The adaptive time-stepping algorithm for Brownian simulation of solute diffusion in three-dimensional complex geometries previously developed by the authors of this paper was applied to heterogeneous three-dimensional polymer hydrogel structures. Thesimulations were performed on reconstructed three-dimensional hydrogels. The obstruction effectfrom the gel strands on water and diffusion of dendrimerswith different sizes were determined by simulations and compared withexperimental nuclear magnetic resonance diffusometry data obtained from the samematerial. It was concluded that obstruction alone cannot explain theobserved diffusion rates, but an interaction between the dendrimers andthe gel strands should be included in the simulations. Theeffect of a sticky-wall interaction potential with geometrically distributed residencetimes on the diffusion rate has been studied. It wasfound that sticky-wall interaction is a possible explanation for thediscrepancy between simulated and experimental diffusion data for dendrimers ofdifferent sizes diffusing in hydrogels.
AUTHORS AND AFFILIATIONS
- Mats Kvarnström, Fraunhofer-Chalmers Centre
- Aron Westergård, The Swedish Institute for Food and Biotechnology
- Niklas Lorén, The Swedish Institute for Food and Biotechnology
- M. Nydén, Dept. of Chemical and Biological Engineering, Chalmers University of Technology