Dual Supramolecular-Coordination Network Engineering for Plasticization-Resistant CO2 Separation in Polyurethane Mixed-Matrix Membranes

This study addresses the permeability-selectivity trade-off in polyurethane (PU)-based mixed matrix membranes (MMMs) for CO 2 capture by exploiting the synergistic interplay between [HNMP][CH 3 SO 3 ] ionic liquid (IL) and ZnO nanoparticles. Beyond conventional additive effects, this work unveils a dual-mode reinforcement mechanism. Structural analysis confirms that ZnO nanoparticles function as 'pseudo-crosslinkers' via dynamic coordination bonds, while the IL acts as a 'supramolecular crosslinker' through anion-mediated hydrogen bridging. This synergistic interplay establishes a rigidified network, where the IL simultaneously serves as a high-solubility pathway. Consequently, the optimized ternary membrane (PU/1%ZnO/6%IL) achieved a solubility-dominated transport regime, yielding a CO 2 permeability of 139.1 Barrer (∼82% increase vs. pure PU) combined with significantly enhanced ideal selectivity for CO 2 /CH 4 (28.10, +38%) and CO 2 /N 2 (82.79, +50%) at 14 bar. Notably, the synergistic dual-crosslinked architecture drastically suppressed CO 2 -induced swelling, restricting the permeability drift to a mere 20% at 14 bar (compared to a severe 102% surge for pure PU) and enhancing thermal char yield. Finally, Genetic Programming (GP) modeling accurately correlated these non-linear transport behaviors (R 2 =0.98), revealing that the model provides conservative estimates under harsh conditions and confirming that the exceptional separation efficiency is governed by the complex coupling of IL-mediated quadrupolar interactions and interfacial structural densification.