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Transcript of C18 polymers
Chapter 18
Polymers
LEARNING OBJECTIVES
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
Chapter 18
Polymers
LEARNING OUTCOMES
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
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
Chapter 18
Polymers
polymer
Polymers are either naturally occurring or synthetic.Polymers are either naturally occurring or synthetic.
Polymers are either Polymers are either addition polymers addition polymers formed by an formed by an addition process, or addition process, or condensation polymerscondensation polymers, formed , formed by the condensation process.by the condensation process.
Chapter 18
Polymers
Classifying Polymers
Chapter 18
Polymers
Polymers Polymers
Synthetic Synthetic NaturalNatural
Polythene, Polythene, PVC, PVC, Polystyrene, Polystyrene, Nylon, Nylon, Teflon ,Teflon , Perspex, Perspex, Terylene, Terylene, Polyurethane Polyurethane
Carbohydrates Carbohydrates Proteins Proteins Rubber (Natural)Rubber (Natural)
Chapter 18
Polymers
PolymersPolymers
Condensation Polymers Condensation Polymers Nylon Nylon Polyesters Polyesters Polysaccharides Polysaccharides ProteinsProteins
Additional polymersAdditional polymersPolythenePolythenePolypropenePolypropenePolychlorethene (PVC)Polychlorethene (PVC)PolyphenylethenePolyphenylethene
Polymerisation Polymerisation is the process whereby two or more
simple molecules (monomers) react and link together to form a much larger molecule called polymer.
There two types of polymerisation: Addition polymerisation and Condensation polymerisation.
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Polymers
Addition polymerisation
In addition polymerisation one 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
Example of addition polymerisationFormation of polyethene from ethene
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Polymers
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:
Chapter 18
Polymers
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.
Chapter 18
Polymers
Other addition polymers and their usesPoly(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
Chapter 18
Polymers
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.
Chapter 18
Polymers
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
Chapter 18
Polymers
Formation of nylon
Chapter 18
Polymers
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 a polyester with a –C–O– linkage. Uses of terylene:
Terylene
Chapter 18
Polymers
O=
Formation of Terylene
Chapter 18
Polymers
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
1. Add 2 cm3 of ethanol to a sample of the unknown in a test tube.
2. Shake the mixture thoroughly.3. Add 2 cm3 of water.
If fat is present, a cloudy white suspension will form at the top of the solution.
Test for Fats
Chapter 18
Polymers
Polysaccharides Polysaccharides are naturally occurring compounds with a general
formula CnH2nOn.
‘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
Chapter 18
Polymers
Polysaccharides
Chapter 18
Polymers
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.
Test for Reducing Sugars – Benedict’s Test
Chapter 18
Polymers
1. Add 2 cm3 of Benedict’s solution to 2 cm3 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.
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
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
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
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.
Chapter 18
Polymers
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
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
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
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
ReferencesReferences
3232
Chemistry for CSEC Examinations by Mike Taylor and Tania Chung
Longman Chemistry for CSEC by Jim Clark and Ray Oliver