Preparation Of Silica Microspheres And Study Of Its Self-assembly Behavior

Monodisperse silica colloidal microspheres has good prospect in fields of optics, material science, biology and so on.Therefore, the preparation and researches of monodisperse silica colloidal microspheres possess an very important value of science and application.Nowadays, using the feature of self-assembly of monodisperse silica colloidal microspheres to prepare colloidal crystals becomes a research highlight because of its outstanding quality in fields of light, electricity, magnetism, etc.The thesis carries on the research work in preparation, self-assembly and other aspects of silica colloidal microspheres.First, monodisperse silica colloidal microspheres are prepared by Stober sol-gel method, and then the influences of each reaction condition are studied by particle size analyzer(DLS),Scanning Electron Microscopy(SEM), such as the concentration of ammonia water, the mass of deionized water, the concentration of TEOS,etc. on the size and feature of silica.The concentration of TEOS has little influence on the particle size;As the mass of ammonia water increases, the diameter of particles increases apparently, and monodispersion as well.As the amount of deionized water increases, the diameter of particles increases gradually. However, if the amount of deionized water becomes too large, the spherize will be worse.The results show that ammonia and deionized water are the two main factors of controlling the size and feature of the diameter of particles of silica.This study found that when ethanol reaches 75ml, TEOS 15ml, ammonia 5ml and deionized water 5ml, the good dispersivity and elementary orbicular of silica colloidal microspheres could be prepared.Second, we make the study of using vertical deposition method to make monodisperse silica colloidal microspheres do the self-assembly of 3D-silica colloidal crystals.The SEM feature of getting silica colloidal crystals show that the temperature, humidity, suspension concentration, and other features of self-assembly process have apparent influence on the self-assembly action.If the temperature is too low, the formative colloidal crystal cannot closely pack and be thin. While if the temperature is too high, the colloidal crystal's degree of order will be worse, and turning up flaws, or even disordered.The increasing of humidity and colloidal crystal's degree of order could let defects deceasing, while suspension concentration becomes large, the thickness of colloidal crystal also increases.Finally, we use PS template method to prepare 2D and3D-silica colloidal crystals with superficially ordered microstructure, and discusse its mechanism;Silica colloidal crystals with 3D-ordered microstructure are prepared by inclined deposition method of PS-SiO2 mixed liquor.