Preparation And Gas Permeability Of Sulfonated Poly (Aryl Ether Ketone) Membranes

As a "green technology", gas membrane separation technology has attracted considerable interest over the past decades. With the advantges of high separation efficiency, simple operation, low energy consumption, and compact device, gas membrane separation technology is widely used in petroleum, metallurgy, natural gas, ammonia and other industry fields. Separation membrane is the core of gas membrane separation technology. The commercial membranes are mostly prepared with polydimethylsiloxane (PDMS), polyimide (PI), cellulose acetate (CA), polysulfone (PS), etc., which have the prevalence of low permeability and selectivity, poor thermal stability and other issues. Therefore, the development of novel gas separation membrane materials has been explored extensively in recent years.Poly (aryl ether ketone)s have gained tremendous attention as high comprehensive performance engineering thermal plastic, due to their excellent mechanical properties, high thermal and chemical stability. With excellent permeability and separation performance, sulfonated poly (aryl ether ketone)s have been widely used in various fields. In this paper, sulfonated poly(phthalazinone ether ketone) (SPPEK) and sulfonated poly(ether ether ketone) (SPEEK) with different ion exchange capacity (IEC) are prepared from poly(phthalazinone ether ketone) (PPEK) and poly(ether ether ketone) (PEEK), respectively. It is confirmed by ’H-NMR and FT-IR that sulfonic group is successfully introduced into polymer. The results show SPPEK and SPEEK have excellent thermal stability and good solubility in NMP, DMAc and other solvents.SPPEK membranes and SPEEK membranes are obtained by solution casting method, respectively. Mechanical properties, water uptake, swelling ratio, hydration number and dynamic contact angle of membranes are investigated in detail. When IEC increases, the tensile strength and dynamic contact angle of SPPEK and SPEEK membranes decrease, while water uptake, swelling ratio, hydration number and water vapor permeability increase. Besides, the tensile strength of SPPEK membranes ranges from 93.6MPa to 96.7 MPa, the initial value of the dynamic contact angle is between 64.36°and 84.86°, and the rate of water absorption changes from 20.1% to 42.5%. The results show that, tensile strength, water uptake, swelling ratio and hydration number of SPPEK membranes are higher than those of SPEEK membranes with similar IEC, while the dynamic contact angles are lower than those of SPEEK membranes. The effects of EEC and temperature on the water vapor permeability (WVP) of SPPEK membranes and SPEEK membranes is investigated in this paper. With the increase of IEC, the WVP of these two homogeneous membranes increase accordingly at the same temperature. The range of WVP of SPPEK membrane at 38℃ is 2.94×10-3g·h-1·cm～4.32×10-3g·h-1·cm-2, which is 1.13～1.35 times higher than those of SPEEK membranes with similar EEC. In addition, an increased temperature will result in an increasing WVP, indicating that temperature dependence of water permeance agrees well with the Arrhenius equation.The effects of IEC and pressure on the N2 and O2 permeability coefficient of SPPEK and SPEEK membranes is investigated. With the increase of IEC, the N2 and O2 permeability coefficient of SPPEK and SPEEK membranes decrease at the same pressure. The N2 permeability coefficient of SPPEK membranes is in the range of 0.31 Barrer-2.46 Barrer, and O2 permeability coefficient is in the range of 1.82 Barrer-15.07 Barrer, which are more than 1.31 times those of SPEEK membranes with similar IEC. In addition, O2 permeability coefficient is higher than N2 permeability coefficient under the same conditions. When the pressure increase from 0.6MPa to 1.2MPa, N2 and O2 permeability coefficient decrease slightly. O2/N2 selectivity of SPPEK and SPEEK membranes is improved by the increasing IEC and decreased by the increasing pressure.