Zwitterionic Nanohydrogels–Decorated Microporous Membrane with Ultrasensitive Salt Responsiveness for Controlled Water Transport

Aqiang Wang1, Wangxi Fang2, Jingya Zhang2, Shoujian Gao2, Yuzhang Zhu*,2（朱玉长）,and Jian Jin*,1,2（靳健）

1 College of Chemistry Chemical Engineering and Materials Science Soochow University Suzhou 215123, China

2 i-Lab Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou 215123, China

Small 2019, 1903925

Highly sensitive responsiveness is vital for stimuli-responsive membranes. However, it is a great challenge to fabricate stimuli-responsive membranes with ultrahigh gating ratio (the ratio of the salt solution permeating flux to the pure water permeating flux) and high response speed simultaneously. In this work, a salt-responsive membrane with an ultrahigh gating ratio is fabricated via a facile strategy by grafting zwitterionic nanohydrogels onto a poly(acrylic acid)-grafting-poly(vinylidene fluoride) (PAA-g-PVDF) microporous membrane. Due to the synergistic effect of two functional materials, PAA chains and zwitterionic nanohydrogels tethered on PAA chains, this stimuliresponsive membrane exhibits an ultrasensitive salt responsiveness with a gating ratio of up to 8.76 times for Na+ ions, 89.6 times for Mg2+ ions, and 89.3 times for Ca2+ ions. In addition, such zwitterionic nanohydrogels–grafted PAA-g-PVDF (ZNG-g-PVDF) membranes exhibit very rapid responses to stimuli. The permeating flux changes swiftly while altering the feed solution in a continuous filtration process. The excellent salt-responsive characteristics endow such a ZNG-g-PVDF membrane with great potential for applications like drug delivery, water treatment, and sensors.

链接：https://onlinelibrary.wiley.com/doi/pdf/10.1002/smll.201903925