Quaternization of a Polystyrene‐block‐poly(4‐vinylpyridine) Isoporous Membrane: An Approach to Tune the Pore Size and the Charge Density

Abstract

Isoporous integral asymmetric membranes derived from the self‐assembly of block copolymers combined with the non‐solvent‐induced phase separation (SNIPS) have gained great attention. To extend their utility, good control over pore size and surface functionality in a facile manner is highly desirable. Here, an approach is proposed to achieve this by quaternization of the poly(4‐vinylpyridine) moiety of a polystyrene‐block‐poly(4‐vinylpyridine) SNIPS membrane using alkyl iodides via a scalable gas‐solid heterogeneous reaction. By changing the size of the alkyl groups of the quaternization agent and the degree of quaternization, the effective pore size of the membrane is tailored in a wide range from the ultrafiltration to the nanofiltration regime. A quaternization of approximately half of the 4VP repeating units of the membranes with methyl iodide, ethyl iodide, or 1‐propyl iodide leads to a retention of methylene blue from a 10 mg L−1 aqueous solution of 96%, 87%, and 83%, respectively.

High-performance asymmetric isoporous nanocomposite membranes with chemically-tailored amphiphilic nanochannels

“…31 Additionally, the reported PS-b-P4VP membrane with positively charged nanochannels exhibited a similar sinking rate of a water droplet as that of SM. 40 Therefore, these results reveal that I0 is a strong hydrophobic membrane, whereas SM turns into a hydrophilic membrane which is ascribed to the introduction of the sulfonate groups along the pore wall. The surface zeta potential (z) of I0 is negative in the pH range of 3.9-10, likely due to the hydrophobic character and preferred absorption of hydroxide ions.…”

“…In a previous work we have demonstrated that the hydrated channels of a quaternized polystyrene-block-poly(4vinylpyridine) (PS-b-P4VP) membrane can be tuned from the ultra-to the nanoltration regime gradually by changing the quaternization agent and the degree of functionalization. 40 SNIPS membranes are mostly fabricated from amphiphilic block copolymers with at least one hydrophobic and one or more hydrophilic segment, 41 e.g. PS-b-P4VP, 24,42,43 polyisoprene-blockpolystyrene-block-poly(4-vinylpyridine) (PI-b-PS-b-P4VP), 44,45 polyisoprene-block-polystyrene-block-poly(N,N-dimethylacrylamide), 36,37 polystyrene-block-poly(4-vinylpyridine)-block-poly(solketal methacrylate), 46 polystyrene-block-poly(4-vinylpyridine)-block-poly(ethylene oxide).…”

Well-defined polyvinylpyridine-block-polystyrene diblock copolymers via RAFT aqueous-alcoholic dispersion polymerization: synthesis and isoporous thin film morphology

“…6c, f and i) can be assigned to the electron-rich iodine, which selectively stained the PVP phase. 71 Due to its high atomic number (53), iodine leads to strong backscattering of electrons. 59 Although SEM and AFM produce similar representations of the thin film surface structure, SEM enabled to capture a large area view of the surface structure at once, while AFM only allowed to view 1 μm × 1 μm areas.…”

A mild and quantitative route towards well-defined strong anionic/hydrophobic diblock copolymers: synthesis and aqueous self-assembly

“…19,20 For polycations, a more commonly employed method involves quaternization of ortho-or para-substituted vinylpyridines. [21][22][23][24][25] These quaternization reactions are, however, often incomplete and thus require thorough analysis in order to determine the exact charge density, which is a crucial parameter when polyelectrolyte complexes are concerned. 26,27 Polystyrene sulfonate is among the easiest accessible strong polyanions, and while it can be synthesized directly from commercially available styrene sulfonate, sulfonation of polystyrene continues to be the most frequently applied route toward this polyelectrolyte.…”