The “Rigid‐Flexible Coupling” Blueprint: Chemically Welded MOF/Polyimide Porous Hybrids for Multifunctional Separations

The 2025 Nobel Prize in Chemistry, awarded for pioneering contributions to metal-organic frameworks (MOFs), underscores their revolutionary impact and growing importance in advanced separation technologies. Hybrid porous media that integrate crystalline MOFs within polyimide matrices represent a state-of-the-art platform for tackling the global water-energy nexus. Nevertheless, their practical performance is often constrained by interfacial incompatibility and inherent structural trade-offs between rigidity and flexibility. This review establishes a unified "rigid-flexible coupling" design paradigm, systematically dissecting interfacial engineering strategies that convert weak physical interactions into chemically welded interfaces via covalent grafting, hydrogen bonding, and defect-mediated coordination. Particular focus is given to the dimensional evolution from two-dimensional mixed-matrix membranes to three-dimensional hierarchical aerogels, which signifies a pivotal shift in mass transport from diffusion-controlled to convection-dominated regimes. Building on this framework, the review elucidates how hierarchical architectures enable multifunctional capabilities, including selective ion separation through Donnan exclusion, Janus-wettability-governed multiphase separation, and photothermal-assisted remediation of high-viscosity crude oil. Finally, it distills materials design principles and discusses emerging frontiers in artificial-intelligence-driven materials discovery and four-dimensional-responsive systems. By bridging interfacial chemistry, structural hierarchy, and transport physics, this review offers a comprehensive blueprint for the rational design of next-generation hybrid porous media for sustainable environmental technologies.