Ionic Network Research Articles

On the interplay between the local structure and dynamics in low concentration mixtures of H2O and HOD in the [Emim+][TF2N−] room temperature ionic liquid

Molecular Dynamics simulations have been employed to investigate the local structural and dynamic properties of low-concentrated water and HOD dissolved in an ionic liquid consisting of the 1-ethyl-3-methylimidazolium cation and the bis(trifluoromethylsulfonyl)imide anion. The results obtained disclose that the water molecules interpenetrate the ionic structural networks and interact with the anions and the cations of the ionic liquid. The calculations have also revealed a strong interaction between the oxygen atoms of the anion and the hydrogen atoms of the water molecules and a quite important interaction between the hydrogen atoms of the imidazolium ring with the water oxygen atoms. The translational and rotational diffusion of water molecules is almost one order of magnitude lower in comparison with pure water, but still one order of magnitude higher in comparison with the ionic liquid's anions and cations. The translational diffusion of the anions is lower than the diffusion of the cations, whereas the rotational diffusion is very similar. However, the reorientational dynamics of the anion and the cation is very anisotropic and the mechanisms of the rotation around different intramolecular axes take place at different time scales. The calculated orientational anisotropy of the O-D vector of HOD in the ionic liquid has been found to be in very good agreement with available experimental data, showing more pronounced differences with the O-H vector reorientational dynamics at long-time scales.

Reactivity of Bioinspired Magnesium-Organic Networks under CO2 and O2 Exposure.

Photosynthesis is the model system for energy conversion. It uses CO2 as a starting reactant to convert solar energy into chemical energy, i.e., organic molecules or biomass. The first and rate-determining step of this cycle is the immobilization and activation of CO2, catalyzed by RuBisCO enzyme, the most abundant protein on earth. Here, we propose a strategy to develop novel biomimetic two-dimensional (2D) nanostructures for CO2 adsorption at room temperature by reductionist mimicking of the Mg–carboxylate RuBisCO active site. We present a method to synthesize a 2D surface-supported system based on Mg2+ centers stabilized by a carboxylate environment and track their structural dynamics and reactivity under either CO2 or O2 exposure at room temperature. The CO2 molecules adsorb temporarily on the Mg2+ centers, producing a charge imbalance that catalyzes a phase transition into a different configuration, whereas O2 adsorbs on the Mg2+ center, giving rise to a distortion in the metal–organic bonds that eventually leads to the collapse of the structure. The combination of bioinspired synthesis and surface reactivity studies demonstrated here for Mg-based 2D ionic networks holds promise for the development of new catalysts that can work at room temperature.

Imidazolium-Based Ionic Network as a Robust Heterogeneous Catalyst in Synthesis of Phenacyl Derivatives

A new imidazolium-based poly(ionic liquid) has been synthesized and used as a robust heterogeneous catalyst for the preparation of phenacyl derivatives by an SN2 reaction of different phenacyl bromides with a broad range of nucleophiles. The products are obtained in high yields under mild conditions. The catalyst can be recycled efficiently.

Reversible Construction of Ionic Networks Through Cooperative Hydrogen Bonds for Efficient Ammonia Absorption

ILs with reversible construction of ionic networks, which mainly consist of cooperative hydrogen bonds (CHBs) were designed for sigmoidal ammonia (NH3) absorption isotherm, which leads to efficient...

High Rate and Stable Solid-State Lithium Metal Batteries Enabled by Electronic and Ionic Mixed Conducting Network Interlayers.

All solid-state lithium (Li) metal batteries (SSLMBs) are attractive for prospective electrochemical energy storage systems on account of their high energy densities and good safeties. However, the incompatible interface between the solid-state electrolyte and Li metal anode limits the ability of SSLMBs. Here, a three-dimensional (3D) electronic and ionic mixed conducting interlayer is proposed to improve the interfacial affinity in SSLMBs. The 3D electronic and ionic mixed conducting interlayer is composed of a Sn/Ni alloy layer-coated Cu nanowire (Cu@SnNi) network. The Li plating demonstrates that the Cu@SnNi network can possess fast Li+ ion transport channels from the Li metal to LiFePO4, acting as a stable interlayer between the Li metal and solid polymer electrolyte. Noticeably, the solid-state LiFePO4/Li cell with a Cu@SnNi interlayer exhibits an excellent rate capability (133 mA h g-1, 2 C; 100 mA h g-1, 5 C) in comparison to the low rate performance of the cell without the interlayer (117 mA h g-1, 2 C; 60 mA h g-1, 5 C). This unique structure design of electronic and ionic mixed conducting interlayer provides an alternative strategy to improve the performance of SSLMBs.

