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A branched polymer was prepared by grafting allyltrimethylammonium chloride onto polyvinyl alcohol (PVA) via free‐radical polymerization. Afterwards, a series of hybrid membranes were prepared by sol‐gel cross‐linking between quaternary ammonium‐PVA and tetraethoxysilane. The obtained membranes were characterized in terms of infrared spectroscopy, ion exchange capacity, water uptake, linear expansion ratio, and acid resistance. The thermal properties of the membranes were investigated as well. The diffusion dialysis performances of the membranes were tested by using a simulated feed solution containing HCl and FeCl2. The diffusion dialysis coefficients and the separation factors were much better than those of the commercial DF‐120 membrane. [ABSTRACT FROM AUTHOR]

To access highly ion-conductive membrane materials which are urgently desired by the technologies like fuel cells, flow batteries, electro-dialysis etc., a novel polymer architecture featured by the densely grafting of three ionic strings onto each benzene ring was developed. Compared with the previous densely functionalized AEMs prepared by closely attaching multiple cations onto polymer main chain, this study aims to achieve the improved nano-phase separation ability through combing the advantages of high cation mobility and high cation density. As a result, distinct ion conducting channels were observed by atomic force microscopy and high Br - conductivity of 50.6 mS/cm was achieved at 80 °C, suggesting the effectiveness of this strategy. [ABSTRACT FROM AUTHOR]

Anion exchange membranes (AEMs) are employed as the gas separator and hydroxide ion conductor between the anode and the cathode of alkaline polyelectrolyte fuel cell (APEFC). Highly conductive and stable AEMs are urgently needed in order to achieve satisfactory fuel cell performance. Nevertheless, the low hydroxide conductivity remains major challenge that limits the development and application of APEFC. In order to improve the hydroxide conductivity of AEMs, highly ordered ion conducting channels must be constructed within the membrane matrix. In this study, an AEM with particular polymer structure was designed to achieve fine ion conducting channels by facilitating the hydrophilic-hydrophobic phase separation. Concretely, the side chain of this polyelectrolyte contains two quaternary ammonium groups and terminates with one long hydrophobic tail. Ascribing to the enhanced nano-phase separation ability, inter-connected ion conducting channels were observed by AFM as well as SAXS. A high hydroxide conductivity of 47 mS/cm at 25 °C and 85 mS/cm at 80 °C was achieved. In addition, when applied in an APEFC system, the synthesized AEM showed an outstanding peak power density of 369.3 mW/cm 2 . Good alkaline tolerance, lowered water uptake and swelling ratio were also observed attributing to its carefully designed polymer structure. [ABSTRACT FROM AUTHOR]

The development of polymeric anion exchange membranes (AEMs) for recycling acid is facing a serious difficulty, the desired acid passage and undesired salt leakage dilemma. Ionic domains are the only channels to conduct H + ions and metallic ions, and thus viable modifications on ionic domains render the permeation of two ions simultaneously enhanced or limited, leading to “trade-off” effect. Herein, we propose an origin strategy of “three-phase” AEMs to beat this “rade-off” effect. Apart from typical hydrophobic polymer backbone and hydrophilic cation phase domains, the auxiliary phase domains built by graphene oxide (GO) sheets were added. Due to the abundant oxygen containing groups distributing on GO, the auxiliary phase domains not only aid to transport H + ions, but also capture metallic ions. With only 0.5 wt% GO loadings, the “three-phase” AEM increased acid recovery efficiency and separation factor by 40% and 51% for the FeCl 2 /HCl system respectively, compared with the “two-phase” AEM. To explain these results, density functional theory (DFT) simulation was applied to study the interactions between GO and Fe 2+ ions. [ABSTRACT FROM AUTHOR]

• In-situ crosslinked AEMs with self-assembled nanostructure were prepared. • The membranes exhibited excellent H+ diffusion coefficient and selectivity. • Balance between the acid recovery efficiency and processing capacity was achieved. The highly selective anion exchange membranes (AEMs) for acid recovery were invented via cationic functionalization of bromo poly(2, 6-dimethyl-1, 4 phenylene oxide). The quantity of tris(2-(2-methoxyethoxy) ethyl) amine (TDA) was precisely adjusted to obtain hydrophilic ion transport channels in the membrane structure. The vinyl part of 2-(dimethylamino) ethyl methacrylate (DMAEMA) was in-situ crosslinked to achieve high selectivity. The cationic groups being efficiently produced by TDA and DMAEMA were responsible for high flux, while the crosslinked nature of the membrane restricted the active transport of Fe2+ ion. The self-assembled nanostructure AEMs showed an excellent selectivity from 49 to 1391 and H+ dialysis coefficients up to 0.0325 m h−1, respectively at 25 °C, which is superior as compared with a commercial DF-120 membrane and some recently reported dense membranes. The representative membranes exhibited better operational stability for 10 consecutive cycles during the entire diffusion dialysis process. [ABSTRACT FROM AUTHOR]