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00:00what's it take to make our modern world I'm David Pogue join me on a high-speed
00:20chase through the elements and beyond as we smash our way into the materials molecules and reactions
00:32it's a really cool enzyme because it makes life on earth possible that make the places we live the
00:38bodies we live in and the stuff we can't seem to live without the only thing between me and certain
00:45death is chemistry from killer snails it's when you think you've heard of everything nature will
00:53surprise you and exploding glass to the price of pepper-eating pogue pays gotta be some easier way
01:00to learn about molecules we'll dig into the surprising way different elements combine together
01:10and blow apart
01:15in this hour we swing from the molecular chains and surf the atomic webs that gives some materials
01:24unique abilities the moldable molasses of molten glass the built-in pulling of rubber the g-forces
01:35are indescribable and the menagerie of modern plastics that these days is both a miracle
01:43and a menace people want to do the right thing but it's really difficult to know exactly what to do
01:49beyond the elements indestructible right now on Nova
02:13the periodic table the who's who of atoms the stuff everything is made of with familiar names like
02:28hydrogen oxygen carbon and iron but what if every substance were made of just one kind of atom just one
02:38kind of element what if a human were made only of carbon what if water were made only of hydrogen and what if salt were made only of poisonous chlorine
03:04of poisonous chlorine
03:12luckily nearly all elements like to stick together it's through the combination of different elements that our world exists
03:19and we've made it an even richer place by learning to harness and even make those combinations to create new materials that have shaped our modern world
03:31such as rubber or plastic materials we've come to depend on but that sometimes come with difficult environmental downsides
03:41but let's start with one of the oldest and most chemically interesting
03:48look at the buildings in any city today and you'll see or see through one of the signature materials of our times
03:57glass
03:59the corning museum of glass in corning new york is home to an internationally famous collection of glass
04:08glass
04:10with examples that range from antiquity
04:12to contemporary art
04:16from the functional
04:18to the fantastic
04:22the museum also runs demonstrations of glass blowing
04:26she's applying glass color
04:28that molten glass
04:30by holding it to the ground gravity takes hold and she gets that beautiful ruffled edge
04:36some
04:38include opportunities for novices like me to get into the act
04:42we're going to be making something we call a roman bottle
04:44good keep going
04:46keep going
04:48all right stop
04:50the kind of glass i'm working with is the most common sort
04:52soda lime glass
04:54the stuff of windows
04:56drinking glasses and glass bottles
04:58give the pipe a tap
05:00whoo
05:02i am good at this
05:06eric meek
05:08one of the hot glass program managers
05:10breaks down the ingredients in soda lime glass for me
05:14so these are the raw materials that we use to make glass
05:16the first main ingredient is silica sand you can see this is a beautiful white pure silica sand this will make really nice clear glass for us
05:26silica is a network of silicon and oxygen atoms where each silicon atom shares electrons with neighboring oxygens in what are called covalent bonds
05:38to get this to melt at a lower temperature we add soda ash so that's sodium carbonate
05:44sodium carbonate
05:46sodium carbonate
05:47two sodiums electrically attracted to three oxygens sharing electrons with a carbon atom
05:52if we melted pure silica it would melt nearly 4,000 degrees if you had soda ash it drops the melting temperature down to around 2,000 degrees Fahrenheit
05:58so easier for us to bring about
06:00easier for us to bring about
06:02easier for us to bring about
06:04and then the final ingredient over here is crushed limestone or calcium carbonate
06:10like sodium carbonate
06:12but with a calcium instead
06:14calcium carbonate
06:16will help to stabilize the glass over time
06:18wow
06:20you just sort of mix that up in a pot
06:22and put it over a medium flame
06:24it's that easy
06:26you mix these together
06:28put it into crucible
06:30melt it at about 2,000 degrees and you have glass
06:32at high temperatures
06:34all those powdery ingredients melt together
06:38to form a viscous liquid
06:40that cools into glass
06:42but there's more to the story
06:44most solids are crystalline
06:48like frozen water
06:50the ice in your glass
06:52in ice
06:54the water molecules are arranged in a regular pattern
06:58if we heat it to its melting point
07:00ice quickly turns to liquid
07:02with water molecules sliding past each other
07:04and then
07:06if we drop the temperature
07:08the water refreezes
07:10and the regular crystalline structure of ice returns
07:14silica sand
07:16the primary ingredient in common glass
07:18typically also has a regular crystalline structure
07:22as you heat it up
07:24it too will melt just like ice does
07:26more or less
07:28all at once transitioning from a solid
07:30to a liquid
07:32with the network of silicon and oxygen atoms
07:34sliding around chaotically
07:36but this
07:38is where glass gets weird
07:40when you cool our liquid silica down
07:42it doesn't find its way back into a crystalline structure
07:46instead
07:48it becomes an increasingly viscous liquid
07:52with jumbled rings of atoms
07:54when it finally cools down enough
07:56that warped irregular structure
07:58becomes locked in place
08:00into what's called
08:02an amorphous solid
08:06the range of temperatures
08:08in which glass remains a viscous goopy liquid
08:10that we can manipulate
08:12is one reason it's such an important material
08:14and has made possible
08:16the amazing art of glass blowing
08:20when most of us talk about glass
08:22we mean silica based glass
08:24ordinary glass
08:26but glass is also the term scientists use
08:30for any material that exists
08:32as an amorphous solid
08:34materials that unlike a crystal
08:36have an irregular structure
08:38and when heated
08:40pass through a phase that's
08:42that's not exactly liquid
08:44and not exactly solid
08:46a phase I call
08:48gooey
08:50so glass comes in many forms
08:52Eric Goldschmidt
08:54a flame worker
08:56demonstrates that glass doesn't have to be
08:58well glass
09:00using a piece of hard candy
09:02and it actually acts
09:04a lot like glass that we use
09:06out of our furnaces here
09:08so I'm softening this material
09:10with some heat getting those atoms moving around
09:12and it simply will never have
09:14the opportunity to come back
09:16to a crystalline network
09:18so we can soften it a little bit
09:20start to inflate it
09:22start to inflate it?
