A-Level Chemistry AQA Notes

3.3.12 Polymers (A-Level)

Polymers (A-Level)

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Condensation Polymers

Condensation polymerisation involves the reaction of two different types of monomers, with different functional groups.
Reacting dicarboxylic acids with diols forms polyesters

Adjacent polyester chains are held together by permanent dipole-dipole attractions due to the presence of the polar carbonyl group
The polyester terylene (PET) is formed from the monomers terephthalic acid and ethylene glycol. Typically used in plastic bottles, sails, sheets and clothing

Reacting dicarboxylic acids and diamines forms polyamides

Adjacent polyamide strands are held together by hydrogen bonds
Nylon is a polyamide used in textiles

Kevlar is a polyamide used in bullet and stab-proof vests

Polypeptides are also condensation polymers made up of amino acids

Disposal of Polymers

Polyalkenes are chemically inert and non-biodegradable due to the non-polar saturated C-C bonds.
Condensation polymers can undergo hydrolysis due to the polar C=O bonds which make them susceptible to attacks by nucleophiles. This makes them biodegradable.
Advantages and disadvantages of different methods of disposal

Advantages of Recycling	Disadvantages of Recycling
Saves diminishing crude oil resources Energy input to refining oil not needed Plastic does not end up in landfill	Plastic must be collected, cleaned, transported and sorted which is expensive and requires energy and time There are concerns about the quality of the products
Landfill A cheap and easy method Damaging to wildlife Uses up large areas of land Methane is released which contributes to global warming Leaks from landfill sites contaminate water supplies	Incineration The heat used in incineration can be used to generate electricity Increases the level of carbon dioxide in the atmosphere Incomplete combustion can lead to toxic carbon monoxide or unburnt carbon (soot) being released Other toxic gases, such as styrene and HCl, can be released