Hydrophilic Ions Research Articles

Ions Speciation at the Water–Air Interface

In typical aqueous systems, including naturally occurring sweet and salt water and tap water, multiple ion species are co-solvated. At the water-air interface, these ions are known to affect the chemical reactivity, aerosol formation, climate, and water odor. Yet, the composition of ions at the water interface has remained enigmatic. Here, using surface-specific heterodyne-detected sum-frequency generation spectroscopy, we quantify the relative surface activity of two co-solvated ions in solution. We find that more hydrophobic ions are speciated to the interface due to the hydrophilic ions. Quantitative analysis shows that the interfacial hydrophobic ion population increases with decreasing interfacial hydrophilic ion population at the interface. Simulations show that the solvation energy difference between the ions and the intrinsic surface propensity of ions determine the extent of an ion's speciation by other ions. This mechanism provides a unified view of the speciation of monatomic and polyatomic ions at electrolyte solution interfaces.

Detection of Interfering Ions Using Ion Flux Phenomena in Flow-Through Cl-ISEs with Ion Exchange Membranes.

Ion-selective electrodes (ISEs) are among the most successful electrochemical sensors used in various applications because of their ability to measure electrolyte concentrations in liquids easily. It is common practice to suppress ion fluxes through the ion-sensitive membranes in ISEs because such fluxes worsen the lower limit of detection. In this study, we propose a method to detect interfering ions using this ion flux phenomenon. As a proof of principle, a flow-type Cl-ISE based on an ion exchange membrane loaded with the target ion chloride was used to acquire transient potential profiles during standstill after the introduction of liquids containing various ion species. When the target ion of the ion-sensitive membrane was measured, there was almost no change in potential over time. In contrast, when hydrophilic interfering ions were measured, the potential gradually decreased, and when hydrophobic interfering ions were measured, the potential gradually increased. The direction and intensity of these changes over time depended on the ion species and concentrations. The main reason for these potential changes is presumed to be the change in the local ionic composition of the sample near the sensing membrane due to ion exchange between the sample and membrane. This phenomenon could not be observed in a hydrophobic ion exchanger membrane doped with a quaternary ammonium salt and was characteristically observable using hydrophilic ion exchange membranes with a high charge density and a high ion diffusion rate. Finally, using a high-throughput flow-type system, we demonstrated the detection of interfering ions in solutions containing multiple ion species by using the ion flux phenomenon.

Sodium hexametaphosphate-treated halloysite based solid-phase extraction of biguanides from dietary supplements.

Raw halloysite was purified by using sodium hexametaphosphate and utilized as the solid-phase extraction sorbent for the determination of biguanides from dietary supplements. The purified halloysite was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The purified halloysite interacted with biguanides through hydrophilic interaction and ion exchange on account of its abundant hydroxyl groups and negative charge. Compared with traditional extraction methods based on hydrophobic interaction and/or ion exchange, the purified halloysite adsorbed more biguanides due to hydrophilicity and ion exchange, with a sample loading volume of up to 100 mL at least. Excellent reproducibility of halloysite purification was achieved, with within-batch (n = 3) and batch-to-batch (n = 3) relative standard deviations in the ranges of 1.5-4.2% and 5.6-8.8%, respectively. Coupled with reversed-phase liquid chromatography-tandem mass spectrometry, a low limit of detection of 0.3 μg kg-1 was obtained. The intra- and inter-day mean recoveries of the biguanides spiked at three levels in dietary supplements were within the ranges of 88.5-107.2% and 86.4-102.0%, respectively. The intra- and inter-day precisions were within the ranges of 1.5-6.4% and 5.4-9.9%, respectively. These results indicated that the developed method is efficient for the determination of trace biguanides in dietary supplements.

Analysis of highly polar pesticides in foods by LC-MS/MS.

Highly polar pesticides (HPP) are a group of pesticides that are characterize as low Log Kow. Many high-throughput multi-residue analysis methods based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of such polar pesticides have been proposed. In this article, we summarize the various sample preparation methods including quick polar pesticides (QuPPe), dispersive solid phase extraction (dSPE), solid phase extraction (SPE) and QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), especially for QuPPe, which are mainly used for the determination of HPP in foods. In addition, we summarize LC-based separation methodologies that are currently used for the analysis of HPP in foods, including reversed-phase chromatography (RPC), hydrophilic interaction liquid chromatography (HILIC), ion chromatography (IC) and mixed-mode chromatography (MMC). Finally, the current mass spectrometry-based methodologies for the analysis of HPP are summarized with a specific focus on MS configurations and acquisition modes.

