Chapter 13: Further Polymers

A polymer is a substance possessing molecules consisting of repeated units (monomers). Polymers have a very large relative molecular mass.

Polymerization

During polymerization, an alkene undergoes an addition reaction with itself. A long hydrocarbon chain is formed.

Additional Polymers

Addition polymers are formed from alkenes. This is called addition polymerization.

 Poly (alkenes) like alkanes are unreactive due to the strong C-C and C-H bonds.

Condensation Polymers
Condensation polymerization 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.

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

  • Polypeptides are also condensation polymers made up of amino acids

Disposal of Polymers

Poly alkenes 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.

The alternative to dumping polymer wastes are more economical and more satisfactory.

  1. Incineration
  2. Recycling
  3. Photodegradable
  4. Dissolving Plastics
  5. Landfill 

Polyesters

It is a type of condensation polymer produced by the reaction of an alcohol group of one molecule and a carboxylic acid group of another molecule to produce a plastic containing ester group. –COOH-