Polymers (Year 2)

Question 1

Formation of POLYESTERS

Answer 1

• formed when MONOMERS are joined together
• by ESTER LINKAGES via CONDENSATION REACTIONS
• WATER molecules formed each time

Question 2

What are TWO ways polyesters can be formed?

What type of polymerisation is this?

Answer 2

METHOD 1 ~ react DIcarboxylic acid monomers with DIol monomers

METHOD 2 ~ React hydroxycarboxylic acid monomers with each other

Type of polymerisation ~ CONDENSATION

Question 3

Uses & Properties of Polyester fibres

Answer 3

USES:

• carpets
• sports clothing
• shirts

PROPERTIES:

• machine washable / dryable
• resistant to stretching & shrinking
• burns easily

Question 4

Forming AMIDE & POLYAMIDES

Answer 4

AMIDE FORMATION:
Carboxylic acid (or acid anhydride or acyl chloride) reacted with an AMINE

POLYAMIDE FORMATION:
Monomers are linked together by amide linkages (NHCO)

Type of polymerisation ~ CONDENSATION ~ water is eliminated

Question 5

What are the TWO ways POLYAMIDES can be formed?

Answer 5

METHOD 1 ~ react DIcarboxylic acid monomers with DIamine monomers

METHOD 2 ~ react amino acid monomers which contain BOTH a carboxylic acid & amino functional group

Question 6

BASE hydrolysis of POLYESTERS & POLYAMIDES

• Reagents & conditions
• products
• equation

Answer 6

REAGENTS & CONDITIONS:
- NaOH (aq)
- heat under reflux

PRODUCTS FOR POLYESTERS:
- dicarboxylate salt (COO-Na+)
- diol (OH)
Polyester n —- n dicarboxylate salt + n diol

PRODUCTS FOR POLYAMIDES:
- dicarboxylate salt
- diamine
Polyamide n — n dicarboxylate salt + n diamine

Question 7

ACID hydrolysis of POLYESTERS & POLYAMIDES

• Reagents & conditions
• products
• equation

Answer 7

REAGENTS & CONDITIONS:
- HCl(aq) or H2SO4(aq)
- heat under reflux

PRODUCTS FOR POLYESTERS:
- dicarboxylic acid
- diol
Polyester — n diol + n dicarboxylic acid

PRODUCTS FOR POLYAMIDES:
- Dicarboxylic acid
- Diammonium salt (NH3+)
Polyamide — n dicarboxylic acid + n diammonium salt

(SLOWER than base hydrolysis)

Question 8

Biodegradable polymers

Answer 8

• Breaks down completely to CO2 & H2O
• contains ESTER functional groups ~ HYDROLYSED

POLY(LACTIC ACID):
- lactic acid obtained from corn starch
- USES ~ bioplastics for disposable tableware, compost bags & food packaging

POLY(GLYCOLIC ACID):
- glycolic acid obtained from sugar cane & unripe grapes
- USES ~ surgical stitches

Question 9

Degradable Polymers

Answer 9

• break down into SMALL FRAGMENTS when exposed to one of :
• LIGHT
• HEAT
• MOISTURE
• only breaks down into CO2

Question 10

Photodegradable Polymers

Answer 10

• SYNTHETIC polymers
• Become WEAK & BRITTLE when exposed to PROLONGED SUNLIGHT

LIGHT SENSITIVE ADDITIVES ~ blended into polymer to catalyse break down in the presence of UV radiation

C=O GROUPS ~ incorporated into backbone, absorb light and fracture polymer chain

PHOTODEGRADABLE PLASTICS:
- initially break down into WAXY compounds
- then finally CO2 & H2O in the presence of BACTERIA

Question 11

Equations:

• MONO ester & amides
• POLY ester & amides

Answer 11

MONO:

REACTANTS:
- no ‘n’ in front of dicarboxylic acid, diol or diamine

PRODUCTS:
- no brackets
- no ‘n’
- H2O

POLY:

REACTANTS:
- ‘n’ in front

PRODUCTS:
- Brackets & n after
- (2n-1)H2O

Question 12

Making polyamides using acyl chlorides:

How will the equation differ?

Answer 12

• HCl is removed instead of H2O

(2n-1)HCl