Viscoelastic and poroelastic relaxations of polymer-loaded hydrogels
Blessing Deeyaa, Christopher Stafford, Edwin Chan, Peter M. Johnson
In this work, we study the viscoelastic and poroelastic contributions on the relaxation behavior of a polymer-loaded hydrogel using a recently develop Poroelastic Relaxation Indentation (PRI) measurement technique. By applying a generalized relaxation model that captures these two concurrent relaxations, we demonstrate that PRI can characterize the diffusion coefficient of solvent and polymer solution within the hydrogel simply via control of indentation depth. Additionally, we show that diffusion of the polymer solution within the hydrogel is qualitatively similar to the principle of size exclusion and the molecular mass dependence of the diffusion coefficient can be described by the Stokes-Einstein relationship for dilute polymer solutions, thus enabling estimation of the hydrodynamic size of the solvated polymer.