Polymer tacticity is directly linked to the physical properties exhibited by synthetic materials. It has been widely shown that introducing even limited degrees of stereoregularity to otherwise atactic materials can have pronounced effects on their thermal, mechanical, and optical properties. In comparison to coordination polymerizations (e.g., ethylene, propylene, etc.), cationic polymerization methods typically display relatively low degrees of stereoinduction and result in materials with undesirable mechanical properties. In an effort to address these shortcomings, we have developed novel methodology to control the stereochemistry of cationic vinyl ether polymerizations using chiral anions. Inspired by recent advancements in asymmetric ion-pairing catalysis, we explored BINOL-based Brønsted acids as a tunable chiral scaffold for stereocontrolled cationic polymerization. Rational design of the catalyst structure through straightforward synthetic manipulations facilitated a systematic study on the effects of various functional groups on the stereoregularity of the polymers produced. Ultimately, a judicious combination of Brønsted and Lewis acids has enabled access to isotactic (&gt; 90% meso diads) poly(vinyl ether)s. This presentation will discuss the application of this methodology to multiple vinyl monomers, as well as the impact of isotacticity on the properties of the obtained materials.

Stereocontrolled cationic polymerization of vinyl ethers using BINOL-based counteranions

256th National Meeting (2018)

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