Construction of all-organic low dielectric polyimide hybrids via synergistic effect between covalent organic framework and cross-linking structure

Polyimide(PI)is a promising electronic packaging material,but it remains challenging to obtain an all-organic PI hybrid film with decreased dielectric constant and loss without modifying the monomer.Herein,a series of allorganic PI hybrid films were successfully prepared by introducing the covalent organic framework(COF),which could induce the formation of the cross-linking structure in the PI matrix.Due to the synergistic effects of the COF fillers and the cross-linking structure,the PI/COF hybrid film containing 2 wt%COF exhibited the lowest dielectric constant of 2.72 and the lowest dielectric loss(tanδ)of 0.0077 at 1 MHz.It is attributed to the intrinsic low dielectric constant of COF and a large number of mesopores within the PI.Besides,the cross-linking network of PI prevents the molecular chains from stacking and improves the fraction of free volume(FFV).The molecular dynamics simulation results are well consistent with the dielectric properties data.Furthermore,the PI/COF hybrid film with 5 wt%COF showed a significant enhancement in breakdown strength,which increased to 412.8 kV/mm as compared with pure PI.In addition,the PI/COF hybrid film achieve to reduce the dielectric constant and thermal expansion coefficient(CTE).It also exhibited excellent thermal,hydrophobicity,and mechanical performance.The all-organic PI/COF hybrid films have great commercial potential as next-generation electronic packaging materials.

Cross-Linking of Sago Starch with Furan and Bismaleimide via the Diels-Alder Reaction

This research paper describes the synthesis of thermo-reversible cross-linking of sago starch by grafting a furan pendant group(methyl 2-furoate)onto the starch backbone,followed by a Diels-Alder(DA)reaction of the furan functional group with 1,1′-(methylenedi-4,1-phenylene)bismaleimide(BM).The proof of principles was provided by FTIR and 1H-NMR analyses.The relevant FTIR peaks are the carbonyl peak(υC=O sym)at 1721 cm^(−1);the two peaks appeared after DA cross-linking,i.e.,at 1510 cm^(−1)(corresponding toυCH=CH BM aromatic rings,stretching vibrations),and at 1173 cm^(−1)(assigned to cycloadduct(C-O-C,δDA ring))while the^(1)H-NMR result shows evidence for the presence of a furan ring in the starch matrices(in the range ofδ6.3-7.5 ppm).The crosslinked starch product is indeed thermally reversible,as is evident from the appearance of exothermal(DA,temperature range of 50℃-70℃)and endothermal(retro DA,temperature range of 125℃-150℃)transitions in the DSC thermograms.This paper not only proves the thermal reversibility but also demonstrates that the final product properties(chemical,morphology,and thermal stability)can be tuned by varying the annealing temperature,BM intake,and reaction time.

Wetting sub-nanochannels via ionic hydration effect for improving charging dynamics

The ionic transport in sub-nanochannels plays a key role in energy storage,yet suffers from a high energy barrier.Wetting sub-nanochannels is crucial to accelerate ionic transport,but the introduction of water is challenging because of the hydrophobic extreme confinement.We propose wetting the channels by the exothermic hydration process of pre-intercalated ions,the effect of which varies distinctly with different ionic hydration structures and energies.Compared to the failed pre-intercalation of SO_(4)^(2-),HSO_(4)^(-) with weak hydration energy results in a marginal effect on the HOMO(Highest Occupied Molecular Orbital)level of water to avoid water splitting during the electrochemical intercalation.Meanwhile,the ability of water introduction is reserved by the initial incomplete dissociation state of HSO_(4)^(-),so the consequent exothermic reionization and hydration processes of the intercalated HSO_(4)^(-) promote the water introduction into sub-nanochannels,finally forming the stable confined water through hydrogen bonding with functional groups.The wetted channels exhibit a significantly enhanced ionic diffusion coef-ficient by~9.4 times.

Mechanism of high Li-ion conductivity in poly(vinylene carbonate)-poly(ethylene oxide)cross-linked network based electrolyte revealed by solid-state NMR

Solid polymer electrolytes(SPEs)have become increasingly important in advanced lithium-ion batteries(LIBs)due to their improved safety and mechanical properties compared to organic liquid electrolytes.Cross-linked polymers have the potential to further improve the mechanical property without trading off Li-ion conductivity.In this study,focusing on a recently developed cross-linked SPE,i.e.,the one based on poly(vinylene carbonate)-poly(ethylene oxide)cross-linked network(PVCN),we used solid-state nuclear magnetic resonance(NMR)techniques to investigate the fundamental interaction between the chain segments and Li ions,as well as the lithium-ion motion.By utilizing homonuclear/heteronuclear correlation,CP(cross-polarization)kinetics,and spin-lattice relaxation experiments,etc.,we revealed the structural characteristics and their relations to lithium-ion mobilities.It is found that the network formation prevents poly(ethylene oxide)chains from crystallization,which could create sufficient space for segmental tumbling and Li-ion co nductio n.As such,the mechanical property is greatly improved with even higher Li-ion mobilities compared to the poly(vinylene carbonate)or poly(ethylene oxide)based SPE analogues.

