Covalent Adaptable Networks with Tunable Exchange Rates Based on Reversible Thiol–yne Cross‐Linking

The design of covalent adaptable networks (CANs) relies on the ability to trigger the rearrangement of bonds within a polymer network. Simple activated alkynes are now used as versatile reversible cross‐linkers for thiols. The click‐like thiol–yne cross‐linking reaction readily enables network synth...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2020-02, Vol.59 (9), p.3609-3617
Main Authors: Van Herck, Niels, Maes, Diederick, Unal, Kamil, Guerre, Marc, Winne, Johan M., Du Prez, Filip E.
Format: Article
Language:English
Subjects:
Alkynes
Chemical Sciences
Chemical synthesis
covalent adaptable networks
Creep (materials)
cross-linking
Foreign exchange rates
Linkages
Michael addition
Network synthesis
Polymers
Stress relaxation
thioacetals
Thiols
thiol–yne
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Summary:The design of covalent adaptable networks (CANs) relies on the ability to trigger the rearrangement of bonds within a polymer network. Simple activated alkynes are now used as versatile reversible cross‐linkers for thiols. The click‐like thiol–yne cross‐linking reaction readily enables network synthesis from polythiols through a double Michael addition with a reversible and tunable second addition step. The resulting thioacetal cross‐linking moieties are robust but dynamic linkages. A series of different activated alkynes have been synthesized and systematically probed for their ability to produce dynamic thioacetal linkages, both in kinetic studies of small molecule models, as well as in stress relaxation and creep measurements on thiol–yne‐based CANs. The results are further rationalized by DFT calculations, showing that the bond exchange rates can be significantly influenced by the choice of the activated alkyne cross‐linker. Controlling reactivity: Reversible thiol–yne cross‐linking is enabled via the double Michael addition of thiols on activated alkynes. The rate of dynamic thiol exchange is manipulated by means of electronic substituents on the activated alkyne, offering a new versatile dynamic platform for the development of covalent adaptable networks.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201912902