Disulfonated Poly(arylene ether sulfone) Random Copolymer Blends Tuned for Rapid Water Permeation via Cation Complexation with Poly(ethylene glycol) Oligomers

Abstract

Here we present fundamental studies of a new blending strategy for enhancing water permeability in ionomeric reverse osmosis membrane materials. A random disulfonated poly(arylene ether sulfone) copolymer containing 20 mol percent hydrophilic units (BPS-20) in the potassium salt (-SO 3 K) form was blended with hydroxyl-terminated poly(ethylene glycol) oligomers (PEG, M n = 600-2 000) to increase the water permeability of BPS-20. Blending PEG with the copolymer resulted in pseudoimmobilization of the BPS-20 polymer chains because PEG complexes with cations in the sulfonated polymer matrix. Strong ion-dipole interactions between the potassium ions of the BPS-20 sulfonate groups (-SO 3 K) and the PEG oxyethylene (-CH 2 CH 2 O-) groups were observed via NMR spectroscopy. These interactions are similar to those reported between crown ethers and free alkali metal systems. The PEG oligomers were compatible with the copolymer at 30 °C in an aqueous environment. Transparent and ductile BPS-20_PEG blend films exhibited a Fox-Flory-like glass transition temperature depression as the PEG volume fraction increased. This depression depended on both PEG chain length and concentration. Both ion-dipole interactions and high coordination of -CH 2 CH 2 O-with -SO 3 K yielded a defined and interconnected hydrophilic channel structure. The water permeability and free volume of BPS-20_PEG blend films containing 5 or 10 wt % PEG increased relative to BPS-20. The blend films, however, exhibited reduced sodium chloride (NaCl) rejection compared to BPS-20. Addition of PEG did not significantly alter the material's dry-and hydrated-state mechanical properties. Unlike commercial state-of-the-art polyamide RO membranes, the blend materials do not degrade when exposed to aqueous chlorine (hypochlorite) at pH 4. This comprehensive suite of measurements provides understanding of the molecular and morphological features needed for rational design of next-generation, chlorine-tolerant water purification materials.

Sulfonated hydrocarbon membranes for medium-temperature and low-humidity proton exchange membrane fuel cells (PEMFCs)

“…SiO 2 content = 10 wt%). Similar results were also observed in other sulfonated polymer matrices (i.e., SPI [109,193] and ® dispersant in solvents [193] and (b) strong interaction between ethylene oxide (EO) units and sulfonated groups in the dispersants and sulfonated copolymers, respectively [231]. [231] Copyright 2011, American Chemical Society.…”

“…When the surfactant-SiO 2 micelles were incorporated into sulfonated copolymer matrices, EO units in the surfactants formed strong complexes via ion-dipole interactions with sulfonated groups in the polymers (Fig. 47(b) [216,231]). It made functionalized SiO 2 particles positioned at the hydrophilic domains, which control water/proton transport in the copolymer systems [193,216,227].…”

Synthesis and investigation of desalinating, antibacterial, and mechanical properties of tetraethylorthosilicate crosslinked chitosan/polyethylene glycol (PEG‐300) membranes for reverse osmosis

“…In these scans, the peak value of tan δ having greatest intensity is considered to be the T g value or the value at which α transitions in membranes take place. It is obvious from this figure that T g is greatly influenced by the concentration of PEG added in the membrane . At low concentration of PEG, that is, 0.1 mL, there is no obvious change in the T g of the modified membrane than that of control.…”

Effect ofN-methyl amide linkage on hydrogen bonding behavior and water transport properties of partiallyN-methylated random aromatic copolyamides

“…All of the PA‐X‐Y membranes with less than 2 μm thickness were successfully prepared by a spin‐coating method. Densities of the dry membranes were measured for estimation of the free volume which affects the water and salt transport properties . With the increase in the ratio of the MDAE unit in the polymer backbone, the dry density clearly decreases relative to PA‐0‐0 (1.31 g/cm 3 ) and PA‐20‐0 (1.30 g/cm 3 ) (Table ).…”