Holey graphenes as the conductive additives for LiFePO4 batteries with an excellent rate performance

Graphene has been investigated and widely used as the high performance conductive additives in lithium ion batteries. Unfortunately, the LiFePO4 batteries with graphene additives present quite a low rate performance because the graphene with planar structure blocks the Li ion transportation. Herein, a binary conductive additive containing only 1 wt% holey graphene (HG) and 1 wt% Carbon Black such as Super-P (SP) has been developed, which achieves excellent high-rate performance for the LiFePO4 battery that is comparable to that of the battery with 10 wt% SP. The HG with large amount of holes and large specific surface area substantially enhances the electronic conductivity of LiFePO4 electrode, but not compromises the high efficient ionic transportation. A small content of SP as the supplement of long-range conductive network formed by HG can contact the LiFePO4 sufficiently for achieving excellent conductivity in the whole LiFePO4 electrode. A balance of electronic conductivity and ionic diffusivity can be achieved using the HG and SP simultaneously. The HG and SP with low content can synergistically construct an excellent ionic and electronic conductive network in LiFePO4 electrode. This study may promote the commercial applications of HG additives for high performance LiFePO4 batteries.

Self-healing Behavior of Ethylene Propylene Diene Rubbers Based on Ionic Association

To meet the increasing demand for safe, environmentally friendly and high-performance smart materials, self-healing rubbers are highly desired. Here, the self-healing performance of ethylene propylene diene monomer rubber (EPDM) is reported, which was designed by graft-polymerization of zinc dimethacrylate (ZDMA) onto rubber chains to form a reversible ionic cross-linked network. Single ionic cross-linked network and dual network, combining covalent and ionic cross-links, could be tuned by controlling vulcanization process to achieve tailorable mechanical and self-healing properties. It was found that ionic cross-linked EPDM showed a recovery of more than 95% of the original mechanical strength through a healing process of 1 h at 100 °C. The covalent cross-links could improve mechanical properties but block self-healing. Adding 50 wt% liquid rubber to “dry” EPDM could effectively enhance self-healing capability of the dual cross-linked network and the healed tensile strength could reach 0.9 MPa. A compromise between mechanical performance and healing capability could be potentially tailored by controlling vulcanization process and liquid rubber content.

Enveloping of catalyst powder by ionomer for dry spray coating in polymer electrolyte membrane fuel cells

This study presents innovative concepts for improving performance of membrane electrode assemblies (MEAs) prepared by the dry-spraying method introduced by the German Aerospace center (DLR). Dry-spraying is a time and cost effective method that involves solvent-free spraying of catalyst powder on polymer electrolyte membrane. The issue which is resolved in this work is the large ionomer particle size in the conventional method. With mechanical grinding, particle size of the ionomer less than 100 nm were not been achieved. However, here the reactive interface of dry-sprayed MEA is optimized by improving ionic conductivity. Our approach is to modify a carbon support by partially enveloping with Nafion® ionomer followed by incorporating Pt black with it. Additionally, commercial catalyst powder was also modified by two-step preparation process with Nafion® dispersion. In this research, both of these modified powders were sprayed over membrane; hot-pressed; characterized, and have shown improved ionic network and distribution, which corresponds to their higher performances. The improvement in the performance does not correlate with electrode surface area but with the ionomer resistance of the catalytic layer. Therefore, with this study we demonstrate a pathway and methodology to further improve performance by optimizing ionomer structure and networks in the catalytic layer.

Buildup of Multi-Ionic Supramolecular Network Facilitated by In-Situ Intercalated Organic Montmorillonite in 1,2-Polybutadiene.

The development of a sacrificial bond provided unique inspiration for the design of advanced elastomers with excellent mechanical properties, but it is still a huge challenge to construct a homogenous polar sacrificial network in a nonpolar elastomer. In this effort, we proposed a novel strategy to engineer a multi-ionic network into a covalently cross-linked 1,2-polybutadiene (1,2-PB) facilitated by in-situ intercalated organic montmorillonite (OMMT) without phase separation. XRD, SEM, and TEM analysis were carried out to characterize the microstructure of the resulting polymers. Crosslinking density, dielectric performance, and cyclic tensile tests were used to demonstrate the interaction of zinc methacrylate (ZDMA) and OMMT. The dynamic nature of ionic bonds allowed it to rupture and reform to dissipate energy efficiently. Stretching orientation brought parallelism between polymer chains and OMMT layers which was beneficial for the reconstruction of the ionic network, ultimately resulting in high strength and a low stress relaxation rate. Overall, our work presented the design of a uniform and strong sacrificial network in the nano-clay/elastomer nanocomposite with outstanding mechanical performances under both static and dynamic conditions.

