Polymers

CESE Chemistry

1. Chapter 18
Polymers
LEARNINGOBJECTIVES
Define polymers
Distinguish between addition and
condensation as reactions in the
formation of polymers
Show how the monomers are linked in
the structure of the polymer
Demonstrate the differences in
properties between the monomer and
the polymer it forms

2. Chapter 18
Polymers
LEARNINGOUTCOMES
Name examples of polymers formed by addition reactions
Draw diagrams to represent the formulae of monomers
State at least one use of each of the following types of
polymers: polyalkene
Name examples of polymers formed by condensation
reactions
Draw diagrams to represent the formulae of compounds
State at least one use of each of the following types of
polymers: polyamide, polyester and polysaccharide
Describe the hydrolysis of proteins
Compare acid hydrolysis of a polysaccharide with
carbohydrate digestion in the body

3. Polymers
Polymers are very large molecules called macromolecules.
A macromolecule or polymer is built up of many small units called
monomers.
Different macromolecules or polymers have different units or
monomers joined by different linkages.
A polymer is a macromolecule which is made up of a large
number of simple molecules called monomers.
monomer monomer monomer monomer
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Polymers
polymer

4. Polymers are either naturally occurring or synthetic.
Polymers are either addition polymers formed by an
addition process, or condensation polymers, formed
by the condensation process.
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Polymers
Classifying Polymers

5. Chapter 18
Polymers
Polymers
Synthetic Natural
Polythene,
PVC,
Polystyrene,
Nylon,
Teflon ,
Perspex,
Terylene,
Polyurethane
Carbohydrates
Proteins
Rubber (Natural)

6. Chapter 18
Polymers
Polymers
Condensation Polymers
Nylon
Polyesters
Polysaccharides
Proteins
Additional polymers
Polythene
Polypropene
Polychlorethene(PVC)
Polyphenylethene

7. Polymerisation
Polymerisation is the processwhereby two or more
simple molecules (monomers) react and link togetherto
form a much larger molecule called polymer.
There two types of polymerisation:
Addition polymerisationand
Condensation polymerisation.
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Polymers

8. Addition polymerisation
In addition polymerisationone monomer adds on to the
another monomer to form a long chain polymer.
The monomers must have a carbon-carbon double bond
so that addition reaction can take place.
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Polymers

9. Example of addition polymerisation
Formation of polyethene from ethene
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Polymers

10. Uses of polyethene
plastic bags
plastic bottles and containers
clingfilm for wrapping fish and vegetables
plastic buckets and hoses
Polyethene is the most widely used form of plastics.
It is used for making common household
items like:
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Polymers

11. Other addition polymers and their uses
Poly Vinyl Chloride (PVC)
It is an addition polymer made from a monomer called vinyl
chloride or chloroethene.
It is used for making water pipes, gloves, rain coats and
shower curtains.
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Polymers

12. Other addition polymers and their uses
Poly(tetrafluoroethene) [PTFE]
It is an addition polymer made from a monomer called
tetrafluoroethene.
It is used for making seals and washers and for coating
non-stick pots and pans.
F F
C = C
F F
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Polymers

13. Condensation Polymerisation
In condensation polymerisation, two or more monomers
join together with the elimination of a small molecule,
such as water.
The monomers must have different reactive functional
groups so that they can react together to form a polymer.
The polymer formed is called a condensation polymer.
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Polymers

14. Example of condensation polymerisation:
Nylon is formed by condensation
polymerisation from a dicarboxylic
acid(hexanedioic acid) and a
diamine(1,6-diamino-hexane).
Uses of nlyon:
Nylon
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Polymers

15. Formation of nylon
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Polymers

16. Terylene is also a condensation polymer.
Terylene is formed by condensation
polymerisation from an diacid(benzene-
1,4-dicarboxylic acid) and a diol(ethane-
1,2-diol).
It is apolyesterwith a –C–O–linkage.
Uses of terylene:
Terylene
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Polymers
O=

17. Formation of Terylene
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Polymers

18. Fats and oils are polyesters.
A fat molecule consists of two parts –glycerol and chains
of fatty acids.
Fats and oils contain three ester functional groups.
When fat is hydrolysed by an enzyme such as lipase,
glycerol and fatty acids are produced.
Fats and Oils
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Polymers

19. 1.Add 2 cm
3
of ethanol to a sample of the unknown in a test
tube.
2.Shake the mixture thoroughly.
3.Add 2 cm
3
of water.
If fat is present, a cloudy white suspension will form at the top of
the solution.
Test for Fats
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Polymers

