Ionic Liquid Monomer Research Articles

Strong, Spontaneous, and Self-Healing Poly(Ionic Liquid) Elastomer Underwater Adhesive with Borate Ester Dynamic Crosslinking.

Adhesion in aqueous environments is often hindered by the water layer on the surface of the substrate due to the water sensitivity of the adhesive, greatly limiting the application environment. Here, a borate ester dynamically crosslinked poly(ionic liquid) elastomer adhesive (PIEA) with high strength, toughness, self-healing abilities, and ionic conductivity is synthesized by copolymerizing hydrophobic ionic liquid monomer ([HPVIm][TFSI]) and 2-methoxyethyl acrylate (MEA). The adhesion strength of PIEA can increase spontaneously from almost no adhesion to 314 kPa after 12 h without any external preloading due to the dissociation of the borate ester in water, leading to noncovalent interactions between the hydroxyl groups of PIEA and the substrate. Additionally, PIEA can be developed for soft sensors or ion electrodes to enable underwater detection and communication. This strategy offers broad application potential for the development of novel underwater smart adhesives.

Structural design and performance correlation of porous Poly(ionic liquid)S for 2-bromophenol adsorption

The demand for bromophenol is on the rise, driven by its extensive applications in industries, including human medicine. This surge in demand has spurred the development of eco-friendly methods for bromophenol recovery and the synthesis of new, low-toxicity compounds. In our study, we prepared a novel poly(ionic liquid) (PIL) featuring a benzene ring. The synthesis of this PIL involved using benzyl alcohol as the primary crosslinking agent, dimethoxymethane as an auxiliary crosslinking agent, and an imidazolium-based ionic liquid monomer, [Dimbb]Cl₂, for the adsorption of 2-bromophenol from aqueous solutions. We designed the PIL to be a high-performance and sustainable adsorbent by optimizing its specific surface area and pore structure. Structural analysis revealed that the PILs have a highly rich micro-mesoporous structure. The adsorption kinetics conformed to pseudo-second-order kinetics, reaching equilibrium in just 6 min. According to the Langmuir model, PIL-1 demonstrated a remarkable maximum adsorption capacity of 434.71 mg/g for 2-bromophenol. Quantum chemical calculations suggested that the adsorption mechanism involves processes such as pore filling, hydrogen bonding, electrostatic interactions, and π-π interactions. Furthermore, the adsorbent can be effectively recovered at least five times using anhydrous ethanol as the desorption agent, while maintaining an adsorption efficiency exceeding 90 %.

Mechanistic insight into the synergy between nickel single atoms and nanoparticles on N-doped carbon for electroreduction of CO2

The synergy of single atoms (SAs) and nanoparticles (NPs) has demonstrated great potential in promoting the electrocatalytic carbon dioxide reduction reaction (CO2RR); however, the rationalization of the SAs/NPs proportion remains one challenge for the catalyst design. Herein, a Ni2+-loaded porous poly(ionic liquids) (PIL) precursor synthesized through the free radical self-polymerization of the ionic liquid monomer, 1-allyl-3-vinylimidazolium chloride, was pyrolyzed to prepare the Ni, N co-doped carbon materials, in which the proportion of Ni SAs and NPs could be facilely modulated by controlling the annealing temperature. The catalyst Ni-NC-1000 with a moderate proportion of Ni SAs and NPs exhibited high efficiency in the electrocatalytic conversion of CO2 into CO. Operando Ni K-edge X-ray absorption near-edge structure (XANES) spectra and theoretical calculations were conducted to gain insight into the synergy of Ni SAs and NPs. The charge transfer from Ni NPs to the surrounding carbon layer and then to the Ni SAs resulted in the electron-enriched Ni SAs active sites. In the electroreduction of CO2, the co-existence of Ni SAs and NPs strengthened the CO2 activation and the affinity towards the key intermediate of *COOH, lowering the free energy for the potential-determining *CO2 → *COOH step, and therefore promoted the catalysis efficiency.

