Preferential Mechanochemical Activation of Short Chains in Bidisperse Triblock Elastomers.

Autor:	Huo Z; Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States., Watkins KF; Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States., Jeong BC; Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana-Champaign, Illinois 61801, United States., Statt A; Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana-Champaign, Illinois 61801, United States.; Department of Materials Science and Engineering, University of Illinois, Urbana-Champaign, Illinois 61801, United States., Laaser JE; Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
Jazyk:	angličtina
Zdroj:	ACS macro letters [ACS Macro Lett] 2023 Sep 19; Vol. 12 (9), pp. 1213-1217. Date of Electronic Publication: 2023 Aug 24.
DOI:	10.1021/acsmacrolett.3c00366
Abstrakt:	Polymer mechanochemistry offers attractive opportunities for using macroscopic forces to drive molecular-scale chemical transformations, but achieving efficient activation in bulk polymeric materials has remained challenging. Understanding how the structure and topology of polymer networks impact molecular-scale force distributions is critical for addressing this problem. Here we show that in block copolymer elastomers the molecular-scale force distributions and mechanochemical activation yields are strongly impacted by the molecular weight distribution of the polymers. We prepare bidisperse triblock copolymer elastomers with spiropyran mechanophores placed in either the short chains, the long chains, or both and show that the overall mechanochemical activation of the materials is dominated by the short chains. Molecular dynamics simulations reveal that this preferential activation occurs because pinning of the ends of the elastically effective midblocks to the glassy/rubbery interface forces early extension of the short chains. These results suggest that microphase segregation and network strand dispersity play a critical role in determining molecular-scale force distributions and suggest that selective placement of mechanophores in microphase-segregated polymers is a promising design strategy for efficient mechanochemical activation in bulk materials.
Databáze:	MEDLINE
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