Results of detailed molecular dynamics simulations on the interfaces between the following amorphous polymers and feed mixtures are reported : poly(dimethyl siloxane) (PDMS) and 90:10 wt% water-ethanol, poly(vinyl alcohol) (PVA) and 90:10 wt% ethanol-water, and poly(methyl phenyl siloxane) (PMPhS) and 20:80 wt% benzene-n-heptane. The simulation results reflect important features of the respective pervaporation processes. In the case of PDMS/wates-ethanol the technically relevant enrichment of the permeate stream with ethanol can be anticipated already from the interface behaviour during the early stages of sorption and absorption of feed molecules, while for the PVA/ethanol-water system the technically utilised depletion of the retentate stream from water molecules is observable. Here the solubility related enrichment factor for water in the membrane is about 4. For the system PMPhS/benzene-n-heptane, on the other hand, a relatively low solubility related enrichment factor for benzene in the membrane of about 2 could be predicted. Therefore, an enrichment of the majority component n-heptane is to be expected in the respective retentate stream.