From Synthesis to Functionality: Tailored Ionic Liquid-Based Electrospun Fibers with Superior Antimicrobial Properties.

Herein, we report an efficient and facile strategy for the preparation of imidazolium-based ionic liquid (IL) monomers ([CnVIm][Br], n = 2, 4, 6, 8, 10, and 12) and their corresponding polymeric ionic liquids (PILs) with potent antimicrobial activities against Gram-negative and Gram-positive bacteria and fungi. The electrospinning technique was utilized to tailor the polymers with the highest antimicrobial potency into porous membranes that can be easily implemented into diverse systems and extend their practical bactericidal application. The antimicrobial mechanism of obtained ILs, polymers, and nanomaterials is considered concerning the bearing chain length, polymerization process, and applied processing technique that provides a unique fibrous structure. The structure composition was selected due to the well-established inherent amphiphilicity that 1-alkylimidazolium ILs possess, coupled with proven antimicrobial, antiseptic, and antifungal behavior. The customizable nature of ILs and PILs complemented with electrospinning is exploited for the development of innovative antimicrobial performances born from the intrinsic polymer itself, offering solutions to the increasing challenge of bacterial resistance. This study opens up new prospects toward designer membranes providing a complete route in their designing and revolutionizing the approach of fabricating multi-functional systems with tunable physicochemical, surface properties, and interesting morphology.

Simple strategy of the use of pharmaceutically functionalized ionic liquids in a new generation of polymer nanocarriers for the combined delivery of ionic p-aminosalicylate and ampicillin

Single and dual bioactive linear poly(ionic liquid)s (PIL) were synthesized for use as nanocarriers in drug delivery systems (DDS). These PILs were obtained through the (co)polymerization of the choline-based monomeric ionic liquids (MIL) with pharmaceutical anions possessing antibacterial properties, specifically [2-(methacryloyloxy)ethyl]trimethyl-ammonium with ampicillin and p-aminosalicylate (TMAMA/AMP and TMAMA/PAS). The copolymers exhibited varying chain lengths defined by a degree of polymerization (DPn = 122–370), and differing contents of ionic fraction and drugs (TMAMA 61–92 %, AMP 61–93 % and PAS 16–21 %). These parameters were adjustable by the monomer conversion (33–92 %) and the initial ratio of comonomers. In aqueous solution, the polymer particles reached nanosizes, i.e. 190–328 nm for AMP systems and 200–235 nm for AMP/PAS systems. In the release process, the pharmaceutical anions were released through exchange by phosphate anions in PBS at pH 7.4 at 37 °C. Depending on the copolymer composition the release of AMP was attained in 72–100 % (11.1–19.5 µg/mL) within 26 h by the single drug systems, while the dual drug systems released 61–100 % of AMP (14.8–24.7 µg/mL) and 82–100 % of PAS (3.1–4.8 µg/mL) within 72 h. The effectiveness in the drug delivery of the designed TMAMA polymers seems to be promising for future applications in antibiotic therapy and the combined therapy.

Piperazinium Poly(Ionic Liquid)s as Solid Electrolytes for Lithium Batteries.

Poly(ionic liquid)s combine the unique properties of ionic liquids (ILs) within ionic polymers holding significant promise for energy storage applications. It is reported here the synthesis and characterization of a new family of poly(ionic liquid)s synthesized from cationic piperazinium ionic liquid monomers. The cationic poly(acrylamide piperazinium) in combination with sulfonamide anions like bis(trifluoromethanesulfonyl) imide (TFSI) and bis(fluorosulfonyl) imide (FSI) are characterized as solid polymer electrolytes. The polymer electrolytes in combination with pyrrolidonium ILs and LiFSI show high ionic conductivity, 5×10-3 S cm-1 at 100 °C. Piperazinium polymer electrolytes show excellent compatibility with lithium metal reversible plating and stripping at high current density and low temperature 40 °C.

