Water and salt transport properties of disulfonated poly(arylene ether sulfone) desalination membranes formed by solvent-free melt extrusion

This paper reports water and salt transport properties of sulfonated polysulfone desalination membranes prepared by solvent-free, melt extrusion. The 20 mol% disulfonated poly(arylene ether sulfone) (BPS-20K) membranes were prepared by melt processing, using poly(ethyelene glycol) (PEG) M̅_n (200 ~ 400 g/mol) as plasticizers at concentrations of 20 wt% to 30 wt%, and different PEG extraction temperatures. Water and salt transport properties of BPS-20K membranes prepared by different processing routes correlated well with water uptake, as expected, based on free volume theory. The melt-extruded BPS-20K membranes show higher water uptake than those of solution cast membranes. As PEG molecular weight and concentration used during extrusion increases and as PEG extraction temperature increases, water uptake also increases. As water uptake increases, water and salt permeabilities and diffusivities increase, consistent with the findings of Yasuda et al. In general, BPS-20K membranes prepared by different processing routes followed the trade-off relationship between water permeability and water/salt permeability selectivity. These results indicate that differences in membrane processing history have significant effects on the transport properties of small molecules in these polymers, similar to other glassy polymers.