page_title: Tacticity
section_title: Describing tacticity
hierarchical_section_title: Tacticity / Describing tacticity
caption_attribution_description: English: Meso diad for tacticity article.
context_page_description: Tacticity is the relative stereochemistry of adjacent chiral centers within a macromolecule. The practical significance of tacticity rests on the effects on the physical properties of the polymer. The regularity of the macromolecular structure influences the degree to which it has rigid, crystalline long range order or flexible, amorphous long range disorder. Precise knowledge of tacticity of a polymer also helps understanding at what temperature a polymer melts, how soluble it is in a solvent and its mechanical properties.
  A tactic macromolecule in the IUPAC definition is a macromolecule in which essentially all the configurational units are identical. Tacticity is particularly significant in vinyl polymers of the type -H₂C-CH- where each repeating unit with a substituent R on one side of the polymer backbone is followed by the next repeating unit with the substituent on the same side as the previous one, the other side as the previous one or positioned randomly with respect to the previous one.
caption: An example of meso diads in a polypropylene molecule.
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