Repeat unit

A repeat unit or repeating unit (or mer) is a part of a polymer whose repetition would produce the complete polymer chain (except for the end-groups) by linking the repeat units together successively along the chain, like the beads of a necklace.[1] [2]

IUPAC definitions

constitutional unit: An atom or group of atoms (with pendant atoms or groups, if any) comprising a part of the essential structure of a macromolecule, an oligomer molecule, a block or a chain.[3]
constitutional repeating unit: The smallest constitutional unit the repetition of which constitutes a regular macromolecule, a regular oligomer molecule, a regular block or a regular chain.[4]

A repeat unit is sometimes called a mer (or mer unit) in polymer chemistry. "Mer" originates from the Greek word meros, which means "a part". The word polymer derives its meaning from this, which means "many mers". A repeat unit (mer) is not to be confused with the term monomer, which refers to the small molecule from which a polymer is synthesized.[5]

  1. ^ Rudin A. "Elements of Polymer Science and Engineering" (Academic Press 1982) p.3 ISBN 0-12-601680-1
  2. ^ "2.2 Chain repeat units". Introduction to Polymers. The Open University (GB). Retrieved 31 July 2019.
  3. ^ "constitutional unit". Gold Book. IUPAC. doi:10.1351/goldbook.C01288. Retrieved 1 April 2024.
  4. ^ "constitutional repeating unit". Gold Book. IUPAC. doi:10.1351/goldbook.C01286. Retrieved 1 April 2024.
  5. ^ Callister, William D. (2007). Materials science and engineering : an introduction (7th ed.) New York : John Wiley & Sons. ISBN 978-0-471-73696-7

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