09:24come on
09:28dude you're making a roman bottle
09:30out of a jolly rancher
09:32in theory can be shaped
09:34into just above anything
09:36because of its ability to sort of
09:38transition from really fluid
09:40to fairly rigid
09:42would this still taste like candy?
09:44I don't think we've cooked the sweetness out of it
09:46is it too hot?
09:48it should be cool enough to touch
09:50excuse me
09:52I guess I feel like I'm eating the wrapper
09:56I've never had candy that
09:58light and flaky
10:00I don't think I've ever had anybody
10:02that I've inflated either
10:06this is gorgeous
10:08this is clearly going to be worth something
10:09straight out
10:10ok
10:11there you go
10:12maybe if I stopped talking and kept working
10:14there's an underappreciated aspect of glass blowing
10:16that I learned about first hand
10:20oh ho
10:21there we go comes right off
10:22after you shape a piece of glass while it's hot
10:24it has to cool slowly
10:26in an annealing oven
10:28that gradually ramps down the temperature
10:30for something this size
10:32it takes about 12 hours
10:34otherwise
10:35differences in thickness
10:36mean differences in cooling
10:38leading to stresses
10:40that can cause the piece to crack
10:42but what happens if you cool some glass really fast?
10:46then you get these
10:56Prince Rupert's drops
10:58named for Prince Rupert of the Rhine
11:00who brought them to England in 1660
11:02as a scientific curiosity
11:04so I'm gonna have you take this hammer
11:08and try to break this drop
11:10are you nuts? it's glass
11:12alright so just grab it down here by the tail
11:14alright and set it down there on the table
11:16alright and set it down there on the table
11:18and just make sure you hit the thick end
11:20just shatter it?
11:22yep
11:24come on
11:26no
11:34oh no
11:36I broke your table
11:38that's insane
11:40we've established that this glass is indestructible
11:42congratulations
11:44we have but there is an Achilles heel
11:46there is a way to break this
11:48considering that this glass just dented
11:50a steel table
11:52I'm skeptical
11:54so snap it down on the tail?
11:56this is me trying to snap off the tail
11:58of this unbreakable glass
12:00what?
12:08where'd it go?
12:10it's gone
12:12what just happened?
