Effect of cross-linking on the diffusion of water, ions and small molecules in hydrogels

Cross-linking;Diffusion;hydrogel;poly(ethylene glycol);rhodamine;hydrogen bonding

Wu, Yanbin ; Aluru ; Narayana R.

关键词: Cross-linking;    Diffusion;    hydrogel;    poly(ethylene glycol);    rhodamine;    hydrogen bonding;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/29463/Wu_Yanbin.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Understanding the diffusion of small molecules in hydrogel system is of major importance in a variety ofapplications including drug delivery systems, tissue engineering and contact lens. Cross-linking density ofhydrogels has been commonly used to tune key parameters like mesh size and molecular weight betweencross-linkers, in order to change macroscopic properties of hydrogels. In this thesis, molecular dynamicsinvestigations of chemically-cross-linked poly(ethylene glycol) (PEG) hydrogels are reported with the aim ofexploring 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 molecularweights of the chains ranging from 572 to 3400. As the cross-linking density is increased, the water diffusiondecreases and the slowdown in diffusion is more severe at the polymer-water interface. The water diffusion atvarious cross-linking densities is correlated with the water hydrogen bonding dynamics. The diffusion of ionsand rhodamine also decreased as the cross-linking density is increased. The variation of diffusion coefficientwith 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.