- 學位論文
以固態乳化合成法製備表面不對稱氧化鋅顆粒
Preparation of ZnO Janus particles by Pickering emulsion
摘要
本研究主要是透過固態乳化法(Pickering emulsion)製備以二氧化矽為核，氧化鋅為殼層的表面不對稱二氧化矽/氧化鋅顆粒(Janus particles)。相較於傳統合成法微流法(Microfluidic methods)製備，固態乳化法能夠製備形貌均一的奈米顆粒，由於二氧化矽核顆粒表面為親水性，不易傾向油相，於是添加入雙十二烷基二甲基溴化銨(DDAB) ，使二氧化矽顆粒表面疏水性增加，使其固定在油水界面上。接著再披覆氧化鋅做為殼層，達到兩端不對稱效果。並探討不同劑量下界面活性劑劑量、油水比與二氧化矽添加量對表面不對稱二氧化矽/氧化鋅顆粒形貌之影響。以SEM、XRD、EDS分析不同配比下顆粒形貌及表面。探討不同配比下形貌之間的不同。實驗結果顯示，隨著界面活性劑的添加量增多，表面疏水性將逐漸增大，經過改質的二氧化矽顆粒會傾向吸附於油水界面上，使之有利於隨後的氧化鋅披覆。而不同水油比下，油相比例提高將不易使固態乳化液穩定。SEM圖顯示出氧化鋅集中分佈於顆粒其中一端，顯示表面的不對稱性結構。XRD及EDS圖也證明了披覆氧化鋅的晶相。相較於傳統合成法，此實驗方式提供了一種可控制型貌的表面不對稱顆粒製備方式。
並列摘要
The aim of this study is the preparation of Janus particles by Pickering emulsion. The Janus particle contains silicon dioxide as a core layer and the zinc oxide as a shell layer. Comparing with traditional “Microfluidic methods” , Janus particles with uniform size can be prepared with this method. Since the silicon dioxide is hydrophilic, it is difficult to control the area of each sides of the Janus particles. By Pickering emulsion , it is possible to control the structure of Janus particle. In this study, we used cationic surfactant DDAB to modify the silica surface. By this surface modification, one can control the contact angle between particles and wax phase. Then, we synthesize a ZnO shell structure on SiO2 core by liquid-phase precipitation method. After removing wax by THF, Janus particle with silicon dioxide as a core layer and the zinc oxide as a shell layer can be prepared.The Janus particles were characterized by SEM, EDS and XRD. Experiment results show that, increasing the amount of the absorbed , the particle became more hydrophobic. The W/O ratio has significant effect on the stability of emulsion suspension. Increasing the amount of the oil phase will destabilize emulsion suspension. The SEM imagine showed that the Janus particles consist of one side covered with ZnO nanoparticles while the other side of particle was silica. The XRD and EDS imagine also show that the ZnO is of crystalline structure. Comparing with traditional method, this study demonstrated that Janus particles with controllable morphology can be prepared.