1. Unit 1: Polymer Chemistry

2. The Bonding of Carbon
To the right of the staircase on the periodic table
It is a non-metal
Has 4 valence electrons meaning it will form 4 bonds
Carbon forms a variety of covalent compounds with other carbon atoms or other non-metals

3. The Bonding of Carbon
As was covered in CH1120, carbon can form polar covalent bonds
In polar covalent bonds carbon and the other atom in the bond have an electronegativity difference (ΔEN) between 0.4 and 2.0

4. Hydrocarbons Compounds containing only hydrogen and carbon
These are often arranged in “chains” or “rings”

5. Diagrams
Structural (Lewis)
Condensed
Line (Geometric)

6. Homologous Series Group of organic compounds with similar structure
Structure varies only by the number of atoms in the chain
Alkanes: CnH2n+2
Alkenes: CnH2n
Alkynes: CnH2n-2

7. Naming Straight Chain Alkanes
CH4 - Methane
C2H6 - Ethane
C3H8 - Propane
C4H10 - Butane
C5H12 - Pentane
C6H14 - Hexane
C7H16 - Heptane
C8H18 - Octane
C9H20 - Nonane
C10H22 - Decane

8. Multiple Bonds
There can be single, double or triple bonds within carbon compounds
With all single bonds: Alkane
With a double bond: Alkene
With a triple bond: Alkyne

9. Functional Groups Groups used to differentiate organic compounds
Have their own characteristics
“R” represents a carbon chain
Compounds can contain more than one functional group

10. Aromatics Single bond: Double bond: Triple bond: 1 Sigma (σ) bond
1 Sigma (σ) bond, 2 Pi (π) bonds
Triple bond:
1 Sigma (σ) bond, 3 Pi (π) bonds

11. Aromatics

12. Aromatics Delocalized π bonds stabilize structures
Flat rings with delocalized π bonds are said to be aromatic
Delocalized π bond is represented with a circle within the ring

13. Aromatics

14. Alcohols
-OH group in chain

15. Carboxylic Acids
-COOH group in chain

16. Esters
-COOR group in chain

17. Ketones
C double bonded to O with 2 carbon chains

18. Aldehydes
C double bonded to O with 1 carbon chain and 1 hydrogen

19. Aldehydes Vs. Ketones

20. Ethers
Oxygen within then chain

21. Amines Nitrogen containing
3 bonds contain at least one carbon chain (the others can be carbon chains or hydrogen)

22. Amines Primary (1⁰) Secondary (2⁰) Tertiary (3⁰) 1 carbon chain
2 hydrogen
Secondary (2⁰)
2 carbon chains
1 hydrogen
Tertiary (3⁰)
3 carbon chains

23. Amides Nitrogen containing
Like amines but carbon directly bonded to nitrogen is double bonded to oxygen (C=O is called carbonyl group)

24. Polymers
AKA Plastics
Large molecules (macromolecules) made of many repeating units
Formed through polymerization
Natural
Wool, silk, biopolymers (carbohydrates, proteins)
Synthetic (focus of this course)

25. Monomers
“one part”
Molecule that chemically bonds to other molecules to create a polymer

26. Repeating Units Polymers are long chains of repeating units
Monomers are changed in order to fit into the chain

27. Industrial Examples

28. Physical Properties
Bonds allow atoms to move around making the molecular chain flexible
Macromolecules have different molecular weights
Sometimes distributed evenly
Sometimes concentrated in one area of chain
Causes polymers to soften over time (no sharp melting point)
Holding various chains together can make polymers harder, denser, less soluble, more resistant to heat

29. Polymers Homopolymer Copolymer Single monomer repeated
Multiple monomers present
Random
Blocked
Graft

30. Linear Polymers Straight chain polymers
Consist of a straight chain of C-C bonds
Actual shape of each carbon is tetrahedral

31. Branched Polymers
Replacement of a substituent (ie. hydrogen atom bonded to the polymer chain) with a chain of carbon atoms
Added chain can be the same as original polymer or may be different

32. Network Polymers More rigid than branched or linear
Chemical bonds are introduced between polymer chains

33. Cross-linking Forming of chemical bonds between polymer chains
More cross-links = more rigid/stronger
Plastic wrap vs. juice container

34. Plastics
Solid polymers that can be formed into various shapes by applying heat and pressure
Thermoplastics
Thermosetting plastic
Elastomers

35. Thermoplastics Can be reshaped Polymer can be melted down and recycled
Milk containers, pop bottles

36. Thermosetting (Thermoset) Plastics
Cannot be reshaped readily
Shaped through irreversible chemical processes
Many adhesives, fibreglass, nylon, polyester

37. Thermoplastics Vs. Thermoset

38. Elastomers Exhibit rubbery/elastic behaviour
Regain shape after stretching or bending
Crosslinking present but not as 3D/close as thermoset
Rubber

