MONOMER

To get a clear idea of the way polymers are formed, you need to look more closely at the monomer molecules! There are many monomer molecules.
Here are some examples:

Each of these monomer molecules seems very different, but they do have some common features. Let's see if you can spot them.
Look again at the first four monomers:

What is the feature found in each of these monomers? Click on this feature.

Actually, these monomers have two distinctive features:
carbon-carbon double bonds and
side groups
The highlighted areas show the side groups on these monomer molecules. These groups give the polymer chain some of its properties.

The double bond, however, is the vital feature that allows these monomers to form the long polymer chains.
Now, let's look at those other four monomers. (Note: we have two different groups of monomers because we have two different polymerization reactions.) These four monomers contain what we call functional groups. You may already know that much of the chemistry of carbon compounds is based on certain groups of atoms that are called functional groups. Let's take a look at a few.
One example of this is the carboxylic acid group:

R means the "Rest" of the molecule.
Here are two example monomers that contain this functional group:

Two other functional groups you may see in polymerization reactions are the amine group, , and the alcohol group, . Below are examples of monomers containing these functional groups:

Notice that each of these monomers contains two functional groups. That is, they are difunctional. It is their difunctionality that allows them monomers to form long polymer chains.
As we move on to polimarization, remember what you read about monomers:
The first group of monomers had
carbon-carbon double bonds and
side groups
The second group of monomers had
functional groups and
two functional groups each (that is, they are difunctional)