Porous poly(ionic liquid)s with tunable wettability and pore structure for efficient oil-water separation

Emulsified oily wastewater is difficult to separate because of the small droplet size and high interfacial stability of emulsified droplets. Herein, a series of porous poly(ionic liquid)s (PILs) with tunable wettability and pore structures were synthesized through Friedel-Crafts crosslinking reactions using cyanuric chloride and imidazole-derived ionic liquid monomers. By regulating the co-crosslinkers and crosslinkers, the surface wettability and porous architectures of the PILs were effectively tailored. The obtained materials exhibited either hydrophobic and oleophilic properties or hydrophilic and underwater oleophobic properties, enabling the selective separation of stratified oil-water mixtures and emulsified oil-water systems. For emulsified oil-water systems, the separation efficiencies exceeded 97%, with a maximum flux of 940 L·m −2 ·h −1 , while separation efficiencies above 99% and a maximum flux of 9251 L·m −2 ·h −1 were achieved for stratified oil-water mixtures. The results indicate that the co-crosslinkers primarily regulate surface wettability, whereas the rigid crosslinker promotes the formation of larger pore volumes and more efficient transport pathways, thereby enhancing permeation performance. This work establishes a structure-property relationship between co-crosslinker chemistry, pore architecture, and separation performance, providing a new strategy for the rational design of porous PIL-based oil-water separation materials.