A Temperature-Gated Nanovalve Self-Assembled from DNA to Control Molecular Transport across Membranes.

Nanopores are powerful nanodevices that puncture semifluid membranes to enable transport of molecular matter across biological or synthetic thin layers. Advanced nanopores featuring more complex functions such as ambient sensing and reversible channel opening are of considerable scientific and technological interest but challenging to achieve with classical building materials. Here we exploit the predictable assembly properties of DNA to form a multifunctional nanovalve that senses temperature for controlled channel opening and tunable transport. The barrel-shaped valve is formed from solely seven oligonucleotides and is closed at ambient temperatures. At >40 °C a programmable thermosensitive lid opens the barrel to allow transport of small molecules across the membrane. The multifunctional DNA nanodevice may be used to create logic ionic networks or to achieve controlled drug delivery from vesicles.

Constructing interconnected ionic cluster network in polyelectrolyte membranes for enhanced CO2 permeation

Membranes with fast CO2 transport pathways have attracted intense attention due to their outstanding CO2 permeability, showing potential for industrial application. Regulating the spatial distribution of CO2-philic groups in polymer-based membranes is expected to be a promising strategy to achieve the fast CO2 transport pathways. In membrane matrix, the interconnected network of concentrated domains of CO2 facilitated transport groups provides membranes with specific CO2 transport pathways and finally leads to their high separation performance. In this study, a novel kind of polyelectrolyte membrane, quaternary ammonium polysulfone with interconnected ionic clusters, is prepared to enhance the CO2 permeability. The hydrophilic quaternary ammonium groups tend to aggregate spontaneously to create ionic clusters. Furthermore, under humidified conditions, these ionic clusters are connected by water to form an ionic cluster network in the membrane matrix. The ionic cluster network plays the crucial role in accelerating the selective transport for CO2 molecules over CH4 by the reversible interaction between CO2 and ion pairs. By tuning the quaternization degree of polysulfone, a series of polyelectrolyte membranes with different size of ionic clusters were developed. Membranes with hydrated ionic clusters (5–9 nm) show dramatic enhancement in CO2 separation performance, especially in CO2 permeability. The as-prepared quaternary ammonium polysulfone membrane with 8.98 nm ionic clusters exhibited the high CO2 permeability of 1109.44 Barrer and a high CO2/CH4 selectivity of 29.70, which exceeds 2008 Robeson upper bound limit. The optimized separation performance of QA-PSf membranes is attractive for potential application such as CO2 capture from flue gas and natural gas.

Preclinical safety and efficacy of cannabidivarin for early life seizures

A significant proportion of neonatal and childhood seizures are poorly controlled by existing anti-seizure drugs (ASDs), likely due to prominent differences in ionic homeostasis and network connectivity between the immature and mature brain. In addition to the poor efficacy of current ASDs, many induce apoptosis, impair synaptic development, and produce behavioral deficits when given during early postnatal development. There is growing interest in new targets, such as cannabidiol (CBD) and its propyl analog cannabidivarin (CBDV) for early life indications. While CBD was recently approved for treatment of refractory childhood epilepsies, little is known about the efficacy or safety of CBDV. Here, we addressed this gap through a systematic evaluation of CBDV against multiple seizure models in postnatal day (P) 10 and 20 animals. We also evaluated the impact of CBDV on acute neurotoxicity in immature rats. CBDV (50–200 mg/kg) displayed an age and model-specific profile of anticonvulsant action. In P10 rats, CBDV suppressed seizures only in the pentylenetetrazole model. In P20 rats, CBDV suppressed seizures in the pentylenetetrazole, DMCM, and maximal electroshock models. Between P10 and P20, we identified significant increases in mRNA expression of TRPV1 in multiple brain regions; when CBDV was tested in P20 TRPV1 knockout mice, anticonvulsant effects were attenuated. Finally, CBDV treatment generally avoided induction of neuronal degeneration in immature rats. Together, the efficacy and safety profile of CBDV suggest it may have therapeutic value for early life seizures.