Enhanced antifouling performance with a synergistic effect of self-renewal antifouling and contact bacteriostasis via the ionic exchange

It is extremely difficult for traditional coatings for antifouling constructed around a single antifouling strategy to adapting to the demands of complex marine environment. Herein, a poly-ionic liquid-based germicidal polyacrylate-3 coating (AFC-3) was prepared via free radical photo-copolymerization using isooctyl acrylate (2-EHA), butyl acrylate (BA) and ionic liquid monomer (IL-PF6) as monomers. Besides the contact bacteriostasis mechanisms, the introduction of IL-PF6 achieved the switch between self-renewal and hydrophilic surface by the exchange of PF6− and Cl− in artificial seawater. Regarding E. coli and S. aureus, the AFC-3 coating showed anti-bacterial efficiency of 100 % and 99.96 %, respectively. Moreover, with the continuous ionic exchange between PF6− and Cl−, the angle towards the water contact (WAC) of the coating became 11.356 °C, contributing to the enhancement of anti-protein property on the surface of the coating. The AFC-3 coating thus exhibited significantly effective antifouling performances, and is a highly promising coating for a broader range of marine anti-fouling and biomedical materials. Besides, the transmittance of the coating was above 92 % between 400 and 800 cm−1, conferring it great potentials for applications on the surface of optical devices like underwater cameras.

Recyclable multifunctional ion conductive elastomers for strain/temperature sensors and bioelectrodes

Ionic conductive elastomers based on polymerizable deep eutectic solvents (PDES) have shown great application prospects in research fields such as lithium-ion batteries, smart soft materials, and wearable devices. However, most of these materials currently face the challenge of difficult recycling and reuse, resulting in environmental pollution and resource waste. In this work, we introduced PDES made of acrylic acid (AA) and choline chloride (ChCl) into polymerizable ionic liquid monomers [ATAC][TFSI] and prepared a physically crosslinked multifunctional ionic conductive elastomer PIL-PDES through a simple and rapid “one-step” photopolymerization strategy. This elastomer not only has satisfactory mechanical properties (tensile strength: 3.93 MPa, elongation at break: 760 %), high transparency (80 %), strong adhesion (iron: 135 kPa) and rapid self-healing but can also be recycled and reused. Based on the good conductivity of the elastomer (conductivity: 2.49 × 10−3 S/m), it can be used not only as a sensor to monitor human activities and changes in environmental temperature but also as a biological electrode to record human electrocardiogram signals. We believe that due to its superior overall performance and simple preparation method, PIL-PDES has broad potential for practical application in flexible wearable electronic devices.

Radiation synthesis of covalently/non-covalently coupled all ionic liquid-based Ionogels with rapid self-healing, environmental tolerance for multifunctional ionic skin

As novel artificial ion-conducting materials with skin-like functionalities, Ionic skins (I-Skins) have attracted wide attention in the field of smart wearables. Nonetheless, the crucial hurdle of maintaining their properties in extreme conditions, such as cold, hot or long-term storage, persists. Herein, ionic liquid monomers, ionic liquid solvents, and ionic liquid cross-linkers are employed to facilitate covalently/non-covalently coupled all ionic liquid-based Ionogel for multimodal artificial I-skin through electron beam irradiation under mild conditions at the first time. Profiting from the covalently/non-covalently interactions in the Ionogel, the Ionogel has tunable mechanical properties, excellent environmental adaptability (−60 to 150 °C), long-term stability (90 days), fast response time (0.1 s), rapid self-healing ability (120 s recovery to 90 % of original), and favorable adhesion properties. Moreover, Ionogel sensors possess the remarkable capability to accurately perceive external stimuli, including strain, temperature, and humidity, similar to human skin, which can effectively monitor human movement behavior, as well as fluctuations in ambient temperature and humidity. It is expected that this all ionic liquid-based Ionogel sensor can fill the gap of I-Skin in extreme conditions and realize multifunctional flexible sensing, thus expanding more application scenarios.

