Responsive Nanoporous Membranes with Size Selectivity and Charge Rejection from Self-Assembly of Polyelectrolyte “Hairy” Nanoparticles

Abstract

We report the preparation and characterization of charged nanoporous membranes by self-assembly of “hairy” silica nanoparticles (HNPs) functionalized with polyelectrolyte copolymer brushes. We show that HNP membranes possess high water flux, have well-defined pore sizes, and rejection up to 80% of charged species in solution. The properties of these membranes can be tuned by controlling the length and composition of polymer brushes and the electrolyte concentration in solution. We demonstrate that membrane pore sizes undergo changes of up to 40% in response to changes in the ionic strength of the salt solution. Using MD computer simulations of a coarse-grained model, we link these tunable properties to the conformations of polymer chains in the spaces between randomly packed HNPs. As polymer length increases, the polymers fill the interparticle gaps, and the pore size decreases markedly. On the basis of their straightforward fabrication and tunable properties, HNP membranes may find applications in size- and charge-selective separations, water desalination, and responsive devices.

Temperature-Responsive Nanoporous Membranes from Self-Assembly of Poly(N-isopropylacrylamide) Hairy Nanoparticles

“…In a previous work, we demonstrated that silica nanoparticles grafted with short polymer brushes can form robust nanoporous membranes via reversible nanoparticle assembly in organic solvents and in water, due to electrostatic and hydrophobic interactions, respectively . We also reported the preparation of charged nanoporous membranes by self-assembly of HNPs functionalized with polyelectrolyte copolymer brushes . We demonstrated that the pore sizes in these membranes undergo changes of up to 40% in response to changes of the ionic strength of the salt solution.…”

“…27 We also reported the preparation of charged nanoporous membranes by selfassembly of HNPs functionalized with polyelectrolyte copolymer brushes. 28 We demonstrated that the pore sizes in these membranes undergo changes of up to 40% in response to changes of the ionic strength of the salt solution. We rationalized this behavior by postulating that polymer brushes in the interstitial spaces between HNPs change their conformation similar to polymer brushes grafted inside the nanopores of preformed porous solids.…”

Voltammetric behaviour of cationic redox probes at mesoporous silica film electrodes

“…The transport of ions and molecules in nanochannels and through nanopores has been extensively studied [1][2][3][4][5][6], notably because nanoporous membranes offer attractive features for applications in separation [7][8][9][10][11][12], sensors [13][14][15], catalysis [16,17], or energy storage [17].…”

Rational ion transport management mediated through membrane structures

“…[ 163 ] The special 3D nanochannels endowed the separator with a high discharge C‐rate capability (60 mAh g −1 when cathode/anode = 3.5/1.7 mg cm −2 ) compared to common PP/PE/PP separators. Carbon (e.g., mesoporous membranes [ 164,165 ] and porous fibers [ 166,167 ] ) (Figure 7F) and SiO 2 (e.g., self‐assembled nanoparticles [ 168,169 ] ) with 3D nanochannels are common inorganic materials for adjusting ion transport.…”