Organic base modulated interfacial polymerization toward highly crosslinked microporous polyamide membranes

Developing advanced nanofiltration membranes for molecular separation in organic solvents is imperative. Microporous polyamide membranes have attracted much attention due to high porosity which can facilitate solvent permeation. However, manipulating the interfacial polymerization of twisted monomers to simultaneously achieve high permeance and precise molecular sieving capacity remains challenging. Herein, we propose using organic base to regulate the interfacial polymerization of tetra-(4-aminophenyl) methane (TAM) and trimesoyl chloride at the alkane/ionic liquid interface. Triethylamine (TEA) is incorporated with TAM and can effectively suppress the protonation of TAM amino groups. Accordingly, the reactivity of TAM monomer is enhanced, leading to higher crosslinking degree of the resultant membrane with the harmonic amide bond density increased from 3.78 mmol g −1 to 4.31 mmol g −1 . The resultant ultrathin microporous polyamide membrane exhibits remarkable solvent permeance of 135.81 L m −2  h −1 bar −1 for ethanol and 311.89 L m −2  h −1 bar −1 for methanol, as well as sharp molecular sieving property with the difference between MWCO (603 Da) and MWRO (518 Da) of only 85 Da, outperforming the state-of-the-art membranes. This research opens a novel pathway to fabricating high-performance microporous polyamide membranes for organic solvent nanofiltration.