INVESTIGATING THE INFLUENCE OF POLYDIMETHYLSILOXANE (PDMS) CROSSLINKING CONTENT ON MEMBRANE SELECTIVITY

Polymer crosslinking has significant importance in the relevant retrofitting of the microstructure of polymer network in terms of polymer swelling, membrane performance and its stability. This research focused on investigating the sorption influence on membrane selectivity in terms of measuring swelling of polydimethylsiloxane (PDMS) at varying polymer crosslinking in alcohol/water solutions. ATR-FTIR spectra for different crosslinked PDMS were obtained using Nicolet FTIR Spectrometer, and solvent concentration was determined by refractometer. The experimental results transpired that swelling degree decreased with increasing crosslinking content, which led to a more rigid polymer network structure resulting in less free volume as well as reduced absorbed liquid in the polymer. The addition of crosslinker resulted in the reduction of PDMS hydrophobicity influencing the sorption of alcohol into the polymer. It was found that PDMS at all crosslinking contents was selective towards ethanol and isopropanol and that addition of the crosslinker at concentrations at or below 10% led to the existence of vinyl and/or Si-H groups in the network. The sorption coefficient for isopropanol was also found to be higher than that of ethanol at all crosslinking contents, with increasing crosslinking content resulted in increased sorption coefficient.