Polymeric ionic liquids(PILs)with high acid density:Tunable catalytic performance for biodiesel production

A series of polymeric ionic liquids(PILs)used as effective heterogeneous catalysts for biodiesel production via esterification of free fatty acids(FFAs)were effectively prepared by the reaction of poly(ethylene imine)(PEI)polymers with different molecular weight and 1,3-propanesultone,followed by the further acidification with differential effective acids,i.e.H2SO4,CF3SO3H,CH3SO3H or p-toluenesulfonic acid(p-TSA).Ultrahigh acidity and catalytic performance were achieved and could be fine-tuned by simply adjusting the molecular weight of PEI and by further treatment of acids.Specifically,under the optimal conditions(i.e.reaction temperature was 70℃,reaction time was 2.0 h,catalyst dosage was 3.15%(mass),and alcohol/acid molar ratio was 14:1)acquired through the Box-BEHNKEN response surface methodology,a high oleic acid conversion of 98.42%could be obtained over the optimal PIL,PEI(70000)-PS-p-TSA.Additionally,our PILs also showed high generality for esterification of other FFAs,with general high conversion over 90%noted in each case even under much milder reaction conditions compared to other conventional catalysts.

Tuning the cross-linked structure of basic poly(ionic liquid)to develop an efficient catalyst for the conversion of vinyl carbonate to dimethyl carbonate

Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium methoxide basic catalyst to produce DMC through the transesterification reaction between vinyl carbonate and methanol.However,the utilization of this catalyst presents several challenges during the process,including equipment corrosion,the generation of solid waste,susceptibility to deactivation,and complexities in separation and recovery.To address these limitations,a series of alkaline poly(ionic liquid)s,i.e.[DVBPIL][PHO],[DVCPIL][PHO],and[TBVPIL][PHO],with different crosslinking degrees and structures,were synthesized through the construction of cross-linked polymeric monomers and functionalization.These poly(ionic liquid)s exhibit cross-linked structures and controllable cationic and anionic characteristics.Research was conducted to investigate the effect of the cross-linking degree and structure on the catalytic performance of transesterification in synthesizing DMC.It was discovered that the appropriate cross-linking degree and structure of the[DVCPIL][PHO]catalyst resulted in a DMC yield of up to 80.6%.Furthermore,this catalyst material exhibited good stability,maintaining its catalytic activity after repeated use five times without significant changes.The results of this study demonstrate the potential for using alkaline poly(ionic liquid)s as a highly efficient and sustainable alternative to traditional catalysts for the transesterification synthesis of DMC.

NMR signal separation of ionic liquids by poly( sodium-p-styrenesulfonate)-assisted chromatographic NMR spectroscopy--Dedicated to Professor Xiuwen Han on the occasion of her 80th birthday

Diffusion-ordered nuclear magnetic resonance spectroscopy(DOSY),dubbed chromato-graphic NMR spectroscopy,can be used to simultaneously distinguish and identify the structures of components in a mixture according to their different diffusion coefficients.In order to improve the resolution of DOSY on the diffusion dimension,a lot of matrices have been developed to expand the application of this technique in mixture analysis.However,there is no matrix to detect the mixture of ionic liquids(ILs).Herein,we introduced a new matrix,poly(sodium-p-styrenesulfonate)(PSSNa),which can be used to fully separate the signals of a mixture of different ILs.The mixture of three imidazolium ILs of 1-butyl-3-methylimidazolium bromide,1-allyl-3-vinylimidazolium bromide and 1-arboxymethy-3-methylimidazolium chloride could be fully distinguished by virtue of their different interactions with PSSNa.We also investigated the influences of PSSNa amount,IL con-centration and solution pH value on the signal resolution of mixtures.This work provides a scientific reference for the analysis of the other IL analytes.

Electrochemical Properties of PP13TFSI-LiTFSI-P（VdF-HFP） Ionic Liquid Gel Polymer Electrolytes

N-Methyl-N-propylpiperidiniumbis（trifluoromethanesulfonyl）imide （PP13TFSI）, bis（triflu- oromethanesulfonyl）imide lithium salt （LiTFSI）, and poly（vinylidene difluoride-co- hexafluoropropylene） （P（VdF-HFP）） were mixed and made into ionic liquid gel polymer electrolytes （ILGPEs） by solution casting. The morphology of ILGPEs was observed by scanning electron microscopy. It was found that the ILGPE had a loosened structure with liquid phase uniformly distributed. The ionic conductivity, lithium ion transference num- bet and electrochemical window were measured by electrochemical impedance spectroscopy, chronoamperometric and linear sweep voltammetry. The ionic conductivity and lithium ion transference number of this ILGPE reached 0.79 mS/cm and 0.71 at room temperature, and the electrochemical window was 0 to 5.1 V vs. Li＋/Li. Battery tests indicated that the ILGPE is stable when being operated in Li/LiFePO4 batteries. The discharge capacity maintained at about 135, 117, and 100 mAh/g at 30, 75, and 150 mA/g rates, respectively. The capacity retentions were almost 100% after 100 cycles without little capacity fading.

