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Simple Method Yields A Wrinkly, Durable, Water-Repellent Coating (acs.org)
ckwu writes: Superhydrophobic coatings that make water droplets dance and roll off of a surface show promise for applications such as self-cleaning cars, buildings, and food processing equipment. A new method creates a durable superhydrophobic coating by combining two common materials -- Teflon and a shrinkable plastic -- in a few simple steps. The researchers took inspiration from work done with the polystyrene material found in Shrinky Dinks -- the children's crafting kit. They deposited Teflon onto a similar material called PolyShrink, heated it, and found that the Teflon formed a crinkled surface that caused water to bead and roll off easily. The best results came from polyolefin shrink wrap coated with a 10nm-thick layer of Teflon. What's more, the surface is durable, having about the same scratch resistance as an aluminum coating, and repels water even after being scratched. Update: 03/09 16:10 GMT by T : Note: That's nm, rather than mm; now fixed.
eom
Teflon is not PFOA. Teflon is PTFE. PFOA is used during the creation of PTFE, but is completely burned off during PTFE manufacturing, leaving no PFOA. Of course, lots of toxic things are used during the manufacturing of safe things all the time - that stainless steel staple used to hold your surgery together, or your frying pan/cooking utensils contains chromium, a nice and toxic heavy metal.
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
It's 10 nanometers. A 10mm thick layer of PTFE would be massive.
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Perfluorooctanoic acid is not teflon, jackass. The process of MANUFACTURING teflon involves the process use of a toxic substance. So do a lot of substances. Chrome electroplating involves immersion a shockingly toxic bath. But finished chrome-plated items are not the least bit toxic, and neither are teflon-finished items, unless heated above 260 C, whereupon pyrolytic breakdown evolves toxic substances.
Since frying typically reaches up to 230 C, I don't regard the safety margin as adequate, and personally I would never fry in a teflon-coated pan. But no, teflon as a substance under ordinary conditions is NOT in the least toxic.
Caveat - if the finished teflon is allowed to be contaminated by traces of perfluorooctanoic acid, then there is trace toxicity present in the finished teflon. But the acid is NOT an integral constituent of teflon, does not HAVE to be used at all, and is being phased out. Overall, teflon cookware is considered an insignificant exposure pathway to perfluorooctanoic acid.
No, moron, we did not. PTFE is one of the least reactive substances in existence and is not dangerous to anyone at all. One of the chemicals *formerly* used in the production of PTFE was found to be toxic. The resulting coating is not.
Teflon IS NOT PTFE. "Teflon" is the brand name of "PTFE-based" formulas by Chemours. Chemours is a spin-off of DuPont Co. What reference to do have that C8 is "completely burned off"?
Pyrolysis of PTFE is detectable at 200 C (392 F), and it evolves several fluorocarbon gases and a sublimate.
While PTFE is stable and nontoxic at lower temperatures, it begins to deteriorate after the temperature of cookware reaches about 260 C (500 F). The degradation by-products can be lethal to birds, and can cause flu-like symptoms in humans. See polymer fume fever.
Meat is usually fried between 204 and 232 C (399 and 450 F), and most oils start to smoke before a temperature of 260 C (500 F) is reached.
Why can't we all use universal measurements like the meter (1 ten millionth the distance through Paris from the pole to the equator)
That's not the definition of a metre.
Yes, that actually was the original definition.
From Wikipedia:
"the commission â" whose members included Lagrange, Laplace, Monge and Condorcet â" decided that the new measure should be equal to one ten-millionth of the distance from the North Pole to the Equator (the quadrant of the Earth's circumference), measured along the meridian passing through Paris.
The definition has been revised several times to base it on bars made of platinum, the wavelength of light and the speed of light, but that doesn't change the origin of the unit.