Simultaneous electropolymerization of pyrrole and anionic or cationic polymerizable monomeric ionic liquids. Linear actuation of the attained materials

The simultaneous galvanostatic electrogeneration of polypyrrole (PPy) and a polyanion, or a polycation, from the concomitant solutions of pyrrole and monomeric ionic liquids (PIL) give films of two interpenetrated polymeric networks: polyanion-PPy (PILA-PPy) and polycation-PPy (PILC-PPy), as corroborated by Fourier transform infrared (FTIR) spectroscopy. The linear actuation was characterized by cyclic voltammetry and chronoamperometry in aqueous electrolyte describing cation-driven actuation of the PILA-PPy actuators (cation exchange during oxidation/reduction) and anion-driven actuation of the PILC-PPy actuation. The exchange of a unique ion in each actuator, corroborated by energy dispersive X-ray (EDX) analysis of the oxidized and reduced materials, allows the control of the actuation direction. The concomitant driving electrochemical reactions are described. Coulovoltammetric responses present a closed loop in the studied potential range indicating that only those reactions (oxidation/reduction) are present in the studied potential range (0.65 V and − 0.6 V). The PILC-PPy strain was 8.7% and the stress gradient 1.45 MPa, overcoming 1.5 times those from PILA-PPy actuators, consuming also a higher charge density, having 2.1 times better conductivity and 1.3 times higher diffusion-coefficients. The stability of the actuators was studied by consecutive cycling. The PILA-PPy and PILC-PPy films are characterized by scanning electron microscopy (SEM), FTIR and EDX spectroscopy.

Polymerized and Colloidal Ionic Liquids─Syntheses and Applications.

The breadth and importance of polymerized ionic liquids (PILs) are steadily expanding, and this review updates advances and trends in syntheses, properties, and applications over the past five to six years. We begin with an historical overview of the genesis and growth of the PIL field as a subset of materials science. The genesis of ionic liquids (ILs) over nano to meso length-scales exhibiting 0D, 1D, 2D, and 3D topologies defines colloidal ionic liquids, CILs, which compose a subclass of PILs and provide a synthetic bridge between IL monomers (ILMs) and micro to macro-scale PIL materials. The second focus of this review addresses design and syntheses of ILMs and their polymerization reactions to yield PILs and PIL-based materials. A burgeoning diversity of ILMs reflects increasing use of nonimidazolium nuclei and an expanding use of step-growth chemistries in synthesizing PIL materials. Radical chain polymerization remains a primary method of making PILs and reflects an increasing use of controlled polymerization methods. Step-growth chemistries used in creating some CILs utilize extensive cross-linking. This cross-linking is enabled by incorporating reactive functionalities in CILs and PILs, and some of these CILs and PILs may be viewed as exotic cross-linking agents. The third part of this update focuses upon some advances in key properties, including molecular weight, thermal properties, rheology, ion transport, self-healing, and stimuli-responsiveness. Glass transitions, critical solution temperatures, and liquidity are key thermal properties that tie to PIL rheology and viscoelasticity. These properties in turn modulate mechanical properties and ion transport, which are foundational in increasing applications of PILs. Cross-linking in gelation and ionogels and reversible step-growth chemistries are essential for self-healing PILs. Stimuli-responsiveness distinguishes PILs from many other classes of polymers, and it emphasizes the importance of segmentally controlling and tuning solvation in CILs and PILs. The fourth part of this review addresses development of applications, and the diverse scope of such applications supports the increasing importance of PILs in materials science. Adhesion applications are supported by ionogel properties, especially cross-linking and solvation tunable interactions with adjacent phases. Antimicrobial and antifouling applications are consequences of the cationic nature of PILs. Similarly, emulsion and dispersion applications rely on tunable solvation of functional groups and on how such groups interact with continuous phases and substrates. Catalysis is another significant application, and this is an historical tie between ILs and PILs. This component also provides a connection to diverse and porous carbon phases templated by PILs that are catalysts or serve as supports for catalysts. Devices, including sensors and actuators, also rely on solvation tuning and stimuli-responsiveness that include photo and electrochemical stimuli. We conclude our view of applications with 3D printing. The largest components of these applications are energy related and include developments for supercapacitors, batteries, fuel cells, and solar cells. We conclude with our vision of how PIL development will evolve over the next decade.