Multidimensional separation and analysis of alpha-1-acid glycoprotein N-glycopeptides using high-field asymmetric waveform ion mobility spectrometry (FAIMS) and nano-liquid chromatography tandem mass spectrometry.

Bottom-up nLC-MS/MS-based glycoprotein mass spectrometry workflows rely on the generation of a mixture of non-glycosylated and glycosylated peptides via proteolysisof glycoproteins. Such methods are challenged by suppression of hydrophilic glycopeptide ions by more abundant, hydrophobic, and readily ionizable non-glycosylated peptides. Commercially available high-field asymmetric waveform ion mobility spectrometry (FAIMS) devices have recently been introduced and present a potential benefit for glycoproteomic workflows by enabling orthogonal separation of non-glycosylated peptides and glycopeptides following chromatographic separation, and prior to MS/MS analysis. However, knowledge is lacking regarding optimal FAIMS conditions for glycopeptide analyses. Here, we document optimal FAIMS compensation voltages for the transmission and analysis of human alpha-1-acid glycoprotein (AGP) tryptic N-glycopeptide ions. Further, we evaluate the effect of FAIMS on AGP glycopeptide assignment confidence by comparing the number of assigned glycopeptides at different confidence levels using a standard nLC-MS/MS method or an otherwise identical method employing FAIMS. Optimized methods will potentiate glycoproteomic analyses by increasing the number of unique glycopeptide identifications and the confidence of glycopeptide assignments. Data are available via ProteomeXchange with identifier PXD036667. Analysis of alpha-1-acid glycoprotein (AGP) tryptic digests via nLC-FAIMS-MS/MS (top) led to the establishment of ideal FAIMS voltages for the analysis of AGP N-glycopeptides (bottom), suggesting that FAIMS can improve the depth of glycoproteome characterization. Pairs of CV magnitudes are shown along the x-axis.

Highly Sulfonated Aromatic Graft Polymer with Very High Proton Conductivity and Low Hydrogen Permeability for Water Electrolysis

An aromatic graft polymer was synthesized for a proton exchange membrane (PEM) by grafting a highly sulfonated poly(phenylene sulfide sulfone) side chain onto a poly(arylene ether sulfone) main chain, thus creating a phase-separated morphology with cocontinuous channels of small hydrophilic ion domains. The graft PEM with the distinct hydrophilic/hydrophobic-separated morphology showed low hydrogen permeability while maintaining high proton conductivity. Along with durable dimensional, mechanical, and thermohydrolytic stabilities, the graft PEM showed effective properties for PEM water electrolysis (PEMWE). The graft PEM afforded a PEMWE performance of 6000 mA cm–2 at 1.9 V, which was 2.1-fold higher than that of N212, and showed a durable performance without loss for 50 h at a high current density (1000 mA cm–2).

Simple and fast determination of tetrodotoxin in human plasma based on hydrophilic-interaction/ion-exchange mixed-mode solid phase extraction combined with liquid chromatography-tandem mass spectroscopy

In this study, we developed and validated a simple, fast and sensitive LC-MS/MS method for the measurement of tetrodotoxin (TTX) in human plasma. Three HILIC-type solid phase extraction (SPE) carriers (PSA, silica, Siphila i HILIX) with different stationary phase functional groups were compared. The Siphila i HILIX SPE plate containing multi-carboxyl groups was finally selected due to obviously better extraction recovery of TTX (about 80% of recovery from plasma samples) than the other two and no significant matrix effects were observed, which was speculated to have mixed-mode synergistic effects of hydrophilic interaction and ion exchange. 100μL plasma sample was precipitated rapidly with acetonitrile containing 1% trichloroacetic acid, and filtrates were loaded onto Siphila i HILIX 96 well SPE plate. After washed with 95% acetonitrile, TTX was eluted with 200μL of 50% acetonitrile containing 1% trichloroacetic acid. 2μL of elution solution was directly injected into LC-MS/MS and the total run time on a BEH amide column was 4.5 min. The method avoids the evaporation and ultrafiltration processes which is simple and timesaving (<30 min). TTX and internal standard (arginine-15N4) were monitored in positive mode using m/z 320.3→162.2 (quantification transition for TTX), 320.3→284.1 (confirmation transition for TTX) and 179.2→63.0 (transition for IS), respectively. The method was linear in the range of 0.1–20 ng/mL for TTX with the low limit of quantification (S/N > 10) of 0.1 ng/mL; the intra- and inter-assay accuracies were in the range of 98.5%-99.8% (relative standard deviations, RSDs ≤ 5.92%) and 98.8–99.5% (RSDs ≤ 6.23%), respectively. Biases of spiking analysis were ranged from -7.00% to 7.43% for healthy human plasma samples (RSDs ≤ 8.83%) and from -5.00% to 3.93% for hemolytic, high triglyceride, high cholesterol and high bilirubin plasma samples (RSDs ≤ 6.40%), which proved the good anti-interference property of the method. The results showed that the method is sensitive, accurate, specific, reliable, and can be used to monitor the concentration of TTX in plasma to meet the needs of clinical research and poisoning screening.

