100 Nano-Stories: Drying Of Polymer/Polyimide Aerogel!🔍
Episode #21: Supercritical Drying: Polymer/Polyimide Aerogel Edition!
I promised you the article on Polymer Aerogels, and here we are! Today, we will talk about a new material that can be of aid in the future when it comes to materials that can be both insulating & strong: Polymer Aerogels!
Wait, Carlos, I am new here to the series, so can you give me your recent article on why we need polymer aerogels?
So let’s get into the supercritical drying of polymer aerogels! Cue the fireworks!
Polymer (Polyimide) Aerogels
This is what a “finished” polymer aerogel looks like.
I know, it doesn’t look that aesthetically pleasing, but this is what many aerospace companies & applications seek to use in spacesuits, rockets, etc.
The reason why is because that polymer aerogels carry both super-insulating properties & thermal stability, similar to classic silica aerogels. The difference here is that the mechanical properties of polymer aerogels have a wider range of applications due to polymer aerogel’s stiffness & elasticity.
But moving on, the real question is what materials/chemicals should be used to develop the polymer aerogels. The material that is commonly used in the development of silica aerogels is Polyimides.
In simple terms, Polyimides are a type of plastic with high-performing mechanical properties such as resistance to high temperature and corrosion (determination of a metal over a period of time).
Oh, now I know why polyimides are such a valuable material/chemical for the creation of polymer aerogels!
However, one of the coolest things about polyimide is when you can turn them into aerogels! When you do this, polyimide aerogels have a property of elasticity that surpasses the elasticity & moisture stability of classic silica aerogel!
But the best part is that they can be formed into rolls, boards, and more, which allows the range of applications for polyimide aerogels to be seemingly endless!
Properties of Polyimides via Supercritical Drying
During the Supercritical Drying of Polyimides (Polymer Aerogel), polyimides carry certain features/properties that allow them to have a wider range of applications!
But what features do they have that make them so special under Supercritical Drying, Carlos?
Polyimides can be stable in temperatures up to about 400° C during the Supercritical Drying!
Secondly, the gaseous thermal conductivity of polyimides is 15 mW/mK! I know, it doesn’t mean a lot to you, but if it helps, normal air has more thermal conductivity (25 mW/mK)!
The (W) is known as Watts, and the (K) is for Kelvin! I can explain more in another article about this, reader!
Let’s also briefly talk about the chemicals I will explain in the next article! Some of these polyimides are also known as precursors! In silica aerogel precursors, we would normally use silica alkoxide.
But for polyimides, the two most common precursors for polyimide aerogels are 2,2ʹ-dimethylbenzidine (DMBZ) and p-phenylenediamine (PPDA).
If we can cross-link the precursors, these polyimide aerogels will not undergo shrinking during supercritical drying. But the best part about using DMBZ & PPDA as our monomers for polyimide aerogels is that their water absorption is so low that the chance of the polyimide network collapsing and undergoing capillary action will not occur.
Because of this, reader, we end up with these types of polymer/polyimide aerogels:
Closing Thoughts 💭
Congrats, reader! Now we know about some of the fundamental properties & chemicals in the supercritical frying of polymer/polyimide aerogels!
Carlos, I learned some new things about polymer/polyimide aerogels, but I want to know more about what is a polyimide, the chemicals, and some technical terms about the chemistry names! Can you help me out?
All right, seems we have a deal, reader! I’ll make sure to talk more about how these chemicals are necessary to erase any mistakes from the drying process in polymer/polyimide aerogels!
Or as my Spanish-Speaking self would say:
Vocabulary → 📓
Cross-Link → A covalent/chemical bond between different chains of atoms in a polymer or a complex molecule.
Covalent Bond → The pairing of electrons by atoms to gain stability in their outer (valence) electron shell.
Polymer Aerogel → A material made up of monomers or macromolecules as the network of the aerogel.
Polyimides → A type of plastic with high-performing mechanical properties such as resistance to high-temperature and corrosion (determination of a metal over a period of time).
Capillary Action → The solid structure will continue to be pulled on by the liquid around the middle of the aerogel, resulting in the entire structure crumbling and collapse in on itself.
Bonus Content → 💻
Previous “100 Nano-Stories” → 🔖
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