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19/04/23Monomers 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
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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.
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19/04/23Another way of drawing it…Instead of circles, let’s use letters…
Ethene
C C
HH
HH
C C
HH
HH
Ethene
H
C C
H
HH
H
C C
H
HH
Poly(e)thene
General formula for addition polymerisation:
C Cn C C
n
e.g. C Cn
H CH3
HH
C Cn
H CH3
HH
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19/04/23Another way of drawing it…Instead of circles, let’s use letters…
Chloroethene
C C
ClH
HH
C C
ClH
HH
H
C C
Cl
HH
H
C C
Cl
HH
Polychloroethene
General formula for addition polymerisation:
C Cn C C
n
e.g. C Cn
H CH3
HH
C Cn
H CH3
HH
Chloroethene
Propene Polypropene