Degrees of triad isotacticity, syndiotacticity, and heterotacticity

{
  "id": "MLC-T-CHM-002957",
  "term": "Degrees of triad isotacticity, syndiotacticity, and heterotacticity",
  "field": "Chemistry",
  "definition": "The mole fractions of isotactic, syndiotactic, and heterotactic triads within a polymer chain. An isotactic triad (mm) consists of two adjacent meso diads, a syndiotactic triad (rr) has two adjacent racemic diads, and a heterotactic triad (mr) contains one meso and one racemic diad. These values are determined experimentally using nuclear magnetic resonance (NMR) spectroscopy, and their sum is always equal to unity.",
  "subject": "Polymer",
  "see_also": [
    "meso",
    "polymer",
    "racemic",
    "constitutional sequence"
  ],
  "references": [
    "Purple Book, 1st ed., p. 45 (http://old.iupac.org/publications/books/author/metanomski.html)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/degrees-of-triad-isotacticity-syndiotacticity-and-heterotacticity/"
}