Inhibiting effect of[HOEmim][BF_4]and[Amim]Cl ionic liquids on the cross-linking reaction of bituminous coal

In order to reduce the hazard of coal spontaneous combustion,the cross-linking reaction between O-containing functional groups of coal should be inhibited.So the inhibitory effect of an ionic liquid(IL) on the cross-linking reaction was studied.The O-containing functional groups change the weight loss and H_2O,CO_2,CO yields of bituminous coal before and after[H0Emim][BF_4]and[Amim]Cl pre-treatment and were detected by Fourier Transform Infrared spectroscopy(FT1R) and Thermo Gravimetric(TC) analysis.The results show that | AmimjCI has a weaker ability to inhibit the cross-linking reaction of bituminous coal compared to[HOEmim][BF_4].Besides,based on Quantum Chemistry calculation,it was found that the different inhibiting effects of |H0Emim][BF_4]and[Amim]Cl are greatly related to their anions and the H linked with C2 atom on the imidazole ring.The H-donor ability of coal will be enhanced by[HOEmim][BF_4]leading to a weaker cross-linking reaction of coal.

Residual alkali-evoked cross-linked polymer layer for anti-air-sensitivity LiNi_(0.89)Co_(0.06)Mn_(0.05)O_(2)cathode

High-energy density lithium-ion batteries(LIBs)with layered high-nickel oxide cathodes(LiNi_(x)Co_(y)Mn_(1-x-y)O_(2),x≥0.8)show great promise in consumer electronics and vehicular applications.However,LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)faces challenges related to capacity decay caused by residual alkalis owing to high sensitivity to air.To address this issue,we propose a hazardous substances upcycling method that fundamentally mitigates alkali content and concurrently induces the emergence of an anti-air-sensitive layer on the cathode surface.Through the neutralization of polyacrylic acid(PAA)with residual alkalis and then coupling it with 3-aminopropyl triethoxysilane(KH550),a stable and ion-conductive cross-linked polymer layer is in situ integrated into the LiNi_(0.89)Co_(0.06)Mn_(0.05)O_(2)(NCM)cathode.Our characterization and measurements demonstrate its effectiveness.The NCM material exhibits impressive cycling performance,retaining 88.4%of its capacity after 200 cycles at 5 C and achieving an extraordinary specific capacity of 170.0 mA h g^(-1) at 10 C.Importantly,this layer on the NCM efficiently suppresses unfavorable phase transitions,severe electrolyte degradation,and CO_(2)gas evolution,while maintaining commendable resistance to air exposure.This surface modification strategy shows widespread potential for creating air-stable LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)cathodes,thereby advancing high-performance LIBs.

Ionic liquid-assisted preparation of hydroxyapatite and its catalytic performance for decarboxylation of itaconic acid

The synthesis of methacrylic acid from biomass-derived itaconic acid is a green route,for it can get rid of the dependence on fossil resource.In order to solve the problems on this route such as use of a preciousmetal catalyst and a corrosive homogeneous alkali,we prepared a series of hydroxyapatite catalysts by an ionic liquid-assisted hydrothermal method and evaluated their catalytic performance.The results showed that the ionic liquid[Bmim]BF_(4) can affect the crystal growth of hydroxyapatite,provide fluoride ion for fluorination of hydroxyapatite,and adjust the surface acidity and basicity,morphology,textural properties,crystallinity,and composition of hydroxyapatite.The[Bmim]BF4 dosage and hydrothermal temperature can affect the fluoride ion concentration in the hydrothermal system,thus changing the degree of fluoridation of hydroxyapatite.High fluoride-ion concentration can lead to the formation of CaF_(2) and thus significantly decrease the catalytic performance of hydroxyapatite.The hydrothermal time mainly affects the growth of hydroxyapatite crystals on the c axis,leading to different catalytic performance.The suitable conditions for the preparation of this fluoridized hydroxyapatite are as follows:a mass ratio of[Bmim]BF4 to calcium salt=0.2:1,a hydrothermal time of 12 h,and a hydrothermal temperature of 130℃.A maximal methacrylic acid yield of 54.7%was obtained using the fluoridized hydroxyapatite under relatively mild reaction conditions(250℃ and 2 MPa of N_(2))in the absence of a precious-metal catalyst and a corrosive homogeneous alkali.