12:14well let's rewind a little
12:16to the key moment
12:18to the key moment
12:20when the drop of hot glass
12:22enters the cold water
12:24the outside of the glass immediately cools
12:30and locks into shape
12:32but the inside cools more slowly
12:34gradually contracting
12:36trying to pull in
12:38the rigid outside glass
12:40creating a tremendous amount of stress
12:42placing the outer layer under compression
12:46a lot of materials under compression are very strong
12:50including glass
12:52so strong you can't break it with a hammer
12:54but there's an Achilles tail
13:00because that part is so thin
13:03when it enters the water
13:05it cools just about all at once
13:07no compression effect
13:09no super strength
13:11I can break it with my hands
13:14and that surface fracture
13:17races through the rest of the compressed material
13:20once that compressive layer is compromised
13:23there's so much energy in there
13:25the whole thing will crack
13:27kablammo
13:29total drop destruction
13:33turns out the surprising strength
13:35of a Prince Rupert's drop
13:37plays a role in how we make glass today
13:41manufacturers take advantage
13:43of the strength of glass under compression
13:45to make a special kind
13:47called tempered glass
13:49so this is a piece of commercial tempered glass
13:52and rather than being cooled with water
13:54this one is just cooled with jets of air on the surface
13:56the jets of air sort of make the skin of the glass rigid
14:00and stiffens the surface of the glass
14:02the core of this cross section is left to cool a little bit more slowly
14:06and so it pulls away from the surface
14:08and that creates a compressive layer on the surface
14:10so it's sort of compressing itself from the inside
14:12from the inside exactly
14:14so then what is this like Prince Rupert's sidewalk
14:20it may seem counterintuitive
14:22every cell in my body is saying this is a bad idea
14:25but by cooling the glass to create compressive stress
14:28generally more than 10,000 pounds per square inch
14:32it becomes physically stronger
14:34I can walk
14:36even jump
14:38on this tempered piece that's about a half inch thick
14:40oh my gosh
14:42duck
14:44what
14:46they can make diving boards out of this stuff
14:48oh man
14:52even pouring molten glass on it
14:58doesn't make it shatter immediately
15:02but give it a minute
15:04that's some strong glass
15:06it is
15:08or four
15:20oh man that was cool
15:22it was like
15:24the molten glass finally compromised the surface
15:26and all that built in stress
15:30broke up the entire sheet
15:34but the remaining shards are relatively safe
15:38because of that tension
15:39when it does break
15:40it breaks all the way out to the very edge
15:42and it all breaks into these little bits
15:44they make these nice little cubes
15:45that aren't nearly as dangerous as a big broken shard of glass
15:52the miracle of glass
15:54is made possible in part
15:56by the element silicon
15:58the second most common element in the earth's crust
16:00after oxygen
16:02silicon atoms have 14 electrons
16:04arranged in three shells
16:06because the outermost shell has four electrons
16:10silicon can share those
16:12to form up to four bonds with other atoms
16:14but one thing that it doesn't do well
16:16but one thing that it doesn't do well
16:18is form a chain with other silicon atoms
16:22to create a compound with a silicon backbone
16:24it's just too reactive
16:26in water
16:28the backbone easily falls apart
16:30the element with the best ability to do that
16:34sits just above silicon
16:38carbon can also form up to four bonds with other atoms
16:42but luckily it can also form strong bonds with other carbon atoms
16:46the result is not only you and me and all life on earth
16:51but also a plethora of other molecules and materials that shape our lives
16:56and can even put a bounce in your step
17:00first up rubber
17:02it turns out that more than half of the world's rubber
17:06ends up wrapped around the wheels of vehicles
17:10motorcycles trucks and cars
17:12so I've come to a place that's rolling in it
17:18the Indianapolis Motor Speedway
17:24it's 11 days away from the running of one of the most famous car races in the world
17:30the Indy 500
17:32the competing teams are here doing practice runs
17:38and some end better than others
17:50before the teams hit the track
17:52some fortunate fans get a taste of the race
17:55they get to ride in a specially adapted two-seater Indy car
18:00at the wheel the legendary champion Mario Andretti
18:06he's one of the most successful American drivers in the history of the sport
18:10he's the only pro ever to win the Indianapolis 500
18:14the Daytona 500
18:16and the Formula One World Championship
18:26and now it's my turn
18:36imagine riding a roller coaster
18:38at over 180 miles an hour
18:40with no rails
18:42flying around the curves
18:44while wondering why we're not smashing into the wall
18:48I've had enough after a couple of laps
18:54how do these drivers do 200 of them?
19:06oh man
19:08the G-forces are just indescribable
19:12I mean you're pressed against the side
19:14and then pressed against the back
19:16and when he takes the curves
19:18and when he takes the curves
19:20I mean there's a concrete wall
19:22coming at you just
19:24so what's the secret ingredient
19:26to staying alive out there?
19:28to find out
19:30I head to the garage that supplies the tires
19:32in the weeks leading up to the Indy 500
19:36in 2019
19:38each team received 36 sets of tires
19:40for practice, qualifying
19:42and the race
19:446,000 tires in all
19:46it's also a chance to talk to the expert himself
19:50what I was surprised at most
19:52was the lateral forces
19:54obviously as a layman
19:56so is it the rubber
19:58that's keeping us from flying into that wall?
20:00that's what it is
20:02that's it
20:04the tires obviously the most important aspect
20:06of the race car
20:08these are the babies you want to kiss
20:10after a run
20:12it speeds up to 230 miles an hour
20:15a driver experiences about 5 G's of force during the turns
20:20that's more than what an astronaut experiences during a space launch
20:24so you know the tires take a beating
20:27do you know enough about the chemistry to know
20:30what kinds of things they can do to the compounds?
20:33like what sorts of things do they add?
