Transport of dilute organics through dense membranes: Assessing impact on membrane-solute interactions

Polydimethylsiloxane (PDMS) membranes were synthesised by varying the degree of crosslinking and were characterised in a pervaporation system coupled to a mass spectrometry (MS) for on-line monitoring and collecting data points with an interval of 2 s. This monitoring approach allows obtaining very precise information about the impact of solutes' solubilisation within the membrane and their influence on solvent permeation. Using dilute aqueous solutions of ethyl acetate and hexyl acetate, it is shown how solutes with diverse nature and diverse partitioning into the membrane, determine the transport of solvent and solute by progressively modifying the membrane transport properties. From the evolvement of the time-dependent diffusion coefficients of the selected solutes during transient transport, it is possible to infer about solute-membrane molecular interactions and their impact in terms of membrane rearrangement and fluidification.