Wet-spun poly(ionic liquid)-graphene hybrid fibers for high performance all-solid-state flexible supercapacitors

It is crucial to develop flexible and wearable electronic devices that have attracted tremendous interest due to their merits on compactness,flexibility and high capacitive properties.Herein we report the continuously ordered macroscopic poly(ionic liquid)-graphene fibers by wet spinning method via liquid crystal assembly for supercapacitor application.The fabricated all-solid-state supercapacitors exhibited a high areal capacitance(268.2 mF cm 2)and volumetric capacitance(204.6 F cm 3)with an outstanding areal energy density(9.31μWh cm-2)and volumetric energy density(8.28 mWh cm-3).The fiber supercapacitors demonstrated exceptional cycle life for straight electrodes of about 10,000 cycles(94.2%capacitance retention)and flexibility at different angles(0°,45°,90°,180°)along with a good flexible cycling stability after 6000 cycles(92.7%capacitance retention).To date,such a novel poly(ionic liquid)-graphene fiber supercapacitors would be a new platform in real-time flexible electronics.

Swelling acidic poly(ionic liquid)s as efficient catalysts for the esterification of cyclohexene and formic acid

Acidic poly(ionic liquid)s(PILs)with swelling ability were synthesized by free radical copolymerization of N-vinylimidazolium ionic liquids,divinylbenzene(DVB)and sodium acrylate(NaAA),and further acidification by sulfuric acid.The swelling ability of acidic PILs was greatly affected by cross-linker content and chain length of 3-alkyl-substituents on imidazolium.Cross-linked network structures could be observed from the cryogenic scanning electron microscopy(cryo-SEM)images of the swollen acidic PILs in formic acid.Acidic PILs with network structures in swollen state exhibited excellent activities in the esterification of cyclohexene and formic acid,and the catalytic activities were in positive correlation with their swelling abilities.Acidic PIL with 3-octyl-substituent and 2.5 mol%DVB(PIL-C8-2.5DVB-HSO4)had the highest swelling ability in formic acid and exhibited comparable catalytic activities with homogeneous catalysts such as sulfuric acid and p-toluenesulfonic acid.

Fabrication of poly(vinylidene fluoride) membrane via thermally induced phase separation using ionic liquid as green diluent

Ionic liquid(IL),1-butyl-3-methylimidazolium hexafluorophosphate([BMIM]PF6)as a new and environmentally friendly diluent was introduced to prepare poly(vinylidene fluoride)(PVDF)membranes via thermally induced phase separation(TIPS).Phase diagram of PVDF/[BMIM]PF6 was measured.The effects of polymer concentration and quenching temperature on the morphologies,properties,and performances of the PVDF membranes were investigated.When the polymer concentration was 15 wt%,the pure water flux of the fabricated membrane was up to nearly 2000 L·m-2·h-1,along with adequate mechanical strength.With the increasing of PVDF concentration and quenching temperature,mean pore size and water permeability of the membrane decreased.SEM results showed that PVDF membranes manufactured by ionic liquid(BMIm PF6)presented spherulite structure.And the PVDF membranes were represented asβphase by XRD and FTIR characterization.It provides a new way to prepare PVDF membranes with piezoelectric properties.

Poly(ionic liquid)-crosslinked graphene oxide/carbon nanotube membranes as efficient solar steam generators

