Strain-stiffening gels based on latent crosslinking

TL;DR

This paper introduces a new class of strain-stiffening gels with latent disulfide crosslinking that activate under mechanical stress, enabling on-demand strengthening for various soft material applications.

Contribution

The study presents a novel responsive gel design utilizing protected disulfides that activate under strain, offering controllable and reversible stiffening behavior.

Findings

Gels exhibit significant strain-stiffening upon mechanical compression.

Disulfide bonds are activated to form crosslinks on-demand.

Molecular shielding controls strain sensitivity and spontaneous crosslinking.

Abstract

Gels are an increasingly important class of soft materials with applications ranging from regenerative medicine to commodity materials. A major drawback of gels is their relative mechanical weakness, which worsens further under strain. We report a new class of responsive gels with latent crosslinking moieties that exhibit strain-stiffening behavior. This property results from the lability of disulfides, initially isolated in a protected state, then activated to crosslink on-demand. The active thiol groups are induced to form inter-chain crosslinks when subjected to mechanical compression, resulting in a gel that strengthens under strain. Molecular shielding design elements regulate the strain-sensitivity and spontaneous crosslinking tendencies of the polymer network. These strain-responsive gels represent a rational design of new advanced materials with on-demand stiffening properties with potential applications in elastomers, adhesives, foams, films, and fibers.