IUPAC definition

Pendant group
An offshoot, neither oligomeric nor polymeric, from a chain.[1]

In IUPAC nomenclature of chemistry, a pendant group (sometimes spelled pendent) or side group is a group of atoms attached to a backbone chain of a long molecule, usually a polymer. Pendant groups are different from pendant chains, as they are neither oligomeric nor polymeric.[2]

For example, the phenyl groups are the pendant groups on a polystyrene chain.

Large, bulky pendant groups such as adamantyl usually raise the glass transition temperature (Tg) of a polymer by preventing the chains from sliding past each other easily. Short alkyl pendant groups may lower the Tg by a lubricant effect.


  1. ^ Jenkins, A. D.; Kratochvíl, P.; Stepto, R. F. T.; Suter, U. W. (1996). "Glossary of basic terms in polymer science (IUPAC Recommendations 1996)". Pure and Applied Chemistry. 68 (12): 2287–2311. doi:10.1351/pac199668122287.
  2. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "pendant group (side group)". doi:10.1351/goldbook.P04472