Highly selective extraction of aromatics from aliphatics by using metal chloride-based ionic liquids

The separation of aromatics from aliphatics is essential for achieving maximum exploitation of oil resources in the petrochemical industry.In this study,a series of metal chloride-based ionic liquids were prepared and their performances in the separation of 1,2,3,4-tetrahydronaphthalene(tetralin)/dodecane and tetralin/decalin systems were studied.Among these ionic liquids,1-ethyl-3-methylimidazolium tetrachloroferrate([EMIM][FeCl_(4)])with the highest selectivity was used as the extractant.Density functional theory calculations showed that[EMIM][FeCl_(4)]interacted more strongly with tetralin than with dodecane and decalin.Energy decomposition analysis of[EMIM][FeCl_(4)]-tetralin indicated that electrostatics and dispersion played essential roles,and induction cannot be neglected.The van der Waals forces was a main effect in[EMIM][FeCl_(4)]-tetralin by independent gradient model analysis.The tetralin distribution coefficient and selectivity were 0.8 and 110,respectively,with 10%(mol)tetralin in the initial tetralin/dodecane system,and 0.67 and 19.5,respectively,with 10%(mol)tetralin in the initial tetralin/decalin system.The selectivity increased with decreasing alkyl chain length of the extractant.The influence of the extraction temperature,extractant dosage,and initial concentrations of the system components on the separation performance were studied.Recycling experiments showed that the regenerated[EMIM][FeCl_(4)]could be used repeatedly.

Interfacial friction induced capillary flow within nanofiber-supported ionic liquid droplets

As global economic growth increases,the demand for energy sources boosts.While fossil fuels have traditionally satisfied this demand,their environmental influence and limited reserves require alternatives.Fossil fuel combustion contributes substantially to greenhouse gas emissions,with a pressing need to halve these emissions by 2030 and target net-zero by 2050.Renewable energy sources,contributing currently to 29%of global electricity,are viewed as promising substitutes.With wind energy's potential,Zheng's team developed a novel method to harness even low wind speeds using well-aligned nanofibers and an innovative“drop wind generator”.This system,combining moisture-saturated ionic liquid 3-Methyl-1-octylimidazolium chloride with specific nanofiber arrays,exploits wind-inducedflows for energy conversion.This study highlights the vast untapped potential of low-speed wind as a sustainable energy source potentially for electronics.

Experimental study of the effect of gas discharge on ionic liquid electrospray

Ionic liquid electrospray(ILE) in an atmospheric environment is often accompanied by the gas discharge phenomenon. It interferes with the normal operation of the electrospray and the measurement of experimental parameters. In this study, electrospray experiments were conducted on the ionic liquid EMI-BF4. The observations revealed that the operating modes of the ionic liquid depend on the voltage polarity at high voltages. Additionally, a correspondence between the operating mode of ILE and the current signal in the circuit was established. The shape of the liquid cone formed at the needle tip bore a striking resemblance to the plume of corona discharge, suggesting that the motion trajectory of electrons influenced the curvature of the liquid cone. Steamer theory provided a clear explanation for the change in curvature as the voltage increased.

Ionically Imprinting-Based Copper(Ⅱ)Label-Free Detection for Preventing Hearing Loss

Copper is a microelement with important physiological functions in the body.However,the excess copper ion(Cu^(2+))may cause severe health problems,such as hair cell apoptosis and the resultant hearing loss.Therefore,the assay of Cu^(2+)is important.We integrate ionic imprinting technology(IIT)and structurally colored hydrogel beads to prepare chitosan-based ionically imprinted hydrogel beads(IIHBs)as a low-cost and high-specificity platform for Cu^(2+)detection.The IIHBs have a macroporous microstructure,uniform size,vivid structural color,and magnetic responsiveness.When incubated in solution,IIHBs recognize Cu^(2+)and exhibit a reflective peak change,thereby achieving label-free detection.In addition,benefiting from the IIT,the IIHBs display good specificity and selectivity and have an imprinting factor of 19.14 at 100μmol·L^(-1).These features indicated that the developed IIHBs are promising candidates for Cu^(2+)detection,particularly for the prevention of hearing loss.

