Interfacial\nConstructing Poly(ionic liquids) on Nanoporous\nBlock Copolymers for Antifouling Ultrafiltration

The remarkable flexibility in structural tunability and\ndesignability\nof poly(ionic liquids) (PILs) has garnered significant attention.\nIntegration of PILs with membranes, novel properties, and functionalities\nis anticipated for applications in the fields of membrane separation.\nHere, we develop a facile method to prepare PIL-functionalized membranes\nin a one-step process by combining selective swelling-induced pore\ngeneration and ionic liquid functionalization. The block copolymer\nof poly(2-dimethylaminoethyl methacrylate)-<i>block</i>-polystyrene\n(PDMAEMA-<i>b</i>-PS, abbreviated as SDMA) films is immersed\nin a mixture of ethanol and bromopropane. In addition to the formation\nof nanoporous structures, an interfacial quaternization reaction between\nthe PDMAEMA blocks and bromopropane occurs to generate poly(methacrylatoethyl\npropyl dimethylammonium bromide), resulting in the PIL-Br-functionalized\nmembrane (SIL-Br) during the swelling process. It is noteworthy that\nbromopropane acting as a reactant also promotes the process of selective\nswelling. The water permeability of the resulting SIL-Br membrane\nis several times higher than that of the SDMA membrane, which is attributed\nto the increased pore size and significantly higher hydrophilicity\nof the SIL-Br membrane. In addition, the anion exchange of SIL-Br\nwith l-proline (l-Pro) readily forms SIL-Pro-functionalized\nmembranes (SIL-Pro), which exhibit exceptional electrical neutrality.\nAntifouling tests demonstrate that both SIL-Br and SIL-Pro have excellent\nresistance to proteins compared to the non-PIL-functionalization SDMA\nmembrane, implying their great potential as antifouling membranes\nfor water treatment.