Cross-linker control of vitrimer flow. Issue 33 (22nd April 2020)

• Record Type: Journal Article
• Authors: El-Zaatari, Bassil M.; Ishibashi, Jacob S. A.; Kalow, Julia A.
• Is Part Of: Polymer chemistry. Volume 11:Issue 33(2020)
• Page Start: 5339
• Page End: 5345
• Publication Date: 2020-04-22
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/d0py00233j
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : The rate of stress relaxation in a vitrimer can be modulated by changing solely the structure of the cross-linker electrophile. 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.