Covanlently Linked Acrylate Derivitized Psf and Amine Functionalized Mesorporous MCM-41 Based Mixed Matrix Membranes For CO2 Separation

Mixed matrix membranes (MMMs), comprising molecular sieving materials embedded in a polymer matrix, are promising candidates with substantial potential to overcome the Robeson’s upper-bound trade-off. These membranes combine the easy processability of the polymers with high flux/selectivity of the inorganic porous materials. However, due to the difference in physio-chemical properties, the formation of defect-free MMMs has proven to be challenging.  The poor interfacial contact between the polymer and the filler results in the formation of so-called microvoids which significantly lower the membrane separation performance. In this work, MMMs composed of acrylate derivatized polysulfone and mesoporous MCM-41 were prepared by solution casting. The voids at the polymer-filler interface were removed by the introduction of covalent linkages between the modified polymer and the functionalized fillers. MCM-41 was chosen as a filler because of several inherent advantages, such as high specific surface area, high CO₂ adsorption, high mechanical and thermal stability and easy surface modificatio. Gas permeation results and SEM images of the synthesized MMMs confirmed a good adhesion and dispersion of the fillers within the polymer matrix. SEM results showed that the interfacial voids were mostly eliminated with a visible, non-porous, defect-free structure, which is ideally suited for gas separation membranes. In comparison to MMMs with unmodified MCM-41, covalently linked MCM-41 fillers rendered the MMMs significantly higher CO₂/CH₄ and CO₂/N₂ selectivities due to the presence of a covalent link between the -NH₂ group of the filler and the acrylate of the polymer. The highest ideal selectivities obtained here for CO₂/N₂ and CO₂/CH₄ were 32.97 and 31.48 (CO₂ permeability = 9.13 Barrer), respectively. The performance of membranes under mixed gas feeds and different operating temperatures was also studied.