Decoupling dynamics and crosslink stability in supramolecular hydrogels using associative exchange

TL;DR

This paper introduces a method to decouple network relaxation from crosslink stability in DNA-based supramolecular hydrogels, enabling tunable dynamics without sacrificing mechanical strength.

Contribution

It demonstrates that associative exchange reactions can independently control hydrogel relaxation timescales while maintaining mechanical integrity.

Findings

Tunable relaxation times over three orders of magnitude.

Associative exchange preserves rupture strength and thermal stability.

Dissociative systems trade dynamics for mechanical weakening.

Abstract

The design of hydrogels that combine mechanical robustness with dynamic reconfigurability remains a fundamental challenge, as increasing crosslink dissociation rates compromise network integrity. This limitation is addressed through the incorporation of an associative crosslink exchange into DNA-based supramolecular hydrogels, enabling the decoupling of network relaxation behavior from crosslink stability. The hydrogels are constructed from enzyme-synthesized single-stranded DNA that self-assembles via hybridization between complementary domains. These crosslinks can reorganize through dissociative melting or associative strand displacement reaction, yielding networks with tunable relaxation timescales spanning over three orders of magnitude. Rheological measurements and thermodynamic modeling confirm that associative exchange facilitates efficient stress dissipation without diminishing rupture strength or thermal stability. In contrast, dissociative systems inherently trade increased dynamics with mechanical weakening. This decoupling is achieved through the implementation of a catalytic reorganization pathway governed by the composition of the sample, independently of crosslink strength. These findings establish the mechanism of reorganization as a key design parameter for engineering adaptive soft materials that combine resilience and responsiveness.