# Enhancing Chemical Stability and Molecular Selectivity of Porous Organic Cages via Core–Shell Polymer Coating

## TL;DR

This paper introduces a method to enhance the stability and selectivity of porous organic cages by coating them with a polymer shell, improving their performance in gas and vapor separation.

## Contribution

A rapid interfacial strategy for creating POC@polymer core–shell nanostructures with improved chemical robustness and molecular selectivity.

## Key findings

- Polymer-coated POCs show exceptional acid resistance confirmed by etching and PXRD analyses.
- PAA-coated materials achieve a CO2/N2 IAST selectivity of 299.5 and a PX/OX selectivity of 11.3.
- The method produces stable, monodisperse core–shell nanostructures suitable for industrial separations.

## Abstract

Porous organic cages (POCs) have emerged as promising molecular materials for gas separation and storage due to their discrete, shape‐persistent structures and accessible cavities. However, their practical application remains limited by intrinsic instability under harsh chemical environments and difficulties in processing. Here, we report a rapid and efficient interfacial strategy for the fabrication of POCs@polymer core–shell nanostructures that exhibit improved chemical robustness and molecular selectivity. Through chiral self‐assembly of enantiomeric cage precursors, well‐defined racemic POC particles are synthesized. A non‐solvent‐induced surface‐aimed polymerization (NISAP) technique enables the formation of dense, conformal polyamic acid (PAA) or polyimide (PI) coatings in a single step, yielding stable, monodisperse core–shell nanostructures. These polymer shells confer exceptional acid resistance upon POC particles, as confirmed by etching and PXRD analyses, and significantly alter their pore environments, leading to enhanced selectivity in gas and vapor separation. Notably, the PAA‐coated materials achieve a CO2/N2 IAST selectivity of 299.5 and a para‐xylene (PX) / ortho‐xylene (OX) selectivity of 11.3, which is a tenfold and fourfold improvement over the uncoated material, respectively. Our results offer a general pathway to robust hybrid molecular materials, opening new avenues for advanced separations under demanding industrial conditions.

This study presents an interfacial method to fabricate POC@polymer core–shell nanostructures combining cage porosity with polymer robustness. Through chiral self‐assembly and non‐solvent‐induced surface polymerisation, uniform ∼20 nm polymer‐coated particles are produced. The shells improve chemical resistance and selectivity, offering a scalable platform for advanced separations in harsh environments.