Synthesis and gas transport properties of polyamide membranes containing PDMS groups

A series of gas-separation polyamide-poly(dimethylsiloxane) (PA-PDMS) membranes containing PDMS groups were synthesized through the polycondensation reaction. The structural characteristics of polymers were evaluated by (1)H-NMR spectroscopy (NMR), Fourier-transform infrared spectroscopy (FTIR) and UV-vis absorption spectroscopy. The permeability and selectivity behavior was studied at different temperatures (25–55 °C) and pressures (1.0–3.0 atm), using various gases, such as H(2), O(2), CO(2), CH(4), and N(2). The effect of chemical structure, PDMS content, operating pressure and temperature on gas permeability was explored and discussed. Gas-permeation measurements showed that polyamides containing PDMS groups exhibited different separation performance. The PA-PDMS-20 membrane with 20 wt% PDMS exhibited the highest selectivity (CO(2)/N(2) = 41.84 and O(2)/N(2) = 7.01) at 35 °C and 3.0 atm while CO(2) and O(2) permeability was 29.29 barrer and 4.91 barrer, respectively.