Improved gas selectivity of polyetherimide membrane by the incorporation of PIM polyimide phase

Abstract

The aim of this work was to prepare blend membranes of a polyetherimide (PEI) and different ratios of a microporous polyimide (PIM-B) in order to obtain an improved material for gas selectivity. Miscibility of the membranes was studied through fourier transform infrared spectroscopy (FTIR), Fluorescence, ultraviolet-visible spectroscopy (UV–vis), polarize light microscope images, X-ray diffraction (XRD), and differential scanning calorimetry analysis. Gas permeability assays were also performed. Results showed blends were partially miscible along the different ratios due to the existence of: (i) absorption shoulders at lower wavenumbers on the carbonyl stretching band; (ii) red-shifting of Fluorescence and UV–vis absorption bands; (iii) decreasing of d-spacing as the amount of PIM-B phase increased; and (iv) composition-dependent glass transition temperatures (Tgs). The mobility selectivity (Di/j) dominated H2 and O2 gas separations. High solubility coefficients (S) linked to PIM-B microporosity improved the ideal gas selectivity of the blend membranes. PEI/PIM-B membrane at the ratio of 80/20 showed impressive H2/CO2 (8.66) and O2/N2 (10.90) gas separation factors.