Evaporation-Driven Cellular Patterns in Confined Hyperelastic Hydrogels

When a hyperelastic hydrogel confined between two parallel glass plates begins to dry from a lateral boundary, the volume lost by evaporation is accommodated by an inward displacement of the air-hydrogel interface that induces an elastic deformation of the hydrogel. Once a critical front displacement is reached, we observe intermittent fracture events initiated by a geometric instability resulting in localized bursts at the interface. These bursts relax the stresses and irreversibly form air cavities that lead to cellular networks. We show that the spatial extent of the strain field prior to a burst, influenced by the air-hydrogel interfacial tension and the confinement of the gel, determines the characteristic size of the cavities.

Automated summary

When a hyperelastic hydrogel dries from a lateral boundary, it undergoes elastic deformation and forms air cavities and cellular networks. The size of these cavities is determined by the confinement of the gel and the interfacial tension between air and hydrogel.