Ionic Liquid-Enhanced Assembly of Nanomaterials for Highly Stable Flexible Transparent Electrodes

The controlled assembly of nanomaterials has demon-strated significant potential in advancing technological devices.However,achieving highly efficient and low-loss assembly technique for nanomate-rials,enabling the creation of hierarchical structures with distinctive func-tionalities,remains a formidable challenge.Here,we present a method for nanomaterial assembly enhanced by ionic liquids,which enables the fabrication of highly stable,flexible,and transparent electrodes featuring an organized layered structure.The utilization of hydrophobic and non-volatile ionic liquids facilitates the production of stable interfaces with water,effectively preventing the sedimentation of 1D/2D nanomaterials assembled at the interface.Furthermore,the interfacially assembled nanomaterial monolayer exhibits an alternate self-climbing behavior,enabling layer-by-layer transfer and the formation of a well-ordered MXene-wrapped silver nanowire network film.The resulting composite film not only demonstrates exceptional photoelectric performance with a sheet resistance of 9.4Ωsq^(-1) and 93%transmittance,but also showcases remarkable environmental stability and mechanical flexibility.Particularly noteworthy is its application in transparent electromagnetic interference shielding materials and triboelectric nanogenerator devices.This research introduces an innovative approach to manufacture and tailor functional devices based on ordered nanomaterials.

Bacterial Cellulose/Zwitterionic Dual-network Porous Gel Polymer Electrolytes with High Ionic Conductivity

Bacterial cellulose(BC)was innovatively combined with zwitterionic copolymer acrylamide and sulfobetaine methacrylic acid ester[P(AM-co-SBMA)]to build a dual-network porous structure gel polymer electrolytes(GPEs)with high ionic conductivity.The dual network structure BC/P(AM-co-SBMA)gels were formed by a simple one-step polymerization method.The results show that ionic conductivity of BC/P(AM-co-SBMA)GPEs at the room temperature are 3.2×10^(-2) S/cm@1 M H_(2)SO_(4),4.5×10^(-2) S/cm@4 M KOH,and 3.6×10^(-2) S/cm@1 M NaCl,respectively.Using active carbon(AC)as the electrodes,BC/P(AM-co-SBMA)GPEs as both separator and electrolyte matrix,and 4 M KOH as the electrolyte,a symmetric solid supercapacitors(SSC)(AC-GPE-KOH)was assembled and testified.The specific capacitance of AC electrode is 173 F/g and remains 95.0%of the initial value after 5000 cycles and 86.2%after 10,000 cycles.

Structure and ion transport properties of organic ionic compounds revealed by NMR

Organic ionic plastic crystals(OIPCs)are emerging as an important material family for solid-state electrolytes and many other applications.They have significant advantages over conventional electrolyte materials,such as high ionic conductivity,non-flammability,and plasticity.Various nuclear magnetic resonance(NMR)spectroscopy techniques including solid-state NMR,pulsed-field gradient(PFG)NMR,and magnetic resonance imaging(MRI)etc.,provide us a versatile toolkit to understand the fundamental level structures,molecular dynamics,and ionic interactions in these materials.This article reviews the commonly used NMR methods including solid-and solution-state NMR,PFG-NMR,dynamic nuclear polarization(DNP)and the application of these methods in revealing the microscopic level structures and ion-transport mechanisms in OIPC materials.

Solvent effects on Diels-Alder reaction in ionic liquids:A reaction density functional study

Extensive experimental studies have been performed on the Diels-Alder(DA)reactions in ionic liquids(ILs),which demonstrate that the IL environment can significantly influence the reaction rates and selectivity.However,the underlying microscopic mechanism remains ambiguous.In this work,the multiscale reaction density functional theory is applied to explore the effect of 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF_(6)])solvent on the reaction of cyclopentadiene(CP)with acrolein,methyl acrylate,or acrylonitrile.By analyzing the free energy landscape during the reaction,it is found that the polarization effect has a relatively small influence,while the solvation effect makes both the activation free energy and reaction free energy decrease.In addition,the rearrangement of local solvent structure shows that the cation spatial distribution responds more evidently to the reaction than the anion,and this indicates that the cation plays a dominant role in the solvation effect and so as to affect the reaction rates and selectivity of the DA reactions.

Fluorescent Double Network Hydrogels with Ionic Responsiveness and High Mechanical Properties for Visual Detection

We developed a fluorescent double network hydrogel with ionic responsiveness and high mechanical properties for visual detection.The nanocomposite hydrogel of laponite and polyacrylamide serves as the first network,while the ionic cross-linked hydrogel of terbium ions and sodium alginate serves as the second network.The double-network structure,the introduction of nanoparticles and the reversible ionic crosslinked interactions confer high mechanical properties to the hydrogel.Terbium ions are not only used as the ionic cross-linked points,but also used as green emitters to endow hydrogels with fluorescent properties.On the basis of the “antenna effect” of terbium ions and the ion exchange interaction,the fluorescence of the hydrogels can make selective responses to various ions(such as organic acid radical ions,transition metal ions) in aqueous solutions,which enables a convenient strategy for visual detection toward ions.Consequently,the fluorescent double network hydrogel fabricated in this study is promising for use in the field of visual sensor detection.

