Preparation of sulfonated SEBS block copolymer membranes and their permeation properties

A series of sulfonated polystyrene-b-poly(ethylene-r-butylene)-b-polystyrene (S-SEBS) membranes with high water permeability and thermo-mechanical stability were prepared to estimate the membrane utility for heating/ ventilation/air conditioner (HVAC) system. The sulfonation degrees of membranes were controlled by the contents of sulfonating reagent (acetyl sulfate) added. Proton conductivity and water permeation properties of the membranes increased with increasing sulfonation degree. And gas permeation properties were measured to investigate effect of sulfonation of the membranes on permeation properties. Membrane stability with increasing sulfonation degree was also studied.

A series of sulfonated SEBS with different degrees of sulfonation were successfully prepared using acetyl sulfate that reacted with sulfuric acid and acetyl anhydride. The sulfonation degrees of SSEBS were controlled by adjusting the amount of sulfonating reagent and the content of sulfuric acid group in SSEBS membranes was confirmed by FT-IR and elemental analysis. The water permeation properties were improved with increasing sulfonation degree. Although high swelling degree leads to a further increase of water permeation properties in SSEBS membranes, those water conducting membranes with high sulfonation degree showed poor mechanical strength. Therefore, SSEBS61 which has shown 140% of water uptake and 2400 g/m2 d of WVTR value was estimated as suitable water conducting membrane for HVAC systems. It is possible to apply for HVAC system with excellent performance.