Monomers and Repeat Units :

The identity of the monomer residues (repeat units) comprising a polymer is its first and most important attribute. Polymer nomenclature is usually based upon the kind of monomer residues comprising the polymer. Polymers can keep only a single kind of repeat unit is known as homopolymers, while polymers containing a mixture of repeat units are well-known as copolymers. Poly (styrene), for example, is composed only of styrene monomer residues, and is therefore classified as a homopolymer. Ethylene-vinyl acetate, on the other hand, contains more than one variety of repeat units and is thus a copolymer. Some biological polymers are composed of a variety of different but structurally related monomer residues; for example, polynucleotides such as DNA are composed of a variety of nucleotide subunits.

Molecule of polymer containing ionizable subunits is well known as a polyelectrolyte or ionomer.