CRITICAL PARAMETERS IN PREPARATION OF SEDIMENTATION-FREE MIXED-MATRIX MEMBRANES BASED ON 6FDA-ODA POLYIMIDE AND SILICALITE-1

Mixed-matrix membranes have the potential to overcome Robeson upper bound of permselectivity. However, their performance is often decreased due to microstructural defects as sedimentation or aggregation of fillers. Thus, we focused on the relationship between membrane microstructure and parameters of their preparation. We developed a process to prepare defect-free mixed-matrix membranes consisted of 6FDA-ODA polyimide and silicalite-1 as filler. The process suppressed both sedimentation and filler aggregation in the polyimide matrix. We demonstrated the homogeneity of the filler in the membranes using spatial distribution of silicalite-1 volume fractions across the membrane length and thickness at Fig. 1 right. We achieved outstanding membrane reproducibility by means of a two-step quality control protocol: i) polyamic acid synthesis arrangement that isolates precursor solution from temperature and moisture fluctuations that affect solution viscosity; ii) a new imidization cell with definite solvent evaporation adjustable through the nitrogen flow rate that sustained fillers fluidized.