Condensation Polymers (Chapter 27.3)

Question 1

What are two important condensation polymers?

Answer 1

Polyesters and polyamides

Question 2

What are common starting materials of condensation polymers?

Answer 2

Carboxylic acids and their derivatives

Question 3

What is condensation polymerisation?

Answer 3

The joining of monomers with the loss of a small molecule, usually H2O or HCl

Question 4

What is needed for condensation polymerisation?

Answer 4

Two different functional groups

Question 5

Describe the formation of a polyester

Answer 5

• When making a polyester, monomers are joined together by ester linkages in a long chain to form the polymer
• Polyesters can be made from one monomer containing both a carboxylic acid and an alcohol group or from two monomers (one with 2 COOH groups and one with 2 OH groups)

Question 6

What is an example of a polyester made from one monomer?

Answer 6

• Poly(glycolic acid) (PGA)

- Glycolic acid: OHCHCOOH

Question 7

What is an example of polyester made from two monomers?

Answer 7

• Terylene made from one diol (ethane-1,2-diol) and one dicarboxylic acid (benzene-1,4-carboxylic acid)

Question 8

Describe the formation of a polyamides

Answer 8

• They are formed when monomers are joined together by amide linkages in a long chain to form the polymer
• They can be made from one monomer containing both a carboxylic acid/acyl chloride and an NH2 group or from two monomers (one with two COOH/COCl groups and one with two NH2 groups)

Question 9

What is an example of a polyamide from one monomer

Answer 9

• Amino acids (monomers with NH2 and COOH groups) undergo condensation polymerisation to form polypeptides/proteins

Question 10

What is an example of a polyamide from two monomers?

Answer 10

• Nylon is formed from one diamine (1,6-diaminohexane) and one dicarboxylic acid (hexanedioic acid) or one diacyl chloride (hexanedioyl chloride)

Question 11

What is the by-product of condensation polymerisation if an acyl chloride is used?

Answer 11

HCl

Question 12

How can polyesters and polyamides (condensation polymers) be hydrolysed?

Answer 12

Using hot aqueous alkali e.g. NaOH or acid e.g. HCl

Question 13

What are the products of the acidic hydrolysis of polyesters?

Answer 13

Dicarboxylic acid and diol

Question 14

What are the products of the alkali hydrolysis of polyesters?

Answer 14

Diol and dicarboxylate salt+Na+

Question 15

What are the products of the acidic hydrolysis of polyamides?

Answer 15

Dicarboxylic acid and diammonium salts (NH3+ on the end)

Question 16

What are the products of the alkali hydrolysis of polyamides?

Answer 16

Diamine and dicarboxylate salt+Na+

Question 17

What are the differences between addition polymerisation (2) and condensation polymerisation (3)?

Answer 17

Addition polymerisation:
1) monomer has C=C double bond
2) the backbone of the polymer is a continuous chain of carbon atoms
Condensation polymerisation:
1) two monomers, each with two of the same functional group/one monomer with two different functional groups
2) the polymer contains ester or amide linkages

Question 18

What is Kevlar formed from and why is it strong?

Answer 18

• It is formed from benzene-1,4-dicarboxylic acid and benzene-1,4-diamine
• It is strong due to the increase intermolecular forces between the aromatic rings as they are planar - ∴ there are stronger hydrogen bonds as the electron density of the two rings can overlap

Question 19

Why are condensation polymers more biodegradable than addition polymers?

Answer 19

• The ester bond in condensation polymers can be hydrolysed by microorganisms in soil and can absorb UV radiation so is photodegradable
• Addition polymers have a fully saturated alkane backbone which is very unreactive