Synthetic design of force-responsive hydrogels with ring-forming catch bonds

TL;DR

This paper introduces a minimal synthetic hydrogel system that mimics catch bond behaviour, enabling materials that become stiffer under force, with potential applications in impact resistance and tissue engineering.

Contribution

It presents a novel reversible ring-forming polymer framework for creating force-responsive hydrogels with tunable mechanical properties.

Findings

Hydrogels with ring-forming polymers show fewer bond-breaking reactions under stress.

The system exhibits non-monotonic strain rate dependence on applied stress.

Reversible ring formation offers a versatile platform for adaptive material design.

Abstract

Catch bonds are interactions whose lifetimes increase under mechanical load, a counterintuitive behaviour that underlies diverse biological processes. Translating this mechanism to synthetic materials offers the potential to create systems that are compliant at low stress but stiffen under applied force, with applications ranging from impact-responsive materials to dynamic tissue scaffolds. However, engineering materials with tunable, force-dependent interactions remains challenging, and existing conceptual designs are limited. Here, we present a minimal synthetic framework for catch bond behaviour in dynamic hydrogels, based on reversible ring-forming polymers. Using coarse-grained molecular dynamics simulations, we show that hydrogels with such a chemistry undergo fewer bond-breaking reactions as the stress increases and can even display a non-monotonic dependence of the strain rate on the applied stress. Our results highlight the potential of reversible ring formation as a versatile platform for designing mechanically adaptive materials with tunable durability and responsiveness.