Linking Molecular Behavior to Macroscopic Properties in Ideal Dynamic Covalent Networks

Dynamic covalent networks (DCvNs) are increasingly used as advanced materials with applications ranging from recyclable thermosets to self-healing hydrogels. However, the relationship between the chemistry at the junctions of DCvNs and their macroscopic properties is poorly understood. Here, we present a framework to predict how complex network behavior in DCvNs emerges from the chemical landscape of the dynamic chemistry at the junction [1]. Ideal boronic ester-based hydrogels were used as model DCvNs. We systematically explored the effect of the chemical environment on network behavior, as the complex properties of boronic ester-based DCvNs are regulated by pH and temperature [2]. We developed physical models that describe how viscoelasticity is linked to the molecular behavior of the dynamic junction, quantified via fluorescence and NMR spectroscopy and DFT calculations. Additionally, shear rheometry was used to quantify the kinetics and thermodynamics of network rearrangements, enabling a mechanistic understanding of the junction. These findings, grounded in molecular principles, advance our understanding and rational design of dynamic polymer networks.

[1] Marco-Dufort et al., J. Am. Chem. Soc. 2020, 142, 15371.
[2] Marco-Dufort et al., Mater. Today Chem., 2019, 12, 16.