Reprogrammable Intrinsic Microporous Polymer Nanofilm Platform for Tunable Molecular Separation

ABSTRACT The development of advanced membranes with tunable separation properties is crucial for energy‐efficient molecular separation, yet conventional polymeric membranes suffer from fixed pore sizes and surface affinities, limiting their adaptability. Here, we report a reprogrammable membrane platform based on an intrinsic microporous polyamide acid (PIMs‐PAA) nanofilm, fabricated via interfacial polymerization of a spirocyclic dianhydride (TA‐TSB) and m‐phenylenediamine (m‐PDA). The resulting non‐crosslinked PIMs‐PAA nanofilm features abundant reactive sites, enabling precise post‐synthetic modifications, including imidization, crosslinking, and fluorination, to independently tune pore size and interfacial chemistry. The derived membranes exhibited high solvent permeance (e.g., 18.19, 11.52, and 12.31 L·m −2 ·h −1 ·bar −1 for methanol, toluene, and DMF, respectively), and could be reprogrammed for on‐demand molecular separations, with a tunable molecular weight cut‐off (MWCO) spanning from 250 to 1300 Da. Importantly, this platform enables a single precursor membrane to be adaptively reconfigured for multiple separation tasks, efficiently handling both polar and nonpolar solvents across a broad MWCO separation range. This work establishes a versatile design framework for reprogrammable separation membranes, bridging advanced polymer materials with sustainable chemical and molecular purification processes.