Creating aerogel with supercritical methanol--- make money online

In previous videos, I used supercritical CO2 to dry my homemade aerogels.  This time, I soaked the aerogel in methanol, then raised the temperature and pressure of the methanol itself to make it supercritical.  This allows the gels to be dried without an additional solvent exchange into CO2.  The downside is that it requires a chamber full of methanol at 460*F and over 1200 psi, which is a much bigger hazard than using CO2.

The aerogels dried with methanol shrank less than the ones dried with CO2, but there was still a lot of cracking, and I have yet to create a high-quality monolith.

hey everyone I'm going to show you

another method to dry aerogel

so in my previous videos I showed a

methanol bath and then an exchange into

liquid co2 and then co2 into

supercritical co2 where we can remove it

without destroying the aerogel structure

but there's an easier way actually

instead of transferring into liquid co2

we can make the methanol itself go

supercritical so apparently this is how

the first aerogels were made just

because the process is actually simpler

in a way the problem is that it's a

little more dangerous because the

methanol has to be brought up to over

460 degrees F over 1200 psi so having a

container full of methanol at those

temperatures and pressures is a little

worrying so this is probably the most

dangerous experiment that I've ever

posted to YouTube so if you want to

flame me for that go ahead I'm probably

not going to try this again I was kind

of happy to get through this without any

problems and we'll probably try

something different next time

so these aerogels here are the ones that

I made with the supercritical co2 method

and this is an aerogel that I just made

today with the supercritical methanol

method and there's less shrinkage so one

of the problems I had with supercritical

co2 is that these aerogels came out with

a smaller volume than when they went in

you can see the diameter here and

compare it to the diameter of this one

that I just made it's this is a bigger

piece even though they came out of the

same mold so I'm not really sure exactly

why that is but as you can see there's

still quite a lot of cracking involved

but getting a lower density is

definitely helpful this piece has a

density of about 100 milligrams per

cubic centimeter which is I think better

than quite a bit better than the

previous gels that I've made but it

still could be much lower so this piece

isn't even lowered this this one is too

hard to measure the volume of but it's

coming in at 250 milligrams for this

piece so that's probably the lowest

density aerogel that I've made yet i

reconfigured my pipe fittings into a

sealed chamber

with just a valve at the bottom and a

compression fitting at the top and I

just plugged up the other hole because I

didn't need it and then from that

compression fitting I made a small gauge

in valve manifold and added another

compression fitting so that I could vent

the chamber remotely so the idea is that

putting a valve and a gauge on the top

of the chamber would be a problem

because the chamber is going to be at

500 degrees F which would probably melt

the valve and make it very difficult to

melt the gauge and make it very

difficult to control the valve so I

removed those pieces from the chamber

just for ease of use I mixed up a few

different batches of aerogel same basic

method with teemo's but this time I made

different densities so I started off

with the typical density the same recipe

that I showed in my earlier video that's

listed on aerogel org and then I

increased the amount of methanol or

decrease the amount of teemo's relative

to the other chemicals to make a less

dense gel now the problem is the less

dense gels didn't hold their shape so if

the original density to high density

aerogel I was able to use my syringe

cast method and formed the gel in a

syringe and then inverted the syringe

over the container full of methanol to

eject the aerogel but the lower density

aerogel is just cracked apart you know

kind of as usual as I was ejecting them

from the syringe so I think in the

future if I try another batch I will use

like a metal container to form the

aerogel and then put the whole metal

container inside the drying chamber so

they don't have to unmold it similarly

to the co2 drying method the next step

is to close the chamber off and start

raising the temperature the pressure

will also rise because we've got a fixed

volume inside there and as the

temperature goes up the pressure will as

well and when I got to about 2,000 psi I

started venting the chamber just to keep

the pressure down even though we hadn't

gotten to the critical point yet

I could let out some of the volume just

to keep the total pressure lower and I

set this up so that I could vent the

vapor coming out of the chamber into a

flask of water and the water would

ensure that all the methanol vapor

coming out of the chamber would be

liquid instead of just gas floating

around the room if you have a slow leak

in the chamber there's going to be a lot

of methanol vapor coming out and in a

few were indoors here so that could be a

problem

originally I thought quite a bit about

how to heat the chamber the best way I

thought about putting it in a toaster

oven because then I could control the

temperature of the air inside the temp

the inside the toaster oven very

accurately but I decided against that

idea because it's a very small volume

inside the toaster oven so if the

chamber were leaking methanol vapor it

would build up really quickly in the

toaster oven and be an explosion hazard

so the next best thing I thought of was

to use an electric heating element and

just wrap it around the chamber and

allow venting to you know air flow to

occur so if there were a slow leak it

would just vent off into the shop but

again I didn't like the sound of that

because it might be hard to identify

such a leak so I ended up just using the

torch my thinking was that if there were

a slow leak it would just ignite as it

was coming out of the chamber

and I would at least be aware of it

right away it was a big leak that could

be a problem

after I reached the critical point which

is four hundred sixty degrees F at

around 1200 psi for methanol I started

releasing the pressure and continued to

apply heat to keep the temperature above

460 and allowed the pressure to come

down slowly once the pressure is below

the critical point about 1200 and the

temperature is still above 460 we can

start venting the chamber more quickly

because we know that there's just gas

inside there all of the supercritical

drying has occurred here's one thing

that I didn't expect when I dumped out

the contents of the chamber the aerogels

that were kind of near the top

looked you know okay I mean they're

cracked but at least you know they're

they're normal looking aerogel but these

stuff at the bottom of the chamber was

kind of mixed in with this ash kind of a

suit or something at the bottom and when

I had done is I had put this aluminum

spacer into the bottom so that the

aerogels that were sitting on the bottom

of the chamber wouldn't fall down into

the valve that's at the bottom so I

don't know what's going on here but

apparently aluminum reacts with

supercritical methanol I think I can't

even remember but I'm pretty sure that I

put a piece of Windows screen inside

here to cover up these holes just

aluminum windows screen and it's gone so

I I don't know what happened there but

I'd be interested to know if you guys

have some knowledge about how

supercritical methanol reacts with

aluminum it looks like it just burned

away although I don't know the chemistry

involved okay well like you say I think

I've pretty much done with aerogel there

might be one or two other things I'm

going to try but next up on the list is

vacuum frying selling someone in my

comments section posted a suggestion

about Trader Joe's vacuum fried fruit so

this is pretty interesting if you put

food into oil and then lower the

pressure and raise the temperature you

can fry it at a lower temperature than

you could in atmospheric pressure so I'm

going to try that and then of course if

that's interesting what about high

pressure frying you could also put the

food into oil raise the temperature and

raise the pressure to prevent the water

from boiling so I'm going to be having

some fun experimenting with that stuff

and I of course I will document and make

some videos all right see you next time

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