Sub-8 nm networked cage nanofilm with tunable nanofluidic channels for adaptive sieving.

Liu, Si-Hua; Zhou, Jun-Hao; Wu, Chunrui; Zhang, Peng; Cao, Xingzhong; Sun, Jian-Ke · Nat Commun · 2024

basic_science · Level V

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Abstract

Biological cell membrane featuring smart mass-transport channels and sub-10 nm thickness was viewed as the benchmark inspiring the design of separation membranes; however, constructing highly connective and adaptive pore channels over large-area membranes less than 10 nm in thickness is still a huge challenge. Here, we report the design and fabrication of sub-8 nm networked cage nanofilms that comprise of tunable, responsive organic cage-based water channels via a free-interface-confined self-assembly and crosslinking strategy. These cage-bearing composite membranes display outstanding water permeability at the 10<sup>-5</sup> cm<sup>2</sup> s<sup>-1</sup> scale, which is 1-2 orders of magnitude higher than that of traditional polymeric membranes. Furthermore, the channel microenvironments including hydrophilicity and steric hindrance can be manipulated by a simple anion exchange strategy. In particular, through ionically associating light-responsive anions to cage windows, such 'smart' membrane can even perform graded molecular sieving. The emergence of these networked cage-nanofilms provides an avenue for developing bio-inspired ultrathin membranes toward smart separation.