39. Polymers in Industry Strength and flexibility gives a variety of uses
Resistant to oxidation
Reinforcing material can be added to make an even stronger product (ie. Fibreglass)

40. Intermolecular Forces
Polymers such as polypropylene and polystyrene are non-polar
Contain only London forces

41. Intermolecular Forces
Most functional groups are polar, adding them makes the polymer polar
With polarity brings in the possibility of Dipole- dipole interactions and Hydrogen bonding
More functional groups increases intermolecular forces

42. Intermolecular Forces
Polymers sometimes have weak intermolecular forces (London) but since they are so large there are many points of interaction
Chain entanglement
Polymers move slowly even when heated

43. Intermolecular Forces
Higher molecular weight means the polymer chain is longer
Larger molecules have more points of interaction therefore more intermolecular forces
Remember from CH1120, stronger/more intermolecular forces increases boiling and melting points

44. Distance of Separation
When chains are closer together they will interact more (more intermolecular forces)
Half the distance doubles the intermolecular force

45. Distance of Separation
High Density Polyethylene (HDPE)
Mostly straight chains
Packed tightly together
More intermolecular forces
Lawn furniture, fuel tanks
Strength more important than flexibility

46. Distance of Separation
Low Density Polyethylene (LDPE)
Branched chains
Cannot pack as tightly as HDPE
Fewer intermolecular forces
Plastic wrap, grocery bags
Flexibility more important than strength

47. Reactions Carboxylic Acid + Sodium Hydroxide
Neutralization reaction, yields a salt and water

48. Reactions Carboxylic Acid + Alcohol
Must add heat (energy/Δ) and acid (H+)
Yields an ester and water

49. Reactions Amine + Hydrochloric Acid
Nitrogen will gain a positive charge by accepting the extra hydrogen
Chlorine becomes an anion

50. Reactions Carboxylic Acid + Amine Temperature must be >100⁰C
Only 1⁰ and 2⁰ amines
OH from acid and H from amine combine
Yields an amide and water

51. Polymerization Always the same steps: Two types Initiation Propagation
Termination
Two types
Free radical addition polymerization
C=C is broken
Condensation polymerization
Water is removed

52. Free Radical Addition Polymerization
1. Initiation
Form a free radical (highly unstable/reactive)
Non-polar compounds can be cleaved to give free radicals
X2  2X•
Addition of energy is needed (heat or light)

53. Free Radical Addition Polymerization
2. Propagation
Free radical attacks the monomer to create a new free radical

54. Free Radical Addition Polymerization
2. Propagation Continued
This step continues as the new free radical continues to attack new monomers
New monomers are added to the chain and new free radicals are formed

55. Free Radical Addition Polymerization
3. Termination
Collision with another chain or a free radical causes the propagation to come to an end
The same free radical may be added that was used in the initiation stage

56. Free Radical Addition Polymerization
Know the mechanisms to create:
Polypropylene
Polystyrene
Polyvinyl chloride (PVC)

57. Free Radical Addition Polymerization (Polypropylene)

58. Free Radical Addition Polymerization (Polystyrene)

59. Free Radical Addition Polymerization (Polyvinyl Chloride)
Polyvinyl chloride (PVC)

60. Copolymerization (Styrene Butadiene Rubber)

61. Copolymerization (Styrene Butadiene Rubber)
Double bonds will be in alternating positions
Styrene and butadiene will also alternate

62. Condensation Polymerization
As the polymer grows water is released as a product

63. Condensation Polymerization
Two types:
Polyester Formation
Dicarboxylic Acid + Dialcohol  Polyester+ Water
-OH is lost from acid, -H from alcohol to make H2O
Initiation: requires heat and strong acid
Termination: cool and neutralize
Polyamide Formation
Dicarboxylic Acid + Diamine  Polyamide + Water
-OH is lost from acid, -H from amine to make H2O
Initiation: heat above 100⁰C
Termination: cool below 100⁰C

64. Condensation Polymerization (Polyester)
Dicarboxylic Acid + Dialcohol Polyester + Water
Acid and heat are required for reaction
Termination is carried out by cooling and neutralizing

65. Condensation Polymerization (Polyester)

66. Condensation Polymerization (Polyester)

67. Condensation Polymerization (Polyamides)
“Nylon” is the common term used for polyamides
Dicarboxylic Acid + Diamine  Polyamide + Water
A temperature of greater than 100℃ is required
Termination is carried out by cooling below 100℃

68. Condensation Polymerization (Polyamides)

69. Condensation Polymerization (Polyamides)

70. Formation of Acetate Cellulose + Acetic Acid  Acetate
Cellulose is already a natural polymer, we alter it with acetic acid
Sulfuric acid and heat are needed to speed up reaction

71. Formation of Acetate

72. Formation of Rayon Cellulose + NaOH + CS2  Rayon
Cellulose is a naturally occurring polymer, in this case we alter it by adding sodium hydroxide and carbon disulfide

73. Formation of Rayon