OC02: polymers

Question 1

what are polymers?

Answer 1

polymers are macromolecules built from monomers with an average Mr of at least 1000 or at least 100 repeat units

Question 2

what polymer is this?

Answer 2

polymer: polyvinyl acetate

Question 3

what polymer is this?

Answer 3

polymer: polyvinyl chloride

Question 4

what polymer is this?

Answer 4

polymer: polytetrafluoroethylene

Question 5

what polymer is this?

Answer 5

polymer: polyvinyl alcohol

Question 6

what polymer is this?

Answer 6

polymer: polyacrylonitrile

Question 7

what polymer is this?

Answer 7

polymer: polystyrene

Question 8

what is polyester formed by?

Answer 8

1. benzene-1,4-dicarboxylic acid
2. ethane-1, 2-diol

Question 9

what is polyamide formed by?

Answer 9

1. hexanedioic acid
2. 1,6-hexanediamine

Question 10

why are polyamides more prone to creasing than polyester?

Answer 10

1. polyamides have strong hydrogen bonds between polymer chains while polyester have relatively weaker pd-pd FOA between polymer chains
2. during washing , the initial pd-pd interactions in polyester is broken, causing polymer chains to move to new positions
3. however when material dries these pd-pd FOA are not strong enough to hold them at new positions.
4. polyamide however, forms strong hydrogen bonds that are strong enough to hold them in new positions and cause creasing

Question 11

polyethene– HDPE vs LDPE

Answer 11

LDPE: polymer chains are highly branched, they cannot be packed together closely and regularly. they are more irregularly tangled together
- this arrangement results in empty spaces between polymer chains and smaller surface area of contact = id-id weaker

HDPE: polymer chains have minimal to no branching, they can arrange parallel to one another and packed closely together giving a more regular structure
- this regular arrangement results in less empty spaces and greater surface area between adjacent chains == strong id-id

Question 12

water-soluble vs water resistant (which polymers are..)

Answer 12

PVA (polyvinyl alcohol): is soluble
1. it formed hydrogen bonds between its chains
2. the -OH group in PVA allows hydrogen bonds to be formed between the polymer chains and H2O molecules
3. water trapped in polymer is used to relieve the eye dryness and soreness as it lubricates the surface of the eye

PVC (polyvinyl chloride): is water resistant
1. forms pd-pd between its chains
2. it is water resistant as there are relatively strong pd-pd FOA between its chains
3. polymer chains are closely packed and hence does not allow water to seep into the PVC material