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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

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