20:36if they would tell me that
20:38they would have to kill me
20:42hopefully that's not a blanket policy
20:45because I've come to Akron, Ohio
20:47looking for some answers
20:49Harvey Firestone founded
20:51the Firestone Tire and Rubber Company
20:53here in 1900
20:55Bridgestone Corporation bought it in 1988
20:59becoming Bridgestone Firestone
21:02this is one of its research facilities
21:06and Laura Kosas is one of its scientists
21:09according to her
21:11it all starts with this
21:13I got to say this feels rubbery
21:15oh man it's all so stinky
21:18yep so that's natural rubber
21:20oh this is what comes out of the tree
21:22yep so it comes out of the tree
21:23and we process it
21:24and it turns into what you have in your hands right now
21:26becomes this
21:27yes
21:28natural rubber begins as sticky runny white liquid
21:34called latex
21:36it's found in more than 2,000 plants
21:39including dandelions
21:41but most of the world's natural rubber
21:43comes from trees
21:44like these
21:45the Hevea brasiliensis
21:47better known as the rubber tree
21:50natural latex is about 55% water
21:54with particles of rubber suspended in it
21:57and if you could zoom in to one of the particles
22:00you'd see it's like a tangled bunch of spaghetti
22:03each noodle is a long molecular chain called a polymer
22:08to get to a polymer you start with monomers
22:11which is one chemical unit
22:12and that's represented by these paper clips here
22:14this here is one chemical unit?
22:16yep consider that one chemical unit
22:18meaning what a molecule?
22:20yep one molecule
22:21so for natural rubber what molecule are we talking about?
22:25so we're talking about isoprene
22:26isoprene
22:27okay
22:28yes
22:29here's what isoprene looks like
22:31it's a molecule with five carbons
22:33bonded to each other
22:35and to eight hydrogens
22:37in natural rubber
22:39isoprenes are bonded together
22:41one after another
22:42to make a chain
22:43a polymer
22:44just like the chain of paper clips Laura showed me
22:47once you get to tens of thousands of these units linked together
22:51you end up with natural rubber
22:52oh tens of thousands?
22:53yep
22:54okay
22:55tens of thousands
22:56in their natural state
22:58the rubber polymer chains can become easily entangled
23:01as they coil up
23:02but when you stretch them out
23:04the chains straighten out
23:06and align themselves in the direction of the stretch
23:09let them go
23:11and the molecules return back to their coiled up states
23:16giving rubber its signature boinginess
23:20so if it's rubber it should be a little boingy
23:23yep it's gonna bounce
23:24okay that's very boingy
23:26I'm sure here at Bridgestone you use that as a chemical property
23:30the boinginess
23:31yes very technical
23:32and oh sorry
23:33oh man
23:35natural rubber is often an ingredient in tires
23:39but it's not the only one
23:41today many tires include synthetic rubber
23:45made out of other monomers not found in latex
23:49oh ho
23:51I'm sensing more polymers
23:54yes
23:55more chains of molecules
23:57what do these represent?
23:58so these are different configurations of polymers that we can make in our laboratory
24:03natural rubber is made of only one type of monomer
24:06here we can use different types and bring them together with our chemistry
24:09and each way of linking them together produces different qualities in the tire that will result?
24:15yep so maybe the amount of monomer can make a difference in the properties
24:18how they're configured can make a difference
24:20and that's basically what we do here is find different ways of putting them together
24:23so that we can achieve the properties that we want
24:25wow
24:28natural rubber
24:30synthetic rubber
24:31turns out there's even more that goes into tire rubber
24:36here in the test lab technicians mix all the ingredients together
24:42like carbon black and silica
24:45which reinforce the tire
24:47another key ingredient is sulfur
24:51element number 16 on the periodic table
24:54the resulting blob then gets rolled into sheets
25:01cut into squares for testing
25:06and baked at high temperature
25:08in a process called vulcanization
25:11in a process in 1839
25:13when he accidentally spilled a mixture of rubber and sulfur on a stove
25:23he named it after vulcan the roman god of fire
25:28cooking the rubber sulfur mixture
25:34causes the sulfur to chemically bond the rubber's polymer chains to each other
25:40forming cross links between them
25:43the Madame and the other
25:46Bill Nyora
25:47Bridgestone's director of innovation
25:49shows me the result
25:50so this little bow tie
25:52this was cut out of one of those squares before vulcanization
25:55It was.
25:56And this is what rubber looks like after that vulcanization.
25:59Correct.
26:00So the only difference between these two is this one was superheated for a while.
26:04Correct.
26:05All right.
26:06And according to you, something property-wise has changed.
26:09It has.
26:10Why don't you take the uncured one and stretch it?
26:12All right.
26:13This guy?
26:14Just pull it?
26:15Oh, wow.
26:16You'll feel, are the polymer chains flowing apart?
26:19It's acting like a liquid.
26:20It's viscous.
26:21It feels exactly like gum.
26:22Stretching gum.
26:23And when you release the force, you'll see that it's float apart.
26:28And the energy that you put in has not been recovered.
26:31And the piece has been permanently deformed.
26:33I broke your rubber sample.
