Photoluminescent particle surfaces in mesoporous hosts
Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
Final Report Abstract
A critical issue for the utilization and integration of nanoparticle systems with desired properties in optical or electronic devices is their immobilization. Aiming at the linkage of, e.g. alkaline earth oxide, nanoparticles to the macroscopic world under preservation of their surface dependent chemical and optical properties their immobilization in porous host materials was investigated. We developed novel synthesis strategies to meso/macroporous oxide networks with different pore size distributions and pore arrangements that were used for the gas phase infiltration with alkaline earth metals. A facile and cost efficient approach towards meso-/macroporous silica and titania materials has been developed by a combination of breath figure (BF) templating with non-hydrolytic sol-gel processing and evaporation-induced self-assembly. Meso/macroporous silica and titania coatings as well as powders can be synthesized by simply casting sols containing the respective metal alkoxide/chloride mixture in the presence of a polymeric cellulose acetate butyrate (CAB) solution and small amounts of water. In addition, porous magnesium oxide with an unusual macrostructure has been successfully prepared by a double replication route. In the first step, the synthesis of a meso/macroporous carbon material was realized through a nanocasting approach using meso/macroporous silica with a fully connected hierarchical pore structure as template. In the second replication step the hierarchical porous carbon was converted into magnesium oxide by infiltration of the pore network with an aqueous magnesium nitrate solution and subsequent heat treatment at 300 °C to convert the nitrate into the oxide. Finally the carbon template was removed by thermal combustion and crystalline MgO with a unique macrostructure built up from interconnected and well-ordered rod-shaped magnesia strands with enclosed macropores has been obtained. A new approach for the gas phase infiltration of these porous materials (mainly silica) with alkaline earth metals has been designed. Electron microscopy and powder X-ray diffraction were used to characterize the influence of metal infiltration on the structural properties of the host materials. Upon infiltration and subsequent thermal processing, composite materials contain either nanocrystalline alkaline earth metal oxides or – depending on the hierarchy of the pore system - silicate phases. In addition to pure silica materials, functionalization strategies have been developed based on novel functional organosilane molecules. A new synthetic route based on hydrosilylation reactions gave access to a variety of isolable organofunctional silanes combining carboxy- and alkoxy groups within one molecule. Besides simple sol-gel processing strategies, e.g. co-condensation with tetraalkoxysilanes to yield carboxy-functionalized silica particles in a one-pot approach, these silanes can be applied as single source precursors by coordinating metal ions and sol-gel processing. This has been successfully shown in the preparation of luminescent coatings via a solvent evaporationinduced self-assembly (EISA) approach of Eu(III)-linked 5-(triethoxysilyl)pentanoate single-source precursors (SSP) in the presence of Pluronic P123 as structure-directing agent using a spin-coating process.
Publications
- Chem. Mater., 2012, 24, 3674-3683
Feinle, F., Lavoie-Cardinal, J. Akbarzadeh, M. Adlung, H. Peterlik, C. Wickleder, N. Hüsing
- Chem. Commun. 2015, 51, 2339- 2341
Feinle, S. Flaig, M. Puchberger, U. Schubert, N. Hüsing
(See online at https://doi.org/10.1039/c4cc08025d) - Microporous and Mesoporous Materials, 2015, 217, 233-243
Feinle, J. Akbarzadeh, H. Peterlik, N. Hüsing
(See online at https://doi.org/10.1016/j.micromeso.2015.06.043)
