Aqueous diffusion through crosslinked poly-(2-hydroxyethyl methacrylate) hyfrogel membranes

Abstract

Transport phenomena of a series of aqueous amides across the poly (2-hydroxyl ethyl methacrylate) (p-HEMA) hydroxyl membrane were studied. Hydrogel membrane were synthesized by the solution polymerization of 2-hydroxyethyl methacrylate(HEMA) in the presence of crosslinking agent tetraethylene glycol dimethacrylate(TEGDMA). By changing the crosslinker contents, four group of membranes were synthesized. Diffusion data of solutes were obtained for each group of membranes. A Leonard-Blumle cell was used throughout the experiments. The overall permeability, the distribution coefficient, the solution volume, the membrane wet thickness and wet area were measured. From these experimental values, the diffusion coefficients of solutes through membranes were calculated. The concentration measurement were carried out by differential refractometry at 546 nm wavelength. Diffusion data were interpreted in terms of the extent of interaction between solute and membrane matrix. It was assumed that there are pores which are the water containing region in the hydrogel. Hydrogen bonding ability and size effect were considered as the factors to affect the diffusion of nonelectrolite solutes. A cylindrical treatment of the configuration of small molecules in membranes was proposed. It was observed that in the membrane of low crosslinker content, the molecular size was the important factor in diffusion, while with increase of crosslinker content, hydrogen bonding effect also become important.