Role of the reactive atmosphere during the sol-gel synthesis on the enhancing of the emission quantum yield of urea cross-linked tripodal siloxane-based hybrids

authors	Freitas, VT; Lima, PP; Ferreira, RAS; Carlos, LD; Pecoraro, E; Ribeiro, SJL; Bermudez, VD
nationality	International
journal	JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
author keywords	Tripodal organic-inorganic hybrids; Tri-ureasils; Sol-gel; Photoluminescence; Laboratory controlled atmosphere
keywords	ORGANIC-INORGANIC NANOCOMPOSITES; CARBOXYLIC-ACID SOLVOLYSIS; METAL ACTIVATOR IONS; BRIDGED SILSESQUIOXANES; ORGANIC/INORGANIC HYBRIDS; LIGHT-EMISSION; TUNABLE PHOTOLUMINESCENCE; LAMELLAR STRUCTURE; ENERGY-TRANSFER; SILICA SPHERES
abstract	Transparent monoliths and films of urea cross-linked tripodal siloxane-based hybrids (named tri-ureasils) were prepared by the sol-gel process, under controlled atmosphere (inside a glove box) and ambient conditions and their structure and optical features were compared. X-ray diffraction data point out that all the materials are essentially amorphous and Si-29 NMR reveal an increase in the condensation degree (0.97) for the hybrids prepared under controlled atmosphere relatively to that found for those prepared under ambient conditions (0.84-0.91). The tri-ureasils are white light emitters under UV/Visible excitation (from 250 to 453 nm) being observed for the composites prepared inside the glove box a significant enhancement (60-80 %) of the absorption coefficient and higher emission quantum yield values (similar to 0.27 and similar to 0.20 for monoliths and films, respectively) relatively to those synthesized under ambient condition.
publisher	SPRINGER
issn	0928-0707
year published	2014
volume	70
issue	2
beginning page	227
ending page	235
digital object identifier (doi)	10.1007/s10971-013-3244-x
web of science category	Materials Science, Ceramics
subject category	Materials Science
unique article identifier	WOS:000335639600009