Application of CH4/N2 separation based on poly(styrene-b-isoprene-b-styrene) (SIS)-poly(dimethylsiloxane-co-methylhydrosiloxane) (PDMS-co-PMHS) crosslinked membrane

This work involves the preparation and characterization of poly(styrene-b-isoprene-b-styrene)-poly(dimethylsiloxane- co -methylhydrosiloxane) (SIS-c-PDMS-co-PMHS) crosslinked membranes towards CH 4 /N 2 separation. SIS-c-PDMS-co-PMHS was synthesized via a simple hydrosilylation reaction with various PDMS-co-PMHS contents. The structure of crosslinked membranes was investigated by Fourier transform infrared spectroscopy , indicating the degree of hydrosilylation reaction. The morphology of sample membranes was observed in detail by means of Scanning Electron Microscope analysis . Thermodynamic stability and the crosslinked behavior of crosslinked membranes were explored by thermogravimetric analysis and Soxhlet extraction experiments. Furthermore, single gas (CH 4 , N 2 ) permeability was measured using the time-lag method. The CH 4 permeability of crosslinked membranes with 70 wt% PDMS-co-PMHS could reach 503 Barrer at 25 °C and 1 bar, which is significantly greater than that of SIS (25.9 Barrer), while the CH 4 /N 2 ideal selectivity hardly changed. Notably, CH 4 permeability further improved by 77.6% (893.4 Barrer) as the temperature increased to 55 °C. For the CH 4 /N 2 (50/50 vol%) mixed gas, the SIS-c-PDMS-co-PMHS-70 sample membrane exhibited ideal gas separation performance relative to that of the pure SIS membrane (CH 4 : 447.4 vs. 24.2 Barrer，N 2 : 188.1 vs. 9.46 Barrer).