Name: 【TED-Ed】Why doesn’t anything stick to Teflon? - Ashwini Bharathula
Uploaded: 2016-12-30T12:55:44.000Z
Duration: 4 min 45 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

who evaded justice for years by bribing and threatening jurors and witnesses.

after one of the slipperiest  materials on Earth.

Teflon was in the spacesuits the Apollo crew wore for the moon landing,

in pipes and valves used  in the Manhattan Project,

and maybe 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?

Teflon is a brand name for polytetrafluoroethylene,

It was stumbled upon accidentally in 1938 by a 27-year-old American chemist

while he was trying to develop  a non-toxic refrigerant fluid for DuPont,

The strange, white substance that formed inside his lab canister

meaning it wouldn't react  with other substances.

It also had an extremely  low coefficient of friction,

making other materials slide right off it.

Teflon's properties make it perfect when you need something slippery,

which means it has a lot of applications.

and even the Rocky Mountains-themed roof of the Denver International Airport.

The incredible properties of PTFE come from its molecular structure.

meaning it's made of long chains of repeating units of atoms strung together.

A PTFE chain has a backbone  of carbon atoms,

each of which is attached  to two fluorines.

The fluorine atoms surround the carbon like armor,

and the bond between carbon and fluorine is incredibly tight.

Like a couple that ignores everyone except each other,

that the normal, intermolecular forces that help substances stick to each other

Even the famously adhesive feet of geckos usually can't get a grip.

how can it be so firmly attached to something like a pan?

or etching it with chemicals  to make it rough.

Then, a special primer is applied, which acts like glue.

Its exact composition is a trade secret guarded by each manufacturer.

and heated to around  800 degrees Fahrenheit.

The layers then solidify into a smooth, slick coating.

When you later cook eggs in this PTFE-coated pan,

just ignore the water and fat and protein molecules in the eggs.

the food just slides around  without sticking.

You might wonder if it's safe to cook in a PTFE-coated pan.

PTFE is stable at moderate temperatures, like you'd use to cook eggs or fish,

but above 500 degrees Fahrenheit, it starts to degrade,

and heating it further releases fumes that can make you feel sick.

An empty pan can reach 500 degrees fast over high heat,

but most kitchens are ventilated  well enough to dissipate the fumes.

People used to also think  that accidentally consuming PTFE

that flaked off a scratched pan was bad for you,

but the current consensus  is that it's harmless.

Because PTFE doesn't interact with other chemicals very well,

it isn't thought to break down inside your body.

Whether it's safe to manufacture Teflon is another story.

now face lawsuits  worth millions of dollars.

They've been accused of polluting the environment for decades

and exposing employees  and local communities

to health risks associated  with a toxic chemical called PFOA.

That chemical was involved in manufacturing Teflon.

in 1992, the Mob boss was finally  convicted of five counts of murder,

That prompted the head of the FBI office in New York City to announce,

The don is covered in Velcro, and all the charges stuck."

Subtitles ListPlay Video

【TED-Ed】Why doesn’t anything stick to Teflon? - Ashwini Bharathula

stick

substance

consume

interact