{"term":{"id":"01573","title":"degrees of triad isotacticity, syndiotacticity, and heterotacticity","longtitle":"IUPAC Gold Book - degrees of triad isotacticity, syndiotacticity, and heterotacticity","doi":"10.1351\/goldbook.D01573","code":"D01573","status":"current","definitions":[{"id":1,"text":"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).","links":[{"term":"meso","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/M03838"},{"term":"polymer","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/P04735"},{"term":"racemic","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/R05026"},{"term":"triads","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/C01287"}],"sources":["Purple Book, 1st ed., p. 45 (http:\/\/old.iupac.org\/publications\/books\/author\/metanomski.html)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/D01573\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/D01573\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/D01573\/plain"},"citation":"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. 10.1351\/goldbook.D01573","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2026-05-12T16:22:47+00:00"}}