Science Activities for Making Polymers From Monomers

The Science

• There are a number of ways to make polymers, depending on the desired end result, but one of the most common methods is a process called ̶0;free-radical polymerization̶1;. In this process, a catalyst like benzoyl peroxide is added to ethylene monomers and heated. This causes the catalyst to split and become a free radical, capable of breaking the double carbon-to-carbon bond in the ethylene. This causes the ethylene monomers to join together in a long chain, creating the polymer polyethylene.

Drawing Activity

• The most basic activity for understanding this reaction is to draw it, stage by stage. To make it clear what is happening, choose one color for the carbon atoms, one for the hydrogen, and another color for the free radicals. Choose a fourth color for the bonds. In your first diagram, draw a series of monomers by themselves. Now draw a few free-radicals, one attached to each carbon atom so that some of the carbon atoms have empty bonds. In the final stage of this process, the free-carbon atoms join together and the free-radicals are removed.

Role Play Activity

• If you have enough children willing to take part, you could role play this reaction. Appoint some children as carbon atoms and have them use both arms as their double bond. The hydrogen actors only need one arm, and the free radicals also only need one arm but can attach only to carbon atoms. You will need a large space to create a polymer, so consider using the school gym or perhaps gather outdoors rather than in the classroom. If you want to make the game a bit more exciting, you could have the monomers waiting patiently, then introduce the free radicals, and time how long it takes the children to fill every bond.

Models

• Most school science labs will be equipped with model atoms. Carbon atoms will usually have four holes while hydrogen atoms have just one. This will help the children create their monomers and polymers, as they will know the model is only correct when every hole is plugged. If your school does not have these available, consider using foam balls and toothpicks. Even different colored cherries or grapes could be used to create an edible model that is also healthy.