Comparison of methods for characterizing microporous membranes for plasma separation

Abstract

To design membranes suitable for therapeutic use, the relationship between membrane structure and permeability needs to be studied. In this work, the solute permeability of small tubular membranes for plasma separation was determined by using radioisotope-labeled solutes. Through analysis of data on solute and pure water permeability and on water content, by means of a tortuous pore model that we have proposed, we can obtain pore diameter, surface porosity and tortuosity. Membrane structure was also analyzed by mercury intrusion and scanning electron microscopy, and the results were compared with each other. The mercury intrusion method is unsuitable for the structural analysis of polymer membranes because of the damage and/or expansion resulting from highly elevated pressure. The tortuous pore model is recommended for the elucidation of membrane structure.