1. Polymers

2. Latin: Plasticus, that which can be molded
Polymer
This name hints at how polymers are made
Many Parts
PLASTICS
Latin: Plasticus, that which can be molded

3. Styrene-butadiene or rubber If a Monomer = A
then a Homopolymer = A-A-A-A-A-A-A-A-
And a Copolymer = A-B-A-B-A-B-A-B-A
Ex: Addition Polymerization- same monomers
C=C C=C C=C    -C-C-C-C-C-C-
monomer monomer monomer homopolymer
Ex: Addition Polymerization (Copolymer) Different monomers
( CH CH2 CH2 CH CH CH2 )n
Styrene-butadiene or
rubber
25.2

4. The simple repeating unit of a polymer is the monomer.
Homopolymer made up of only one type of monomer.
( CF2 CF2 )n
Teflon
( CH2 CH2 )n
Polyethylene
( CH2 CH )n Cl
PVC

5. Copolymer Terylene Made up of two different monomers
benzene-1,4-dicarboxylic acid
Old name: terephthalate
ethane-1,2-diol
Esterification
PET (Polyethylene terephthalate) – used to made plastic soda bottles

6. Condensation polymers
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POLYMER REACTIONS
Addition polymers
Condensation polymers
long chain from monomers
AND
no other products
long chain molecules from monomers
AND
another small molecule product (e.g. water)

7. Addition Polymer of Ethene

8. POLYMERISATION OF ALKENES ADDITION POLYMERISATION
The equation shows the original monomer and the repeating unit in the polymer
ethene poly(ethene)
MONOMER POLYMER
n represents a large number

9. Free Radical Polymerization (3 minute clip)

10. Free radical mechanism 3 stages: Initiation Propagation Termination
THE MECHANISM OF ADDITION POLYMERISATION
Free radical mechanism 3 stages:
Initiation
Propagation
Termination

11. ADDITION POLYMERIZATION
Initiation:
An ether is cleaves (cut) in half using heat. Now we have the crazy 1 e-.
1 e- or a single or an unpaired electron is VERY reactive.
Free Radical
Another
Free Radical
REACTIVE (Ether)

12. ADDITION POLYMERIZATION
Propagation:
Free radicals from the first step starts the addition process

13. ADDITION POLYMERIZATION
Termination:
Two radicals react and deactivate themselves

14. Summary of Free Radical Polymerization

15. STOPPING POLYMERIZATION REACTIONS
How can the polymerization reaction end or be stopped?
Run out or reactants (monomers)
ii) 2 free radial monomers combine head to head
2 ways

16. Sterioisomers ISOTACTIC SYNDIOTACTIC ATACTIC CH3 groups on same side
CH3 groups alternate sided
ATACTIC
random

17. BRANCHING CHAINS STRAIGHT CHAINS
Low density poly(ethene) LDPE
200C, 2000 atm, O2
Molecules loosely packed due to branching
Flexible & soft
Bags, cling flim
BRANCHING CHAINS
High density poly(ethene) HDPE
60C, 2 atm,
Catalyst: Ziegla-Natta
TiCl3 and Al(C2H5)3
Molecules tightly packed
Stiffer & harder
Buckets, bottles
STRAIGHT CHAINS

19. Polyethylene
1) HDPE, called high density polyethylene, with straight chains.
It is hard and molecules tightly packed, lots of intermolecular forces holding.
Ex: Buckets
2) LDPE has many branching chains .
It is soft, Ex: “cling wrap”

20. Polymerisation of Ethene

21. DIFFERENT KINDS OF PLASTIC EXAMPLES OF ADDITION POLYMERISATION
ETHENE
POLY(ETHENE)
PROPENE
POLY(PROPENE)
CHLOROETHENE
POLY(CHLOROETHENE)
POLYVINYLCHLORIDE PVC
TETRAFLUOROETHENE
POLY(TETRAFLUOROETHENE)
PTFE “Teflon”

22. PVC
Every other hydrogen is replaced with a chlorine atom

23. PVC Addition

24. PVC

25. Other Addition Products
Ex: PTFE / Teflon

26. Polystyrene

27. POLYMERISATION OF ALKENES
SPOTTING THE MONOMER

28. POLYMERISATION OF ALKENES
SPOTTING THE MONOMER

29. Polymerisation of Propene

31. poly(propene)

32. Cellulose made of chains of the sugars
POLYMERS
Large molecules (macromolecules) madefrom monomers.
Natural polymers
Protein, cellulose
Synthetic polymers
Polyethylene, poly (vinyl chloride) polystyrene, etc…..
NATURAL POLYMER
Cellulose made of chains of the sugars
Homopolymer
Copolymer

33. Thermosoftening v Thermoset

34. ADDITION POLYMERISATION
Chemical Properties
Fairly inert. Why do plastics melt but not react?
2) Biodegradability
Addition polymers do NOT break down
Condensation polymers DO, why? Answer:Nu can attack the polar bonds; i.e. C-N and C-O bonds which link every polymer unit and as a result the polymers can be broken
The carbon–carbon covalent chemical bonds are strong so they do not break and react.
But weak forces responsible for the physical properties and plastics should melt a very low temperatures, but here are many, thousands of these atoms, so plastics melt but at reasonably high temperatures Ex: 150 0C (polyethene), like butter does.