Graphene oxide(GO)is regarded as a promising candidate to construct solar absorbers for addressing freshwater crisis,but the easy delamination of GO in water poses a critical challenge for practical solar desalination.Herein,we improve the stability of GO membranes by a self-crosslinking poly(ionic liquid)(PIL)in a mild condition,which crosslinks neighbouring GO nanosheets without blemishing the hydrophilic structure of GO.By further adding carbon nanotubes(CNTs),the sandwiched GO/CNT@PIL(GCP)membrane displays a good stability in pH=1 or 13 solution even for 270 days.The molecular dynamics simulation results indicate that the generation of water nanofluidics in nanochannels of GO nanosheets remarkably reduces the water evaporation enthalpy in GCP membrane,compared to bulk water.Consequently,the GCP membrane exhibits a high evaporation rate(1.87 kg m^(-2)h^(-1))and displays stable evaporation rates for 14 h under 1 kW m^(-2)irradiation.The GCP membrane additionally works very well when using different water sources(e.g.,dye-polluted water)or even strong acidic solution(pH=1)or basic solution(pH=13).More importantly,through bundling pluralities of GCP membrane,an efficient solar desalination device is developed to produce drinkable water from seawater.The average daily drinkable water amount in sunny day is 10.1 kg m^(-2),which meets with the daily drinkable water needs of five adults.The high evaporation rate,long-time durability and good scalability make the GCP membrane an outstanding candidate for practical solar seawater desalination.

Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions

The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging.In this study,acidic poly(ionic liquid)s with swelling ability(SAPILs)were designed and synthesized via the free radical copolymerization of ionic liquid monomers,sodium p-styrenesulfonate,and crosslinkers,followed by acidification.The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength.The thermogravimetric analysis results in the temperature range of 300–345°C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H)(245°C).Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional(3D)honeycomb structure in water,which was ascribed to the swelling-induced self-assembly of the molecules.Moreover,we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol,and determined that their catalytic activity was much higher than that of homogeneous acid catalysts.The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures.Depending on the reaction mixture,the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it,which suggested the high enrichment ability of SAPILs for cyclohexyl acetate.The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate,which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.

Pyrolyzing soft template-containing poly(ionic liquid)into hierarchical N-doped porous carbon for electroreduction of carbon dioxide

Heteroatom-doped carbon materials have demonstrated great potential in the electrochemical reduction reaction of CO_(2)(CO_(2)RR)due to their versatile structure and function.However,rational structure control remains one challenge.In this work,we reported a unique carbon precursor of soft template-containing porous poly(ionic liquid)(PIL)that was directly synthesized via free-radical self-polymerization of ionic liquid monomer in a soft template route.Variation of the carbonization temperature in a direct pyrolysis process without any additive yielded a series of carbon materials with facile adjustable textural properties and N species.Significantly,the integration of soft-template in the PIL precursor led to the formation of hierarchical porous carbon material with a higher surface area and larger pore size than that from the template-free precursor.In CO_(2)RR to CO,the champion catalyst gave a Faraday efficiency of 83.0%and a current density of 1.79 mA·cm^(-2)at-0.9 V vs.reversible hydrogen electrode(vs.RHE).The abundant graphite N species and hierarchical pore structure,especially the unique hierarchical small-/ultramicropores were revealed to enable better CO_(2)RR performance.

Mesoporous poly(ionic liquid)s with dual active sites for highly efficient CO_(2)conversion

Atmospheric CO_(2)concentrations are soaring due to the continued use of fossil fuels in energy production,an anthropogenic activity that is playing a leading role in global warming.Thus,research aimed at the capture and conversion of CO_(2)into value-added products,such as cyclic carbonates,is booming.While CO_(2)is an abundant,cheap,non-toxic,and readily accessible Cl feedstock,its thermodynamic stability necessitates the development of highly efficient catalysts that are able to promote chemical reactions under mild conditions.In this work,a novel mesoporous poly(ionic liquid)with dual active sites was synthesized through a facile method that involves co-polymerization,post-synthetic metalation,and supercritical CO_(2)drying.Due to a high density of nucleophilic and electrophilic sites,the as-prepared poly(ionic liquid),denoted as P2D-4BrBQA-Zn,offers excellent performance in a CO_(2)cycloaddition reaction using epichlorohydrin as the substrate(98.9%conversion and 96.9%selectivity).Moreover the reaction is carried out under mild,solvent-free,and additive-free conditions.Notably,P2D-4BrBQA-Zn also efficiently promotes the conversion of various other epoxide substrates into cyclic carbonates.Overall,the catalyst is found to have excellent substrate compatibility,stability,and recyclability.

