Term: degrees of triad isotacticity, syndiotacticity, and heterotacticity
https://doi.org/10.1351/goldbook.D01573

Definition:
The fractions of triads in a regular vinyl polymer that are of the mm, rr and mr = rm types, respectively. In cases where triad analysis is not attainable, the diad isotacticity and diad syndiotacticity may be defined as the fractions of diads in a regular vinyl polymer that are of the m and r types, respectively. (m = meso; r = racemic).

Related Terms:
1) triads (<em>in polymers</em>) (http://doi.org/10.1351/goldbook.C01287-1).
2) polymer (<em>in polymers</em>) (http://doi.org/10.1351/goldbook.P04735).
3) diads (<em>in polymers</em>) (<em>in polymers</em>) (http://doi.org/10.1351/goldbook.C01287-2).
4) meso (<em>in polymers</em>) (http://doi.org/10.1351/goldbook.M03838).
5) racemic (<em>in polymers</em>) (http://doi.org/10.1351/goldbook.R05026).

Source: Purple Book, 1st ed., p. 45 (http://old.iupac.org/publications/books/author/metanomski.html)

Citation: 'degrees of triad isotacticity, syndiotacticity, and heterotacticity' 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.D01573

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