Bouncing Droplets: Superhydrophobic and Superhydrophilic Surfaces

This video introduces the concept of surface tension, and shows how roughness can make a surface superhydrophobic or superhydrophilic. The Wenzel and Cassie-Baxter models are explained. Special thanks to the MIT BioInstrumentation Lab.
License: Creative Commons BY-NC-SA
More information at k12videos.mit.edu/terms-condit...

[@Obbliteration]

Amazing video. This would have saved me an hour of reading wikipedia.

[@kingcheese77]

That was incredibly helpful and well done.

[@zojacheung1738]

This is what I have been doing in these 2 months! Studying the water droplet behaviours on surfaces.

[@premshadow]

One of the best videos I have ever seen.

[@juanrafael9070]

I know this was 11 years ago but it was still very clear and easy to understand! :)

[@shahiduzzamanakash]

Thanks a lot. Great job. Superbly Explained. I am exactly looking for this video!

[@jeffbeaudoin4544]

Very well explained, and equally appreciated.

[@samianholt]

Great Explanation ! - More please !

[@hatran4173]

well summarize and easy to understand

[@alsarat4068]

Cool , highly appreciated!

[@XxXDanielGXxX]

Great explanation. Thank you!

[@y.sflower4384]

Great job!

[@user-fo3hk8nc5z]

That was an amazing video which helped me a lot. Thank you!!

[@kashifazmi3898]

Amazing video. Nice explained

[@jaishetty4469]

Superb explanation

[@whtnasarp]

superb video... precise and concise

[@mauddeclomesnil6907]

Thank you for this video ! it helped me a lot :)

[@syuhada9627]

Thank you! u're a life saviour!

[@mjl7810]

Amazing

[@mdjulker9]

The best one ever.....

[@frankjohnson123]

At 6:15, the cosine of a greater angle if they're both less than 180 degrees will always be less. Shouldn't you then compare the absolute values of the cosines?

[@jacobbenson2103]

is this the same lady who made the videos about leaves using phi to grow efficiently?

[@emharrje99]

wow, im not even 14 yet, and i found this fascinating!

[@debarchan123]

Since you're 18 now, how do you feel about it after so many years?

[@hilariousharry1890]

@@debarchan123 lol true

[@Spurs424]

Mind=Blown

[@rajneeshverma2408]

Thanks a Lot. Can you also provide some link or anything on the derivation of the cassie baxter and wenzal equation

[@EndangeredSpecie98]

Wow so smart

[@dumboxthomas6151]

are there any textbooks out there that addresses this topic?

[@Ericchan8126]

what is the disadvantage/side-effect of superhydrophobe ?

[@frankjohnson123]

Also, at 7:06, is it supposed to be the decimal of the solid?

[@leeschloss4840]

All these people saying thanks for the simplification. Here I am thinking, "she's going too fast!" lol

[@maryemoubella8798]

I did an experiment on ABS plastic, the contact angle of smooth ABS plastic is around 70° which means hydrophilic surface, but when I treated the surface of this plastic by grinding using sandpaper 240um and 400um, the contact angle of the ABS plastic grounded is more than 90° ''around 100°", which mean the surface become hydrophobic. So, how can you explain these results ?!! and thank you so much

[@groundcontrol6876]

How can I make a surface Cassie-Baxter rough? (With regular tools and materials) or do I need a really expensive laser etching machine, an electron microscope to verify the surface, etc?

[@ahmedfarajalarbi2397]

Hi, just coating your surface with superdrophbic coating

[@vanessasim2024]

is it possible for a superhydrophobic coating to be in wenzel state?

[@mdjulker9]

It depends on how you define hydrophobicity, Conditions to be super-hydrophobic are;- 1. WCA>150 deg., 2. low CA hysteresis 150 deg with Wenzel state for moderately rough surface with introducing hydrophillic nano-spikes or by other means. The conclusion is, yes, hydrophobic coating can be in Wenzel state but will definitely show highly adhesive superhydrophobicity.

[@dayslee8098]

6:09 is wrong i think. When Cos(theta*)>Cos(thetaE)，we get theta*

[@w00tse]

No, that was Vihart.

[@LinyEasow]

Excellent! And what you told about the desert beetle left me wondering how evolutionists can fool themselves to think that this highly engineered surface can happen by random chances.

[@ayushranjan5631]

I want to model in comsol can anyone help?

[@earthman4222]

That is what I thought. Um...

[@TheStarvingSamurai]

Wait, what?

[@zookey500]

Don't call them unhappy molecule..... Just no.

[@MassMultiplayer]

amazing writing horrible sqaure lol, i mean its square paper how cna you miss it