Definitions and notations relating to tactic polymers (IUPAC Recommendations 2020)

This document summarizes and extends definitions and notations for the description of tactic polymers and the diad structures of which they are composed. It formally recognizes and resolves apparent inconsistencies between terminology used in the polymer field to describe tactic polymers and terminology in more common use in organic chemistry. Specifically, the terms m and r diads are recommended to replace the terms meso and racemo diads. The definitions are also updated from those in the existing Stereochemistry Document to use the term 'stereogenic centre', rather than 'chiral or prochiral atoms'. Further, the terms relating to tacticity have been defined for the constituent macromolecules, rather than for the polymers composed of those macromolecules. Therefore, this document also forms an addendum and corrigendum to the 1981 document, `Stereochemical definitions and notations relating to polymers'.