Monomers

A monomer (from Greek mono "one" and meros "part") is a small molecule that may become chemically bonded to other monomers to form a polymer. A monomer is a molecule or compound, usually containing carbon, with a relatively low molecular weight and simple structure; monomers form the fundamental building blocks of polymers, synthetic resins, and elastomers. Thus, vinylidene chloride is the monomer from which polyvinylidene chloride is made, and styrene is the monomer from which polystyrene resins are produced. One of the simplest monomers, ethylene, consists of two carbon atoms (represented by C) linked by a double bond, with two hydrogen atoms (represented by H) connected to each carbon. In ethylene the carbon- hydrogen bonds are single covalent bonds, while the carbon-carbon bond is a double covalent bond.

In the presence of heat, light, and an appropriate catalyst the ethylene molecule can be excited into a reactive state in which the carbon-carbon double bond is dissociated. If two excited molecules come into contact, it is possible to link the ethylene molecules with single covalent bonds between molecules. When this process repeats itself, on the order of thousands of times, a chain is produced with a carbon backbone.

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?
Actually, these monomers have two distinctive features:

i. carbon-carbon double bonds and

ii. side groups