Term: chain
https://doi.org/10.1351/goldbook.C00946

Definition:
The whole or part of a macromolecule, an oligomer molecule or a block, comprising a linear or branched sequence of constitutional units between two boundary constitutional units, each of which may be either an end-group, a branch point or an otherwise-designated characteristic feature of the macromolecule.

Notes:
0) Except in linear single-strand macromolecules, the definition of a chain may be somewhat arbitrary.
1) A cyclic macromolecule has no end groups but may nevertheless be regarded as a chain.
2) Any number of branch points may be present between the boundary units.
3) Where appropriate, definitions relating to 'macromolecule' may also be applied to 'chain'.

Related Terms:
1) macromolecule (http://doi.org/10.1351/goldbook.M03667).
2) oligomer molecule (http://doi.org/10.1351/goldbook.O04286).
3) block (http://doi.org/10.1351/goldbook.B00682).
4) sequence (http://doi.org/10.1351/goldbook.ST06775).
5) constitutional units (http://doi.org/10.1351/goldbook.C01288).
6) end-group (http://doi.org/10.1351/goldbook.E02092).
7) branch point (<em>in polymers</em>) (http://doi.org/10.1351/goldbook.B00728).

Source: PAC, 1996, 68, 2287. 'Glossary of basic terms in polymer science (IUPAC Recommendations 1996)' on page 2293 (https://doi.org/10.1351/pac199668122287)

Citation: 'chain' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.C00946

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