Monomer Definition and Examples

The Building Block of Polymers

Polyvinyl chloride (PVC)
Polyvinyl chloride (PVC) is a polymer consisting of linked vinyl chloride monomer subunits. LAGUNA DESIGN, Getty Images

A monomer is a molecule that forms the basic unit for polymers, which are the building blocks of proteins. Monomers bind to other monomers to form repeating chain molecules through a process known as polymerization. Monomers may be either natural or synthetic in origin.

Oligomers are polymers consisting of a small number (typically under 100) of monomer subunits. Monomeric proteins are protein molecules that combine to form multi-protein complexes. Biopolymers are polymers consisting of organic monomers found in living organisms.

Because monomers represent a huge class of molecules, they are commonly categorized into various subgroups such as sugars, alcohols, amines, acrylics, and epoxides.

The term "monomer" combines the prefix mono-, which means "one," and the suffix -mer, which means "part."

Examples of Monomers

Glucose, vinyl chloride, amino acids, and ethylene are examples of monomers. Each monomer may link in different ways to form a variety of polymers. In the case of glucose, for example, glycosidic bonds may link sugar monomers to form such polymers as glycogen, starch, and cellulose.

Names for Small Monomers

When only a few monomers combine to form a polymer, the compounds have names:

  • Dimer: Polymer consisting of two monomers
  • Trimer: Three monomer units
  • Tetramer: Four monomer units
  • Pentamer: Five monomer units
  • Hexamer: Six monomer units
  • Heptamer: Seven monomer units
  • Octamer: Eight monomer units
  • Nonamer: Nine monomer units
  • Decamer: 10 monomer units
  • Dodecamer: 12 monomer units
  • Eicosamer: 20 monomer units