Block Copolymer Sequence Inversion through Photoiniferter Polymerization

Easterling, Charles P.; Xia, Yening; Zhao, Junpeng; Fanucci, Gail E.; Sumerlin, Brent S.

doi:10.1021/acsmacrolett.9b00716

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Block Copolymer Sequence Inversion through Photoiniferter Polymerization

Easterling, Charles P.·Xia, Yening·Zhao, Junpeng·Fanucci, Gail E.·Sumerlin, Brent S.

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Abstract

Block copolymers prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization are often restricted to a specific comonomer blocking sequence that is dictated by intermediate radical stability and relative radical leaving group abilities. Techniques that provide alternative pathways for reinitiation of thiocarbonylthio-terminated polymers could allow access to block copolymer sequences currently unobtainable through the RAFT process. In this paper, we report a method for preparing “inverted” block copolymers, whereby the traditional order of monomer addition has been reversed through the use of photoiniferter-mediated radical polymerization. Specifically, thiocarbonylthio photolysis of xanthate- and dithiocarbamate-functional macromolecular chain transfer agents (macro-CTAs) led to the direct formation of leaving group macroradicals otherwise unaffordable by an addition–fragmentation mechanism. We believe this method could provide a route to synthesize multiblock copolymers of synthetically challenging comonomer sequences.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY Copolymerization Copolymers Organic compounds Photodissociation RAFT polymerization

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Easterling, Charles P., Xia, Yening, Zhao, Junpeng, Fanucci, Gail E., Sumerlin, Brent S.. 2019-10-15. Block Copolymer Sequence Inversion through Photoiniferter Polymerization. https://doi.org/10.1021/acsmacrolett.9b00716

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