Controllable Assembly And Properties Research Of Au/SiO₂Composite Particles

The noble metal nanoparticles as the basic unit to build a multi-level orderedcomposite material, we can prepare the nano composite material,which has thesuperior optics (such as SPR,SERS etc.) and catalytic property.This method hasbecome a hotspot of new material research in recent years.The appearance ofassemble technique provides a new idea for the preparationof these functionalmaterials.It also has become the effective way to the practical application of thesematerials in the macro level.But, to date,the majority of assembly has not exploredthe mechanism more deeply, the maneuverability of assembly can not be solvedeffectively. So, it is very difficult to convert the assemble technique to the theoreticalguidance. This paper will set out a method to assemble the gold nanoparticles on thesurface of silica through the reaction of electrostatic,then obtained several kinds ofAu/SiO2composite materials.The experiment studies the effects of different pHvalues and other factor on the structure and propertis of materials systematically andthorughly.Realized the control of the performance of SPR,which provides antheoretical basis for its potential application in different field.1. Firstly, using the method of St ber to synthesize the uniform-sized andwater-soluble silica nanoparticles,then, using the3-aminopropyltriethoxysilane(APTES) to modified the surface of silica particles.Using the method of Frens tosynthesize the gold nanoparticles; Regulate the pH values of solution to get two kindsof particles with different electric surface charge, the gold nanoparticles are assembledonto the surface of silica particles by electrostatic effect. Changing the molar ratio to control the process of assembly precisely, the optimum conditions are determines, andobtain stable Au/SiO2NPs assembly. Finally, the experimental results are verifiedprevious.2. Adding the sodium nitrate solution to the assemble system to regulate the ionicstrength,can change the distance of gold nanoparticles. Then it can realize the controlof the surface plasmon resonance effect. Following, the regulation of experimentconditions (arginine modified gold nanoparticles, appropriate pH values, adding thestabilizer etc.) can synthesize the assembled structure with double floor goldnanoparticles. We prove that the double assembly structure was obtained successfullyby the color change, plasma resonance absorption detection and TEM etc.theassembly structure has obvious absorption peaks in the long wavelength region, thismethod also realizes the regulation of the assemblies body surface plasmon resonanceeffect. Due to the surface plasmon resonace effect have great application value in thefield of surface enhanced Raman (SERS) scattering. So we make an experiment tocompare the SERS effect of4-mercaptobenzoic acid (P-MBA) from spherical goldnanoparticles, monolayer assemblies and bilayer assemblies.