Mass transport properties of co(polyether)polyurethane membranes II: permeability and sorption characteristics

A series of co(polyether)polyurethane polymers containing polyethylene glycol 600, 1000, or 1540 was synthesized, purified by reprecipitation, and cast into clear, tough, flexible membranes using the solution method. Hydration and membrane swelling increased with increasing polyethylene glycol molecular weight. Paroxypropione, 5-nitrosalicylic acid, sulfaguanidine, and phenylbutazone were used as penetrants of a 1 mM donor concentration. Transport rates through the 1540 and 1000 copolymer membranes were in decreasing order: paroxypropione greater than 5-nitrosalicylic acid greater than sulfaguanidine greater than phenylbutazone; however, through the 600 copolymer membrane the rates were paroxypropione greater than 5-nitrosalicylic acid approximately sulfaguanidine. Phenylbutazone did not penetrate during the experiment. Good agreement was obtained between apparent diffusion coefficients calculated by both the time lag and nonsteady-state methods. Boundary layer effects were examined by variations in stirring speeds. Evidence that diffusion may occur primarily through the aqueous region of the hydrated membranes is presented.