Synthesis and Applications of Novel Periodic Mesoporous Organosilicas by Chun Xiang (Cynthia) LIN Abstract This dissertation is concerned with the synthesis, functionalization, and applications of periodic mesoporous organosilica (PMO) with a unique hollow spherical morphology, with the main objectives as follows: • Developing new techniques to synthesize mesoporous silica and organosilica materials • Designing different approaches to modify PMO and silica materials to meet various applications • Developing innovative applications of novel PMO materials in biological fields. The key features that have been achieved in this work are highlighted as follows: • A series of studies has been carried out and resulted in a new strategy for the synthesis of PMO material with a novel hollow morphology. This new approach employs both hydrocarbon and fluorocarbon surfactants as mixed structure-directing-agents in alkaline medium. Moreover, a vesicle and liquid crystal "dual-templating" mechanism has been proposed. • Detailed observation on the formation mechanism of hollow PMO has revealed that the demixing temperature (Td) plays an important role on the formation of highly ordered mesostructure of PMO hollow spheres. Beside that, dissimilarity on the hydrophobic nature of silica - organic silica precursors has brought differences in the resulted materials. • Different approaches in the modification of PMO hollow spheres with several functional groups and commercial magnetic ferrite nanoparticles have shown some unique features of this material. It was found that different reactive sites of each functional group bring different disruptive effect on the mesopore geometry of hollow PMO. Furthermore, hollow PMO material show different behavior on encapsulating the commercial magnetic ferrite nanoparticles compared to superparamagnetic particles, where different techniques should be applied, which involved several factors that need to be carefully adjusted. • Applications of hollow PMO in biological field were performed on drug and DNA delivery. A comparison between periodic mesoporous silica (PMS) and PMO as drug carriers showed the differences in wall composition between pure silica and hybrid organic silica, also the morphology (hollow and solid spheres) play important roles in controlling adsorption capacity and drug release rate. In addition, different pH value of release medium also brings significant effect on release profile. As a carrier of DNA, magnetic modified hollow PMO material showed biocompatibility towards sugarcane callus. Moreover, this study has introduced a new innovative technique on delivering DNA into plant cell through the application of modified hollow PMO with barium magnetic core and enzyme digestion approach.
| Identifer | oai:union.ndltd.org:ADTP/253967 |
| Creators | Chun Xiang (Cynthia) Lin |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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