Maintaining Dynamic Crosslink Engagement Under Network Perturbation Limits the Loss of Hydrogel Viscoelastic Function

Dynamic hydrogels are widely used to emulate viscoelastic extracellular matrices, yet stabilization against dissolution does not necessarily preserve viscoelastic function under physiological swelling. Here, we interrogate how network topology governs the retention of dynamic mechanics in swollen hydrogels. Using a modular thiol-ene platform in which a dynamic supramolecular guest-host network is architecturally decoupled from the stable covalent network, we first demonstrate that as-prepared hydrogels occupy a structured, low-dimensional viscoelastic manifold parameterized by the relative fraction of stable and dynamic crosslinks. This structured design space demonstrates that hybrid network viscoelasticity can be rationally defined by the crosslinker composition across a broad range of relaxation behaviors. However, upon equilibration in aqueous media, this tunable viscoelastic space collapses; hydrogels spanning a broad range of relaxation extents converge toward a restricted mechanical regime despite preservation of the macroscopic structure, consistent with swelling-induced dilution of guest-host bonding partners that were never architecturally coupled to the stable scaffold. To restore dynamic function without increasing permanent crosslink density, we introduce multivalent electrostatic interactions to enforce heteropolymer proximity. Increasing crosslinker charge preserves frequency-dependent elasticity and dissipation in the swollen state, with the maximally charged crosslinker retaining a normalized high-frequency modulus approximately three-fold greater than that of the uncharged control. Competitive disruption confirms that viscoelastic retention remains contingent on guest-host engagement. Together, these findings reveal that limiting loss of viscoelastic function under swelling requires architectural coupling of reversible motifs to a stable network and that stabilization against dissolution alone is insufficient to preserve dynamic mechanical function.