Study Of The Modification And Characterization Of Colloidal Microspheres

Ordered nanostructure films can be prepared by monodisperse colloidal particlesused self-assembly technique. Surface-patterned nanostructures have attracredintensive interese because they exhibit unique pattern-dependent propertis and showpromising applications in a variety of technologically important areas includingbiological and chemical sensing and energy conversion. Up to now, many lithographymethods for patterning surface have been developed, such as photolithography, andelectron beam lithography.A simple but versatile technique of layer-by-layer self-assembly was used onpolystyrene (PS) colloidal templates to produce Au, Ag nanoparticles （NPs）, CdTequantum dots (QDs) and Fe3O4NPs modified PS colloidal spheres. In addition, Anovel and interesting site-selective deposition effect of NPs with different sizes on PSspheres was introduced. The major contributions of this work are as follows:(1) The templates were obtained by self-assembly of monodispersed suspension ofPS spheres on glass slides. Au NPs, Ag NPs, CdTe QDs and Fe3O4NPs weredeposited on PS spheres through electrostatic force with a media layer ofpolyelectrolyte.(2) A novel and interesting site-selective deposition effect of NPs with different sizeson PS spheres was introduced. This site-selective deposition effect benefited fromthe uniform microporous structures of the monolayer PS templates, which servedas sieves to filter the NPs. Only small NPs like CdTe QDs can go through the pathways of the micropores of the PS templates. Big NPs like Ag NPs can not gothrough the uniform pores due to the steric hindrance effect. Finally, CdTe QDsmodified PS spheres with Ag NPs caps were obtained. It was a new class ofdual-function microspheres with applications both in fluorescence and insurface-enhanced Raman scatting (SERS).