Polymers

Question 1

polymers

Answer 1

large molecules built by repetitive linking of smaller units called monomers
- natural polymers e.g., carbohydrates and proteins
- synthetic polymers e.g., plastics

Question 2

Polymer properties

Answer 2

• Density
• Melting point
• Flexibility
• Stability (height, light, chemicals)
• strength
• weight

Question 3

Addition polymerisation

Answer 3

• monomers are added together using the electrons from the double bond
• all atoms present in the monomers are present in the polymer

Example:
Polyethylene, polypro pane, polytetrafluoroethene

Question 4

Chain length

Answer 4

The length of polymers allows them to have substantial dispersion forces and therefore high melting points.

Question 5

Extent of branching

Answer 5

• if poler forms long chains with very few, short branches they can pack closely together - high density. Leads to an orderly crystalline arrangement making it tough with a high melting point.
• If polymer has a lot of branching they cannot align themselves as well - low density. The structure is non-crystalline making it more flexible, soft and low melting point.

Question 6

Arrangement of side groups

Answer 6

• the way side groups arrange along a polymer chain can impact properties
  –> isotactic - all the side groups on one side of the chain
  –> atactic - side groups randomly distributed
  –> syntactic - side groups alternate

Question 7

Condensation polymerisation

Answer 7

• monomers with functional groups react with each other
• small molecule (e.g., water) is eliminated
  See class notes for examples