Abstract: | Porous polyelectrolyte membranes stable in a highly ionic environment are obtained by covalent crosslinking of an imidazolium‐based poly(ionic liquid). The crosslinking reaction involves the UV light‐induced thiol–ene (click) chemistry, and the phase separation, occurring during the crosslinking step, generates a fully interconnected porous structure in the membrane. The porosity is on the order of the micrometer scale and the membrane shows a gradient of pore size across the membrane cross‐section. The membrane can separate polystyrene latex particles of different size and undergoes actuation in contact with acetone due to the asymmetric porous structure. |