Alkenes: Addition Polymers

Question 1

What are polymers?

Answer 1

• A polymer is formed when many repeating units made from monomers join together to form a long chain molecule

Question 2

How are addition polymers formed?

Answer 2

• Double bonds in alkenes can open up and join together to make polymers
• Addition polymerisation

Question 3

How do you draw the monomer?

Answer 3

• Draw the alkene

- Put n

Question 4

How do you draw the polymer?

Answer 4

• Draw ‘alkane’ form of alkene
• Instead of C=C, it has C-C and extended bonds reaching out sideways across a bracket
• Put n

Question 5

How do you draw the repeating unit?

Answer 5

• Draw the polymer but without the brackets or the n

Question 6

What other types of alkenes can act as monomers in addition polymerisation?

Answer 6

• Substituted alkenes

- Where one of the hydrogen atoms has been swapped for another atom or group

Question 7

What is a repeating unit?

Answer 7

• The part of a polymer whose repetition would produce the complete polymer chain

Question 8

What are the IUPAC rules for naming addition polymers?

Answer 8

• Find monomer
• Put poly in front of monomer
• If monomer contains numbers, put monomer in brackets
• E.g poly(but-2-ene) and polypropene

Question 9

How has understanding of production and properties of polymers developed over time?

Answer 9

• People have used natural polymers to make fabrics, jewellery etc. for many years
• During 19th century, researches managed to make synthetic polymers - artificial silk and hard rubber
• More developments made in 20th century - nylon and Kevlar
• Developments still being made - research for cheaper materials or better performing materials

Question 10

Why are polymers unreactive?

Answer 10

• They are saturated and usually non-polar
• So don’t attract electrophiles
• In order for them to react you also have to break strong C‒C covalent bonds

Question 11

Describe the intermolecular forces in addition polymers

Answer 11

• The forces between the polymer chains are usually weak intermolecular forces
• E.g van der Waals forces or permanent dipole-dipole forces

Question 12

How will increasing the branching in the polymer structure affect the strength of the intermolecular forces between polymer chains?

Answer 12

• Increased branching means the polymer chains have fewer points of contact (cannot pack as close together)
• Therefore weaker van der Waals forces

Question 13

What is poly(chloroethene)?

Answer 13

• Aka polyvinyl chloride, or PVC

- Addition polymer formed from chloroethene monomers

Question 14

What intermolecular forces does PVC have and how does it affect its properties?

Answer 14

• van der Waals forces
• Permanent dipole-dipole from polar C-Cl bond
• Makes PVC hard and brittle

Question 15

Name some uses for PVC

Answer 15

• Drainpipes
• Vinyl
• Window frames

Question 16

What is a plasticiser?

Answer 16

• Chemicals that make polymers bendier
• The plasticiser molecules get between polymer chains and push them apart
• Reduces strength of intermolecular forces so chains can slide around more, making them more flexible

Question 17

How is plasticised PVC different to uPVC (unplasticised PVC)?

Answer 17

• Plasticised PVC is much more flexible

- Used to make electrical cable insulation, flooring tiles and clothing

Question 18

What is a monomer?

Answer 18

• A small molecule which can join together with other monomers to form a polymer