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US 12,291,621 B2Granted
Fabrication of aerogels and aerogel composites by ambient pressure sublimation of frozen solvents
AssigneeVirginia Commonwealth University
InventorsMassimo Bertino, Tyler Selden
Life of this patent
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Abstract
Drying polar solvents which do not form hydrogen bonds with a wet gel or aerogel, or eutectics or solvent mixtures with the drying solvents, are utilized in a solvent exchange with wet gels used in the formation of aerogels. Preferably the drying solvents are non-polar solvents. The drying solvent or solvent mixtures results in profoundly less shrinkage, thereby allowing for the production of aerogels of preferred materials properties.
Claims19
A method of preparing an aerogel, comprising:
- preparing a wet gel containing a gelation solvent;
- exchanging the gelation solvent with a drying solvent in the wet gel, wherein the drying solvent does not form hydrogen bonds with pore walls of the wet gel or aerogel and is a solvent with a freezing point near an ambient temperature between 10° C. and 200° C., and a vapor pressure near ambient pressure between 0.005 Torr and 10 Torr;
- freezing the drying solvent in the wet gel below its freezing temperature to produce a gel with frozen drying solvent;
- and
- removing frozen drying solvent from the gel by exposing the gel to a vacuum, dry air, or dry inert gases, wherein the step of removing the frozen drying solvent results in gel shrinkage of >0% and <10%.
2 more elements
A method of preparing an aerogel, comprising:
- preparing a wet gel containing a gelation solvent;
- exchanging the gelation solvent with a drying solvent in the wet gel, wherein the drying solvent does not form hydrogen bonds with pore walls of the wet gel or aerogel and is a solvent with a freezing point near an ambient temperature between 10° C. and 200° C., and a vapor pressure near ambient pressure between 0.005 Torr and 10 Torr;
- freezing the drying solvent in the wet gel below its freezing temperature to produce a gel with frozen drying solvent;
- and
- removing frozen drying solvent from the gel by exposing the gel to a vacuum, dry air, or dry inert gases, wherein at the termination of the exchanging step, solvent in the pores of the wet gel is 90-99% or more the same as the drying solvent prior to its exposure to the wet gel.
2 more elements
Dependencies are inferred from the claim text.