Conformational Entropy as a Means to Control the Behavior of Poly(diketoenamine) Vitrimers In and Out of Equilibrium

Control of equilibrium and non‐equilibrium thermomechanical behavior of poly(diketoenamine) vitrimers is shown by incorporating linear polymer segments varying in molecular weight (MW) and conformational degrees of freedom into the dynamic covalent network. While increasing MW of linear segments yie...

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Bibliographic Details
Published inAngewandte Chemie Vol. 132; no. 2; pp. 745 - 749
Main Authors He, Changfei, Christensen, Peter R., Seguin, Trevor J., Dailing, Eric A., Wood, Brandon M., Walde, Rebecca K., Persson, Kristin A., Russell, Thomas P., Helms, Brett A.
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 07.01.2020
Subjects
Chemistry
Entropy
Equilibrium
Freezing
Konformationsentropie
Mechanische Eigenschaften
Molecular weight
Network topologies
Poly(diketoenamine)
Polymers
Rheologie
Rubbery plateau modulus
Segments
Storage modulus
Stress relaxation
Thermomechanical properties
Topology
Vitrimere
Vitrimers
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Summary:Control of equilibrium and non‐equilibrium thermomechanical behavior of poly(diketoenamine) vitrimers is shown by incorporating linear polymer segments varying in molecular weight (MW) and conformational degrees of freedom into the dynamic covalent network. While increasing MW of linear segments yields a lower storage modulus at the rubbery plateau after softening above the glass transition (Tg), both Tg and the characteristic time of stress relaxation are independently governed by the conformational entropy of the embodied linear segments. Activation energies for bond exchange in the solid state are lower for networks incorporating flexible chains; the network topology freezing temperature decreases with increasing MW of flexible linear segments but increases with increasing MW of stiff segments. Vitrimer reconfigurability is therefore influenced not only by the energetics of bond exchange for a given network density, but also the entropy of polymer chains within the network. Entropisches Klima: Mikrostrukturelle und Architektur‐Attribute von Vitrimeren sind leistungsfähige Gestaltungselemente für die Kontrolle ihrer mechanischen und rheologischen Eigenschaften. Die Konformationsentropie ihrer Monomersegmente dominiert anscheinend diese Eigenschaften in ähnlich aufgebauten Vitrimer‐Netzwerken.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201912223