0:00:06.826,0:00:08.030
What do silk,

0:00:08.030,0:00:08.707
DNA,

0:00:08.707,0:00:09.470
wood,

0:00:09.470,0:00:10.298
balloons,

0:00:10.298,0:00:12.930
and Silly Putty all have in common?

0:00:12.930,0:00:14.719
They're polymers.

0:00:14.719,0:00:17.152
Polymers are such a big part of our lives

0:00:17.152,0:00:18.608
that it's virtually impossible

0:00:18.608,0:00:20.832
to imagine a world without them,

0:00:20.832,0:00:22.416
but what the heck are they?

0:00:22.416,0:00:24.226
Polymers are large molecules

0:00:24.226,0:00:26.890
made of small units called monomers

0:00:26.890,0:00:29.773
linked together like the railroad cars from a train.

0:00:29.773,0:00:31.302
Poly means many,

0:00:31.302,0:00:32.800
and mono means one,

0:00:32.800,0:00:35.683
and mers or mero means parts.

0:00:35.683,0:00:37.853
Many polymers are made by repeating

0:00:37.853,0:00:40.689
the same small monomer over and over again

0:00:40.689,0:00:42.481
while others are made from two monomers

0:00:42.481,0:00:44.404
linked in a pattern.

0:00:44.404,0:00:46.932
All living things are made of polymers.

0:00:46.932,0:00:49.459
Some of the organic molecules in organisms

0:00:49.459,0:00:50.788
are small and simple,

0:00:50.788,0:00:53.943
having only one of a few functional groups.

0:00:54.467,0:00:57.372
Others, especially those that play structural roles

0:00:57.372,0:00:59.071
or store genetic information,

0:00:59.071,0:01:00.838
are macromolecules.

0:01:00.838,0:01:04.254
In many cases, these macromolecules are polymers.

0:01:04.254,0:01:06.636
For example, complex carbohydrates

0:01:06.636,0:01:08.790
are polymers of simple sugars,

0:01:08.790,0:01:11.094
proteins are polymers of amino acids,

0:01:11.094,0:01:13.758
and nucleic acids, DNA and RNA,

0:01:13.758,0:01:15.718
which contain our genetic information,

0:01:15.718,0:01:18.249
are polymers of nucleotides.

0:01:18.249,0:01:19.546
Trees and plants are made

0:01:19.546,0:01:21.515
of the polymer cellulose.

0:01:21.515,0:01:24.485
It's the tough stuff you find in bark and stems.

0:01:24.485,0:01:25.177
Feathers,

0:01:25.177,0:01:25.726
fur,

0:01:25.726,0:01:26.263
hair,

0:01:26.263,0:01:27.136
and fingernails

0:01:27.136,0:01:29.183
are made up of the protein keratin,

0:01:29.183,0:01:30.773
also a polymer.

0:01:30.773,0:01:32.423
It doesn't stop there.

0:01:32.423,0:01:33.923
Did you know that the exoskeletons

0:01:33.923,0:01:36.431
of the largest phylum in the animal kingdom,

0:01:36.431,0:01:37.448
the arthropods,

0:01:37.448,0:01:39.328
are made of the polymer chitin?

0:01:39.928,0:01:41.660
Polymers also form the basis

0:01:41.660,0:01:44.691
for synthetic fibers, rubbers, and plastics.

0:01:44.691,0:01:48.076
All synthetic polymers are derived from petroleum oil

0:01:48.076,0:01:51.276
and manufactured through chemical reactions.

0:01:51.276,0:01:53.442
The two most common types of reactions

0:01:53.442,0:01:54.710
used to make polymers

0:01:54.710,0:01:55.939
are addition reactions

0:01:55.939,0:01:58.143
and condensation reactions.

0:01:58.143,0:01:59.465
In addition reactions,

0:01:59.465,0:02:02.553
monomers simply add together to form the polymer.

0:02:02.553,0:02:04.608
The process starts with a free radical,

0:02:04.608,0:02:07.657
a species with an unpaired electron.

0:02:07.657,0:02:08.961
The free radical attacks

0:02:08.961,0:02:11.524
and breaks the bonds to form new bonds.

0:02:11.524,0:02:13.606
This process repeats over and over

0:02:13.606,0:02:15.603
to create a long-chained polymer.

0:02:15.603,0:02:17.272
In condensation reactions,

0:02:17.272,0:02:19.101
a small molecule, such as water,

0:02:19.101,0:02:22.407
is produced with each chain-extending reaction.

0:02:22.407,0:02:23.933
The first synthetic polymers

0:02:23.933,0:02:25.386
were created by accident

0:02:25.386,0:02:28.107
as by-products of various chemical reactions.

