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3 18/09/2015 Monomers and Polymers Ethene Here’s ethene again. Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics… Step 1: Break the double bond Step 2: Add the molecules together: This molecule is called POLYETHENE, and the process that made it is called POLYMERISATION

4 Polyethene >Ethene put under pressure and heated with a catalyst will polymerise to form poly(ethene). >Note that there are no double bonds in the polymer. >Poly(ethene) is an alkane. It is a saturated hydrocarbon. >A polymer which is formed from monomers added together where no other substance is produced is called an addition polymer.

5 18/09/2015 Another way of drawing it… Instead of circles, let’s use letters… Ethene CC H H HH CC H H HH H C C H H H H C C H H H Poly(e)thene General formula for addition polymerisation: C C n C C n e.g. C C n H CH 3 H H C C n H H H

6 18/09/2015 Another way of drawing it… Instead of circles, let’s use letters… Chloroethene CC Cl H HH CC H HH H C C H H H C C H H Polychloroethene General formula for addition polymerisation: C C n C C n e.g. C C n H CH 3 H H C C n H H H Chloroethene Propene Polypropene

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