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Chain‐Growth Polymerization of Aryl Grignards Initiated by a Stabilized NHC‐Pd Precatalyst
Author(s) -
Bryan Zachary J.,
Smith Mitchell L.,
McNeil Anne J.
Publication year - 2012
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201200096
Subject(s) - monomer , polymer chemistry , polymerization , living polymerization , chemistry , chain growth polymerization , phenylene , catalysis , thiophene , materials science , polymer , organic chemistry , radical polymerization
An N‐heterocyclic carbene‐ligated palladium catalyst was discovered to mediate living, chain‐growth polymerizations of both phenylene‐ and thiophene‐based monomers. Polymerization of a fluorene‐based monomer, on the other hand, did not proceed through a living, chain‐growth pathway. Excitingly, block copolymerizations of phenylene and thiophene proceeded via a chain‐growth pathway, regardless of the order of monomer addition. Although some chain termination was observed during these copolymerizations, this pathway could be minimized when the second monomer was added shortly after consumption of the first monomer. These results suggest that the catalyst resting‐state at the end of polymerization is unstable. As a result, modifications to the NHC‐scaffold or the 3‐chloropyridine ligand will be necessary to generate an improved catalyst.