Entropy‐Driven Selectivity for Chain Scission: Where Macromolecules Cleave |
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| Authors: | Kai Pahnke Josef Brandt Dr Ganna Gryn'ova Dr Ching Y Lin Dr Ozcan Altintas Dr Friedrich G Schmidt Dr Albena Lederer Prof Michelle L Coote Prof Christopher Barner‐Kowollik |
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| Institution: | 1. Preparative Macromolecular Chemistry, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany;2. Institut für Biologische Grenzfl?chen, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany;3. Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany;4. Technische Universit?t Dresden, Dresden, Germany;5. ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University (ANU), Canberra, ACT, Australia;6. Ecole polytechnique fédérale de Lausanne, Switzerland;7. Evonik Industries AG, Marl, Germany |
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| 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. |
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| Keywords: | cycloadditions entropic effects polymers supramolecular chemistry thermodynamics |
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