Chiral polyamide nanofilms via biphasic organic interfacial polymerization for enantiomer and antibiotic purification

The efficient purification of high-value pharmaceuticals is fundamentally hindered by the energy-intensive nature of conventional separation techniques. Although nanofiltration offers a sustainable alternative, traditional thin-film composite (TFC) membranes are constrained by the strict aqueous solubility requirements of amine monomers. To overcome this limitation, we report a microenvironment-modulated biphasic organic interfacial polymerization (BOIP) strategy to fabricate inherently chiral, microporous polyamide nanofilms. By utilizing a DMAc/n-hexane biphasic system doped with trace water, this approach mitigates the oversolvation of trimesoyl chloride (TMC) and drives the dynamic interfacial assembly of the highly hydrophobic, axially chiral ( S )-(−)-1,1′-binaphthyl-2,2′-diamine ( S -BINAM). The resulting ultrathin (∼30 nm) selective layer possesses intrinsic sub-nanometer free-volume cavities and highly specific stereogenic chiral microenvironment. These engineered composite membranes demonstrate robust dual-functionality: during antibiotic desalination, they achieve a water permeance of 18.9 L m −2  h −1 bar −1 and a bacitracin/NaCl separation factor of 112.7. Simultaneously, the nanofilms yield an enantiomeric excess ( ee ) of nearly 100% in the resolution of racemic ibuprofen. Coupled with robust hydraulic stability and anti-fouling resistance, this BOIP methodology enables the simultaneous realization of stereochemical precision and exact molecular size-sieving, thereby offering a versatile platform for sustainable, high-purity pharmaceutical separations.