1. An Introduction to Polymers “Plasticus, that which can be molded”
Addition Polymerisation
Condensation Polymerisation

2. Polymers
Are long chain molecules that are formed by the joining together of a large number of repeating units called monomers by a process of polymerization. (DNA, protein, plastics, rubber, cotton)

3. Uses of Polymers Cotton

4. Uses of Polymers Rubber

5. The decks, fence, stepping stones, house shingles, and the sweat shirt, were all made from recycled plastic.

6. Uses of Polymers World’s largest rubber band ball – 8200 lb

7. Uses of Polymers Bulletproof glass

8. Uses of Polymers Plastics

9. Uses of Plastics

10. Uses of Plastics Garbage Islands

11. Polymers
To categorize polymers we can sort them out as synthetic (plastics) or natural.
Synthetic polymers can be differentiated based on their response to heat.
Thermoplastic polymers soften and melt when heated.
Thermoset polymers do not soften or melt when heated.

12. Thermoplastic polymers
Long chain hydrocarbons have mainly van der Waals forces with some dipole forces due to substituted groups. (so can slide due to weak attraction)
Can be remolded. (parafilm demo)

13. Thermoset polymers The chains are cross-linked by covalent bonds
We can control the amount of cross-linking and hence the strength of the plastic.

14. Thermoset polymers

15. Thermoplastic vs Thermosetn a P o l y m T s b d , w u f p . W g S t r e c h C o s - L i n k d P l y m T a g . W , p w u ' f R x

16. Polymer Production
Addition Polymers – monomers are linked through addition reactions
Condensation Polymers – monomer units are linked through condensation reactions (a small molecule is formed as a by product)

17. Addition Polymerization
Ethene
H2C
CH2
ethene
CH2
Polyethylene – insulating wires, plastic containers 6

18. Addition Polymerization
Propene
propene
H2C
CHCH3 CH
CH3
Polypropylene – rope, carpets 6

19. Addition polymerization Examples
Polycholorethene – PVC, raincoats
Methyl methacrylate – plexiglass
Tetrafluroethene - Teflon
CHCl
CH2
CF2
CF2

20. Addition Polymerisation
The polymer is the only product
Involves the opening out of a double bond
Reaction proceeds by a free radical mechanism
A small amount of oxygen is needed to begin reaction.

21. Mechanism Initiation .. RO •
H2C
CHCH3 7

22. Mechanism Initiation .. RO •
H2C
CHCH3 7

23. ..
RO:
Mechanism
H2C
CHCH3 • 9

24. Mechanism Propagation..
RO:
H2C
CHCH3 •
CHCH3
H2C 10

25. ..
RO:
Mechanism
H2C
CHCH3
H2C
CHCH3 • 10

26. ..
RO:
Mechanism
H2C
CHCH3
H2C
CHCH3
CHCH3
H2C • 10

27. ..
RO:
Mechanism
H2C
CHCH3
H2C
CHCH3
H2C
CHCH3 • 10

28. ..
RO:
Mechanism
H2C
CHCH3
H2C
CHCH3
H2C
CHCH3
CHCH3
H2C • 10

29. Mechanism Termination..
RO:
H2C
CHCH3
H2C
CHCH3
H2C
CHCH3
CHCH3
H2C • •
RO: 10

30. Mechanism Termination..
RO:
H2C
CHCH3
H2C
CHCH3
H2C
CHCH3
CHCH3
H2C
RO: 10

31. Ethylene has two carbons which have a doublebond between them
Ethylene has two carbons which have a doublebond between them. High temperature or UV light can cause two of these shared (paired) electrons to become unshared (unpaired). C H H H
These unpaired electrons are eager to pair up with another electron. If this ethylene molecule bumps another ethylene molecule, the unpaired electrons will cause the one it bumped into to lend one of its inner electrons. C C - - C C H H - - C - C - - - C C - -

32. Here’s another way to see the chain reaction
Here’s another way to see the chain reaction. These are the carbon atoms with their double-bond (2 shared electrons each). The hydrogen atoms are not shown. A collision breaks the first bond.
Once the first double bond is broken, a chain reaction will occur. In about a second an entire chamber of compressed ethylene gas turns into the polymer, polyethylene.

33. Properties of Plastics
Plastics used as containers for a number of substances so need to be unreactive.
Converting (alkenes) into single bond (alkane) molecules become fairly stable and unreactive.

34. Cross - Linking
Monomers with two double bonds can be used (increases strength. Why?)
i.e. Neoprene
Monomer
Similar to natural rubber
Because of 2 double bonds able to add chains in multiple directions Cl
CH2
C CH CH2

35. Cross - Linking
CH2 C
CCl
New bonds Cross Links
CH2
CCl
CH2 C

36. Cross - Linking
We can control the rigidity depending on the number of dienes in the starting monomers.
i.e. polyethylene with varying amounts of dienes is used to make garbage bags, fencing and netting to wrap trees.

37. Condensation Polymerization Polyester
Polyester is made from the two monomers, terephthalic acid (note: “ph” is silent) and ethylene glycol (car antifreeze). This makes a popular plastic called PETE, which is short for Polyethylene Terephthalate. The synthesis is also a dehydration reaction because water is given off.

38. Condensation Polymerization Polyester
OH PETE HO O
OH + O o C c o o o H O
dioic acid diol dioic acid diol
dimer/copolymer

39. Condensation Polymerization Polyester
O O O O
HO R O R R O R O R R OH
H2O
H2O
H2O
Hence the name Polyester
ESTER groups formed

40. Condensation Polymerization Nylon (polyamide)
Tetramethylene dicarboxylic acid (adipic acid)
Hexamethylene diamine
methylene x 6 (hexa)
amine x 2 (di)
Nylon is actually a “copolymer” or dimer because is it made from two monomers.
Nylon was discovered in The name nylon is derived from two cities where it was discovered namely New York (NY) and London (LON).
dehydration reaction is a condensation reaction with water as the molecule that comes off.

41. Condensation Polymerization Nylon (polyamide)

42. Condensation Polymerization Nylon (polyamide)
Dehydration Reaction

43. Condensation Polymerization Kevlar (polyamide)

44. Condensation Polymerization Kevlar (polyamide)
Used in bullet proof vests
stronger than steel

45. Uses of polyamides
The main use of polyesters and polyamides is as fibres in clothing.
Most clothing now has a degree of manufactured fibres woven into the natural material (such as cotton).
This gives the material more desirable characteristics, such as stretchiness, and better washability.
Also are used in baby diapers, polymethylacrylate – crystal polymer used to absorb water

48. O C O