Selective Transport through Membranes with Charged Nanochannels Formed by Scalable Self-Assembly of Random Copolymer Micelles

Abstract

Membranes that can separate compounds based on molecular properties can revolutionize the chemical and pharmaceutical industries. This study reports membranes capable of separating organic molecules of similar size based on their electrostatic charge. These membranes feature a network of carboxylate-functionalized 1-3 nm nanochannels, manufactured by a simple, scalable coating process: a porous support is coated with a packed array of polymer micelles in alcohol, formed by the self-assembly of a water-insoluble random copolymer with fluorinated and carboxyl functional repeat units. The interstices between these micelles serve as charged nanochannels through which water and solutes can pass. The negatively charged carboxylate groups lead to high separation selectivities between organic solutes of similar size but different charge. In single-solute diffusion experiments, neutral solutes permeate up to 263 times faster than negatively charged compounds of similar size. This selectivity is further enhanced in experiments with mixtures of these solutes. No permeation of the anionic compound was observed for over 24 h. In filtration experiments, these membranes separate anionic and neutral organic compounds while exhibiting water fluxes comparable to that of commercial membranes. Furthermore, carboxylate groups can be functionalized, creating membranes with nanopores with customizable functionality to enable a broad range of selective separations.

Thermal properties and structure of electrospun blends of PVDF with a fluorinated copolymer

“…Membranes for filtration are manufactured using several fabrication methods. Common approaches include use of ultrathin layers of material employing deposition techniques on substrates, spin casting, solution‐casting, and nonsolvent induced phase separation processes …”

“…12 Membranes with advanced functionalities have been fabricated through the design of functional polymers 11,[13][14][15][16] which enhance membrane performance. [17][18][19] Membranes for filtration are manufactured using several fabrication methods. Common approaches include use of ultrathin layers of material employing deposition techniques on substrates, [19][20][21][22] spin casting, 20 solution-casting, 21 and nonsolvent induced phase separation processes.…”

“…[17][18][19] Membranes for filtration are manufactured using several fabrication methods. Common approaches include use of ultrathin layers of material employing deposition techniques on substrates, [19][20][21][22] spin casting, 20 solution-casting, 21 and nonsolvent induced phase separation processes. [22][23][24] Electrospinning (ES) is another popular fabrication method used to make fibrous membranes, [25][26][27][28] due to its simplicity and scalability.…”

Chemically Tailored Multifunctional Asymmetric Isoporous Triblock Terpolymer Membranes for Selective Transport

“…[9] The interstices of the packed array of spherical silica colloidal crystals and random copolymer micelles have also been utilized as nanochannels with ionic or chiral moieties. [10] The periodic-ordered nanostructure of a block copolymer (BCP) can be translated into high-performance membranes employing the evaporation-induced self-assembly together with the nonsolvent-induced phase separation (SNIPS). [11] It is a straightforward and very fast one-step scalable method to fabricate mechanically robust membranes having high porosity and uniform pores at the surface.…”

Fine tuning the hydrophobicity of counter‐anions to tailor pore size in porous all‐poly(ionic liquid) membranes

“…There are generally three effective strategies for the fabrication of CPMs. (i) The self‐assembly and dewetting of block copolymers or their blends on a substrate to obtain CPMs . (ii) Electrostatic layer‐by‐layer assembly of specific building blocks of opposite charge under carefully designed conditions to make CPMs .…”