Differentiation of Chemisorption and Physisorption of Carbon Dioxide on Imidazolium-type Poly(ionic liquid)Brushes

Amine-functionalized imidazolium-based poly(ionic liquid)brushes on mesoporous silica were synthesized via"grafting through"technique and were applied as model sorbents to understand physisorption and chemisorption of carbon dioxide molecules.The experimental results reveal that the total adsorption capacity of model sorbents derived from temperature programmed desorption(TPD)approach reaches 1.72 mmol·g^-1 that is much higher than the sum of adsorption capacity of bare mesoporous silica and free polymers at 25℃under carbon dioxide partial pressure of 0.2 bar.The proposed physical adsorption and chemical adsorption of carbon dioxide molecules in TPD response curves were validated by volumetric desorption measurement.It is also observed that physical adsorption is completely reversible and chemical adsorption is irreversible.The results demonstrate that the temperature programmed desorption technique is an effective approach to differentiate chemisorption and physisorption of gaseous species on solid sorbents,which is beneficial for understanding of adsorption mechanism and materials design.

Poly(Ionic Liquid) as an Anion Exchange Membrane for a 3.3 V Copper–Lithium Battery

Metal–metal battery bears great potential for next-generation large-scale energy storage system because of its simple manufacture process and low production cost.However,the cross-over of metal cations from the cathode to the anode causes a loss in capacity and influences battery stability.Herein,a coating of poly(ionic liquid)(PIL)with poly(diallyldimethylammonium bis(trifluoromethanesulfonyl)imide)(PDADMA^(+)TFSI^(−))on a commercial polypropylene(PP)separator serves as an anion exchange membrane for a 3.3 V copper–lithium battery.The PIL has a positively charged polymer backbone that can block the migration of copper ions,thus improving Coulombic efficiency,long-term cycling stability and inhibiting self-discharge of the battery.It can also facilitate the conduction of anions through the membrane and reduce polarization,especially for fast charging/discharging.Bruce-Vincent method gives the transport number in the electrolyte to be 0.25 and 0.04 for PP separator without and with PIL coating,respectively.This suggests that the PIL layer reduces the contribution of the internal current due to cation transport.The use of PIL as a coating layer for commercial PP separator is a cost-effective way to improve overall electrochemical performance of copper–lithium batteries.Compared to PP and polyacrylic acid(PAA)/PP separators,the PIL/PP membrane raises the Coulombic efficiency to 99%and decreases the average discharge voltage drop to about 0.09 V when the current density is increased from 0.1 to 1 mA cm^(−2).

New methacrylic imidazolium poly (ionic liquid) gel with super swelling capacity for oil-in-water emulsions

A new polymeric ionic liquid gel was prepared with 1-[(2-methacryloyloxy)ethyl]-3-methylimidazolium bromide(MEMImBr) via radiation-induced polymerization and cross-linking at room temperature.The resultant PMEMImBr gel exhibits high strength and flexibility as well as special swelling behavior in oil-in-water(O/W)emulsions.The swelling behavior of PMEMImBr gel in emulsions is similar to that in water except that the swelling rate in emulsions is slightly smaller than that in water.The organic solvents with higher polarity in the emulsions contribute to the swelling of PMEMImBr gels,and the O/W proportion of emulsion in the swollen gel equals approximately that of original emulsion when the concentration of organic solvent is lower than 0.2 g/g.

Ionic liquid/poly(ionic liquid)-based electrolytes for lithium batteries

The growing demand for portable electronic devices,electric vehicles,and large-scale advanced energy storage has aroused increasing interest in the development of high energy density lithium batteries.The electrolyte is an important component of lithium batteries and is an essential part of performance and safety improvements.Commercially available electrolytes mainly consist of lithium salts and organic carbonate solvents that are prone to decomposition due to their narrow electrochemical windows and tend to react with lithium metal anodes forming an unstable solid electrode/electrolyte interface(SEI).In particular,the flammability of organic solvents raises concerns about battery safety.Ionic liquid/poly(ionic liquid)(IL/PIL)-based electrolytes enable batteries with good safety,high energy/power density and long-term stability.This review focuses on the applications of IL/PIL-based liquid,quasi-solid,and solid electrolytes and electrolyte additives in lithium batteries.The perspectives and challenges of IL/PIL electrolytes in the field of lithium batteries are also proposed.

