Transport in PEG-Based Hydrogels: Role of Water Content at Synthesis and Crosslinker Molecular Weight

Poly(ethylene glycol) (PEG) hydrogels are hydrophilic, high water content, polymeric networks that represent excellent candidates as engineering biomaterials for a broad range of applications. A key challenge for many biomedical applications is the control of transport properties within the resulting 3D crosslinked gels. The effects of the water content at synthesis and crosslinker molecular weights on gel chemical structure and equilibrium volumetric swelling ratio, Q, are studied for a series of PEG hydrogels. In addition, the translational diffusion coefficients of a model probe molecule, Rhodamine 110, are determined directly within the hydrogels by fluorescence correlation spectroscopy measurements. Increasing the water content at synthesis results in larger observed swelling behavior and faster particle transport within the formed PEG hydrogels for two different crosslinker molecular weights due to fewer physical crosslinks in the gels. Comparison of the particle translational diffusion coefficient to the swelling ratio shows a linear relationship for all crosslink densities examined.