Copolymer

The term copolymer refers to a polymer that consists of more than one type of monomer ("structural units"). Meaning when one considers the chemical structure of a copolymer, there are two patterns that are repeated instead of one (as this is the case for example with Polyester PET, Polyoxadiazole POD or Acetate CA). 

A copolymer thus very roughly exists out of two polymers or more. Perflouroalkoxy PFA for example exists of the two polymers tetraflouroethylene TFE and perflouroether.

Copolymers can be built in various patterns. The monomers can alternate, repeat periodically, be in blocks or then be grafted.