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

Area of Science:

• Materials Science
• Polymer Chemistry
• Supramolecular Chemistry

Background:

• Dynamic covalent networks (DCNs) offer adaptive and self-healing properties.
• Benzalcyanoacetate (BCA) thia-Michael acceptors provide a tunable platform for DCNs.
• Understanding structure-property relationships in DCNs is crucial for advanced materials.

Purpose of the Study:

• To investigate phase-separated dynamic covalent networks based on BCA thia-Michael acceptors.
• To correlate molecular dynamics with macroscopic relaxation modes.
• To explore the impact of electronic modifications on network behavior and thermomechanical response.

Main Methods:

• In situ kinetic studies on small molecule model systems.
• Macroscopic characterization of phase stability and stress relaxation.
• Synthesis and electronic modification of benzalcyanoacetate (BCA) units.

Main Results:

• Electronic modification of BCA units significantly impacts exchange dynamics, specifically dissociation rates and equilibrium constants.
• Electron-withdrawing groups decrease dissociation rates and increase equilibrium constants.
• Below a critical temperature, stress relaxation is governed by molecular exchange dynamics.

Conclusions:

• Phase-separated DCNs based on BCA acceptors exhibit tunable thermomechanical properties.
• Molecular exchange dynamics are key to controlling stress relaxation in these networks.
• The findings enable the design of materials with predictable and tailored responses.