A PHENOMENOLOGICAL MODEL FOR HYDROGELS WITH RIGID SKIN FORMATION

Abstract

A phenomenological model for stimuli sensitive hydrogels immersed in water subject to changes in temperature is presented and analyzed. In short, the model takes into account conservation of mass and momentum for polymer network and interstitial fluid with an expression for permeability to capture the rigid skin formation during shrinking. The nature of this expression is secured from the observation of and validation with experimental deformation kinetics. Overall, good agreement is achieved between model predictions and their experimental counterparts; the rigid skin formation and rigid core presence are also captured reasonably well. The model can be extended to account for arbitrary-shaped hydrogels as well as for other types of stimuli-sensitive hydrogels that exhibit rigid-skin formation during shrinking.