Water uptake, transport and structure characterization in poly(ethylene glycol) diacrylate hydrogels

Crosslinked poly(ethylene glycol) (PEG) free-standing films were prepared by UV-induced photopolymerization of poly(ethylene glycol) diacrylate (PEGDA) crosslinker in the presence of varying amounts of water or monofunctional poly(ethylene glycol) acrylate (PEGA). The crosslinked PEGDA films exhibited polymerization induced phase separation (PIPS) when the water content of the prepolymerization mixture was greater than 60 wt%. These phase separated films contain pores that scatter visible light, rendering them translucent or opaque. Visible light absorbance measurements, water uptake, water permeability, and salt kinetic desorption experiments were used to characterize the structure of these phase separated, crosslinked hydrogels. The films with PIPS exhibited a porous morphology in CryoSEM studies. Dead-end filtration experiments using deionized water and 1 g/l bovine serum albumin (BSA) solutions were performed to explore the fundamental transport and fouling properties of these materials. The total flux of pure water through the films after prior exposure to BSA solution was nearly equal to that measured for the as-prepared material, indicating that these PEGDA films resist fouling by BSA under the conditions studied.