End groups are an important aspect of
polymer synthesis and characterization. In
polymer chemistry, end groups are functionalities or constitutional units that are at the extremity of a macromolecule or oligomer (
IUPAC). In polymer synthesis, like
condensation polymerization and
free-radical types of polymerization, end-groups are commonly used and can be analyzed for example by nuclear magnetic resonance (
NMR) to determine the average length of the polymer. Other methods for characterization of polymers where end-groups are used are
mass spectrometry and vibrational spectrometry, like
infrared and
Raman spectrometry. Not only are these groups important for the analysis of the polymer, but they are also useful for grafting to and from a polymer chain to create a new
copolymer. One example of an end group is in the polymer poly(ethylene glycol) diacrylate where the end-groups are circled.