Back Cover: In article number 2100585 by Karim Aissou and co‐workers, a nanoporous layer of perforated lamellae (PL) is produced on top surface of asymmetric triblock terpolymer membranes generated by non‐solvent induced phase separation. The thickness of the PL phase is adjusted by varying the duration of the solvent vapor annealing (SVA) treatment.
Asymmetric and nanostructured polystyrene-block-poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO or SVEO, S:V:EO ≈ 56:34:10, 79.5 kg mol -1 ) thick films blended with 20 wt% of a short PS homopolymer (hPS, 10.5 kg mol -1 ) are achieved by combining the non-solvent induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment. Here, the NIPS step allows for the formation of a highly-permeable sponge-like substructure topped by a dense thin layer exhibiting poorly-ordered nanopores while the subsequent SVA treatment enables to reconstruct the material top surface into a porous monolayer of well-ordered hexagonal perforated lamellae (HPL). This optimized film architecture generated by NIPS-SVA shows a water permeability of 860 L h -1 m -2 bar -1 , which is roughly two times higher than the flux measured through NIPS made PS-b-P2VP-b-PEO/hPS materials having poorly-ordered nanopores. The post-SVA treatment is also revealed as a powerful tool to tailor the thickness of the nanostructure formed within the blended material because monoliths entirely composed of a HPL phase are produced by increasing the time of exposure to a chloroform stream. The water flux of such PS-b-P2VP-b-PEO/hPS monoliths is found to be an order of magnitude lower than that of their asymmetric film homologues.
Amphiphilic block copolymer (BCP) thick films with stimuli-responsive pores are promising candidates for the manufacturing of next-generation ultrafiltration (UF) membranes since their smart nanochannels facilitates the removal of fouling which is considered as one of the biggest challenges in membrane technology. In this work, a well-defined polystyrene-blockpoly(2-vinylpyridine)-block-poly(N-isopropylacrylamide) (PS-b-P2VP-b-PNIPAM) terpolymer was prepared for the first time via reversible addition-fragmentation chain transfer (RAFT) polymerization. The combination of the nonsolvent-induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment was used to produce nanostructured pH-and thermo-double sensitive ABC-type BCP thick films. Here, the NIPS-made PS-b-P2VPb-PNIPAM thick film, comprising a microporous spinodal-type network substructure, topped by a dense thin layer of poorly defined nanopores is transformed into a monolith entirely composed of a well-ordered perforated lamellar (PL) phase upon exposure to a chloroform vapor during 6h. Such kind of PL-structured monoliths, showing a permeance value as high as 18 L.h -1 .m -².bar -1 at 46°C and pH = 7 with an excellent temperature cyclability, are highly desired to manufacture smart separation-based UF materials able to transit their pore state from hydrophilic to hydrophobic (and vice versa), thereby leading to much more efficient detachment of foulants during the cleaning process.
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