Scientists Develop Super-Slippery Material

Hugh Pickens writes writes "Anyone who is partial to ketchup with their food will know how difficult it is to get the final dregs from the bottle but now the Telegraph reports that scientists have created one of the most slippery materials ever that promises to result in new self-cleaning surfaces that never get dirty, could be used to coat the inside of bottles and jars to help consumers get all of the food inside, or in the energy industry for making oil flow more efficiently through pipes. Professor Joanna Aizenberg, a materials scientists at Harvard University, was inspired by the carnivorous Nepenthes pitcher plants, which has a highly slippery surface at the top of its flute-shaped leaves so that insects tumble down into the digestive juices contained inside. The new material, known as a Slippery Liquid Infused Porous Surface or SLIPS boasts a rare trait called "omniphobicity", which means it can repel both water and oily materials. "If we used substance like ours to coat the inside of bottles, it would be possible to get it all out," says Aizenberg. "The only problem may be that the sauce may come out a little too easily on to their food.""

Re:Not for cooking sadly

[richy freeway]

In other article covering same research project, they sadly say [evenweb.com] that said material is very temperature sensitive, thus unusable for cooking. Still nice curiosity.

Goatse

Re:Prior Art

[DikSeaCup]

I disagree. This sounds more like the Orange Propulsion Gel than the blue stuff.

"The only problem may be that the sauce may come out a little too easily on to their food."

Now, if it comes shooting out of the top after you open it, that would be the blue gel.

Neverwet

[data2]

Have a look at http://www.neverwet.com/ [neverwet.com] They also have some amazing case studies showing off what the material can do, and where some use cases are.

Re:Accident waiting to happen...

[fuzzyfuzzyfungus]

If you look at the top surface of an aircraft's wings(large airliners anyway) there are a variety of marked walkways with various messages to the effect of "ONLY WALK INSIDE THE LINES. NO, NOT THERE YOU MORON!" in large print, presumably to keep somebody from putting a foot through something delicate or falling off and cracking on the tarmac.

I assume that, in this use case, they'd coat the rest of the wing and either ignore or otherwise deal with the service walkways.

Re:Simpler approach

[Yvan256]

Here's another tip: don't put regular plastic containers in the microwave.

Re:New Teflon

[hjf]

I'm tired of this bullshit articles. I mean, kudos to the guy who came up with this, and I'm sure it works great in a lab, but in real life it probably is just as good as teflon. And as someone who actually cooks, I can tell you that teflon is overrated.

You know what's a good non-stick surface? Take a good ol regular steel pan, the black ones. Rub it with cooking oil, and leave it to burn. You get a cloud of white smoke (man, a tiny bit of oil goes a long way!). When it's done, you have a layer of burnt oil that has penetrated every pore in the steel surface. BAM! Instant "teflon", wash your pan thoroughly with manual dishwashing detergent (don't use a dishwasher machine, it will take the layer off), and you're good to cook.

This is how pans and pots and everything has been "cured" for centuries, and works perfectly. It's how you treat a wok when you buy it, and it's what happens to your grill over time.

Wanna test it? Try frying an egg. On brand new, pristine condition Teflon, the egg won't stick. After a few uses the teflon surface gets microscopic scratches, and the egg starts sticking. On burnt oil? It never sticks. And every time you cook, some oil refills the new scratches so it auto-protects itself.

Re:Could you use this on a submarine?

[jbengt]

You are misinformed. (about pipelines, not about golf balls.)
The pressure drop rate in a pipeline depends on velocity, the ratio of inertial forces to viscous forces (aka Reynolds number), and the ratio of the dimension of pipe surface roughness to pipe diameter (aka e/D). For relatively low velocity, low density, high viscosity flows the pipe surface roughness does not matter. For relatively high velocity, high density, low viscosity flows the pressure drop is a proportional to the square of the velocity times length divided by diameter and function of the log of e/D (greater pressures with higher roughness). Investigate the Darcy Weisbach equation [wikipedia.org] and formulas for estimating friction factors [wikipedia.org]
Still, even if proven to be cheap, I imagine this might have limited application in pipelines, since age, corrosion, and erosion take their toll in actual service.

Re:Environmental impact

[BlueParrot]

Specifically, one wonders about the environmental impact--how hard must this stuff be *to clean* when it gets stuck on something, for example? If we put it on a hundred million bottles a year, how will that impact the environment?

Slippery doesn't mean it is hard. Notice how teflon is fairly non-stick, but you can still scratch it quite easily with any metal utensil. In the same way I kinda suspect you will be able to just scrub this stuff away. It is also likely to be sensitive to temperature and some chemicals.

It is REALLY hard to make a material which will resist corrosion from alkaline solutions as well as acid, heat , scratching , fracture and so on all at the same time. People that design satellites, space probes or nuclear reactors additionally have to deal with intense radiation that can alter the chemical properties.

Then there is photo-damage. Many organic materials degrade under exposure to sunlight. You got oxidation to worry about, redox reactions with salts and other ionic compounds. If the material is porous then small molecules can diffuse into it and weaken it from the inside.

Basically you will not be able to make a material I cannot find a way to dissolve or destroy. Granted, if you put something quite tough onto a very sensitive fabric, I may not be able to get rid of it without destroying the cloth. There's no need for super-slippery materials for this however. Just rub some used motor oil into your clothes and they are pretty much permanently ruined.

some observations from reading the paper

[snoop.daub]

Just a couple points I want to make:

- Nowhere in the paper is there anything about using this stuff in ketchup bottles. I'm sure the researchers seized on this when they got interviewed as a simple way to explain lyophobicity to a general audience, the effect of which was to make "getting all the ketchup out of the bottle" the only thing anyone remembers. Typical.

- As for the significance of the research, there has been a ton of work in the last, oh, say 10-20 years on superhydrophobic surfaces, which have texture on the scale of a few nm that prevents water or other high surface tension liquids from penetrating into these tiny cracks. The water drops energetically prefer to remain as spherical as possible and so the liquid is repelled. This doesn't work with low surface tension liquids like light oils because it would rather penetrate inside the texturing than stay in a roughly spherical drop. The neat advance in this work is the addition of a low surface tension liquid which is introduced into the textured Teflon or fluorinated silane surface and repels both water and oil. They can use lots of different chemicals for the liquid, so as they continue the research they will find that some resist high heat, others are bio-inert, etc etc. so there are many possible applications.