26:35I'm okay with that.
26:37With all the new ingredients, our unbaked tire mixture is far less boingy
26:43than the rubber I saw in Laura's lab.
26:46When you stretch it, the mixture's loosely coiled polymer strands slide past each other.
26:52And keep on sliding.
26:54Only weak interactions hold the network of strands together.
26:58So under stress, it pulls apart.
27:01Okay.
27:02And then after vulcanization, same test?
27:05Indeed.
27:06Oh, man.
27:07It's much harder to pull.
27:10And when you release the force, you'll see that it's recovered its original shape.
27:15And that's a characteristic of elasticity.
27:18Stretch out this vulcanized, interconnected web of strands.
27:24And instead of ripping apart, the network springs back to its original shape.
27:30Right.
27:31It's a cross section.
27:32But as Bill shows me with cross sections from different tires, vulcanization doesn't just
27:38connect up individual rubber molecules.
27:41It connects up everything in the whole tire mixture.
27:45As we cure the tire, as we heat it, that vulcanization reaction not only cures the rubber within a compound,
27:51it cures across compounds to connect all of that into one unit.
27:56In the end, it's essentially one molecule.
27:58The whole tire?
27:59It is.
28:00The whole tire is a molecule?
28:01It is.
28:02Well, how is that a molecule?
28:04So, a molecule is a collection of atoms that are chemically attached.
28:08Yeah.
28:09We've done that through polymerization.
28:10We've attached monomers to make polymers.
28:12And then through vulcanization, we've attached the polymers to make the finished product.
28:17So, I guess, therefore, since this is all connected molecularly linked to molecularly linked,
28:23it is one giant molecule.
28:25It's beautiful.
28:26Now that I know just how much engineering goes into those giant tire-shaped molecules,
28:39I have a new appreciation for the rubber that keeps us all on the road.
28:45And for the people behind it.
28:47Like Cara Adams, Director of Race Tire Engineering and Production for Bridgestone Firestone,
28:54she oversees the race tire operation, including Indy.
29:00Although, interviewing her at the office turns out to be...tough.
29:05One of the things that you're trying to look at with a race car is aerodynamics.
29:12If you think about a tire, this is the only point of contact between the cars in the ground now.
29:18That was a very small, 4-inch wide rim.
29:21That's what you get for trying to film a race car.
29:22Yes, exactly.
29:23So, we move to a somewhat quieter place.
29:24We think of car racing as excitement and adrenaline really cool.
29:40How much actual science is there to it?
29:42Well, there's a lot of science and chemistry that actually goes in the tire.
29:46So, we have engineers that work with physics to make sure the tires are strong enough.
29:50And then we have people that are really smart in chemistry.
29:52And they are actually able to design those tread compounds that are running at 240 miles per hour
29:57and adhering to the ground.
29:58It's really exciting.
29:59So, are you trying to tell me that the only thing between Mario and me and certain death is chemistry?
30:08Chemistry?
30:09Chemistry and physics.
30:10Absolutely.
30:16Both the natural rubber and synthetic rubber used in tires are elastomers.
30:21Polymers with elastic properties.
30:24They allow tires to be both flexible and durable.
30:27Marvels of engineering.
30:32But they have their limits.
30:34So, what if you need an elastomer that can hold it together no matter what you throw at it?
30:44Michael Tidd from the company LineX has invited me here, a lift in a back lot in West Springfield, Massachusetts,
30:52to see an elastomer that can be a protective coating.
30:57The day begins with a tale of two pumpkins.
31:01Pumpkins seem like they already are blessed with a certain degree of protection.
31:06Nature has provided a pretty good membrane, but I don't know if it was in the original design to drop it from 50 feet.
31:11Well, let's do a scientific test.
31:13We could always give it a try and see what happens.
31:15On three, ready?
31:16One, two, three.
31:17One, two, three.
31:24Well, no surprise here.
31:29It's a squash vegetable and a floor wax.
31:32That was the control of an uncoated pumpkin, as you would find them in nature.
31:37Yes.
31:39Now it's time for a pumpkin covered with Michael's protective LineX coating.
31:43I have to say, it feels a little bit like plastic.
31:47It is a lot like plastic.
31:48It has characteristics of plastic.
31:50However, it is an elastomer, which means it can be stretched, but it will return to its original shape.
31:56Let's see if this has any better effect.
31:59One, two, three.
32:01One, two, three.
32:08The LineX coated pumpkin flexes to absorb the impact, then springs back into shape.
32:16We try a few more household objects.
32:18This experiment is entitled, When Pigs Fly.
32:24Can you guess what will happen to the egg when we drop it?
32:33The flower pot's last moments.
32:39And I run a few comparisons myself.
32:41Finally, bringing out the big guns.
32:55No way.
33:08Okay, I get it.
