Sub-micron tailoring of bi-soft segment asymmetric polyurethane membrane surfaces with enhanced hemocompatibility properties.

Enhancement of membrane hemocompatibility is achieved through the control of the surface morphology. Bi-soft segment integrally skinned poly(ester urethane urea) (PEUU) membranes containing polycaprolactone (PCL) as a second soft segment are synthesized with PCL-diol ranging from 0% to 15% (w/w). Scanning electron microscopy and atomic force microscopy characterized membrane asymmetry and sub-micron roughnesses, R(a), of top dense surfaces as major assets to the development of platelet/membrane surface interactions. Here we show that the top dense surfaces of asymmetric PEUU membranes can be tailored with different morphologies when the ratio of the two soft segments PPO/PCL varies. A strong correlation between the top surface roughnesses, R(a) and platelet deposition is identified. The membrane with 15% (w/w) of PCL-diol, PEUU 85, shows the smoothest top dense layer with a R(a) as low as 1 nm which is 5 times below the characteristic value of the PEUU membrane with a single soft segment. The PEUU 85 asymmetric membrane displayed minimal platelet deposition and inhibition of extreme stages of platelet activation.