2.4.6 condensation polymers (HL)

chem modelsofbondingandstructure

Structure 2.4.6 - condensation polymers form by the reaction between functional groups in each monomer with the release of a small molecule

see 2.4.4 polymers
see 3.2.2 functional groups and classes of compounds

[A][H].[B]O[H]>>[A][B].[H]O[H]

monomers with 2 functional groups can be used to make condensation polymers, which can be thought of as “active ends” where condensation reactions can occur.

carboxylic acid + alcohol → polyester

when a monomer has two groups and the other monomer has two groups, an ester link forms. the chain extends in both directions and is known as a polyester.

reaction between benzene-1,4-dicarboxylic acid and ethane-1,2-diol

PET - polyethylene terephthalate

carboxylic acid + amine → polyamide

when a monomer has two groups and the other monomer has two groups, an amide link forms. the chain extends in both directions and is known as a polyamide.

1,6-diaminohexane and hexanedioic acid

6,6-nylon

hydrolysis

all biological macromolecules are condensation polymers synthesised in cells by condensation reactions

starch is produced by linking glucose into long chains.

the reverse reaction is known as hydrolysis

hydrolysis reactions occur during digestion, decomposition, and when stored materials need to be mobilised. condensation and hydrolysis reactions are controlled by enzymes (biological catalysts)