Ultrastiff, Tough, and Healable Ionic-Hydrogen Bond Cross-Linked Hydrogels and Their Uses as Building Blocks To Construct Complex Hydrogel Structures.

We report the ultrastiff and tough poly(acrylamide- co-acrylic acid)/Na-alginate/Fe3+ (P(AM- co-AA)/Na-alginate/Fe3+) hydrogel via the formation of hybrid ionic-hydrogen bond cross-linking networks. The optimal P(AM- co-AA)/Na-alginate/Fe3+ hydrogel possessed super high elastic modulus (∼24.6 MPa), tensile strength (∼10.4 MPa), compression strength (∼44 MPa), and toughness (∼4800 J/m2). The P(AM- co-AA)/Na-alginate/Fe3+ hydrogel was highly stable and maintained its superior mechanical properties in 0.5-2 M NaCl solution, aqueous solution with pH ranging from 4 to 10. The ionic cross-linking networks of the P(AM- co-AA)/Na-alginate/Fe3+ hydrogels can be locally and selectively dissociated by treating with aqueous NaOH solution with pH of 13 for 1 min and reformed by locally adding the additional Fe3+ solutions, making the hydrogels healable and cohesive. The healed hydrogels from the cutting surfaces can bear a tensile strength of up to 7.1 MPa. Various complex hydrogel structures can be constructed by using the P(AM- co-AA)/Na-alginate/Fe3+ hydrogels as building blocks via the adhesion of as-prepared hydrogels.

Insights into multi-component adsorption of reactive dyes on MIL-101-Cr metal organic framework: Experimental and modeling approach

Reactive dyes are frequently applied in textile industries owing to varied color and texture. Treatment of such dye laden wastewater from textile industry is a major problem. Over the last few decades the most convenient removal mechanism adopted was adsorption using conventional adsorbents. Metal organic frameworks (MOFs) are porous compounds with metal ionic network bridged using organic ligands possessing high surface area, adjustable pore size and high stability. In this study, an in depth investigation of adsorption of toxic reactive dyes on MIL-101-Cr MOF was undertaken. Four reactive dyes (reactive yellow 15, reactive black 5, reactive red 24 and reactive blue 2) were adsorbed onto highly porous MIL-101-Cr MOF from their aqueous solution. Real life study with industrial dye laden wastewater was also investigated. The process was simulated using a multi-component modeling derived from first principles to understand the interaction among the dye molecules and between the adsorbate and adsorbent. The adsorbent was characterized using scanning electron microscopy, BET surface area, FTIR, particle size and zeta potential. Reactive dyes were completely adsorbed in pH range 3.0–10.0. Maximum Langmuir adsorption capacities of nascent MIL-101-Cr for above mentioned dyes were in the range of 377–397 mg/g at room temperature (30 °C). Effects of pH, temperature, salt concentration, adsorbent dosing and kinetic study for the adsorbent dosing were investigated. Regeneration efficiency of the spent MIL-101-Cr adsorbent was also envisaged.

High-Charge Density Polymerized Ionic Networks Boosting High Ionic Conductivity as Quasi-Solid Electrolytes for High-Voltage Batteries.

Solid-state electrolytes are actively sought for their potential application in energy storage devices, especially lithium metal rechargeable batteries. However, one of the key challenges in the development of solid-state electrolytes is their lower ionic conductivity compared with that of liquid electrolytes (10-2 S cm-1 at room temperature), where a large gap still exists. Therefore, the pursuit of high ionic conductivity equal to that of liquid electrolytes remains the main objective for the design of solid-state electrolytes. Here, we show a series of high-charge density polymerized ionic networks as solid-state electrolytes that take inspiration from poly(ionic liquid)s. The obtained quasi-solid electrolyte slice displays an astonishingly high ionic conductivity of 5.89 × 10-3 S cm-1 at 25 °C (the highest conductivity among those of the state-of-art polymer gel electrolytes and polymer solid electrolytes) and ultrahigh decomposition potential, >5.2 V versus Li/Li+, which are attributed to the continuous ion transport channel formed by an ultrahigh ion density and an enhanced chemical stability endowed by highly cross-linked networks. The Li/LiFePO4 and Li/LiCoO2 batteries (3.0-4.4 V) assembled with the solid electrolytes show high stable capacities of around 155 and 130 mAh g-1, respectively. In principle, our work breaks new ground for the design and fabrication of the solid-state electrolytes in various energy conversion devices.