Metabolomics: Going Deeper, Going Broader, Going Further.

Metabolomics is a continuously dynamic field of research that is driven by demanding research questions and technological advances alike. In this review we highlight selected recent and ongoing developments in the area of mass spectrometry-based metabolomics. The field of view that can be seen through the metabolomics lens can be broadened by adoption of separation techniques such as hydrophilic interaction chromatography and ion mobility mass spectrometry (going broader). For a given biospecimen, deeper metabolomic analysis can be achieved by resolving smaller entities such as rare cell populations or even single cells using nano-LC and spatially resolved metabolomics or by extracting more useful information through improved metabolite identification in untargeted metabolomic experiments (going deeper). Integration of metabolomics with other (omics) data allows researchers to further advance in the understanding of the complex metabolic and regulatory networks in cells and model organisms (going further). Taken together, diverse fields of research from mechanistic studies to clinics to biotechnology applications profit from these technological developments.

Preparation of high hydrophilic H2TiO3 ion sieve for lithium recovery from liquid lithium resources

Extraction of lithium from liquid lithium resources has become a popular research field, among which H2TiO3 material has great application potential. In this work, we further explored the correlation that the hydrophilicity of H2TiO3 with its adsorption performance based on the existing work. The double surfactants method was used to regulate the morphology and hydrophilic functional groups of the surface to regulate the material hydrophilia and prepare nano-sized lithium ion sieve. The effect of surfactant and preparation method on the hydrophilicity and adsorption properties of the materials were investigated. The results show that the synthesized lithium ion sieve H2TiO3-4 (HTO-4) has excellent hydrophilicity and adsorption performance reflected with the maximum adsorption capacity of 56.03 mg·g−1. Meanwhile, the adsorption capacity loss of the material is only 3.8 % after five cycles, which shows a satisfactory cyclic stability.

An extended Stokes–Einstein model for condensed ionic water structures with topological complexity

‘What is the structure of water?’ This has been a perplexing question for a long time and water structure with various phases is a great topic of research interest. Topological complexity generally occurs because hydrophilic ions strongly influence the size and shape of condensed water structures owing to their kosmotropic and chaotropic transitions. In this study, an extended Stokes–Einstein model incorporating Flory–Huggins free energy equation is proposed to describe the constitutive relationship between dynamic diffusion and condensed water structure with a topological complexity. The newly developed model provides a geometrical strategy of end-to-end distance and explores the constitutive relationship between condensed ionic water structures and their dynamic diffusion behaviors. A free-energy function is then formulated to study thermodynamics in electrolyte aqueous solution, in which the condensed ionic water structures undergo topologically complex changes. Finally, effectiveness of the proposed model is verified using both molecular dynamics simulations and experimental results reported in literature.

Ionic liquid and octadecylamine co-derived carbon dots for multi-mode high performance liquid chromatography

