Transparent Polysilsesquioxane Films Obtained from Bridged Ureasil Precursors: Tunable Photoluminescence Emission in the Visible Region and Filtering of UV-Radiation
✍ Scribed by María L. Gómez; Diana P. Fasce; Roberto J.J. Williams; Carlos M. Previtali; Hernán A. Montejano
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 435 KB
- Volume
- 295
- Category
- Article
- ISSN
- 1438-7492
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✦ Synopsis
Abstract
Bridged ureasil precursors were synthesized by the reaction of either ethylenediamine (1 mol) or m‐xylylenediamine (1 mol) with isocyanatepropyltriethoxysilane (2 mol). Transparent polysilsesquioxane films were obtained by the hydrolytic condensation of the pure precursors or their co‐condensation in a 50:50 molar ratio. Films based on pure ureasil precursors showed a blue photoluminescent emission band assigned to the photoinduced proton‐transfer among H‐bonded urea groups and the subsequent radiative recombination of ionized groups. Films synthesized by the co‐condensation of both precursors exhibited a significant red‐shift of their absorption, excitation, and emission spectra, associated to de‐localization of H‐bonds, and a high absorption of UV‐radiation.magnified image