Before we can talk about what a polymer is, we need to know about ATOMS and ELEMENTS and MOLECULES. To learn about atoms and elements and molecules, click here.
Polymers are made up of many many molecules all strung together to form really long chains (and sometimes more complicated structures, too).
What makes polymers so fun is that how they act depends on what kinds of molecules they're made up of and how they're put together. The properties of anything made out of polymers really reflect what's going on at the ultra-tiny (molecular) level. So, things that are made of polymers look, feel, and act depending on how their atoms and molecules are connected, as well as which ones we use to begin with! Some are rubbery, like a bouncy ball, some are sticky and gooey, and some are hard and tough, like a skateboard.
This is a polymer. It's a very large molecule.
Poly- means "many" and -mer means "part" or "segment". Mono means "one". So, monomers are those itty bitty molecules that can join together to make a long polymer chain.
This is MONOMER. He's a small mouse lemur. He's holding a monomer, a small molecule
This is a simple diagram of a chain of monomers.
How many is "many many many"? Well, usually a single polymer molecule is made out of hundreds of thousands (or even millions!) of monomers! Wow! That's a lot!
By the way, we use the special name of "monomer" because not all molecules can form polymers.
(but not a polymer...)
|Hmmm, I'll bet they're called "polymers" because "polymolecules" sounds way too silly! Try saying "polymolecule" five times fast and you'll see what I mean!||
"polly molly cool
polly molly clue
polly collie loo!"
Sometimes polymers are called "macromolecules". "Macro" means "large" and by now you've figured out that polymers must be very large molecules!
Most of the polymers we'll talk about here are linear polymers. A linear polymer is made up of one molecule after another, hooked together in a long chain. This chain is called the backbone.
Now, linear polymers don't have to be in a straight, rigid line. Those single bonds between atoms in the backbone can swivel around a bit, kinda like paper clips hooked together end-to-end.
A LINEAR polymer chain starts at the beginning and goes straight to the end. You can take your finger and trace the curvy path from one end to the other.
To the rest of the world, "linear" means "straight and not curved" but for polymers, linear means "straight and not branched".
A BRANCHED polymer chain has extra beginnings (branches!) along the chain and so it has lots of ends.
No matter where you start, you can't trace the entire polymer without backtracking.
The atoms that make up the backbone of a polymer chain come in a regular order, and this order repeats itself all along the length of the polymer chain. (Boy, that makes sense, doesn't it - given that polymers are made by hooking up one molecule after another after another after another.....)
For example, look at polypropylene (sounds like polly-pro-pill-een):
Its backbone chain is made up of just two carbon atoms repeated over and over again. One carbon atom has two hydrogen atoms attached to it, and the other carbon atom has one hydrogen atom and one pendant methyl group (CH3). (What's a pendant group? Click here to find out.)
This is called the repeat structure or the repeat unit.
Mouse over the polymer below to see the repeat units:
To make things simple, we usually only draw |
one unit of the repeat structure, like this:
Another example: styrene monomers join together to make polystyrene:
Below the diagram of styrene you can see a model of the styrene monomer and the polystyrene molecule it forms. It's amazing how that cute little styrene monomer can make a long twisted chain of polystyrene like that. Pretty cool! Now drag your mouse over each model to see them in 3-D.
Polymers don't start out big. They start as tiny little molecules. But how do they do that? Click here to make your own virtual polymer.
So now you know what happens when certain small molecules get together to form long chains. You get polymers. But don't think that polymers are some kind of rare special molecules. They're everywhere, as you will learn from exploring more of this site.