Surface Modified Of Monodisperse Colloidal Silica And Preparation Of SiO₂/Ag Core/Shell Particles

Colloidal crystal has attracted an increasing interest due to its various applications in the fields of photonic band-gap crystals and photoelectron devices etc.Monodisperse colloidal silica particles with uniform size have wide application in industries including pigment and pharmacy.Because nano-silica has high energy surface,it is easily to gather into groups and hardly to fully mixed with the organic solvent.To resolve the above-mentioned problem of dispersion and compatibility with organic component,the surface of nano-silica must be modified.Core-shell materials have peculiar properties in aspects of light,electricity and chemical properties as a results of the their composition,size and structure,so that in recent years scientists have take much attention.Monodisperse silica coated metal shell can not only maintain its narrow size,but also has size characteristic effect and surface characteristic the metal particle itself.The optical properties and electrical properties have become very unique.Based on the plenty of the present literatures,we mainly have carried out the following work on the following aspects:(1) The monodispersed silicon dioxide colloidal particles were synthesized in solution of alcohol-water system in the reaction process TEOS as silicon material and ammonia as catalyst.The silica then was assembled by the vertical deposition method.We can judge the quality of the colloidal crystal by observing the light intensity of transmittance with spectrophotometer.The peak position can be used to speculate the size of the silica.(2) The monodisperse silica surface was modified.The silica surface has decreased potential and less hydrophilic after modified by silane coupling agent.The potential of the silica surface has greatly increased after modified by Succinic acid.We can determine the effect of the modified silica by measuring the wettability.(3) Prepared SiO₂/Ag composite microspheres with their own monodisperse silica microspheres as nuclear and a variety of reducing agents to restore the silver ions as shell.The effect of coating can be judged by means of micro-electrophoresis and UV-Vis spectrophotometer.