This review highlights recent advances in the development of poly(ionic liquid)-based composites for diverse materials applications.

The electrode-electrolyte interface is pivotal in the electrochemical kinetics. However, modulating the electrochemical interface at the atomic or molecular level is challenging due to the lack of efficient interfacial regulators. Here, we employ a porous amine cage as an interfacial modifier to Pt cluster in a confining configuration, largely enhancing alkaline HER kinetics by facilitating charge transfer. In situ electrochemical surface-enhanced Raman spectra, in combination with the ab initio molecular dynamics simulation, elucidates that the interaction between water and the -NH- moiety of cage frame softens the H-bonds net of interfacial water, making it more flexible for charge transfer. Moreover, our investigation pinpointed that the -NH- moiety acted as a pump for charge transfer by Grotthuss mechanism, lowering the kinetic barrier for hydrogen adsorption. Our findings highlight the strategy of establishing a soft-confining interfacial modifier by porous cage, offering opportunities to optimize electrochemical interfaces and promote reaction kinetics in a targeted way.

The capability to significantly shorten the synthetic period of a broad spectrum of open organic materials presents an enticing prospect for materials processing and applications. Herein we discovered 1,2,4‐triazolium poly(ionic liquid)s (PILs) could serve as a universal additive to accelerate by at least one order of magnitude the growth rate of representative imine‐linked crystalline open organics, including organic cages, covalent organic frameworks (COFs), and macrocycles. This phenomenon results from the active C5‐protons in poly(1,2,4‐triazolium)s that catalyze the formation of imine bonds, and the simultaneous salting‐out effect (induced precipitation by decreasing solubility) that PILs exert on these crystallizing species.

The construction of hierarchically nanoporous composite for high-performance catalytic application is still challenging. In this work, a series of host-in-host ionic porous materials are crafted by encapsulating ionic organic cages into a hyper-crosslinked, oppositely charged porous poly(ionic liquid) (PoPIL) through an ion pair-directed assembly strategy. Specifically, the cationic cage (C-Cage) as the inner host can spatially accommodate a functional Au cluster, forming a [Au⊂C-Cage⁺]⊂PoPIL⁻ supramolecular composite. This dual-host molecular hierarchy enables a charge-selective substrate sorting effect to the Au clusters, which amplifies their catalytic activity by at least one order of magnitude as compared to Au confined only by C-Cage as the mono-host (Au⊂C-Cage⁺). Moreover, we demonstrate that such dual-host porous system can advantageously immobilize electrostatically repulsive Au⊂C-Cage⁺ and cationic ferrocene co-catalyst (Fer⁺) together into the same microcompartments, and synergistically speed up the enzyme-like tandem reactions by channelling the substrate to the catalytic centers via nanoconfinement.

Biological cell membrane featuring smart mass-transport channels and sub-10 nm thickness was viewed as the benchmark inspiring the design of separation membranes; however, constructing highly connective and adaptive pore channels over large-area membranes less than 10 nm in thickness is still a huge challenge. Here, we report the design and fabrication of sub-8 nm networked cage nanofilms that comprise of tunable, responsive organic cage-based water channels via a free-interface-confined self-assembly and crosslinking strategy. These cage-bearing composite membranes display outstanding water permeability at the 10⁻⁵ cm² s⁻¹ scale, which is 1–2 orders of magnitude higher than that of traditional polymeric membranes. Furthermore, the channel microenvironments including hydrophilicity and steric hindrance can be manipulated by a simple anion exchange strategy. In particular, through ionically associating light-responsive anions to cage windows, such ‘smart’ membrane can even perform graded molecular sieving. The emergence of these networked cage-nanofilms provides an avenue for developing bio-inspired ultrathin membranes toward smart separation.