16 Jul 2012

Polypropylene Stereochemistry and Identification by 13C NMR Spectroscopy

Five Slides About

Submitted by Shirley Lin, United States Naval Academy

These 6 slides introduce the nomenclature used to describe the stereochemistry of various polypropylenes (PPs) that can be synthesized by metallocene-catalyzed polymerizations. Although PP is the specific polymer discussed, the nomenclature applies to other alpha-olefin polymerizations.

Learning Goals: 

Learning Goals: From viewing and learning the material on these slides, the audience should be able to

  • identify/draw isotactic, syndiotactic, and atactic PPs;
  • use the meso/racemo nomenclature to describe the relative stereochemistry of neighboring methyl groups on the polymer chain;
  • match structure to 13C NMR of the polymer and vice-versa.


Implementation Notes: 

These slides can be used as a stand-alone or in conjunction with materials about 1) the mechanistic steps in the catalytic cycle for metallocene-catalyzed propylene polymerizations and/or 2) how polymer stereochemistry is related to metallocene structure (Ewen’s symmetry rules).

Time Required: 
10-15 minutes
Evaluation Methods: 

A relatively straightforward transfer question was included at the end of the slide presentation. The question asks the audience to predict what the 13C NMR spectrum of an isotactic-atactic stereoblock polypropylene would look like. This question could also be used as a quiz/exam question.

Creative Commons License: 
Creative Commons Licence

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