Dual hydrogen bond donor functionalized hierarchical porous poly(ionic liquid)s for efficient CO2 fixation into cyclic carbonates

CO2 capture and conversion to high-value-added products is critical for the purposes of environmental preservation and carbon resource utilization. In this study, a novel class of porous poly(ionic liquid)s has been synthesized, incorporating dual hydrogen bond donors (amide and hydroxyl groups) and nucleophiles (Br-) as multiple effective active sites for the cycloaddition reaction between CO2 and epoxides. The presence of dual hydrogen bond donors not only provides two active sites for synergistic catalysis with epoxides but also enhances the capacity for CO2 adsorption. Comprehensive characterization has been conducted to elucidate the structural features and properties of these innovative materials. By regulating the ratio between ionic liquid monomer and divinylbenzene, a hierarchical porous structure favorable for the reaction was constructed, resulting in optimized catalytic activity comparable to that of bulk ionic liquid monomers. Furthermore, this catalyst exhibits remarkable structural stability with minimal activity loss even after five consecutive use cycles. Combining density functional theory calculations with in-situ Fourier transform infrared spectroscopy analysis, the catalytic mechanism was proposed that the dual hydrogen bond donors and Br- synergistically promote ring-opening reactions of epoxides, while amide groups serve as basic sites to enhance CO2 adsorption during the reaction process.

Ultra-stretchable and highly tough ionogels with underwater repeatable adhesion and anti-swelling capacity for real-time motion detection, signal transmission and electrochemical monitoring platforms

Hydrophobic ionogels have received growing interest as a flexible underwater sensing material. However, it remains a significant challenge to improve the tensile properties, prolonged underwater repeatable adhesion, and multifunctionality of the hydrophobic ionogel due to the restricted selection of monomers and curing strategies. Herein, a hydrophobic multifunctional fluorine-rich ionogel with ultra-stretchability and superior long-term underwater repeatable adhesion is designed by virtue of the introduction of a rigid and flexible macromolecular cross-linker and a structure of rigid cationic imidazole-benzene rings in a hydrophobic ionic liquid monomer. The macromolecular cross-linker significantly improves the mechanical properties of the ionogel because of the reduction in stress concentration. And the structure of short imidazole-benzene rings with high rigidity exposes a larger amount of adhesion groups on the surface of the ionogels compared to the flexible groups, leading to enhanced long-term underwater repeatable adhesion performance of the ionogel. The ionogels are applied to real-time monitoring of exposure to water, underwater swimming motion monitoring, underwater Morse code transmission and electrochemical monitoring platforms. And this work is expected to provide ideas for the multifunctionalization of underwater sensing technology and the integration of functional units in underwater flexible electronic skin.

Architected Poly(ionic liquid) Composites with Spatially Programmable Mechanical Properties and Mixed Conductivity.

Structural electrolytes present advantages over liquid varieties, which are critical to myriad applications. In particular, structural electrolytes based on polymerized ionic liquids or poly(ionic liquids) (pILs) provide wide electrochemical windows, high thermal stability, nonvolatility, and modular chemistry. However, current methods of fabricating structural electrolytes from pILs and their composites present limitations. Recent advances have been made in 3D printing pIL electrolytes, but current printing techniques limit the complexity of forms that can be achieved, as well as the ability to control mechanical properties or conductivity. We introduce a method for fabricating architected pIL composites as structural electrolytes via embedded 3D (EMB3D) printing. We present a modular design for formulating ionic liquid (IL) monomer composite inks that can be printed into sparse, lightweight, free-standing lattices with different functionalities. In addition to characterizing the rheological and mechanical behaviors of IL monomer inks and pIL lattices, we demonstrate the self-sensing capabilities of our printed structural electrolytes during cyclic compression. Finally, we use our inks and printing method to spatially program self-sensing capabilities in pIL lattices through heterogeneous architectures as well as ink compositions that provide mixed ionic-electronic conductivity. Our free-form approach to fabricating structural electrolytes in complex, 3D forms with programmable, anisotropic properties has broad potential use in next-generation sensors, soft robotics, bioelectronics, energy storage devices, and more.