33:10The stuff is tough.
33:12But what's going on inside that coating?
33:16Did the object survive intact?
33:18Michael cuts open our dropped pumpkin to see the state of affairs.
33:33It's pumpkin pudding.
33:35A lot of damage.
33:37So the pumpkin is gone, but the coating did just fine.
33:41Correct.
33:42But when would you care about not protecting the guts of something, but the outside is fine?
33:47A lot of times we will put it on a membrane such as a wall or a floor where we're trying to protect what's on the other side.
33:56Here's a test of that idea.
33:59This simulated car bomb blows down an exterior wall.
34:08But with a coating of LineX on the outside and the inside of the wall,
34:13it becomes more of a dust-up.
34:18So what is this stuff?
34:22Well, there's more than one flavor of LineX, but the coating on our power pumpkins is the result of a reaction between two ingredients.
34:30The first is a highly reactive molecule.
34:36At each end of its carbon backbone, there's a nitrogen, carbon, and oxygen group called an isocyanate that acts like a hook to lock onto the second chemical ingredient.
34:49It's a polyamide, a member of a chemical group called resins.
34:55LineX heats the two ingredients and feeds them under pressure to this sprayer, which mixes them just as they exit.
35:03Immediately, the first ingredient hooks onto part of the resin, and all those linkages create long and tangled polymer chains similar to rubber so that they're flexible but also much tougher.
35:18The resulting elastomer is called a polyurea, a cousin to the more familiar polyurethanes.
35:28So that's the general idea, though they tweak the chemistry for different applications.
35:34Most of LineX's consumer business is spray-on truck bed liners, not so much for protecting produce or making kids' toys last forever.
35:51The main ingredients for LineX and synthetic rubber come from fossil fuels like refined crude oil.
35:58When we pump oil from the ground, it's a rich soup of molecules built around that tinker toy wonder element, carbon.
36:09They come in chains, rings, trees, and other shapes.
36:14Refining separates those molecules by kind, and in some cases breaks up bigger ones, turning them into smaller, more useful molecules like gasoline.
36:26Refining also supplies industry with the basic building blocks for another group of synthetic polymers that came to dominate our way of life in the 20th century.
36:39Plastics.
36:40Today, plastic is everywhere.
36:43You can find it in tea bags, ribbon, the inside of paper coffee cups, sunscreen, toothpaste, sponges, most clothing, the fish you eat, and even salt.
36:58Malika Jeffries-Ell plays with the molecular building blocks of plastic for a living.
37:07She's a polymer chemist at Boston University.
37:10So clearly, there's all kinds of different plastics, but is there something that unites them all that makes a plastic a plastic?
37:18Plastics are a subset of polymers in that they're known not just for having their macromolecular structure, but the processing and mechanical properties that come from as a result of that structure.
37:29Like bendiness and strength?
37:30Exactly.
37:31Strength.
37:32Strength.
37:33Exactly.
37:34Strength, flexibility, rigidity would be another property.
37:38Like rubber, all plastics are polymers, long molecules made up of subunits called monomers.
37:45What makes each of these polymer-based materials distinct are the combinations of the different monomers used to make them.
37:53For example, this is actually really hard and rigid, and one of the units in here is styrene, and this is polystyrene.
38:00Not hard and rigid at all.
38:01Not hard and rigid at all, but when you blend in the other molecules, you get different properties.
38:06Wow.
38:07But it's not all chemistry.
38:09Processing can turn the same plastic into very different products.
38:13These were actually molded and blown into this bottle shape, and in this case, really small fibers were spun from the polymer and then processed to make this.
38:25And it comes out soft and comfortable?
38:26Comes out soft and comfortable.
38:28Our age of plastics isn't very old.
38:34It was this guy, Leo Bakeland, who gets credit for the first fully synthetic plastic.
38:40He called it Bakelite.
38:43And by the 1920s, it had become a big hit in all kinds of products, from radios, to kitchenware, to kids' toys, and coming in a variety of colors.
38:55Malika has offered to whip up some of this landmark plastic.
39:00It's made from two monomers.
39:04Phenol, a ring of six carbon atoms bonded to five hydrogens, and an oxygen bonded to a hydrogen, and formaldehyde, one carbon atom bonded to two hydrogens, and double bonded to an oxygen.
39:22After dissolving this solid phenol into the formaldehyde solution, Malika adds two acids to start up the process.
39:31Then we wait.
39:34There should kind of be this a-ha moment, and it should just go.
39:39Are you saying it's going to harden?
39:41Yeah, it should get cloudy, and polymers should come crashing out.
39:45I feel like it's getting pinker, which is an indication that the chemistry's changing.
39:48Oh!
39:49Did you see that?
39:50Like, instantaneously!
39:51Right before our eyes, the phenol and formaldehyde molecules link up, giving off water molecules while creating long polymer chains.
