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Plastics usually stop electricity in its tracks, but scientists have figured out a way to keep the electrons flowing.

Hosted by: Hank Green
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Hank: You’ve probably noticed that electrical wires are often wrapped in plastic, or that electricians use gloves and tools with plastic coating. That’s because they don’t want to get electrocuted, which is smart.

Plastics prevent fatal zaps by blocking the flow of electrons. They are good insulators. And for decades, that’s all scientists thought plastics could be, until a mistake in a lab forever changed the future of electronics.

It was 1974, and a Japanese chemist named Hideki Shirakawa was testing new ways of making plastics. When someone in his lab accidentally added 1,000 times more of one thing to the reaction than normal, the result was bizarre: a silvery, shiny foil that was a plastic, but looked a lot like metal.

Shirakawa showed his strange plastic to a fellow chemist named Alan MacDiarmid, and then they brought in a physicist, Alan Heeger, and together, they found a way to tweak the metallic-looking plastic so it conducted like a metal, too. That had never happened before, and the three won the Nobel Prize in Chemistry in 2000 for discovering conductive plastics.

Today, scientists have invented thousands of conductive plastics to do all sorts of things, like protecting your electronics from static shocks or building cheaper solar panels. All plastic—from Tupperware to the bristles of your toothbrush—is made of polymers, which are just long chains of repeating chemical segments.

For instance, Shirakawa’s polymer, polyacetylene, is just a chain of carbon atoms. But what makes polyacetylene special is an alternating pattern of double and single bonds. Usually bonds hold their electrons in place, but this pattern lets the double bonds share their electrons. And this electron-sharing, or conjugation, allows polymer chains move electrons like a microscopic bucket brigade, passing them along to conduct electricity.

But conjugation on its own isn’t enough to transform an insulator into a conductor. Polyacetylene, after all, didn’t conduct electricity very well right away. That’s because it was too packed with electrons. Imagine being in a bucket brigade where everyone is holding a bucket. You can’t take the bucket from the person beside you, because your hands are already full of the bucket, and you can’t pass your bucket on because that person also already has a bucket.

But if you just take out a few buckets, problem solved. And that is exactly what the scientists did to the plastic. They removed some of its electrons. With a few gaps in the chain, electrons could easily be passed around, and polyacetylene became more than 10 million times more conductive. Voila!

Now, polyacetylene is important to the origin story of conductive polymers, but in the last 40 years scientists have developed a bunch of other ones, including PEDOT. It’s in a bunch of things, but it's best known for preventing static shocks.

Static electricity might annoy you, jolting you a little after walking across some carpet to open the door. But static shocks can be fatal to delicate electronics. Those tiny packets of current can superheat an unprepared transistor and fry it.

So some companies have started covering flat screen TVs and photographic film with PEDOT. Because PEDOT is conductive, electrons can move easily, dispersing the charge from real and potential shocks before there’s any damage. After all, a trickle isn’t as dangerous as a fire hose.

And one big perk of PEDOT and other newer conductive plastics is that they can be printed. Researchers have hacked old ink jet printers to print working transistors and other electronics. And factories working on a larger scale can go even further, building things like solar cells on huge, flexible sheets.

Solar cells are usually made from silicon. But that makes them heavy and expensive. Plastic is lightweight and cheap to produce. So, even though polymer solar cells right now are less efficient than the silicon kind, eventually, scientists think they’ll be able to put solar cells on just about anything, from your window shades to your backpack.

Conductive plastics are also poised to replace all sorts of other devices. Scientists are working to invent flexible screens and power sources. That means you may someday be able to just roll up your screen, or even your whole phone! You know, someday we’re gonna look at this thing and be like, “oh my god, can you believe that outdated, terrible piece of technology?”

So, conductive plastics used to be an oxymoron. But an accident—and a lot of hard work—has changed that for good, and I cannot wait for my bendy smartphone.

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