Selective Swelling of Block Copolymers: An Upscalable Greener Process to Ultrafiltration Membranes?

Block copolymers (BCPs) have long been pursued as precursors to nanoporous membranes, and selective swelling-induced pore generation has emerged as an extremely simple strategy to BCP membranes with both well-defined nanoporosity and inherently functional surfaces. In this Perspective, we briefly discuss the principles of this pore-making method and summarize its key features and most recent progress on thus-produced ultrafiltration membranes. Exciting results toward the upscaling of this method are highlighted: the large-scale, affordable synthesis of polysulfone-based BCPs and the continuous manufacturing of BCP membranes by melt extrusion coupled with microwave-boosted selective swelling. Importantly, we reveal the greener nature of this selective swelling process compared to conventional phase inversion methods as it involves less aggressive solvents and produces no wastewaters. An outlook on the remaining challenges and future efforts to push selective swelling to real-world applications is also presented.