LB Self-assembly And Properties Of SiO₂ Microspheres

Photonic crystal has different dielectric constant in 3D direction, and it can modulate the transmission of electromagnetic waves. It makes photonic crystal have broad application prospects in the laser engineering, high speed computing and spectroscopy. Because of the low cost and mature technology, colloid self-assembly packing method has become the most potential method in photonic crystal preparation research. But the samples of colloid self-assembly packing method have poor mechanic performance, which limits the application of the method seriously.Experience of the experiment shows that the increasing of the film adhesion is the key point to improve the mechanical properties of colloid crystals. It is difficult to observe the interaction between the microspheres and the base directly because colloidal crystal has numerous layers. And through the single layer particles, we can observe the change of single layer particles under various process and their interaction with the base from every angle. Comparing several single layer particles preparation technologies, LB film method has a more broad spectrum scope and a better quality control, so it is chosen to prepare single layer particles.LB film method is a surface self-assembly technique, and it has a high requirement for particles’ surface properties. We use chemicals to surface modification. One or two kinds of silane coupling agent are used to change the properties of SiO₂ particles surface. By investigating the Zeta potential, surface tension, the surface modification of SiO₂ particles surface is analyzed. Therefore, LB film method is used to prepare single layer particles.Since the silane coupling agent is high-cost and not eco-friendly, the influence of thermal treatment on the surface of the microspheres is studied. With the inspiration of the PS balls surface hydrophobic by heat treatment, this paper studies the change of SiO₂ particles surface after heat treatment. Zeta potential, TG/DSC, FTIR and SEM are used to analyze particles surface after heat treatment and the order of single layer particles.But it’s hard to prevent the formation of micro area in the solely by the electric repulsion of microsphere, which limits the order of single layer particles severely. In this paper, vibration is added to the preparation to improve the order of the single layer particles. Surface tension, SEM, reflection spectrum are used to analyzed the preparation process and the film of single layer particles.In this paper, we will enhance the mechanical properties of single layer particles whose base is made by glass or quartz. Heat treatment is used to enhance the contact area and connection strength between the base and ball, ball and ball. Reflection spectrum, SEM, damage experiment are used to analyzed changes of single layer particles structure and performance during heat treatment.