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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 14: Elastomers and Gels

CPP 14.7: Vortrag

Dienstag, 15. März 2011, 12:15–12:30, ZEU 114

Micro- to Mesoscale Simulation of Hydrogel Swelling Dynamics Based on a Phase field Model — •Daming Li, Hongliu Yang, and Heike Emmerich — Materials and Process Simulation (MPS), University of Bayreuth

Hydrogels consist of three-dimensional charged polymer networks, mobile ions, and solvent, and they are usually synthesized by chemically cross-linking charged polymers. Hydrogels can swell or shrink by the absorption or squeeze of solvent if it is under the external stimuli, e.g., temperatures, pH, ionic strength, etc. Stimuli-response hydrogels have attracted much attention for their potential in wide range of applications, e.g. drug delivery, biosensors, tissue engineering etc.

Here we contribute to a precise understanding of the mechanisms responsible for the hydrogels' swelling kinetics as well as dynamics by proposing for the first time a model approach that can resolve the inherent short range correlation effects along the hydrogel-solution interface jointly with the long range ionic transport fields. To that end we investigate the swelling dynamics of hydrogels, which is a moving boundary problem, by a phase field model, which couples the Nernest-Planck like equation for the concentration of mobile ions, Poisson equation for the electric potential, mechanical equation for the displacement and an equation for the phase field variable. Simulation reveals that under the chemical stimulation the hydrogel will swell or shrink if the concentration of mobile ions inside bath solution decreases or increases. This is in agreement with the experimental results qualitatively.