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Polymers
What's
a polymer?
BY DEBBIE SWANSON
If you've ever made a
long paper chain, you already have a visual image of a polymer.
The
term comes from the Greek words poly,
meaning "many," and meros,
meaning "part."
Combine
the two and you get "many parts."
The
simplest definition of a polymer is long chain formed by joining many smaller
molecules, called monomers [source: Larsen].
While
a paper chain presents a simple image of a polymer, in practical applications,
polymers have much greater uses.
They
make up the components of many objects used in daily life: plastic containers,
nylon products, rubber tires and many more.
To
understand polymers, we first need to get to know the monomer, which is a
single molecule that has the ability to join with at least two other monomers.
The
process of joining is called polymerization, in which two separate molecules of
the same or different types bind by sharing pairs of electrons. This union
forms a covalent bond [source: Larsen].
When
monomers join with other monomers through the process of creating covalent
bonds, they form larger molecules, called polymers. The word polymer represents
any unspecified number of monomer units – just any amount greater than one [source: Britannica].
The
number of bonds created by the monomers dictates the resulting chemical
structure of the polymer.
If
a monomer bonds with only two other molecules, the result is a chain-like structure.
If it bonds with three or more molecules then three-dimensional, cross-linked
structures can form [source: Innovate Us].
Polymers
can occur naturally, or we can manufacture them.
Two
common examples of a natural polymer are the basic chemicals that define life:
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Other
naturally occurring polymers include silk, wool, hair, fingernails, toenails,
cellulose and proteins.
Man-made
polymers are often commonly referred to as plastics; they can be shaped and
molded into different forms with many household and industrial uses.
Most
synthetic polymers are derived from petroleum oil, and different types include
nylon, polyethylene, polyester, rayon, Teflon and epoxy. The plastic or rubber
items you encounter daily are all a type of polymer [source: Larsen].
The
origin of man-made polymers traces back to Central America and the ancient
Aztecs, Olmecs and Mayas, who all made a form of rubber by combining natural
latex found in plants with the juice of morning glory vines [source: Kaufman].
The
resulting rubber was more pliable than brittle latex, and was used to make
sandals, as well as balls for ceremonial games.
Approximately
3,000 years after the Central Americans were playing ball, Charles Goodyear
combined natural rubber with sulfur to create vulcanized rubber, a polymeric
substance still popular today – you may recognize Goodyear's name from the
brand of automobile tires.
As
you go about your day, stop and consider all the structures around you.
It's
hard to believe that a plastic lemonade container, the case around your
smartphone or the tires that get you where you need to go, are all the result
of tiny individual monomers bonding together to form polymers.
Strength
in numbers, right?
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