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: 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.
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).
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.