Correlation between structure and transport properties of polymeric membranes for immunoisolation

Laboratory-made asymmetric polyurethane membranes designed for immunoisolat ion were investigated. Two types of EK and ES membranes were prepared in di fferent spinning conditions. The membrane structure was characterised by the skin pore radius measuremen ts using differential scanning calorimetry (DSC). Diffusive transport prope rties of membranes were determined by in vitro method for albumin and creat inine. The scanning electron microscopy (SEM) was applied to study the morp hology of membranes. It has been found that the DSC technique is a useful tool for the evaluatio n of pore radii in the skin layer for PU membranes. Calculated pore radii w ere in the range from 1.95 to 2.47 nm for the EK and ES types. A correlatio n between the skin pore radii and the transport properties was not found in this case of investigated membranes. However, the transport properties dat a can serve for the estimation of selectivity of membranes. Thus, the selec tivity of membranes for solutes of various molecular size was estimated fro m the D-m/D-w ratio of diffusion coefficients for albumin and creatinine. T he SEM micrographs reveal the finger-like internal structure of capillary m embranes, as well as various skin thickness.