Dynamics of Swelling and Drying in a Spherical Gel

As appreciated by those familiar with disposable diapers, polymeric hydrogels swell to absorb a remarkable amount of liquid. Although gels are widely used in many applications from moisture control to drug delivery, the mechanisms of fluid uptake and release are complex, highly nonlinear, and not well understood. The authors use modeling and experiment to show that the processes of swelling and drying are inherently transient and dynamic---and strikingly different from each other.