40:06You made plastic!
40:10Look at that.
40:12Genuine, crusty, hard, hard plastic.
40:17So this is an example of a thermoset plastic.
40:20Once it's set into place with heat, you can't reform it or reshape it with additional heat.
40:25Oh, okay.
40:26So unlike a plastic drink bottle...
40:29That's right.
40:30...you can't melt this down and reform it into something else.
40:34No.
40:35This is Bakelite now and forever.
40:36That's stuck like that forever, yep.
40:39In a thermoset plastic like Bakelite, the bonds between the polymer chains are extremely strong.
40:47By the time you've applied enough heat to break them, the chains themselves have decomposed.
40:52So you can't re-melt thermoset plastics or reshape them for recycling.
41:00But not all plastics are thermoset.
41:03There's nylon, the first commercially successful plastic that wasn't.
41:08It came to public attention at the 1939 World's Fair as a substitute for silk in women's stockings.
41:17And its importance grew during World War II.
41:21At the time, the main source of silk for parachutes was America's enemy, Japan.
41:27So the military recruited nylon as a replacement.
41:33Malika offers me some first-hand experience making nylon.
41:37If you wanted to make nylon, don't you need, like, a factory?
41:40Well, if you want to make a lot of nylon, yeah, then you're going to need a factory.
41:44But if we're just going to do a demo, we're going to make a little bit of nylon and we could do it in a little beaker.
41:49All right, like for mouse stockings.
41:51Yes, exactly.
41:52To do this, we're going to mix together two chemicals.
41:56There are lots of variations on nylon.
41:59Our two key components will be two molecules that are simpler than they sound, hexamethylenediamine and a dip oil chloride.
42:09Since they each have a six-carbon chain, we're making what's called nylon 6-6.
42:21So the first thing we're going to do is we're going to add the hexamethylenediamine.
42:26So mostly colored water.
42:28Mostly colored water with some cool organics in there.
42:31All right.
42:32And then we're going to add our organic layer of the adipochloride solution.
42:38And because the density of this is less than that of the water, it should float on the surface of the water.
42:46Kind of like oil and vinegar.
42:47Where the two liquids meet, the molecules of the hexamethylenediamine and a dip oil chloride link up, one after another, releasing hydrogen chloride as a gas.
43:01Malika gives me the honor of pulling the newborn nylon polymer out of the beaker.
43:07And as more of the two liquids come into contact, they make more nylon.
43:13You have a ladder, Malika?
43:15There you go.
43:16Look at that.
43:17Look at that.
43:18Yes.
43:19Freshly baked free-range nylon.
43:22Amazingly, this really is a junior version of how bulk nylon is manufactured.
43:29All right.
43:30Anyone need stockings?
43:32Unlike Bakelite, nylon is an example of a thermoplastic, which we can reheat and reform.
43:39That's the basis of some plastic recycling.
43:42You know, get the...
43:44Malika wants to show me one more example.
43:47And this time, what are we going to make?
43:49Um, so for this demonstration, I thought I would show you how we make polyurethane foams.
43:54And what do we use polyurethane foam for in the world?
43:58Uh, polyurethane, um, is used in, like, seat cushions, uh, and also insulation.
44:03So, you think about, like, blown foam and things like that.
44:05Oh, yeah.
44:06E.T. blown foam.
44:07Yeah, I remember that.
44:08There are two key reactants.
44:13First up is a type of molecule with an oxygen-hydrogen hook at either end.
44:19Aside from its role in polyurethanes, this one shows up in paintballs and laxatives, too.
44:26The other reactant we've already met at Linex.
44:30That carbon-backboned isocyanate molecule with the nitrogen-carbon-oxygen hooks at either end.
44:36And we stir those together.
44:40And so you can already see it's starting to react because it's starting to get milky and it's starting to grow inside.
44:45You can see it's rising up a little bit.
44:48The two molecules begin to link up to form a polyurethane polymer.
44:55At the same time, one ingredient also reacts with some water, generating carbon dioxide gas.
45:01That's what causes the bubbling and, ultimately, the foam when the polyurethane grows rigid.
45:08I know I'm tacky, but...
45:15Oh-ho-ho!
45:17And the cup's entombed inside there!
45:20Yeah, the cup is, the cup is gone.
45:22Yeah.
45:23Pretty cool.
45:24But it's just a start.
45:27Because, when in foam, do as the foam-mans do?
45:43Here we go.
45:44Years of snowman training.
45:49We'll open a 529 plan.
45:51We'll buy some diapers.
45:52Nothing but the best for you.
45:55He has your smile.
46:01At this point...
46:02Polycarbonate.
46:03You're probably getting the idea...
46:05Polyethylene terephthalate.
46:06P-E-T-E.
46:07That there are lots of different plastics.
46:10Polyvinyl chloride.