An Intrinsic Self-Healable, Anti-Freezable and Ionically Conductive Hydrogel for Soft Ionotronics Induced by Imidazolyl Cross-Linker Molecules Anchored with Dynamic Disulfide Bonds.

Hydrogels are ideal materials for flexible electronic devices based on their smooth ion channels and considerable mechanical flexibility. A substantial volume of aqueous solution is required to enable the smooth flow of ions, resulting in the agony of low-temperature freezing; besides, long-term exposure to bending/tensile tress triggers fatigue issues. Therefore, it is a great challenge to prepare hydrogels with both freeze-resistance and long-term durability. Herein, a polyacrylic acid-based hydrogel with both hydrophobic interaction and dynamic reversible covalent bonding cross-linking networks is preparing (DC-hydrogel) by polymerizing a bi-functional imidazole-type ionic liquid monomer with integrated disulfide and alkene bonds (DS/DB-IL) and an octadecyl methacrylate, achieving self-healing. The DS/DB-IL anchored into the polymer backbone has a high affinity with water, reducing the freezing point of water, while the DS/DB-IL with free ions provides superior ionic conductivity to the DC-hydrogel. The polyacrylic acid with abundant carboxyl gives hydrogel good self-adhesiveness to different substrates. Ionotronics with resistance-type sensors with stable output performance are fabricated and explored its application to joint motion and health information. Moreover, hydrogel-based sensing arrays with high resolution and accuracy are fabricated to identify 2D distribution of stress. The hydrogels have great promise for various ionotronics in many fields.

Molecular engineering of poly(ionic liquid)-based random copolymer electrolytes for enhanced performance of solid-state lithium batteries

Solid polymer electrolytes (SPE) usually present low ionic conductivity and poor anti-oxidation resistance, which significantly restricts their applications in high-voltage lithium metal batteries. In this study, poly(ionic liquid)-based random copolymers (CPIL) with rigid-flexible segments are successfully synthesized using cross-liked copolymerization reactions by precisely adjusting the ratio of 1-vinyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)imide (VEIM-TFSI) soft segment to 1-vinyl-3-ethylimidazolium hexafluorophosphate (VEIM-PF6) hard segment. The soft segment in CPIL exhibits fast ion migrations due to large volume and more delocalized structure of TFSI-, while the hard segment demonstrates high anti-oxidative property. As a result, SPEs fabricated with optimized CPIL exhibit an ionic conductivity of 1.06 × 10-4 S cm−1 and an electrochemical stability voltage of 4.5 V at 25 °C. The solid-state LiNi0.8Co0.1Mn0.1O2/CPIL SPE/Li batteries exhibit an initial discharge capacity of 159.3 mAh g−1 and a superior capacity retention of 70.8 % after 600 cycles at 1 C. In addition, the enhanced electrochemical performance of LiNi0.9Co0.05Mn0.05O2 and LiFePO4 cells incorporating CPIL SPE also further substantiates the efficacy of CPIL SPE as a highly efficient solid-state electrolyte for high-performance batteries. This work has proved the efficiency of adjusting the ratio of ionic liquid monomer with different anions in designing novel PIL-based random copolymers, and as-prepared electrolyte is a promising candidate for practical application in solid-state lithium batteries.

Construction of cationic covalent organic framework for efficient gold extraction.

In this work, we report a rare ionic covalent organic framework (named as ECUT-iCOF-5) synthesized by the Knoevenagel reaction using an ionic liquid monomer. ECUT-iCOF-5 is found to show a promising potential for gold extraction with a high extraction ability towards gold, including a high extraction capacity (3260 mg g-1), good selectivity over both cations and anions, and good recycle use (at least six times).