A Modification of LiMn2O4 by Ionic Conductive Agent and Electronic Conductive Agent Coating

Carbon was used as electronic conductive agent, and metasilicic acid lithium (Li2SiO3) as ionic conductive agent, the two factors were investigated cooperatively. We evaluated their effect by using spherical spinel LiMn2O4 which prepared ourselves as cathode material. Then Li2SiO3/carbon surface coating on LiMn2O4 (LMO/C/LSO) which Li2SiO3 inside and carbon/Li2SiO3 coated LiMn2O4 (LMO/LSO/C) were prepared, All of materials were characterized by X-ray diffraction (XRD) and electrochemical test;spherical LiMn2O4 was characterized by scanning electron microscopy (SEM);and coated materials were characterized by transmission electron microscopy (TEM). While uncoated spinel LiMn2O4 maintained 72% of capacity in 60 cycles by the rate of 0.2C, and LMO/LSO/C showed the best electrochemical performance, 89% of the initial capacity remained after 75 cycles at 0.2C. Furthermore, the rate performance of LMO/LSO/C also improved obviously, about 30 mAh·g-1 of capacity attained at the rate of 5C, higher than LMO/C/LSO and bare LiMn2O4.

Ionic liquid derived electrocatalysts for electrochemical water splitting

Hydrogen production from electrochemical water splitting is a promising strategy to generate green energy,which requires the development of efficient and stable electrocatalysts for the hydrogen evolution reaction and the oxygen evolution reaction(HER and OER).Ionic liquids(ILs)or poly(ionic liquids)(PILs),containing heteroatoms,metal-based anions,and various structures,have been frequently involved as precursors to prepare electrocatalysts for water splitting.Moreover,ILs/PILs possess high conductivity,wide electrochemical windows,and high thermal and chemical stability,which can be directly applied in the electrocatalysis process with high durability.In this review,we focus on the studies of ILs/PILs-derived electrocatalysts for HER and OER,where ILs/PILs are applied as heteroatom dopants and metal precursors to prepare catalysts or are directly utilized as the electrocatalysts.Due to those attractive properties,IL/PIL-derived electrocatalysts exhibit excellent performance for electrochemical water splitting.All these accomplishments and developments are systematically summarized and thoughtfully discussed.Then,the overall perspectives for the current challenges and future developments of ILs/PILs-derived electrocatalysts are provided.

Ionic liquids as the effective technology for enhancing transdermal drug delivery: Design principles, roles, mechanisms, and future challenges

Ionic liquids (ILs) have been proven to be an effective technology for enhancing drug transdermal absorption. However, due to the unique structural components of ILs, the design of efficient ILs and elucidation of action mechanisms remain to be explored. In this review, basic design principles of ideal ILs for transdermal drug delivery system (TDDS) are discussed considering melting point, skin permeability, and toxicity, which depend on the molar ratios, types, functional groups of ions and inter-ionic interactions. Secondly, the contributions of ILs to the development of TDDS through different roles are described: as novel skin penetration enhancers for enhancing transdermal absorption of drugs;as novel solvents for improving the solubility of drugs in carriers;as novel active pharmaceutical ingredients (API-ILs) for regulating skin permeability, solubility, release, and pharmacokinetic behaviors of drugs;and as novel polymers for the development of smart medical materials. Moreover, diverse action mechanisms, mainly including the interactions among ILs, drugs, polymers, and skin components, are summarized. Finally, future challenges related to ILs are discussed, including underlying quantitative structure-activity relationships, complex interaction forces between anions, drugs, polymers and skin microenvironment, long-term stability, and in vivo safety issues. In summary, this article will promote the development of TDDS based on ILs.

Revealing structure correlation between ionic liquid and metal-organic framework matrix

Solid-state batteries are rising rapidly in response to the fast-increasing energy demand.Metal-organic framework(MOF)loaded with ionic liquids has brought new opportunities for solid-state batteries owing to its good interfacial compatibility and high ionic conductivity.MOF-808 is selected to be filled with Li-contained ionic liquid for structure and ion dynamics investigation using nuclear magnetic resonance(NMR)and X-ray diffraction.This study finds that the introduced ionic liquid would partially soften the matrix of MOF-808 and thus yield amorphous phase.By selective isotope replacement under cycling symmetric 6Li metal cell,Lit ion is observed to mainly go cross ionic liquid in the open channel of matrix under potential polarization.