46:11P-V-C.
46:12Each made out of polymers.
46:14These are examples of polyamides, commercially known as nylon.
46:18Constructed sort of the same way.
46:20Polystyrene.
46:21But out of different subunits.
46:23Polypropylene.
46:24P-P.
46:25To obtain very different material properties.
46:28Low-density polyethylene.
46:30L-D-P-E.
46:32And then if you start throwing in additives and fillers.
46:35Polyvinyl alcohol.
46:37P-V-A.
46:39Like colorants.
46:40High-density polyethylene.
46:42H-D-P-E.
46:44Flame retardants.
46:45Glass or carbon fibers.
46:46Polymethylmethacrylate.
46:48P-M-M-A.
46:49You end up with tens of thousands of grades of plastic.
46:53Polyoxymethylene.
46:55P-O-M.
46:57Each tailored for a specific purpose.
47:00Which has created the problem.
47:02What do we do with them when that job is finished?
47:05Mostly, we throw them out.
47:1191% of all the plastic we make ends up in landfills.
47:16Or burned.
47:18Or just escapes into the environment.
47:21The remaining 9% is recycled.
47:26But first, the plastic has to be carefully separated by type.
47:31Those recycling number symbols.
47:33Any mix up there can contaminate an otherwise reusable plastic.
47:38Rendering it worthless.
47:41And there aren't many places willing to do that separating work.
47:46In 2018, China stopped accepting shipments of bulk unsorted plastic from the U.S.
47:54Or anywhere else in the world.
47:57With the economics of recycling in turmoil,
48:00lately the discussion has shifted to single-use plastics.
48:04About half of all the plastic we produce.
48:07Much of it is food-related.
48:12To learn more, I travel to the University of Georgia to meet Jason Lachlan,
48:18a chemistry professor and the director of its New Materials Institute.
48:22Well, thanks for meeting me here, Jason.
48:24I brought you breakfast.
48:25All right.
48:26Well, breakfast and a bag of single-use problems.
48:32This is called a clamshell container.
48:35Less than 1% of all polystyrene is recycled globally.
48:38If this makes its way into the landfill, which is exactly where it'll go,
48:42it'll persist there forever.
48:44We have a plastic straw.
48:46It'll stay there for hundreds if not thousands of years.
48:49Is that really a way to design packaging?
48:53To have a material that you use for 10 seconds,
48:56and then it goes to a landfill for a thousand years?
48:59Even packaging that looks recyclable, like paper takeout containers,
49:04may not be because, well, they have to hold food.
49:09If you put food into a paper towel, what happens to it?
49:15It's going to get soggy and fall apart.
49:16Exactly.
49:17So in order to make this a takeout container, we have to coat it with plastic.
49:21It essentially prohibits our ability to recycle it.
49:25Wow.
49:26So is there any solution to that problem?
49:28So here's just an example.
49:30If you pull the film off that plastic, this is about what it looks like.
49:33But this film is made out of a material called PHA.
49:38PHAs, polyhydroxyalkanoates, are a type of plastic produced from polymers
49:45harvested from certain bacteria.
49:49For the bacteria, the polymers are essentially kind of like fat,
49:53a way to store energy.
49:55But because they come from bacteria, PHAs have a huge advantage.
50:00They're completely biodegradable.
50:03Researchers in Jason's lab are among several scientists and companies around the world
50:09developing a PHA-based coating that could replace the traditional plastics
50:14that often make our takeout boxes unrecyclable.
50:19Although the cost of PHAs still needs to come down to be competitive.
50:24And finally, what does Jason think about that eco-friendly looking green bag I brought breakfast in?
50:32This is a great example of some absolute greenwashing.
50:37Biodegradable.
50:38You see it in big bold claims.
50:40If you read the fine print, it says 49.28% biodegradation in 900 days under non-typical conditions.
50:51No evidence of further biodegradation.
50:54Come on!
50:55Sounds like a total scam.
50:57But look at the size of the green leaves.
51:00That makes me feel good about myself.
51:03It has a leaf on it.
51:04This is simply adding to the confusion of people like yourself,
51:09people in the general public that want to do the right thing.
51:12This makes it really difficult to know exactly what to do.
51:16When it comes to creating new materials, we may be the victims of our own success.
51:25We've invented some that are useful and so durable that they last more than a human lifetime.
51:35And now we're drowning in them.
51:38But attitudes are changing, with engineers and chemists harnessing biology to combat the problem.
51:47In the end, the human ingenuity that helped create the current crisis may help solve it as well.
51:57The only thing between me and certain death is chemistry?
52:05As we move beyond the elements.
52:08we measure and blood fragments.
52:31To order this program on DVD, visit Shop PBS or call 1-800-PLAY-PBS.
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53:05NoVA is also available on Amazon Prime Video.
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53:14Let's get started!
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