Conjugated
microporous polymers (CMPs) featuring a well-structured
microporosity are desirable molecular sieving materials, but most
are fabricated under harsh synthesis conditions (e.g., high temperature
and pressure) and are insoluble, which is challenging for processing
them into continuous membranes. Herein, in situ formation of imine-linked,
31-nm-thick CMP nanofilms supported on porous polymeric substrates
via catalysis diffusion-controlled interfacial polymerization (IP)
under mild conditions is reported. The diffusion of catalyst acetic
acid (AcOH) from the water phase to the interface enables acceleration
of the aldehyde-amine condensation from the oil phase and thus the
formation of CMP nanofilms within 10 min. The micropore size and thickness
of CMP membranes were feasibly regulated by rational utilization of
molecular ligands and control of IP parameters. Importantly, introducing
hydroxyl groups adjacent to aldehyde enlarges CMP pore apertures from
1.0 to 1.7 nm due to the reduced reactivity induced by steric hindrance
and the formed intramolecular hydrogen bonds. The newly synthesized
2,5-dihydroxyterephthaldeyde–m-phenylenediamine
membranes display an extraordinarily high water permeance (240.0 L
m–2 h–1 bar–1) and an excellent brilliant blue R (825.9 Da) rejection
(i.e., 98.3%). In addition, the CMP membranes achieve an unprecedented
sieving capability for both dye/dye and dye/divalent salt mixtures.
This catalysis diffusion-controlled, interface-confined polymerization
means may enable the development of new coherent microporous organic
polymer films with potential for water purification, adsorption, and
gas purification.