Shi-Peng Sun

This review provides a comprehensive overview of HC-COFMs for water treatment, covering design, physicochemical properties, fabrication strategies, and applications, while outlining challenges and future directions for next-generation membranes.

The long-standing trade-off between enantioselectivity and permeability remains a central challenge in mem-brane-based chiral separation. Materials capable of strong chiral recognition often suffer from slow molecular transport, while highly permeable membranes generally exhibit limited enantioselectivity. Here, we show that intrinsic microporosity provides an effective route to alleviate this limitation. We construct a pair of enantio-meric polymers of intrinsic microporosity (HBIN-Is) through the one-step polymerization of BINOL and isatin. The resulting polymers combine rigid contorted backbones, permanent microporosity, and homochiral envi-ronments, enabling the formation of robust free-standing membranes. The membranes exhibit simultaneous high enantioselectivity and permeation flux toward BINOL and Br-BINOL racemates, achieving enantiomeric excess values up to 97.7% together with high fluxes around 0.38 mmol·m-2·h-1, among the highest reported for polymer-based chiral membranes. Adsorption experiments, density functional theory calculations, and non-covalent interaction analyses reveal that chiral discrimination originates from cooperative hydrogen-bonding and stereochemically matched host–guest interactions within the microporous framework. This work identifies intrinsic microporosity as a powerful design principle for integrating molecular recognition and rapid transport in chiral membranes and provides a scalable platform for energy-efficient enantiomer separation.

Ultra‐selective ion‐ion separation is significant but technically challenging. Achieving the accurate separation of similar ions with nanofiltration requires constructing well‐defined solute‐transferred channels and controllable membrane structures. Herein, a pioneering molecular encapsulation‐mediated gradient catalytic interfacial polymerization is proposed to synchronously control the diffusion of the monomers and polymerization reaction. The nanocapsule orderly disintegrates and releases the reactive monomers with the catalysis of HCl to participate in interfacial polymerization. The innovative strategy enhances the homogeneity of monomer diffusion and allows the polymerization reaction to proceed in stages, resulting in the formation of channels with more ordered nanostructures and more homogeneous ion transport. The membrane exhibits size‐dependent ion sieving with sub‐angstrom precision and shows high permeability (17.9 L·m ⁻² ·h ⁻¹ ·bar ⁻¹ ) and precise separation efficiency (>95 for Ac ⁻ and ~10% for Cl ⁻ ). The innovative method may provide a paradigm shift for the fabrication of highly uniform polyamide membranes for precise molecular sieving.

The development of biocatalytic membranes is often hindered by the lack of recyclable carriers and platforms, as conventional systems require disposal upon enzyme inactivation. We address this critical issue by designing a smart supramolecular membrane platform by integrating interfacial polymerization with reversible host‐guest chemistry. A cross‐linked network was fabricated on a membrane via the reaction between trimesoyl chloride and β‐cyclodextrin (β‐CD). Enzymes were covalently functionalized with a pH‐responsive guest molecule, dansyl chloride, enabling their directional immobilization through host–guest complexation with the membrane‐bound β‐CD. This design features a supramolecular switch, where the binding strength is pH‐modulated, allowing for reversible enzyme loading and carrier regeneration. The resulting membrane achieves a high enzyme loading of 0.64 mg cm ⁻² and retains > 85% activity across multiple cycles. Its universality is proven by the effective immobilization of multiple enzymes, underscoring its potential as a versatile platform for sustainable biocatalysis.

Biomimetic ion channels demonstrate potential for nanoscale molecular separations by leveraging their unique confined recognition capabilities. Metal-organic framework (MOF)-based mixed matrix membranes (MMMs) offer a promising platform that integrates the ångström-scale pores of MOFs with polymer processability. However, slow MOF nucleation kinetics and weak interfacial interactions impede precise channel formation. Here, we present a confined molecular encapsulation (CME) strategy that synchronously regulates MOF nucleation kinetics and interfacial interactions, transforming precursors into flexible gel-network metal-organic gels (MOGs) via supramolecular assembly. Molecular dynamics simulations and in-situ optical detection show that stronger MOG-polymer interactions and confined diffusion govern enhanced interfacial compatibility and uniform dispersion. Optimized MMMs deliver a F⁻/Cl⁻ separation ratio of 32.0 with ionic current rectification. COMSOL simulations demonstrate that synergistic coupling of aligned MOF arrays and uniform surface charge enables efficient ion differentiation. This CME strategy establishes a versatile nanoscale platform for fabricating high-performance monovalent ion-selective membranes and nanofluidic devices.

The increasing global reliance on alternative water sources underscores the critical need for enhanced desalination efficacy. Covalent organic frameworks (COFs), with their ordered porosity and tunable architectures, hold immense potential for next-generation desalination membranes. However, current COF membranes often fail in efficient seawater desalination due to pore sizes largely exceeding hydrated monovalent ion dimensions. Here we present a structurally stable, ultramicroporous COF membrane for low-pressure reverse osmosis (RO) desalination, engineered through a hydrogen-bond fortification strategy. Rational introduction of phenolic hydroxyl adjacent to aldehyde moieties yielded β-ketoenamine configurations enriched with hydrogen bonds, promoting AB-stacking and enhanced crystallinity in Tp-Bth COF membranes. The resultant COF membranes achieved 99.6% sodium chloride rejection with 1.7 L m⁻² h⁻¹ bar⁻¹ water permeability at 15 bar, demonstrating high-performance low-pressure RO desalination. Notably, these membranes exhibited high acid resistance, retaining their initial performance after 30 days in a solution at pH 3. This work demonstrates a hydrogen-bond-mediated strategy to precisely tailor COF pore architecture for high-performance desalination.