Ultrafast Water Transport in Two‐Dimensional Channels Enabled by Spherical Polyelectrolyte Brushes with Controllable Flexibility

Abstract

Fast water transport channels are crucial for waterrelated membrane separation processes.However,overcoming the trade-off between flux and selectivity is still am ajor challenge.T oa ddress this,w ec onstructed spherical polyelectrolyte brush (SPB) structures with ah ighly hydrophilic polyelectrolyte brush layer,a nd introduced them into GO laminates,w hichi ncreased both the flux and the separation factor.A t7 0 8 8C, the flux reached 5.23 kg m À2 h À1 ,a nd the separation factor of butanol/water increased to % 8000, which places it among the most selective separation membranes reported to date.I nterestingly,f urther studies demonstrated that the enhancement of water transport was not only dependent on the hydrophilicity of the polyelectrolyte chains, but also influenced by their flexibility in the solvent. Quartz crystal microbalance with dissipation and molecular dynamics simulations revealed the structure-performance correlations between water molecule migration and the flexibility of the ordered polymer chains in the 2D confined space.

General synthesis of ultrafine metal oxide/reduced graphene oxide nanocomposites for ultrahigh-flux nanofiltration membrane

“…Broadening the interlayer spacings have been employed to modulate the water transport behaviors in GO membranes, generally via intercalation of soft polymers including cationic porphyrin 26 , polyacrylonitrile gel 27 , polyelectrolyte brushes 28 . However, incorporating polymer additives often cause very limited enhancement of water permeability, mainly owing to the intrinsic elastoplastic of the polymers and their uneven distribution on the GO surface 29 , 30 .…”

GO-Based Membranes for Desalination

“…This makes the separation performance of small molecules weaker, and interlayer spacing must be reduced to ensure the separation selectivity of the membrane. However, the reduction in interlayer spacing tends to lead to a decrease in permeability [ 49 ]. Therefore, precise adjustment of the size of the two-dimensional mass transfer channels between GO layers is significant regarding simultaneous improvement of the selectivity and permeability of the membrane and mitigation of the trade-off effect.…”

Functional molecular cross‐linked zeolite nanosheets heighten ion selectivity and conductivity of flow battery membrane

“…Recently, two‐dimensional MFI‐type zeolite nanosheets (ZN)‐based membranes exhibit excellent performance in ions and molecules separation owing to the large lateral dimension, and nanometer‐sized thickness in preferred straight channel direction 38–41 . High‐aspect‐ratio ZN, which can maximize the ion discrimination ability and minimize proton transport path, 42–45 have extreme potential as functional building blocks for the development of novel proton conductive membranes. Despite the attractive advantage of ZN in proton selective transport, it still needs to develop suitable strategies to tap its potential and promote the practical application in proton conductive membrane.…”