Entropy-Driven Selectivity for Chain Scission: Where Macromolecules Cleave

Kai Pahnke, Josef Brandt, Ganna Gryn'ova, Ching Y. Lin, Ozcan Altintas, Friedrich G. Schmidt, Albena Lederer, Michelle L. Coote, Christopher Barner-Kowollik

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

We show that, all other conditions being equal, bond cleavage in the middle of molecules is entropically much more favored than bond cleavage at the end. Multiple experimental and theoretical approaches have been used to study the selectivity for bond cleavage or dissociation in the middle versus the end of both covalent and supramolecular adducts and the extensive implications for other fields of chemistry including, e.g., chain transfer, polymer degradation, and control agent addition are discussed. The observed effects, which are a consequence of the underlying entropic factors, were predicted on the basis of simple theoretical models and demonstrated via high-temperature (HT) NMR spectroscopy of self-assembled supramolecular diblock systems as well as temperature-dependent size-exclusion chromatography (TD SEC) of covalently bonded Diels-Alder step-growth polymers.

Original languageEnglish (US)
Pages (from-to)1514-1518
Number of pages5
JournalAngewandte Chemie - International Edition
Volume55
Issue number4
DOIs
StatePublished - Jan 22 2016

Bibliographical note

Funding Information:
C.B.-K., M.L.C., and A.L. are grateful for continued support from and the excellent collaboration with Evonik Industries. C.B.-K. additionally acknowledges funding from the KIT via the Helmholtz association (BIFTM and STN programs) as well as the German Research Council (DFG). M.L.C. acknowledges generous allocations of supercomputing time on the National Facility of the National Computational Infrastructure and an Australian Research Council Future Fellowship.

Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Keywords

  • cycloadditions
  • entropic effects
  • polymers
  • supramolecular chemistry
  • thermodynamics

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