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Effect of Cross-Linking on the Diffusion of Water, Ions, and Small Molecules in Hydrogels Yanbin Wu, Sony Joseph, and N. R. Aluru*
 

Summary: Effect of Cross-Linking on the Diffusion of Water, Ions, and Small Molecules in Hydrogels
Yanbin Wu, Sony Joseph, and N. R. Aluru*
Department of Mechanical Science and Engineering, Beckman Institute for AdVanced Science and Technology,
UniVersity of Illinois at Urbana-Champaign, Urbana, IL-61801
ReceiVed: September 12, 2008; ReVised Manuscript ReceiVed: December 16, 2008
The present study reports on molecular dynamics investigations of chemically cross-linked poly(ethylene
glycol) hydrogels with the aim of exploring the diffusion properties of water, ions, and rhodamine within the
polymer at the molecular level. The water structure and diffusion properties were studied at various cross-
linking densities with molecular weights of the chains ranging from 572 to 3400. As the cross-linking density
is increased, the water diffusion decreases and the slowdown in diffusion is more severe at the polymer-water
interface. The water diffusion at various cross-linking densities is correlated with the water hydrogen bonding
dynamics. The diffusion of ions and rhodamine also decreased as the cross-linking density is increased. The
variation of diffusion coefficient with cross-linking density is related to the variation of water content at
different cross-linking densities. Comparison of simulation results and obstruction scaling theory for hydrogels
showed similar trends.
Introduction
Hydrogels, composed of polymer networks and water, have
been used increasingly in drug delivery systems, tissue engi-
neering, contact lenses, and so forth1-5
due to their interesting

  

Source: Aluru, Narayana R. - Department of Mechanical and Industrial Engineering, University of Illinois at Urbana-Champaign

 

Collections: Engineering; Materials Science