Rapid Synthesis and Applications of Functional Submicronspheres

• Main Authors: Yu-Cheng Kuo, 郭育丞
• Other Authors: Hui Chen
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/11899909143993689357

博士 === 國立中央大學 === 化學工程與材料工程學系 === 101 === In general, the tranditional colloid opals were constructed mostly by hard spheres, such as PS (Polystyrene), SiO2 (Silicon dioxide) and so on. These opals exhibited awful mechemical and film properties, thus limited the application fields. For these reasons, the main purpose of this thesis was based on the conceptions to overcome above-mentioned disadvantages. At first, the promoted film properties of opal were carried out by constructing from hard core-soft shell structure spheres instead of typic hard spheres. Secondly, the opals with a series of mechanical properties between rigid-brittle and soft-tough polymer behaviors were further prepared by blending two different diameter spheres. In order to synthesize various, required spheres, a rapid, novel synthesis technique was also presented herein. Base on this technique, the monodispersed organic or organic/inorganic spheres with various diameters, structure and properties were able to synthesize in the same procedure. In the first chapter, the technique for rapid synthesis (2 h) of organic/organic core-shell structure spheres was presented. Monodispersed PS core was polymerized for a period of time, and then BMA (Butyl methacrylate) monomer was introduced to the reaction system to prepare the core-shell PS/PBMA spheres. Subsequently, these core-shell spheres were self-assembled into opal, and examed by pencil hardness test. The results indicated that the mechanical properties of opals were able to promote from original lower than 6B to HB as the core-shell shperes were applied. However, the category of above opal is hard film. Therefore, a series of submicrospheres with different Tg between -34 ℃ and 112 ℃ were prepared, and further blended with nano PS apheres (≒20 nm) to construct opals. The SEM results indicated that the soft submicrospheres were hexagonally arranged, and the nano PS apheres occupied the interstices, to keep the periodical structure. According to the stress-strain diagram, the mechanical properties of opals were able to tune by two main ways to make the film behavior changed from typical elastomers to brittle plastic. One of wich was increasing of submicrospheres Tg from -34 ℃ to 8 ℃; And second way was to increase the blended content of nano PS apheres from 5 wt. % to 25 wt. % in the presence of -34 Tg submicrospheres in opal. Base on the above approaches, the ultimate tensile strength and maximum elongation of opals were able to achieve 4.7 Mpa and 1236 %, respectively. The opal with elastic polymer behaviors possessed great application values because of which exhibited the relationship between the film elongation and optical properties, called mechanical respounsed ability. Thus, the PBA elastic opal was choosen to further study. The results indicated that the red-shifted photonic band gap of elastic film was able to controll by the increased diameter of PBA spheres, or small PS content in opal. On the other hand, the bule-shefted photonic band gap was observed as the elastic film was stretched. And the shifted behavior of λmax was corresponded to the Poisson effect. Different from the previous technique of rapid synthesis of organic/organic spheres, mixed silane was choosed as introduced monomer to extend the technique to synthesize organic/inorganic PS/SiO2 spheres. The polarity of mixed silane and the mechanical properties of fabricating SiO2 were able to tune by adjusting the feeding ratio between MTES (Triethoxymethylsilane) and TEOS (Tetraethyl orthosilicate). Subsequently, the silane was introduced onto the surface of PS particle, just by acting force of simple diffusion, and further reacted to SiO2. Finally, the monodispersed, hollow SiO2 spheres were obtained by calcinating the PS/SiO2 spheres.