A succinct strategy for construction of nanoporous ionic organic networks from a pyrylium intermediate.

Hydroxyl group and pyridinium salt-bifunctionalized nanoporous ionic organic networks prepared via a simple two-step strategy under metal- and template-free conditions are presented. The structural features of the resultant polymer (e.g. high surface area, abundant hydroxyl groups and ionic functionalities) made it a promising candidate as an efficient scavenger of toxic oxo-anions from water.

Utilization of biomass pectin polymer to build high efficiency electrode architectures with sturdy construction and fast charge transfer structure to boost sodium storage performance for NASICON-type cathode

Electronic and ionic conductive network accelerate transfer of Na+ among particles and thus enabling cathode to show remarkable rate capability.

Nanopalladium on Magnetic Ionic Nanoparticle Network (MINN) as an Efficient and Recyclable Catalyst with High Ionic Density and Dispersibility

A novel magnetic ionic nanoparticle network (MINN) comprising ultrasmall iron oxide nanoparticles as seeds and an immobilized ionic liquid as the interfacing ionic linker was prepared using a simple coupled ligand exchange–sol–gel strategy. The material demonstrated a combination of interesting features such as network structure, high ionic density, pronounced ionic liquid content, excellent redispersibility, magnetic response, and high surface area, never observed simultaneously in the previous ionic nanoparticle networks. It was found that MINN is an effective support for the immobilization of Pd nanoparticles. The catalyst exhibits outstanding catalytic activity, stability, reproducible dispersibility, and durability in the Suzuki cross-coupling of highly challenging substrates such as heteroaryl halides, ortho-substituted aryl halides, as well as aryl chlorides. Also, the catalyst was efficiently recovered using a new magnetic separation/redispersion strategy and exhibited no noticeable loss of perfor...

Synthesis of multifunctional high strength, highly swellable, stretchable and self‐healable pH‐responsive ionic double network hydrogels

AbstractThe multifunctional double network (DN) soft hydrogels reported here are highly swellable and stretchable pH‐responsive smart hydrogel materials with sufficient strength and self‐healing properties. Such multifunctional hydrogels are achieved using double crosslinking structures with multiple physical and chemical crosslinks. They consist of a copolymer network of acrylamide (AM) and sodium acrylate (Na‐AA) and other reversible network of poly(vinyl alcohol)–borax complex. They were characterized by Fourier transform IR analysis and studied for their hydrogen bonding and ionic interaction. The degree of equilibrium swelling was observed to be as high as 5959% (at pH 7.0) for a hydrogel with AM/Na‐AA = 25/75 wt% in the network (GS‐6 sample). The highest degree of swelling was observed to be 6494% at pH 8.5. The maximum tensile strength was measured to be 1670, 580 and 130 kPa for a DN hydrogel (GS‐2 sample: AM/Na‐AA =75/25 wt% with 20, 40 and 60 wt% water content, respectively). The self‐healing efficiency was estimated to be 69% for such a hydrogel. These multifunctional DN hydrogels with amalgamation of many functional properties are unique in hydrogel materials and such materials may find applications in sensors, actuators, smart windows and biomedical applications. © 2018 Society of Chemical Industry

Catalytic and ionic cross-linking actions of l-glutamate salt for the modification of cellulose by 1,2,3,4-butanetetracarboxylic acid

The sodium l-glutamate is reported as an efficient catalyst for the cross-linking between 1,2,3,4-butanetetracarboxylic acid (BTCA) and cellulose. Results presented ester absorbance of the treated fabrics strongly increased in the presence of the homemade l-glutamate salt, a mixture of l-glutamic acid (LGA) and NaOH at a specific ratio. Importantly, anti-wrinkle properties of the treated fabrics were significantly improved. Based on the relative concentration calculation, l-glutamate promoted the reaction of BTCA with cellulose by accelerating the formation of BTCA anhydrides and the esterification of anhydrides with cellulose. Besides, the improved anti-wrinkle property was partially attributed to the fact that the generated LGA reacted with cellulose and formed ionic cross-linking networks through amino groups with carboxyl groups in BTCA, which was confirmed by the Fourier transform infrared spectra and the computational calculations. Through detailed comparisons, l-glutamate catalyzed fabrics showed as good durability as sodium hypophosphite, indicating a possible alternative for phosphorus-containing catalysts.