20. Polysaccharides
Polysaccharides are naturally occurring compounds with a general
formula C
nH
2nO
n.
‘Mono’ means one and ‘saccharide’ means sugar.
Monosacharides are simple, single sugar molecules which comprise
only one single basic unit. E.g. glucose, fructose, galactose
Diasaccharides are complex sugars made up of two simple sugar
molecules. They are formed by condensation reactions. E.g. sucrose,
lactose, maltose
Polysaccharides are made up of a large number of monosaccharides
joined together by numerous condensation reactions. E.g. starch,
glycogen, cellulose
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Polymers

21. Polysaccharides
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Polymers

22. Test for Starch
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Polymers
1.Add a few drops of iodine solution to the unknown substance.
2.Observe the colour change, if any.
If starch is present, the iodine solution will turn from brown to
blue-black.

23. Test for Reducing Sugars –Benedict’s Test
Chapter 18
Polymers
1.Add 2 cm
3
of Benedict’s solution to 2 cm
3
of glucose solution or any other food
solution to be tested.
2.Shake the mixture and immerse the test
tube in a beaker of boiling water for two
minutes.
3.Observe and record any changes in colour.
If reducing sugar is present, a brick red
ppt. (or green, yellow, or orange ppt.) is
formed. If no reducing sugar is present,
the solution remains blue in colour.

24. Plastics
Plastics are one of the most common materials
used in the world today.
It has wide applications in making a host of things
ranging from spectacles to aeroplane parts.
There are many kinds of plastics, such as:
Polyethene
Nylon
PVC
Polystyrene
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Polymers

25. Properties of plastics
Advantages
Light and durable
Corrosion resistant
Can be easily moulded into a wide variety
of shapes and sizes
Relatively cheap
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Polymers

26. Properties of plastics
They burn easily to produce toxic fumes.
Most plastics are non-biodegradable,
(cannot be decomposed by air and
bacteria), and hence causes pollution
to the environment.
They are not as strong as metals.
Disadvantages
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Polymers

27. Problems caused by the use of plastics
The use of plastics in society has increased at a tremendous rate.
We use twenty times more plastic than we did fifty years ago.
The manufacture of plastics uses up about 8% of the world’s oil
supply, leading to more competition for petroleum.
Since most plastics are non-biodegradable, the amount of plastic
waste accumulating is rapidly increasing in our environment.
Discarded plastics in rivers and oceans cause the death of many sea
creatures like turtles, fish and whales.
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Polymers

28. Some ways to reduce pollution
caused by plastics
1.Reduce the use of plastics for packaging and
transportation of goods.
2.Reduce the use of takeaway plastic bags when you
shop at supermarkets.
3.Practise and promote the use of proper disposal of
plastics used at home and on the beaches.
4.Reuse and recycle the used plastics.
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Polymers

29. Quick check
1.What is a polymer? Give two examples of polymers.
2.(a) State two reasons for using plastics in place of metals.
(b) Why is the body of a motor car not entirely
made of plastics?
3.(a) What is the difference between addition
polymerisation and condensation polymerisation?
(b) Give two examples each of addition polymers
and condensation polymers.
4.Deduce the structure of the monomers from which the following
polymers are built from.
(a) (b)
Solution
Chapter 18
Polymers

30. Solution to Quick Check
1.A polymer is a macromolecule made up of many small
units called monomers, e.g. nylon & Terylene.
2.(a) Plastics are lighter and easier to mould.
(b) Plastics are not strong enough to protect the
occupants in the car in case of accidents.
3.(a) In addition polymerisation, monomers are added
one to another to form a polymer, without any
molecule being removed from the reaction.
In condensation polymerisation, monomers are
joined together with the elimination of a small
molecule, such as water.
(b) Addition polymers: polyethene, polypropene
Condensation polymers: nylon, Terylene.
4.(a) (b)
Return
Chapter 18
Polymers

31. 1.http://en.wikipedia.org/wiki/Polymer
2.http://www.chemheritage.org/EducationalServices/nylon/chem/chem.html
3.http://www.chemguide.co.uk/organicprops/esters/polyesters.html
4.http://www.plasticsresource.com/s_plasticsresource/index.asp
5.http://www.sdplastics.com/plastics.html
To learn more about Macromolecules and Plastics,
click on the links below!
Chapter 18
Polymers

32. References
32
Chemistry for CSEC Examinations
by Mike Taylor and Tania Chung
Longman Chemistry for CSEC by
Jim Clark and Ray Oliver