100 Nano-Stories: More Polymers & Polymerization!
Episode #24: Polymer/Polyimide Aerogel Supercritical Drying!
Preface → ✨
We’re back, reader!. . . except no more going through organic chemistry! For now, let’s move on to the actual polyimide aerogels & the supercritical drying process!
Wait, Carlos! I’m new here, so does this mean that I have to read a previous article in order to follow along?
This is the more important article to proceed with the series, but don’t be mad! It’s only 3 minutes of organic chemistry, so once you’re done learning the fundamentals of the precursors used for polymer/polyimide aerogels, you can follow along with this article! 😉
If you have read my previous article, then let’s move on to. . . you guessed it. . .
Polyimide Aerogels!
Polymerization & Supercritical Drying! → 🔩
Now that we talked about 2,2ʹ-dimethylbenzidine (DMBZ) & p-phenylenediamine (PPDA), let’s discuss the range of additional polymers that can be used in the production of polymer/polyimide aerogels.
Most of the polymer aerogels produced by the precursors (DMBZ) & (PPDA) have been produced via a process called solution polymerization. Polymerization is when a large number of monomer molecules chemically react to create a 3-dimensional network of polymer chains! These polymer chains create the network of our polymer aerogel!
After the solution polymerization, we can proceed to the supercritical drying process with liquid carbon dioxide (liquid CO2.) This is the process that is used to create classic silica aerogel, otherwise known as Low-Temperature Supercritical Drying (LTSCD).
The process is about the same for polymer/polyimide aerogels, but there is one key difference when it comes to the supercritical drying of polymer/polyimide aerogels: the polymer/polyimide aerogel can now be composed of organic material. 😮
Wait, Carlos, what is that supposed to mean? Doesn’t sound that clear to me!
Organic materials are basically carbon-based compounds, which means that there is carbon in the molecule/compound. However, organic materials are divided into 3 categories due to where the compounds came from:
- Cellulosic Materials
- Proteinaceous Materials
- Organic Polymers
Cellulosic Materials come from plants or other furniture in your home. Some of these polymers can come from wood, bark, plants, grass, etc.
Proteinaceous Materials come from any living organism/animal. Some of these polymers can come from humans, feathers, skin, hair, fur, etc.
Organic Polymers come from any type of oil and/or fossil fuels.
Oh my God! Do they use human flesh or something to make aerogels?
Oh no, reader! Don’t worry about that! Cellulosic Materials are mostly used in the production and drying of Polymer/Polyimide Aerogels!
Closing Thoughts → 💭
When using the supercritical drying process to produce polymer aerogels, we can retain the wet gel structure to produce the 3-dimensional network of the polymer aerogel, similar to the LTSCD of classic silica aerogel.
By doing this process, the polymer aerogel (15 mW/mK) can reach a thermal conductivity that is less than air (25 mW/mK)! This means that normal air has a higher chance of starting a fire than the polymer aerogel! That’s crazy! 🤯
So what’s stopping us from even creating these aerogels, Carlos?
Sigh. . . It’s the cost of the solvent, the supercritical CO2, and the environmental harm we cause because of the amount of energy use when creating the aerogels.
I think it’s valuable if we explain all of these concepts in another article, reader! That way, we can analyze the true problems behind the creation of our favorite futuristic material!
Who knows? Maybe one of you might find it. . . and make Master Yoda happy. 😉
Vocabulary → 📓
Supercritical Drying → Liquid in a gel/substance is being transformed into a gas with the absence of the surface tension and the capillary stress of the gel. It’s what allows for a silica gel to transform into an aerogel.
Solvent → The liquid in which a solute is dissolved to form a solution.
Electronegative → The tendency of an atom to attract a bonding pair of electrons is very high, and oxygen’s electronegativity is now of the highest on The Periodic Table Of Elements.
Polymerization → A large number of monomer molecules chemically react to create a 3-dimensional network of polymer chains.
Bonus Content → 💻
Previous “100 Nano-Stories” →🔖
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