Characterization of asymmetric polysulfone membranes by atomic force microscopy

Atomic force microscopy (AFM) has been used to investigate the surface of ultrafiltration membranes. Surface structures of asymmetric (integrally skinned) membranes made from polysulfone were prepared following the traditional wet-phase inversion process. AFM was used to measure the root-mean-square of surface-rip distance, W, as a function of the typical dimension of the scanned region, L. From AFM images, a method to determine the size of nodules constituing the membrane structure is shown. in this study, it was found that W, which is a natural measure of surface roughness, increases with molecular; weight cutoff (MWCO) of membranes. Preliminary analysis addresses the relationship between surface roughness and permeability.