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===Isotactic polymers===
Isotactic polymers are composed of isotactic macromolecules (IUPAC definition).<ref>[[IUPAC]] [http://www.iupac.org/reports/1996/6812jenkins/molecules.html macromolecular glossary] {{webarchive|url=https://web.archive.org/web/20080211121815/http://www.iupac.org/reports/1996/6812jenkins/molecules.html |date=2008-02-11 }}</ref> In isotactic macromolecules, all the substituents are located on the same side of the macromolecular backbone. An isotactic macromolecule consists of 100% {{nobr|m diads}}, though IUPAC also allows the term for macromolecules with at least 95% {{nobr|m diads}} if that looser usage is explained.<ref name="danrotp" /> [[Polypropylene]] formed by [[Ziegler–Natta catalyst|Ziegler–Natta catalysis]] is an example of an isotactic polymer.<ref>Stevens, P. S. Polymer Chemistry: An Introduction, 3rd ed.; Oxford Press: New York, 1999; pp 234–235</ref> Isotactic polymers are usually [[semicrystalline]]<ref name=":0" /> and generally (but not exclusively) crystallize in a helical configuration.<ref>{{Cite journal |last=Yashima |first=Eiji |last2=Maeda |first2=Katsuhiro |last3=Iida |first3=Hiroki |last4=Furusho |first4=Yoshio |last5=Nagai |first5=Kanji |date=2009-11-11 |title=Helical Polymers: Synthesis, Structures, and Functions |url=https://doi.org/10.1021/cr900162q |journal=Chemical Reviews |volume=109 |issue=11 |pages=6102–6211 |doi=10.1021/cr900162q |issn=0009-2665|url-access=subscription }}</ref><ref>{{Cite journal |last=Auriemma |first=Finizia |last2=De Rosa |first2=Claudio |last3=Corradini |first3=Paolo |date=2004 |title=Non-Helical Chain Conformations of Isotactic Polymers in the Crystalline State |url=https://onlinelibrary.wiley.com/doi/abs/10.1002/macp.200300126 |journal=Macromolecular Chemistry and Physics |language=en |volume=205 |issue=3 |pages=390–396 |doi=10.1002/macp.200300126 |issn=1521-3935|url-access=subscription }}</ref> 

:[[File:Isotactic-A-2D-skeletal.png|400px|isotactic polymers]]
:[[File:Isotactic-polypropylene-3D-balls.png|400px|isotactic polypropylene]]