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  • I remember watching this video online and being mesmerized.

  • The more liquid they spilled on the items the more I thoughthow was this even working?,

  • what's going on here?”

  • This is a superhydrophobic coating with properties that are seemingly impossible.

  • But this material science field is making some exciting developments with materials

  • that are even more impressive, and omniphobic.

  • You might have heard of a term called hydrophobic, which can mean you're really scared of water,

  • but in this case we're talking about an object being extremely water repellent.

  • You might see this with water on a nonstick cooking pan when it beads up and rolls around

  • with ease.

  • But surfaces can not only be only hydrophobic, but omniphobic, meaning virtually any kind

  • of liquid, from water to oil can slide off a surface with ease.

  • Which isn't material you'd find in nature.

  • The applications for a property like this are endless.

  • They could help with the day to day cleaning of your house, make electronics water resistant,

  • could help ships glide through water faster and even help heat transfer at nuclear power

  • plants.

  • Reasons like these are probably why scientists have spent years trying to get it right.

  • Soo what's the hold up?

  • Well let's start with the fact not all liquids are the same and they have different surface

  • tensions, which causes them to interact with materials differently.

  • Let's take water for example.

  • Inside the liquid, there are intermolecular attractive forces at play, meaning the water

  • molecules want to cling together.

  • But when there are dissimilar molecules above them, like air for instancethose cohesive

  • forces help the water molecules bond stronger with their neighbors - creating a thinbarrier

  • of sorts.

  • This is the phenomenon that creates droplets, and help water bugs stay afloat.

  • But like I mentioned before, this surface tension changes from liquid to liquid.

  • Water has a very high surface tension whereas oil has a very low surface tension, so it

  • seeps into everything.

  • So knowing that, material scientists have created nanostructures made of small pillars

  • spaced out just enough so that liquid can sit on small pockets of air.

  • That way the liquid's own surface tensions lifts it up, causing all of these beads and

  • droplets to form.

  • And it totally works!

  • Buut it relies on every pillar being perfect and this structure is only as strong as its

  • weakest link.

  • If one pillar breaks, the liquid can seep through the air pockets and there goes all

  • your omniphobicity.

  • And just to keep things more complicated, the materials also have to withstand condensation.

  • If water vapor makes its way into the pockets within the omniphobic structure, it can condense

  • into liquid and destroy repelling properties.

  • This has been one of the biggest hurdles that material scientists have tried to overcome.

  • And now researchers at MIT are tackling this problem head on, They've used nanotechnology

  • to create not only microscopic, but condensation-resistant “T” shaped structures.

  • The difference between this new development and earlier studies is that they made the

  • air pockets disconnected, rather than connected.

  • The disconnection would prevent a liquid from penetrating a single air pocket and spreading

  • throughout the whole material, which helps with the issue of condensation!

  • They've nailed a proof of concept, but they still need more work to bring it into market.

  • But MIT isn't the only team working on omniphobic materials.

  • A US Navy funded project from the University of Michigan made an omniphobic coating.

  • Instead of building it, the material can be sprayed on.

  • And as far as durability and clarity goes, it's one of the best coatings yet.

  • Typically, researchers mix together a filler, giving it repelling properties, and a binder,

  • giving it durability.

  • But that doesn't always work, instead the team focused on a property calledmiscibility”.

  • They did mathematical calculations of the properties of many chemical substances in

  • order to predict the best solution.

  • And it worked.

  • Their coating is clear, durable, can be applied to numerous surfaces and sheds just about

  • any liquid.

  • They're hoping it could last up to a year.

  • Which sounds like a good goal since they're interested in putting it on naval ships to

  • reduce drag and save on fueling cost.

  • However, some of the chemicals they used might not be the safest and they want to reformulate

  • so they're nontoxic and more commercially viable.

  • They have a goal to get the coating out in the next year or two, so we'll keep a lookout.

  • It's almost a race of who will create the perfect omniphobic innovation, but regardless

  • who gets there first, the real winner will be us, reaping the benefits of decades of

  • work like we always do and it's going to be amazing.

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  • One last fun fact before you go, The MIT design is so nice to look at because the periodic,

  • nanoscale features on the surface diffract light, causing the colors in the image.

  • If you love material sciences like this then go ahead and subscribe.

  • And don't forget to watch this video about how we're making these even stranger materials

  • better for electronics.

  • Thanks so much for watching!

I remember watching this video online and being mesmerized.

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液體排斥材料(These Liquid-Repelling Materials Defy Nature’s Design, Here’s How)

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    joey joey 發佈於 2021 年 04 月 12 日
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