Aerogel compositions and methods
The present disclosure provides an aerogel composition which is intrinsically hydrophobic without surface modification by a hydrophobizing agent, is durable and easy to handle, which has favorable performance in aqueous environments, and which also has favorable combustion and self-heating properties. Also provided is a method of preparing an aerogel composition which is intrinsically hydrophobic without surface modification by a hydrophobizing agent, is durable and easy to handle, which has favorable performance in aqueous environments, and which has favorable combustion and self-heating properties.
1. A method comprising:
providing a precursor solution comprising silica gel precursor materials and a solvent, wherein the precursor solution includes greater than 30% of at least one silica gel precursor material which is an alkylsilane having only one alkyl group attached to silicon;
providing a basic catalyst solution wherein the basic catalyst is a catalytic amount of guanidine hydroxide, and wherein the basic catalyst allows the silica gel precursor materials to transition into a gel composition;
combining the precursor solution and the basic catalyst solution;
allowing the silica gel precursor materials to transition into a gel composition; and
extracting at least a portion of the solvent from the gel composition to obtain a silica-based aerogel composition, wherein the silica-based aerogel composition is intrinsically hydrophobic without surface modification with a hydrophobizing agent.
2. The method of claim 1 , wherein the alkyl group attached to silicon is a methyl group.
3. The method of claim 1 , further comprising incorporating a reinforcement material into the silica-based aerogel composition.
4. The method of claim 1 , further comprising incorporating an additive into the silica-based aerogel composition.
5. The method of claim 4 , wherein the additive is present in a range of about 0.1 wt % to about 10 wt % of the silica-based aerogel composition.
6. The method of claim 4 , wherein the additive is present in a range of about 0.5 wt % to about 3 wt %.
7. The method of claim 4 , wherein the additive is selected from the group consisting of boron carbide, diatomite, manganese ferrite, manganese oxide, nickel oxide, tin oxide, silver oxide, bismuth oxide, titanium carbide, tungsten carbide, carbon black, titanium oxide, iron titanium oxide, zirconium silicate, zirconium oxide, iron oxide, iron (II) oxide, iron (III) oxide, manganese dioxide, iron titanium oxide (ilmenite), chromium oxide, silicon carbide, phyllosilicate clay, kaolin or kaolinite, metakaolin, halloysite, meta-halloysite, endellite, mica, diaspore, gibbsite, boehmite, montmorillonite, beidellite, pyrophyllite, nontronite, bravaisite, smectite, leverrierite, rectorite, celadonite, attapulgite, chloropal, volkonskoite, allophane, racewinite, dillnite, severite, miloschite, collyrite, cimolite and newtonite, sodium bicarbonate, magnesium hydroxide, magnesium dihydroxide, alumina trihydrate, gypsum, barringtonite, nesquehonite, lansfordite, hydromagnesite, dolomite, lithium carbonate or mixtures thereof.