Branching Regulation in Olefin Polymerization via Lewis Acid Triggered Isomerization of Monomers

We present a new strategy to regulate branching in chain‐walking olefin polymerization by triggering a rapid isomerization of 1‐alkene monomers into internal olefins by adding a Lewis acid. Polymerization of internal alkenes proceeds via chain‐walking to give polymers with much higher branching than...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2020-03, Vol.59 (12), p.4743-4749
Main Authors: Basbug Alhan, Hatice E., Jones, Glen R., Harth, Eva
Format: Article
Language:English
Subjects:
Acids
Adducts
Alkenes
Block copolymers
Branching
Chain branching
chain-walking
Chains (polymeric)
Chemical synthesis
Coordination
Isomerization
Lewis acid
Lewis acids
Monomers
olefins
Polymerization
Polymers
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Summary:We present a new strategy to regulate branching in chain‐walking olefin polymerization by triggering a rapid isomerization of 1‐alkene monomers into internal olefins by adding a Lewis acid. Polymerization of internal alkenes proceeds via chain‐walking to give polymers with much higher branching than 1‐alkene analogues. The utility of this approach is exemplified by synthesis of well‐defined block copolymers with distinct branching characteristics per block by addition of Lewis acid midway through a reaction. We propose a novel mechanism whereby Lewis acid undergoes a counterion swap with the complex which favors isomerization as well as forming adducts with ancillary ligands, freeing coordination sites for internal alkene coordination polymerization. Branch manager: Addition of AlCl3 to a Pd‐mediated chain‐walking polymerization results in rapid isomerization of 1‐alkenes to internal alkenes which polymerize with high branching. Block copolymers can be prepared by adding AlCl3 midway through the reaction.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201914742