Aminoethylaminopropylisobutyl POSS—Polyimide nanocomposite membranes and their gas transport properties

A series of polyimide-POSS (PI-POSS) nanocomposite membranes were prepared using aminoethylaminopropylisobutyl group functionalized polyhedral oligomeric silsesquioxanes (POSS) as nanofiller. The membranes were characterized by DSC, TGA, AFM, FESEM, XRD, etc. The effects of incorporation of POSS into the four structurally different fluorinated polyimide membranes on their gas transport properties with four gases (CH4, N2, O2 and CO2) were investigated at 35 °C and at an applied pressure of 3.5 atm. All the nanocomposite membranes showed comparable glass transition temperature values but a little lower thermo-oxidative stability compared to their corresponding untreated polyimide membranes. The Young's modulus and maximum stress values of the polyimide-POSS membrane were slightly higher than those of the virgin polyimide membranes; however the elongation at break values were lower. POSS nanoparticles were well distributed as observed from FESEM image and AFM study exhibited no significant increase of the roughness of the hybrid membranes. The order of permeability of these gases were found as CO2 > O2 > N2 > CH4. The permeability of all the gases through the composite membranes increased significantly with comparable selectivity for different gas pairs, e.g., CO2/CH4 and O2/N2.