Issue 33, 2020

Cross-linker control of vitrimer flow

Abstract

Vitrimers are a class of covalent adaptable networks (CANs) that undergo topology reconfiguration via associative exchange reactions, enabling reprocessing at elevated temperatures. Here, we show that cross-linker reactivity represents an additional design parameter to tune stress relaxation rates in vitrimers. Guided by calculated activation barriers, we prepared a series of cross-linkers with varying reactivity for the conjugate addition—elimination of thiols in a PDMS vitrimer. Surprisingly, despite a wide range of stress relaxation rates, we observe that the flow activation energy of the bulk material is independent of the cross-linker structure. Superposition of storage and loss moduli from frequency sweeps can be performed for different cross-linkers, indicating the same exchange mechanism. We show that we can mix different cross-linkers in a single material in order to further modulate the stress relaxation behavior.

Graphical abstract: Cross-linker control of vitrimer flow

Supplementary files

Article information

Article type
Paper
Submitted
12 feb 2020
Accepted
02 apr 2020
First published
08 apr 2020

Polym. Chem., 2020,11, 5339-5345

Author version available

Cross-linker control of vitrimer flow

B. M. El-Zaatari, J. S. A. Ishibashi and J. A. Kalow, Polym. Chem., 2020, 11, 5339 DOI: 10.1039/D0PY00233J

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