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Connecting Molecular Exchange Dynamics to Stress Relaxation in Phase-Separated Dynamic Covalent Networks

Published

Author(s)

Neil Dolinski, Ran Tao, Nicholas Boynton, Anthony Kotula, Charlie Lindberg, Kyle Petersen, Aaron M. Forster, Stuart Rowan

Abstract

A suite of phase separated dynamic covalent networks based on highly tunable dynamic benzalcyanoacetate (BCA) thia-Michael acceptors are investigated. In situ kinetic studies on small molecule model systems are used in conjunction with macroscopic characterization of phase stability and stress relaxation to understand how the molecular dynamics relate to relaxation modes. Electronic modification of the BCA unit strongly impacts the exchange dynamics (particularly the rate of dissociation) and the overall equilibrium constant (Keq) of the system, with electron-withdrawing groups leading to decreased dissociation rate and increased Keq. Critically, below a chemistry-defined temperature cutoff (related to the stability of the hard phase domains), the stress relaxation behavior of these phase separated materials is dominated by the molecular exchange dynamics, allowing for networks with a tailored thermomechanical response.
Citation
ACS Macro Letters
Volume
13

Keywords

dynamic covalent chemistry, exchange kinetics, stress relaxation, phase separation

Citation

Dolinski, N. , Tao, R. , Boynton, N. , Kotula, A. , Lindberg, C. , Petersen, K. , Forster, A. and Rowan, S. (2024), Connecting Molecular Exchange Dynamics to Stress Relaxation in Phase-Separated Dynamic Covalent Networks, ACS Macro Letters, [online], https://doi.org/10.1021/acsmacrolett.3c00717, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956894 (Accessed March 1, 2024)
Created January 22, 2024, Updated January 24, 2024