In this work, a novel kind of carbon dots (CDs) are synthesized by citric acid, 1-aminoethyl-3-methylimidazolium bromide ionic liquid and octadecylamine. Due to the variety of precursors, the synthesized CDs possess multiple functional groups including carboxyl, amino, hydroxyl and imidazole groups. One CDs functionalized silica gels (Si-CDs) chromatographic column can be applied in three separation modes including reversed-phase liquid chromatography, hydrophilic interaction liquid chromatography and ion exchange chromatography, suitable for separating compounds with different properties. Polycyclic aromatic hydrocarbons, alkylbenzenes, alkaloids, pesticides, antibiotics, sulfonamides, glycosides, inorganic anions, aromatic acids, nucleosides and bases as test compounds can be separated well on this Si-CDs column. For four adjacent analytes of triadimefon, tebuconazole, diniconazole and diclofop, the resolution reaches 3.77, 2.34 and 5.17 with an average column efficiency of 9500 plates/m. Retention mechanism contains hydrophobic, π-π stacking and electrostatic interactions according to linear solvation energy relationship. This Si-CDs column is used for real sample analysis of residual thiamphenicol and chloramphenicol in milk. With simplified sample pretreatment process, spiked recoveries between 89.3%-112% indicates the developed detection method based on this Si-CDs column is not only rapid but also reliable. Using CDs with multiple functional ligands as modifiers for multi-mode stationary phases avoids multi-step modification process of various small molecules on silica gels, which is helpful to the evolution of multi-mode chromatography and nanomaterials-based separation science.

Self-assembled proton conduction networks consisting of SPEEK, NH2-POSS, and IL with enhanced proton conduction and decreased IL loss

To enhance the conductivity of sulfonated polyether ether ketone (SPEEK, SP) membrane and avoid the loss of ionic liquid (IL), using aminopropyloligosisiloxane (NH 2 -POSS) as molecular hybrid filler, a self-assembled medium temperature and non-humidified SP/IL/NH 2 -POSS hybrid membrane was prepared. NH 2 -POSS can be assembled into the hydrophilic domain ion phase of SPEEK. In which, –NH 2 of NH 2 -POSS and –SO 3 H of SPEEK formed acid-base pairs at the interface which were conducive to the construction of proton transport channel. In addition, NH 2 -POSS enriched IL in the hydrophilic domain, which retained IL while synergistically increased the conductivity. The results showed that the IL loss rate of SP/IL/NH 2 -POSS-2 membrane was 46.9 wt%, which was about 55.8% of SP/IL membrane; the conductivity of SP/IL/NH 2 -POSS-2 membrane at 200 °C without humidification was 5.51 mS·cm −1 , which was about 4 times that of SP/IL membrane. • Molecular-level network SP/IL/NH 2 -POSS proton exchange membrane was prepared. • -NH 2 and –SO 3 H constructed ordered proton transport channels via acid-base pairs. • IL is enriched on NH 2 -POSS and SPEEK interface through hydrogen bonding. • Acid-base pairs and IL-rich layer synergistically increase proton conductivity.

Ion transport across bilayer lipid membranes in the presence of tetraphenylborate.

A pair of symmetrical cathodic and anodic peaks is observed in cyclic voltammograms for the ion transport across a bilayer lipid membrane (BLM) between two aqueous phases in the presence of tetraphenylborate (TPhB-). Although TPhB- serves as a carrier of a hydrophilic counter ion (Na+) under the steady-state condition, the reason for the appearance of symmetrical peaks has not been clearly explained until now. From the chronoamperometric analysis, it is turned out that the symmetrical peaks are attributed to the translocation of TPhB- between two adsorbed layers on the surface of the BLM.

Potentiometric properties of the electrochemical cells equipped with ionic liquid salt bridge and its application to determine the solubility of the ionic liquid and the mean activity coefficients of the chloride salt of the ionic liquid-constituent cation in water

Potentiometry of electrochemical cells equipped with ionic liquid salt bridge (ILSB) has been studied and applied for determination of the solubility in water of a sparingly soluble ionic liquid (IL) employed for the ILSB consisting of B + and A − , and also the mean activity coefficient of the chloride salt of the IL-constituting cation, BCl. In the case of an electrochemical cell with ILSB made of BA sandwiched by two electrolyte solutions, one containing only hydrophilic ions and the other containing BCl, the cell voltage, E cell , involves the term of the solubility of the IL, enabling the potentiometric determination of the solubility of BA in water based on the Debye-Hückel limiting law. Experimentally, from measured E cell values the solubility of tributyl(2-methoxyethyl) phosphonium bis(pentafluoroethanesulfonyl) amide ([TBMOEP + ][C 2 C 2 N − ]) is determined to be 0.15 mmol dm −3 at 25 °C. The value obtained is of thermodynamic nature because it does not involve the activity coefficient terms. An estimated value of the mean activity coefficient of tributyl(2-methoxyethyl) phosphonium chloride (TBMOEPCl) in aqueous 0.0093 M TBMOEPCl, 0.88 ± 0.01 at 25 °C, agrees with 0.87 ± 0.02 in aqueous 0.01 M TBMOEPCl obtained by the cell in which the ILSB is sandwiched by two aqueous TBMOEPCl solutions, suggesting the consistency in the present potentiometric approach.