从ILs到PILs:聚合离子液体介孔材料的制备性质及结构调控方法

聚合离子液体(PILs)是一种特殊聚电解质,兼具聚合物和离子液体(ILs)特性。根据PILs组成和结构的变化,它可以是固体、液体或凝胶状软物质,目前已成为ILs和介孔聚合材料领域的前沿研究方向之一。本文简要回顾了ILs的特性、潜在应用及其设计和应用过程中面临的挑战,分析了PILs概念提出的必然性,综述了PILs的主要合成方法、ILs单体的种类以及PILs性质和多尺度结构的调控方法,指出未来PILs的研究方向应集中在如下几个方面:PILs的新合成路线、产品的系统表征(如相对分子质量、链段结构、微/介观结构、机械强度和机械加工性等)以及PILs的组成-结构-性质关系,为面向特定应用的PILs材料的设计提供理论指导。

聚醋酸乙烯酯(PVAc)/聚离子液体(PILs)半互穿聚合物网络膜的制备及气体分离性能

利用紫外光固化法,制备了聚醋酸乙烯酯(PVAc)/聚离子液体(PILs)半互穿聚合物网络膜,用于CO2/N2的分离,并对其化学结构、形貌及热稳定性进行了表征.结果表明,加入PILs后,半互穿膜的热稳定性增加,并且PILs与PVAc的相容性较好,随着PILs含量的增加,PVAc/PILs半互穿膜的CO2和N2渗透系数和溶解度系数均提高,渗透选择性先增后减,当PILs含量为50%时达到最大值64.20.

Poly(VBMIMPF_6)/BMIMPF_6离子凝胶的制备与性能

以1-乙烯基-3-丁基咪唑六氟磷酸盐(VBMIMPF6)为单体,1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)为溶剂和电解质,并以聚乙二醇二丙烯酸酯(PEGDA)为交联剂,采用原位紫外交联的方法制备出了一种新型聚离子液体基离子凝胶电解质。通过扫描电子显微镜、流变性能、力学拉伸和电化学交流阻抗等手段,考察了离子凝胶电解质的微观结构、流变性能、力学性能和电学性能。流变性能测试结果表明,离子凝胶具有很高的储能模量(10~4~10~5 Pa),且温度200℃内储能模量基本保持不变。拉伸性能测试结果表明,体系具有很强的力学性能且拉伸强度达到10~5 Pa数量级。电学性能测试结果表明室温下离子凝胶具有很高的电导率(10^(-4)~10^(-3)S/cm),且电导率随BMIMPF6含量的增加而增大。

Poly(amide-6-b-ethylene oxide)/[Bmim][Tf2N] blend membranes for carbon dioxide separation

Poly（amide-6-b-ethylene oxide）（Pebax1657）/1-butyl-3-methylimidazo-lium bis[trifluoromethyl）sulfonyl]-imide（[Bmim][Tf2N]） blend membranes with different [Bmim][Tf2N] contents were prepared via solution casting and solvent evaporation method. The permeation properties of the blend membranes for CO2, N2,CH4 and H2 were studied, and the physical properties were characterized by differential scanning calorimeter（DSC） and X-ray diffraction（XRD）. Results showed that [Bmim][Tf2N] was dispersed as amorphous phase in the blend membranes, which caused the decrease of Tg（PE） and crystallinity（PA）. With the addition of [Bmim][Tf2N], the CO2 permeability increased and reached up to approximately 286 Barrer at 40 wt%[Bmim][Tf2N], which was nearly double that of pristine Pebax1657 membrane. The increase of CO2 permeability may be attributed to high intrinsic permeability of [Bmim][Tf2N], the increase of fractional free of volume（FFV） and plasticization effect. However, the CO2 permeability reduced firstly when the [Bmim][Tf2N]content was below 10 wt%, which may be due to that the small ions of [Bmim][Tf2N] in the gap of polymer chain inhibited the flexibility of polymer chain; the interaction between Pebax1657 and [Bmim][Tf2N]decreased the content of EO units available for CO2 transport and led to a more compact structure. For Pebax1657/[Bmim][Tf2N] blend membranes, the permeabilities of N2, H2 and CH4decreased with the increase of feed pressure due to the hydrostatic pressure effect, while CO2 permeability increased with the increase of feed pressure for that the CO2-induced plasticization effect was stronger than hydrostatic pressure effect.

COSMO-based models for predicting the gas solubility in polymers

We like to highlight the extension of COSMO-based models(COSMO RS-FV and COSMO SAC-FV)to the prediction of gas solubility in polymers,including polymerized ionic liquids(PILs)for the first time.To verify the applicability of COSMO-based models,the predicted values for gas solubility in both common polymers(CH_(4)/N_(2)+PEG)and PELs(CO_(2)+P[MATMA][BF_(4)]/P[VATMA][BF_(4)])were evaluated based on previous experimental data.It was confirmed that the COSMO-RS(Klamt)model performs better than the COSMO-SAC model for common polymers,whereas the COSMO-RS(ADF-Lei 2018)exhibits the best predictions for PILs.The moderately accurate predictions of COSMObased models demonstrate the high potential for predicting gas solubility in polymers.