Synthesis of magnetic-responsive imidazole-based poly (ionic liquid)s as a recycle adsorbent for simultaneously removing iodine molecules and iodide ions

Nuclear waste management and nuclear energy generation require the proper disposal of 129I and 131I, which are radioactive isotopes of iodine. For recognition of different types’ iodine, a magnetic poly (ionic liquid)s (Fe3O4@SiO2-MPS-PILs) was formed by the selected imidazole ionic liquid monomer and core–shell Fe3O4@SiO2-MPS via free radical polymerization. The resulting adsorbent containing plenty of imidazole N-heterocycle units, benzene rings, and ionic bonds in the backbones was suitable for simultaneously adsorbing iodine molecules and iodide ions. The adsorption mechanisms for iodine in cyclohexane and iodide ions from aqueous solution were based on charge transfer and ion exchange mechanisms, respectively. The adsorption equilibrium for iodine in cyclohexane was attained at 12 h, and the kinetics of iodine adsorption closely followed the pseudo-second-order model. Iodine adsorption on Fe3O4@SiO2-MPS-PILs was best described by Langmuir model with a maximum iodine adsorption capacity of approximately 714.29 mg g−1. Iodide ions adsorption was best explained with Freundlich model and a maximum adsorption capacity of 335.80 mg g−1 was achieved in an iodide solution with a 500 mg L–1 concentration. Notably, Fe3O4@SiO2-MPS-PILs retained over 90 % of its original adsorption performance after the 5th cycle. This work proves that the adsorbent Fe3O4@SiO2-MPS-PILs was efficient and recyclable, and has good application prospects in the practical treatment of iodine and iodide.

Thin Reinforced Anion-Exchange Membranes for Non-Aqueous Redox Flow Battery Employing Fe/Co-Metal Complex Redox Species

Non-aqueous redox flow batteries (NARFBs) have been attracting much attention because they can significantly increase power and energy density compared to conventional RFBs. In this study, novel pore-filled anion-exchange membranes (PFAEMs) for application to a NAPFB employing metal polypyridyl complexes (i.e., Fe(bpy)32+/Fe(bpy)33+ and Co(bpy)32+/Co(bpy)33+) as the redox species are successfully developed. A porous polyethylene support with excellent solvent resistance and mechanical strength is used for membrane fabrication. The PFAEMs are prepared by filling an ionic liquid monomer containing an imidazolium group and a crosslinking agent into the pores of the support film and then performing in situ photopolymerization. As a result, the prepared membranes exhibit excellent mechanical strength and stability in a non-aqueous medium as well as high ion conductivity. In addition, a low crossover rate for redox ion species is observed for the prepared membranes because they have relatively low swelling characteristics in non-aqueous electrolyte solutions and low affinity for the metal-complex redox species compared to a commercial membrane. Consequently, the PFAEM is revealed to possess superior battery performance than a commercial membrane in the NARFB tests, showing high energy efficiency of about 85% and stable operation for 100 cycles.

High-Toughness and High-Strength Solvent-Free Linear Poly(ionic liquid) Elastomers.

Solvent-free elastomers, unlike gels, do not suffer from solvent evaporation and leakage in practical applications. However, it is challenging to realize the preparation of high-toughness (with both high stress and strain) ionic elastomers. Herein, high-toughness linear poly(ionic liquid) (PIL) elastomers are constructed via supramolecular ionic networks formed by the polymerization of halometallate ionic liquid (IL) monomers, without any chemical crosslinking. The obtained linear PIL elastomers exhibit high strength (16.5 MPa), Young's modulus (157.49 MPa), toughness (130.31 MJ m-3 ), and high crack propagation insensitivity (fracture energy 243.37 kJ m-2 ), owing to the enhanced intermolecular noncovalent interactions of PIL chains. Furthermore, PIL elastomer-based strain, pressure, and touch sensors have shown high sensitivity. The linear noncovalent crosslinked network endows the PIL elastomers with self-healing and recyclable properties, and broad application prospects in the fields of flexible sensor devices, health monitoring, and human-machine interaction.