaction of n-butanol situ reduction of gold chloride acid the experiments selected W / O type microemulsion template and surfactant octadecylamine molecules on the morphology and size of the hydrophobic gold nanoparticles still has good control effect. The preparation of the the hydrophobic gold particle dispersion having a high single large area is formed at the air / water interface of the short-range-ordered monolayer film. 4 to synthesize the novel surfactant 4 - n-heptyl group, a benzyl amine (HOBA), the amphiphilic molecules having good surface activity, compatibility with n-butanol, n-heptane, etc. can be formed a stable W / O type micro- emulsion. Microwave radiation, HOBA / n-butanol / n-heptane / the propionaldehyde / the HAuCl 4 · 4H 2 OW / O microemulsion as a template, by propionaldehyde the restore the HAuCl 4 can HOBA gold nanoparticles change HOBA amount can significantly change the size of the gold nanoparticles, the morphology of the particles polygon. The to HOBA / C 18 NH 2 mixed surfactant instead of single surfactant HOBA protected gold nanoparticles can significantly reduce the size of the gold particles, and with HOBA / C 18 NH 2 molar ratio decreases gradually become spherical particle morphology from the polygon. 5 use Octadecylamine / n-butanol / n-heptane / formic acid / the HAuCl 4 · 4H 2 O inverting microemulsion system as a template, under microwave irradiation, formic acid as a reducing agent was successfully synthesized octadecylamine protected morphology of gold nanoparticles. Experimental results show that the With the amine / Jinmo Er ratio decreases, the size of the resulting gold particles gradually increases from the spherical particles gradually transition to the pine needle-like morphology; a fixed amine / Jinmo Er ratio, the amount of formic acid increases also able to achieve the morphology of the particles from the spherical to the pine needle-like. Compared with conventional hydrophobic gold particle preparation method, the organic solvent of this thesis to safety n-heptane as the oil phase of W / O Microemulsion Template, which has the obvious advantages of low pollution, and the preparation method is simple, and the reaction controllable conditions. This method provides an effective way to further explore the morphology and size of the hydrophobic gold nanoparticles to control the synthesis and physico-chemical properties of the gold material and practical application.

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