Promotion of morphology transition of di-block copolymer nano-objects was achieved via RAFT dispersion copolymerization because of the enhancement of the mobility of the solvophobic block.

Covalent triazine framework (CTF) nanosheets featured with uniform intrinsic nanoporosity and excellent stability are promising building blocks for fast, selective membranes. However, it remains challenging to produce ultrathin CTF nanosheets, significantly hindering the development of CTF-based membranes. Herein, we develop a mild oxidation strategy to exfoliate CTFs, enabling the preparation of highly permeable membranes with stacked CTF nanosheets as the selective layers. The interlamellar spacing of CTF is effectively expanded following the mechanism of “proton donating–accepting” in which dimethyl sulfoxide (DMSO) works as a soft oxidant, leading to ultrathin CTF nanosheets with the assistance of ultrasonication. Furthermore, oxygen-containing functional groups are also introduced onto the CTF nanosheets through mild oxidation, improving surface hydrophilicity. The CTF nanosheet can be stacked onto porous substrates by vacuum filtration to form composite membranes with the thickness of the stacked CTF nanosheets down to ∼30 nm. Thus-obtained membranes exhibit impressive dye separation performances with both high water permeance and high rejection. This work provides not only an efficient method to synthesize ultrathin CTF nanosheets but also a process to prepare fast but selective membranes for molecular separations.

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.

Nanoporous polymers with functionalizable surfaces are desired in the preparation of reactors for continuous flow catalysis.