35. Chemsheets AS006 (Electron arrangement)
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POLYESTERS

36. e.g. terylene
(PET)

37. Polyesters e.g. terylene (PET) ethane-1,2-diol
benzene-1,4- dicarboxylic acid
repeating unit
polymer structure

38. dicarboxylic acid
diol
–H2O

39. Dicarboxylic acid + diol
Polyesters
Dicarboxylic acid + diol
– H2O
–H2O
repeating unit
polymer structure

40. Chemsheets AS006 (Electron arrangement)
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POLYAMIDES

41. e.g. Kevlar

42. 2 Condensation Reactions
Amidification
Esterification

43. Polyamides
e.g. nylon-6,6
1,6-diaminohexane
hexane-1,6-dioic acid
repeating unit
polymer structure
Note: The Cambridge Exam asks for repeating unit it is the polymer
WITHOUT the brackets

44. Polyamides Ex : 2 e.g. Kevlar 1,4-diaminobenzene
benzene-1,4- dicarboxylic acid
repeating unit
polymer structure

45. dicarboxylic acid
diamine
–H2O

46. Dicarboxylic acid + diamine
Polyamides
Dicarboxylic acid + diamine
–H2O
polymer
polymer structure
Short hand
repeating unit

47. Amino acids join together via an amide or peptide link
PEPTIDES
Reagents amino acids
Equation H2NCCH2COOH H2NC(CH3)COOH ——> H2NCCH2CONHHC(CH3)COOH + H2O
Product peptide (the above shows the formation of a dipeptide)
Eliminated water
Mechanism addition-elimination
Amino acids join together via an amide or peptide link
2 amino acids joined dipeptide
3 amino acids joined tripeptide
many amino acids joined polypeptide
a dipeptide

48. contains both acid + amine group
Amino acids
(Polyamides)
POLYMER
MONOMER
repeating unit
contains both acid + amine group
polymer structure

49. HYDROLYSIS OF PEPTIDES
+ HOH (water)
HOOCCH2NH HOOCCH(CH3)NH2
Acid
hydrolysis
The acid groups remain as they are and the amine groups are protonated

50. PROTEINS
• polypeptides with large relative molecular masses (>10000)
• chains can be lined up with each other
• the C=O and N-H bonds are polar due to a difference in electronegativity
• hydrogen bonding exists between chains
dotted lines represent hydrogen bonding

51. Plastic can be bad

52. Plastics Uses and Problems

53. Disadvantages of Plastic
Most plastics are non-biodegradable.
2) Plastics are made from fossil fuels which are non-renewable
3) During combustion toxic fumes are released.
Combustion and toxic fumes
(CH2CHCl)n + O2  CO2 + CO + HCl + H2O
The chlorines in the PVC combine with the hydrogen atoms to form hydrogen chloride gas (HCl).
When this contacts water in lungs or mouth, it turns to hydrochloric acid (HCl(aq)).

54. They are cheap and easy to make. They don’t oxidize (rust).
Advantages of Plastics
They are cheap and easy to make.
They don’t oxidize (rust).
Plastics are resistant to chemical attack
They are easy to mould into shape and colour
They last a lot longer than many metals .

55. Biodegradable Plastics
Instead of using fossil fuel derived monomers for polymerization,
Starch from foods (corn starch or potato starch can be used, they
can polymerize and form plastics as well as ethene or propene.
Advantage: pollution control as these will rot in less than a year
Disadvantage: using food when the world still has hungry
people is grossly unethical. These plastics do not work as well

56. Boardworks GCSE Science: Chemistry Making Polymers
How much waste plastic?
(5 minutes)
There are three ways to dispose of waste plastics:
landfill
incineration (burning)
recycling
Each has its own advantages and disadvantages.
Photo credit: University of Oklahoma Physical Plant

57. Landfill Disposal of Polymers 1 Advantages Disadvantages
Cambridge Question : Addition polymers are
non-biodegradable but ccondensation polymers can
degrade, why the difference?
Answer :Nu can attack the polar bonds; i.e. C-N and C-O bonds which link every polymer unit and as a result the polymers can be broken
Landfill
Advantages
Disadvantages
No sorting costs
Modern landfills do not pollute.
Plastics break down to make methane which can generate electricity.
Distance to landfill sites so transport costs.
If too much methane builds up, explosions can occur.

58. Incineration (burning)
Disposal of Polymers 2
Incineration (burning)
Advantages
Disadvantages
Burning plastics produces heat energy.
Polythene produces more energy than burning coal or oil.
Saves fossil fuels
Burning at low temperatures can produce harmful dioxins
Old incinerators (low temperature) produce harmful gases.

59. Recycling Disposal of Polymers 3 Advantages Disadvantages
Plastic is lightweight even when compressed.
Cheaper to recycle plastics than make then from scratch.
Recycled plastics can be used to make lots of useful materials
Some plastics can be broken down to make raw materials for other products.
Plastics must be collected and sorted.
Many plastics contain materials that need to be removed.
Cost of transporting to nearest recycling plant.
Recycled materials are weaker

60. Plastics How They are Made

61. Quiz