Sol-gel synthesis and characterization of tetra-alkoxysilane and bridged-polysilsesquioxane materials in non-polar solvents

Conference · Tue Oct 01 04:00:00 EDT 1996

OSTI ID:370608

Yamanaka, S A; Martino, A; Kawola, J S; Loy, D A ^[1]

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1. Sandia National Laboratories, Albuquerque, NM (United States)

Although the sol-gel method has widely been used for the encapsulation of molecules in porous glass materials, the variety of dopants has been limited by the solvents used in processing. Polar solvents, such as ethanol, methanol or tetrahydrofuran, are typically added as cosolvents to prevent phase separation between the organic metal alkoxide and water. Non-polar solvents are generally not suitable for sol-gel processing since they are immicible with the aqueous phase. Our study increases the availability of solvents that may be used in sol-gel processing and therefore expands the range of molecules suitable for encapsulation. Here, we report a novel method for preparing both silica sol-gel materials and bridged-polysilsesquioxane materials in a non-polar, hydrocarbon solvent. The method involves the formation of an inverse micelle upon addition of the surfactant, didodecyldimethylammonium bromide, to toluene. The dynamic nature of the micelle allows sol-gel reactions to occur between water (soluble in the polar core of the micelle) and the metal alkoxide precursor (soluble in the solvent phase). Materials prepared by this technique have been characterized by nitrogen sorption porosimetry, SEM, solid state {sup 29}Si NMR, TGA and XRD. Photochemical conversion of technetium fluorides and oxyfluorides is largely uninvestigated. Because technetium was introduced into U.S. uranium enrichment plants, decommissioning and decontamination of these plants will involve technetium fluorides and oxyfluorides. Photochemical conversion of such compounds may facilitate waste minimization and cost avoidance goals during plant clean-up. Photochemical fluorination using ultraviolet photolysis of a mixture of fluorine and oxygen gases is an effective means of converting solid, nonvolatile fluorides of fight actinides, such as U, Np, and Pu, into volatile hexafluorides thereby removing surface radioactive contamination.

• Research Organization: Sandia National Laboratory
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 370608
• Report Number(s): CONF-960376--
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
36 MATERIALS SCIENCE
66 PHYSICS
ACTINIDES
AMMONIUM COMPOUNDS
BROMIDES
ENCAPSULATION
NMR SPECTRA
POLYMERS
PORE STRUCTURE
SILANES
SILICA GEL
SILICON 29
SOL-GEL PROCESS
SURFACTANTS
TOLUENE
X-RAY DIFFRACTION