Solute diffusion in swollen membranes. Part V: Solute diffusion in poly(2‐hydroxyethyl methacrylate)

Studies with phenylalanine diffusing in well‐characterized poly(2‐hydroxyethyl methacrylate) (PHEMA) membranes swollen in water at 37°C were conducted. Films were prepared by reaction of HEMA monomer with the cross‐linking agent ethylene glycol dimethacrylate (EGDMA) at cross‐linking ratios, X, of 0.005, 0.01, 0.0128, 0.025, and 0.050 mole EGDMA/mole HEMA in the presence of 40 weight percent water at 60°C for 12 hours. These membranes were subsequently swollen in water at 37°C and their structure analyzed using a modified Gaussian distribution equation of swelling. The calculated values of M̄ c varied between 1,700 and 3,425 daltons, which corresponded to a correlation length of the mesh size, egr, of 24 to 35 A. The phenylalanine solute diffusion coefficient varied from 0.17 × 10 −6 to 0.97 × 10 −6 cm 2 /s, and depended on the aforementioned structural parameters of the membranes.