feasibility of making aerogel

[Eric Davies]

This article looked interesting:
http://inhabitat.com/chinese-scientists-create-ultralight-fire-resistant-carbon-nanotube-aerogels-from-low-cost-biomass/

Executive summary: get some bacterial cellulose, freeze dry it, and then heat in an argon atmosphere to get rid of anything that isn't carbon. It looks like one source of bacterial cellulose could be your friendly neighbourhood Philipino store for a desserted called Nata de Coco ( https://en.wikipedia.org/wiki/Nata_de_coco ). For freeze drying, I was thinking about just letting it sit in my freezer for a few months until the water subliminated out. Does this sound practical for making a sample piece of aerogel?



Contents of the paper below:

Researchers at the Hefei National Laboratory for Physical Sciences at Micrscale (HFNL), Univeristy of Science and Technology of China used a low-cost biomass, bacterial cellulose, which can be produced industrially in a microbial fermentation process, to fabricate the aerogels. The resulting material, composed of interconnected three-dimensional networks of cellulose nanofibers, exhibits remarkable electrical properties, extraordinary strength and efficiency in heat conduction.

Small pieces of cellulose nanofibers were trimmed, freeze-dried and then pyrolyzed at 1300 degrees Celsius under argon to convert the cellulose into graphitic carbon. The result was ultralight nanofibrous carbon aerogel with outstanding compressibility, which is impossible in case of common aerogels due to their fragility. The high surface reactivity of the carbon nanofibers in aerogel form, extremely high porosity and excellent mechanical properties predispose this material to use in many industries such as easy dyes removal or selective adsorbents for oil-spill cleanup or for 3D composite, conductive gels, catalysts support, electrodes for lithium-ion batteries or supercapacitors.

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Eric Davies

250 595-0639

[Jim Cliffe]

I wondered about using a volatile solvent in place of water. It still feels like a drastic oversimplification, but if you were to make a gel using, say isoprpyl alcohol, and let it evapourate, you might wind up with something interesting.
 

Jim Cliffe
Victoria, BC
48˚ 57'N 123˚ 13'W

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[Eric Davies]

Hi Jim,

Thats how they made the original aerogel, but to keep the gel from collapsing as it evaporated, they had to use a very elaborate process called Supercritical drying in which the alcohol is gradually replaced by liquid CO2, and then the pressure gradually dropped. See http://www.aerogel.org/?p=1340   . 

The elegance of the freeze-drying is that your gel, being frozen and hence rigid, doesn't shrink/collapse as the liquid is being removed, and you don't have to deal with anything that might scare your neighbours when something goes wrong :-).

[Jim Cliffe]

And to go right out on a limb, 3D printing with aerogel! (OK, not exactly aerogel, but still!)

http://www.sciencealert.com/you-can-now-3d-print-one-of-the-world-s-lightest-materials-aerogel

Jim Cliffe
Victoria, BC
48˚ 57'N 123˚ 13'W

[Eric Davies]

I would say that isn't printing an aerogel, that's printing something that will become an aerogel. Its still a cool trick though. I'm guess supports and bridges are out though.

[Eric Davies]

I take that back, they can do supports with water.