Sodium binding is not required for fluoride channel Fluc dimerization but stabilizes the active state

To exhibit their various functions, ion channels need to faithfully assemble into the membrane. They must form stable structural scaffolds to support continuous, hydrophilic ion pathways and utilize mechanisms to link protein stability to selectivity, conductance, and gating. To better understand how ion channels balance stability and function, we studied the dimeric fluoride channel Fluc, a model system for interrogating equilibrium ion channel assembly in membranes. Single-molecule photobleaching and bulk FRET experiments demonstrate that wild-type Fluc is a long-lived dimer in membranes, in line with electrophysiological findings showing a high open probability around 95%.

Resolving Heparan Sulfate Oligosaccharide Positional Isomers Using Hydrophilic Interaction Liquid Chromatography-Cyclic Ion Mobility Mass Spectrometry.

Heparan sulfate (HS) is a linear polysaccharide covalently attached to proteoglycans on cell surfaces and within extracellular matrices in all animal tissues. Many biological processes are triggered by the interactions among HS binding proteins and short structural motifs in HS chains. The determination of HS oligosaccharide structures using liquid chromatography-mass spectrometry (LC-MS) is made challenging by the existence of positional sulfation and acetylation isomers. The determination of uronic acid epimer positions is even more challenging. While hydrophilic interaction liquid chromatography (HILIC) separates HS saccharides based on their composition, there is a very limited resolution of positional isomers. This lack of resolution places a burden on the tandem mass spectrometry step for assigning saccharide isomers. In this work, we explored the use of the ion mobility dimension to separate HS saccharide isomers based on molecular shape in the gas phase. We showed that the combination of HILIC and cyclic ion mobility mass spectrometry (cIM-MS) was extremely useful for resolving HS positional isomers including uronic acid epimers and sulfate positions. Furthermore, HILIC-cIM-MS differentiated multicomponent HS isomeric saccharide mixtures. In summary, HILIC-cIM-MS provided high-quality data for analysis of HS oligosaccharide isomeric mixtures that may prove useful in the discovery of new structural motifs for HS binding proteins and for the targeted quality control analysis of commercial HS products.

Porous and biofouling-resistant amidoxime-based hybrid hydrogel with excellent interfacial compatibility for high-performance recovery of uranium from seawater

For a massive uranium recovery from seawater, designing an adsorbent with ultrahigh uranium uptake capacity and good biofouling-resistant activity is crucial, but difficult. Here, a facile and eco-friendly freeze-thawing strategy was explored for the first time to create a physically crosslinked poly(amidoxime) (PAO)-chitosan (CS) hybrid hydrogel (PAO@CHM) with excellent interfacial compatibility, superior uranium uptake capacity and good anti-biofouling activity. The porous 3D network architecture of PAO@CHM, combined with its good hydrophilicity as well as antibacterial property, synergistically constructs numerous hydrophilic and biofouling-resistant ion channels for the rapid diffusion of uranyl ions into the interior of the hydrogel, achieving maximum use of adsorption active sites on PAO@CHM. Consequently, superior uranium uptake capacities (743.87, 865.27, and 1091.53 mg g−1 for PAO fixed on hydrogel) were obtained in 8, 16, and 32 ppm U-spiked water, respectively. Benifiting from the enhanced uranium adsorption activity and good antibacterial property, the uranium extraction capacity of PAO@CHM reached 7.46 mg g−1 after 28 days of exposure in 500 L of natural seawater, which is significantly higher than that of most of adsorbents. The O and N atoms in amidoxime group act as main bonding sites for uranium uptake. The finding of this study provides a facile and eco-friendly strategy to construct hydrophilic and biofouling-resistant amidoxime-based adsorbent for efficient uranium recovery from seawater.

