Why doesn’t anything stick to Teflon? - Ashwini Bharathula
-
0:09 - 0:11Nothing stuck to Mafia boss John Gotti
-
0:11 - 0:16who evaded justice for years by bribing
and threatening jurors and witnesses. -
0:16 - 0:19That earned him the name
the Teflon Don -
0:19 - 0:23after one of the slipperiest
materials on Earth. -
0:23 - 0:27Teflon was in the spacesuits the Apollo
crew wore for the moon landing, -
0:27 - 0:30in pipes and valves used
in the Manhattan Project, -
0:30 - 0:35and maybe in your kitchen as the nonstick
coating on frying pans and cookie sheets. -
0:35 - 0:40So what is this slippery solid,
and why doesn't anything stick to it? -
0:40 - 0:43Teflon is a brand name for
polytetrafluoroethylene, -
0:43 - 0:46or PTFE.
-
0:46 - 0:51It was stumbled upon accidentally in 1938
by a 27-year-old American chemist -
0:51 - 0:53named Roy Plunkett
-
0:53 - 0:57while he was trying to develop
a non-toxic refrigerant fluid for DuPont, -
0:57 - 0:59a chemicals company.
-
0:59 - 1:02The strange, white substance that formed
inside his lab canister -
1:02 - 1:04was chemically inert,
-
1:04 - 1:07meaning it wouldn't react
with other substances. -
1:07 - 1:10It also had an extremely
low coefficient of friction, -
1:10 - 1:14making other materials slide right off it.
-
1:14 - 1:18Teflon's properties make it perfect
when you need something slippery, -
1:18 - 1:19chemical resistant,
-
1:19 - 1:20or waterproof,
-
1:20 - 1:23which means it has a lot of applications.
-
1:23 - 1:25It can be found all over the place,
-
1:25 - 1:27as a coating on raincoats,
-
1:27 - 1:28industrial ball bearings,
-
1:28 - 1:29artificial joints,
-
1:29 - 1:31circuit boards,
-
1:31 - 1:35and even the Rocky Mountains-themed roof
of the Denver International Airport. -
1:35 - 1:40The incredible properties of PTFE
come from its molecular structure. -
1:40 - 1:41It's a polymer,
-
1:41 - 1:46meaning it's made of long chains of
repeating units of atoms strung together. -
1:46 - 1:50A PTFE chain has a backbone
of carbon atoms, -
1:50 - 1:53each of which is attached
to two fluorines. -
1:53 - 1:56The fluorine atoms surround the carbon
like armor, -
1:56 - 1:57spiraling around the chain,
-
1:57 - 2:01and the bond between carbon and fluorine
is incredibly tight. -
2:01 - 2:04Like a couple that ignores everyone
except each other, -
2:04 - 2:06carbon and fluorine interact so strongly
-
2:06 - 2:11that the normal, intermolecular forces
that help substances stick to each other -
2:11 - 2:13don't stand a chance.
-
2:13 - 2:17Even the famously adhesive feet of geckos
usually can't get a grip. -
2:17 - 2:18But wait!
-
2:18 - 2:21If PTFE doesn't stick to anything,
-
2:21 - 2:24how can it be so firmly attached
to something like a pan? -
2:24 - 2:27One method involves sandblasting the pan
-
2:27 - 2:31or etching it with chemicals
to make it rough. -
2:31 - 2:35Then, a special primer is applied,
which acts like glue. -
2:35 - 2:39Its exact composition is a trade secret
guarded by each manufacturer. -
2:39 - 2:42The pan is sprayed with liquid PTFE
-
2:42 - 2:46and heated to around
800 degrees Fahrenheit. -
2:46 - 2:49The layers then solidify into
a smooth, slick coating. -
2:49 - 2:53When you later cook eggs
in this PTFE-coated pan, -
2:53 - 2:55the extra tight carbon-fluorine bonds
-
2:55 - 2:59just ignore the water and fat and protein
molecules in the eggs. -
2:59 - 3:01Without those interactions,
-
3:01 - 3:04the food just slides around
without sticking. -
3:04 - 3:08You might wonder if it's safe to cook
in a PTFE-coated pan. -
3:08 - 3:10The answer is yes, if you're careful.
-
3:10 - 3:16PTFE is stable at moderate temperatures,
like you'd use to cook eggs or fish, -
3:16 - 3:20but above 500 degrees Fahrenheit,
it starts to degrade, -
3:20 - 3:24and heating it further releases fumes
that can make you feel sick. -
3:24 - 3:28An empty pan can reach 500 degrees fast
over high heat, -
3:28 - 3:32but most kitchens are ventilated
well enough to dissipate the fumes. -
3:32 - 3:35People used to also think
that accidentally consuming PTFE -
3:35 - 3:39that flaked off a scratched pan
was bad for you, -
3:39 - 3:42but the current consensus
is that it's harmless. -
3:42 - 3:45Because PTFE doesn't interact with other
chemicals very well, -
3:45 - 3:48it isn't thought to break down
inside your body. -
3:48 - 3:52Whether it's safe to manufacture Teflon
is another story. -
3:52 - 3:54DuPont and its spin-off company Chemours
-
3:54 - 3:57now face lawsuits
worth millions of dollars. -
3:57 - 4:00They've been accused of polluting
the environment for decades -
4:00 - 4:02and exposing employees
and local communities -
4:02 - 4:08to health risks associated
with a toxic chemical called PFOA. -
4:08 - 4:12That chemical was involved
in manufacturing Teflon. -
4:12 - 4:13As for John Gotti,
-
4:13 - 4:18in 1992, the Mob boss was finally
convicted of five counts of murder, -
4:18 - 4:19among other charges.
-
4:19 - 4:23That prompted the head of the FBI office
in New York City to announce, -
4:23 - 4:25"The Teflon is gone.
-
4:25 - 4:28The don is covered in Velcro,
and all the charges stuck."
- Title:
- Why doesn’t anything stick to Teflon? - Ashwini Bharathula
- Description:
-
View full lesson: http://ed.ted.com/lessons/why-doesn-t-anything-stick-to-teflon-ashwini-bharathula
Teflon was in the spacesuits the Apollo crew wore for the moon landing, in pipes and valves used in the Manhattan project, and it may be in your kitchen, as the nonstick coating on frying pans and cookie sheets. So what is this slippery solid — and why doesn’t anything stick to it? Ashwini Bharathula describes the science behind Teflon.
Lesson by Ashwini Bharathula, animation by Andrew Foerster.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:45
Jessica Ruby approved English subtitles for Why doesn’t anything stick to Teflon? - Ashwini Bharathula | ||
Jessica Ruby accepted English subtitles for Why doesn’t anything stick to Teflon? - Ashwini Bharathula | ||
Jessica Ruby edited English subtitles for Why doesn’t anything stick to Teflon? - Ashwini Bharathula | ||
Jennifer Cody edited English subtitles for Why doesn’t anything stick to Teflon? - Ashwini Bharathula | ||
Jennifer Cody edited English subtitles for Why doesn’t anything stick to Teflon? - Ashwini Bharathula |