Periodic mesoporous organosilicas (PMOs): A new class of organic-inorganic hybrid nanocomposites.

摘要

Synthetic routes to a new class of hybrid organic-inorganic materials called periodic mesoporous organosilicas (PMOs) through self-assembly were developed. The mesoporous materials contain organic and inorganic groups linked together at a molecular level inside the framework. For the synthesis, hydrolysable and polymerizable bridged poly(trialkoxysilyl)organic monomers which are obtained either commercially or synthesized through various organic and organometallic synthetic routes from readily available reagents undergo self-assembly in the presence of surfactant micelles and liquid-crystals to result in ordered mesostructured materials containing various organic and organometallic functional groups uniformly distributed in the walls. Similar synthetic routes from the co-condensation of organotrialkoxysilanes and tetralkoxysilanes afforded terminal organic functionalized mesoporous materials and some of which have the highest loading of terminal organic groups. Further combination of the above two methods resulted in novel bifunctional and multifunctional PMO materials that have two or more than two different kinds of organic functional groups and properties.; The various chemical, physical, thermal and surface properties of the resulting porous materials were studied and some unique properties were observed. The accessibility of the bridging and/or terminal functional groups has been investigated through in-situ reactions. Unprecedented thermal transformations in some PMOs resulted in new hybrid ordered mesoporous and microporous materials.; The inclusion of organic functional groups in a highly ordered and high surface area and pore volume containing mesoporous material is a potentially efficient way to modify the chemical, thermal, mechanical and physical properties of the material as well as to make it useful as a platform for various applications in catalysis, separations, and nanoelectronics and as membranes, electrodes, and sensors. Moreover, the diverse possibility of incorporating various chiral, saturated, unsaturated, aromatic, organometallic, electroactive, conjugated chromophore, hydrophobic, and hydrophilic organic groups and the possibility of making these materials with various pore sizes, and in the form of various shapes and thin films will potentially bring many of the aforementioned applications into reality in the near future. For example, the successful preparation of sulphonic and amine functionalized PMO materials and their solid acid and solid base properties, respectively for potential heterogeneous catalysis and separation applications are also discussed.