Talk:Structural unit

Similarity to repeat unit

This page appears to cover the same concept as repeat unit. Unless someone can establish that there is an actual difference between these two pages, the should probably be merged.

Locke9k (talk) 21:33, 2 June 2008 (UTC)Locke9k

The two concepts are not always identical. This can be seen for the polyester example in this article, for which the repeat unit is uniquely defined as -O-CH₂-CH₂-O-CO-Ph-CO-, as its repetition leads to the structure of the polymer. However this is usually considered as TWO structural units -O-CH₂-CH₂-O- and -CO-Ph-CO-, because the macromolecule is normally synthesized from diol and diacid monomers (or in practice their derivatives). The repeat unit is therefore a more fundamental concept when it exists, because it is uniquely defined and does not depend on the assumed method of synthesis.

However a repeat unit does not always exist, as in a random copolymer. For protein polypeptide chains, there can be as many as 20 different amino acid structural units, and no repeat unit.

As for the suggested merge, it is true that the two articles are related and that both articles are quite short. So I suggest merging into one article named Repeat unit, but with both examples and counterexamples of the identity of Repeat unit to Structural unit. Dirac66 (talk) 23:02, 2 June 2008 (UTC)