0:02:28.107,0:02:29.350
Thinking they were useless,

0:02:29.350,0:02:31.627
chemists mostly discarded them.

0:02:31.627,0:02:33.910
Finally, one named Leo Baekeland

0:02:33.910,0:02:35.794
decided maybe his useless by-product

0:02:35.794,0:02:38.086
wasn't so useless after all.

0:02:38.086,0:02:39.715
His work resulted in a plastic

0:02:39.715,0:02:42.178
that could be permanently squished into a shape

0:02:42.178,0:02:44.521
using pressure and high temperatures.

0:02:44.521,0:02:46.172
Since the name of this plastic,

0:02:46.172,0:02:50.068
polyoxybenzylmethylenglycolanhydride,

0:02:50.068,0:02:51.353
wasn't very catchy,

0:02:51.353,0:02:53.594
advertisers called it Bakelite.

0:02:54.502,0:02:56.468
Bakelite was made into telephones,

0:02:56.468,0:02:57.355
children's toys,

0:02:57.355,0:02:59.988
and insulators for electrical devices.

0:02:59.988,0:03:02.104
With its development in 1907,

0:03:02.104,0:03:04.608
the plastics industry exploded.

0:03:04.608,0:03:06.621
One other familiar polymer, Silly Putty,

0:03:06.621,0:03:08.774
was also invented by accident.

0:03:08.774,0:03:09.859
During World War II,

0:03:09.859,0:03:11.601
the United States was in desperate need

0:03:11.601,0:03:14.190
of synthetic rubber to support the military.

0:03:14.190,0:03:16.107
A team of chemists at General Electric

0:03:16.107,0:03:17.626
attempted to create one

0:03:17.626,0:03:20.176
but ended up with a gooey, soft putty.

0:03:20.176,0:03:22.192
It wasn't a good rubber substitute,

0:03:22.192,0:03:24.461
but it did have one strange quality:

0:03:24.461,0:03:27.109
it appeared to be extremely bouncy.

0:03:27.109,0:03:28.715
Silly Putty was born!

0:03:28.715,0:03:30.926
Synthetic polymers have changed the world.

0:03:30.926,0:03:32.018
Think about it.

0:03:32.018,0:03:33.859
Could you imagine getting through a single day

0:03:33.859,0:03:35.553
without using plastic?

0:03:35.553,0:03:37.520
But polymers aren't all good.

0:03:37.520,0:03:40.858
Styrofoam, for example, is made mainly of styrene,

0:03:40.858,0:03:43.023
which has been identified as a possible carcinogen

0:03:43.023,0:03:45.605
by the Environmental Protection Agency.

0:03:45.605,0:03:47.735
As Styrofoam products are being made,

0:03:47.735,0:03:51.025
or as they slowly deteriorate in landfills or the ocean,

0:03:51.025,0:03:52.690
they can release toxic styrene

0:03:52.690,0:03:54.359
into the environment.

0:03:54.359,0:03:56.017
In addition, plastics that are created

0:03:56.017,0:03:58.294
by addition polymerization reactions,

0:03:58.294,0:03:59.352
like Styrofoam,

0:03:59.352,0:04:00.210
plastic bags,

0:04:00.210,0:04:01.212
and PVC,

0:04:01.212,0:04:03.416
are built to be durable and food-safe,

0:04:03.416,0:04:04.956
but that means that they don't break down

0:04:04.956,0:04:06.366
in the environment.

0:04:06.366,0:04:08.119
Millions of tons of plastics

0:04:08.119,0:04:10.221
are dumped into landfills every year.

0:04:10.221,0:04:12.462
This plastic doesn't biodegrade,

0:04:12.462,0:04:13.524
it just breaks down

0:04:13.524,0:04:15.560
into smaller and smaller pieces,

0:04:15.560,0:04:16.729
affecting marine life

0:04:16.729,0:04:19.734
and eventually making their way back to humans.

0:04:19.734,0:04:21.724
Polymers can be soft or hard,

0:04:21.724,0:04:22.937
squishy or solid,

0:04:22.937,0:04:25.042
fragile or strong.

0:04:25.042,0:04:27.326
The huge variation between

0:04:27.326,0:04:28.240
means they can form

0:04:28.240,0:04:30.605
an incredibly diverse array of substances,

0:04:30.605,0:04:31.434
from DNA

0:04:31.434,0:04:33.408
to nylon stockings.

0:04:33.408,0:04:35.024
Polymers are so useful

0:04:35.024,0:04:37.493
that we've grown to depend on them every day.

0:04:37.493,0:04:38.680
But some are littering

0:04:38.680,0:04:41.063
our oceans, cities, and waterways

0:04:41.063,0:04:42.272
with effects on our health

0:04:42.272,0:04:44.555
that we're only beginning to understand.