Evaluation of thermal/morphological performance of SSPCM based nanoclay: Influence of the interlayer microstructure of hydrophilic and hydrophobic

The COVID-19 pandemic has led to an increase in construction energy consumption and indoor occupancy; this, in turn, has increased the demand for energy efficiency. Thermal energy storage is an effective method for energy saving and improving efficiency. In this study, improved shape-stabilized phase change materials (SSPCMs) for enhancing the energy efficiency of buildings were manufactured and evaluated. These SSPCMs were prepared via the vacuum impregnation of n-octadecane into bentonite nanoclay. Bentonite exhibits a layered tetrahedral and octahedral crystal structure with Na + cations (which feature high cation exchange capacity) in the interlayer space. The Na + ion is a hydrophilic ion that affects the properties of the interlayer. However, paraffin-PCMs are hydrophobic and have poor compatibility with water. Therefore, hydrophobicity is induced in the organic nanoclay by using an organic modifier as the PCM container. Cloisite Na + , Cloisite 15, Cloisite 20, and Cloisite 93 were used to fabricate the SSPCMs. This study compares the amount of PCM impregnated depending on the compatibility of different PCMs between hydrophilic/hydrophobic nanoclays and also evaluates the thermal performance. The observed reduction in peak temperature and the time lag effect of the PCMs confirmed that the organically modified nanoclay and the PCM composites significantly improved the amount of PCM impregnated, thermal conductivity, and latent heat characteristics. The latent heat of the hydrophobic organic nanoclay was 209% higher than that of the SSPCM-based hydrophilic nanoclay. • Composites using paraffin PCM and nanoclay were fabricated and analyzed. • Hydrophobic nanoclay showed 124% higher PCM impregnation than hydrophilic nanoclay. • It was observed that PCM impregnation was affected by the microstructure. • SSPCMs showed up to 84% improved thermal conductivity than pure PCM. • The overall thermal performance in the SSPCM based hydrophobic nanoclay were high.

Speciation of metals in indigenous plants growing in post-mining areas: Dihydroxynicotianamine identified as the most abundant Cu and Zn ligand in Hypericum laricifolium

Ag, As, Cu, Pb and Zn were found to be the principal metallic contaminants of a post-mining area of Peru (Hualgayoc, Cajamarca). Study of metal distribution amongst roots, stems, and leaves of four indigenous hypertolerant plant species, Arenaria digyna, Puya sp., Hypericum laricifolium, Nicotiana thyrsiflora indicated significant translocation of Zn (0.6 < TF ≤ 10.0) and Cu (0.4 < TF ≤ 6.5) into aerial plant organs and substantial water-extractable fraction (20–60%) of these metals, except for A. digyna (root and stems). A study of the metal speciation by ultrahigh-performance size-exclusion (fast-SEC) and hydrophilic ion interaction (HILIC) liquid chromatography with dual ICP (inductively coupled plasma) and electrospray (ESI) Orbitrap MS detection revealed the presence of nicotianamine and deoxymugineic acid copper and zinc complexes in roots, stem and leaves of N. thyrsiflora and Puya sp., and nicotianamine alone in A. digyna. A previously unreported compound, dihydroxy-nicotianamine was identified as the most abundant Cu and Zn ligand in H. laricifolium. The presence of arsenobetaine and an arsenosugar was confirmed by ESI MS. Ag and Pb were hardly translocated to leaves and were found as high molecular species; one of the Pb-containing species co-eluted in fast-SEC-ICP MS with rhamnogalacturonan-II-Pb complex commonly found in in the walls of plants.

Hydrophobic Effect on Alkaline Stability of Graft Chains in Ammonium‐type Anion Exchange Membranes Prepared by Radiation‐Induced Graft Polymerization

AbstractVinylbenzyltrimethylammonium hydroxide (VBA) and styrene (St) cografted poly(ethylene‐co‐tetrafluoroethylene) anion exchange membranes (VBA/St‐AEM) were prepared by the radiation‐induced graft polymerization of chloromethylstyrene and St and sequential quaternization and anion exchange reactions. Increasing the St content in the grafts to 63 % resulted in a gradual 21 % and 34 % decrease in the conductivity and water uptake, respectively, compared to those in the VBA‐homo‐grafted AEM. AEMs with a higher St content (81 %) showed a 9 % and 18 % higher conductivity and water uptake, respectively. Small‐angle neutron scattering showed that the sudden growth of “water puddles” consisting of water‐rich nano‐domains dispersed randomly in phase‐separated hydrophilic ion channels enhanced the conductivity and water uptake. In the alkaline durability test of VBA/St‐AEM in 1 M potassium hydroxide at 80 °C for 720 h, the loss of the conductivity was suppressed from 43 % to 8 %, when the St contents in the grafts were increased from 0 % to 63 %.