Fabrication of unary and binary colloidal crystals by isothermal evaporation induced self-assembly

• Main Authors: Pei-HuaTsai, 蔡佩樺
• Other Authors: Yu-chun Wu
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/53021083370096352060

碩士 === 國立成功大學 === 資源工程學系碩博士班 === 98 === Choosing the powder of silica (SiO2) and latex (PS) to perform in the isothermal heating evaporation induced self-assembly (IHEISA) research. Silica and latex prepared with the process of St?ber and dispersion polymerization respectively. In the aspect of the self assembly of unary colloidal crystal films (C.C.Fs), solutions with various pH values will affect the behavior of potential on particle surface. Observation from the experiment results that show although the addition of acid or base will increase the surface potential of particles but electrolyte added will contribute to the concentration of ions increasing and decrease the depth of the electric double layer instead. These will cause the flocculated between particles easily and unable proceed the following IHEISA process. Besides, set the evaporation rate of the solvent and the surface properties of the substrate as the parameters which affect the array degree of the colloidal crystal films. And observe the pH range which is suitable for self-assembly. Further, the relation between the evaporation rate and particle size, deposition methods, concentration of the suspension and tilted angle of the substrate on the thickness of the colloidal crystal films will also be probed in the research. More, find out one thing in the research is that controlling the evaporation rate carefully will get the colloidal crystal films with high array degree. Because there are the optimum range for evaporation rate and it has the closed relation with the particle size、particle density、substrate position and so on. In the aspect of the self assembly of binary colloidal crystal films, take the condition of repelling potential between the surface of SiO2 and PS colloidal particle to take part in the IHEISA process research. And find out from the front C.C.Fs experiment, electrolyte added easily cause the weakly flocculated between particles and unable proceed the following IHEISA process. So it take the original pH after mixing to continue the following IHEISA reaction, and the pH range locates from 9 to 10.The experiment results reveal that the preparation of the binary colloidal crystal films is strongly affected with the particle size ration (rS/L) and number ratio (N) of the two colloidal particles and, and while the optimum evaporation rate changed, there are an obviously difference compare to the self-assembly of the C.C.Fs.