Atomic force microscopy (AFM) has been used to investigate the surface
of ultrafiltration membranes. Surface structures of asymmetric (integ
rally 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.