POLYACRYLONITRILE CAPILLARY MEMBRANES FOR MEMBRANE OSMOMETRY

Capillary-shaped polyacrylonitrile (PAN) membranes have been applied i n a membrane osmometer with a short response time based on a concentri c design of the solvent and solution cells. The highly asymmetric morp hology and the large pore density of the membrane allow a high solvent permeability with molecular weight cutoff around 20000 g/mol for poly styrene in toluene. A further decrease of the molecular weight cutoff down to 5000 g/mol is achieved by coating the PAN membrane with a thin crosslinked polydimethylsiloxane layer, which does not significantly increase the osmometer response time.