PIM-1 pore-filled thin film composite membranes for tunable organic solvent nanofiltration

Herein, a novel thin film composite (TFC) membrane pore-filled with polymer of intrinsic microporosity, PIM-1, has been developed for organic solvent nanofiltration (OSN). The TFC membranes were facilely prepared by dip-coating of PIM-1/chloroform solution onto polyacrylonitrile support membranes followed by a solvent vapor annealing (SVA) process. The relationship between preparation conditions, selective layer morphologies and OSN performances of the prepared TFC membranes were studied systematically. It was found PIM-1 was evidently filled into the near surface pores of support membranes due to the infiltration of PIM-1 solution. With the elongation of SVA time, the thickness of the PIM-1 layer decreased and the PIM-1/PAN interface gradually disappeared, which is advantageous to enhance the interfacial bonding. The prepared TFC membranes were used to reject organic molecules in organic solvents and exhibited tunable solvent permeability and solute rejection. Especially, the membranes were suitable for the removal of neutral molecules and anionic dyes from ethanol. The typical membrane demonstrated an ethanol permeance of 4.3 L m(-2) h(-1) bar(-1) with a rejection of 93.7% towards Methyl Orange (327 Da). By comparing the permeance of various solvents, it is found that the closer the Hansen solubility parameter of solvent is to that of PIM-1, the higher the solvent permeance. This indicates the affinity between solvent and membrane plays an important role in solvent permeability. This work offers a novel and convenient strategy to prepare highly permeable membranes with controllable microstructures and tunable permselectivity to meet the diverse demands of molecular separation in organic solvents.