Illustrated Glossary of Organic Chemistry

Copolymer: A polymer containing at least two different monomers.


Polyethylene terephthalate (PET) is a copolymer formed by copolymerization of two different monomers: terephthalic acid and ethylene glycol.


Polystyrene is formed from just one monomer (styrene), so polystyrene is not a copolymer.