Chemical synthesis and characterization of poly(3,4-ethylenedioxythiophene)/tungsten composite materials in the presence of ionic liquids

Poly(3,4-ethylenedioxythiophene)/tungsten (PEDOT/W) composites were prepared by an in situ chemical oxidative polymerization of 3,4-ethylenedioxythiophene in different ionic liquids; 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF₆), 1-butyl- 3-methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIMTFSI), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMPTFSI). These polymer/metal hybrids (PEDOT/W) were subsequently characterized for their structural, crystalline, thermal and morphological properties by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The significant enhancement in properties can be attributed to the nanoscale particle size and uniform size distribution of PEDOT/W and the synergistic effect between the inorganic nano-W and organic PEDOT material.     

Study of tribochemical decomposition of ionic liquids on a nascent steel surface

Tribological properties and the decomposition process of ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide) on a nascent surface of bearing steel 52100 were investigated by a ball-on-disk friction tester in a vacuum chamber equipped with a quadrupole mass spectrometer (Q-MS). Ionic liquids exhibited better tribological properties than synthetic hydrocarbon oil (multialkylated cyclopentane (MAC)) in high vacuum conditions. The induction period for decomposition of MAC was about 10 km, while no obvious gaseous products were observed for ionic liquids even after a sliding distance of 22 km under the same mechanical conditions. The mass spectra indicated that both the anionic and cationic moieties of ionic liquids decomposed on the nascent steel surface during friction processes. The cationic moiety with a longer alkyl chain was more difficult to decompose on the nascent steel surface than that with a shorter alkyl chain. XPS analysis revealed that the tribofilm formed by ionic liquid was mainly composed of FeF₂ and FeS, which deactivated the nascent surface. As a result, desorption rate of gaseous products decreased appreciably comparing with MAC. The critical load for the mechanical activation of the decomposition correspondingly increased from 1.1 N of MAC to 8 N of ionic liquids.     

Green synthesis of ZnO nanoparticles in a room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Nanoparticles of ZnO with the wurtzite structure have been successfully synthesized via a microwave through the decomposition of zinc acetate dihydrate in an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, as a solvent. Fundamental characterizations including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were conducted for the ZnO nanostructures.To explore the growth mechanism, the samples have been prepared in different irradiation time and also cetyltrimethylammonium bromide (CTAB) has been used as the capping reagent.     

Preparation and properties of a gel polymer electrolyte system based on poly-ε-caprolactone containing 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Gel polymer electrolytes (GPE) obtained by immobilizing a solution of zinc triflate (ZnTr) in an ionic liquid, namely 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [emim][Tf₂N] within a biodegradable polymeric matrix of poly-ε-caprolactone (PCL) were prepared by a simple solvent cast technique for different concentrations of the ionic liquid. The electrolyte with the composition 75 wt% PCL: 25 wt% ZnTr+100 wt% [emim][Tf₂N] showed the highest ionic conductivity of 1.1×10⁻⁴ S cm⁻¹ at 25 °C and favored by the rich amorphous phase of the GPE as confirmed from room temperature X-ray diffraction analysis (XRD). The morphology of the GPE was examined using scanning electron microscopy (SEM) which revealed the homogeneity of the prepared GPE system. The temperature dependence of electrical conductivity of the GPE followed the Arrhenius behavior. The Zn²⁺ ionic transport number has been determined to be ~0.62 which denotes the predominant contribution of zinc ion towards total ionic conductivity. The electrochemical stability window of GPE is found to be 2.5 V with a thermal stability upto 200 °C. This eco-friendly and safe electrolyte may be used to fabricate compostable batteries, in future, with a suitable selection of other components of the battery system.     

Electrical properties of ion gels based on PVDF-HFP applicable as gate stacks for flexible devices

Electrical characteristics of ion gels prepared by loading different amounts of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) in Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) are investigated and compared with those of ion liquid, [EMIM][TFSI] for possible application as a gate stack for flexible electronic devices. Capacitance and impedance as a function of frequency are measured, which can be well accounted for by a simple circuit model identifying the local device components. The operation of a flexible field effect transistor based on graphene and the ion gel as a top gate stack is also demonstrated.     

Synergistic effect of probe sonication and ionic liquid for extraction of phenolic acids from oak galls

Phenolic acids of oak gall were extracted using ultrasonic-probe assisted extraction (UPAE) method in the presence of ionic liquid. It was compared with classical ultrasonic-bath assisted extraction (CUBAE) and conventional aqueous extraction (CAE) method, with and without the presence of ionic liquid. Remarkably, the UPAE method yielded two-fold higher extraction yield with the presence of ionic liquid, resulting 481.04 mg/g for gallic acids (GA) and 2287.90 mg/g for tannic acids (TA), while a decreased value of 130.36 mg/g for GA and 1556.26 mg/g for TA were resulted with the absence of ionic liquid. Intensification process resulted the highest yield of 497.34 mg/g and 2430.48 mg/g for GA and TA, respectively, extracted at temperature 50 °C with sonication intensity of 8.66 W/cm² and 10% duty cycle, diluted in ionic liquid, 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [Bmim][Tf₂N] at concentration of 0.10 M with sample-to-solvent ratio 1:10 for 8 h. Peleg’s model successfully predicted the UPAE process confirming that extraction capacity is the controlling factor in extracting phenolic acids. Hence, it can be concluded that UPAE method and ionic liquid have synergistic effect as it effectively enhanced the extraction efficiency to increase the bioactive constituents yield.     

Electrical and electromechanical properties of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide-blended cellulose

The effect of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI) blending on the electromechanical and electrical properties of cellulose was premeditated by taking bending actuator test and electrical impedance analysis. Dispersion of BMITFSI in cellulose matrix was carried out by solution blending technique. Upon blending BMITFSI, bending displacement of the actuator was enhanced by eight times as compared to that of the pristine cellulose. Similar improvement in the AC conductivity of cellulose was observed. The effect of BMITFSI content and humidity on electromechanical and electrical properties of BMITFSI-loaded cellulose was discussed.     

Dielectric and thermal features of zinc ion conducting gel polymer electrolytes (GPEs) containing PVC / PEMA blend and EMIMTFSI ionic liquid

A new series of gel polymer electrolytes (GPEs) based on an optimized composition of polymer blend-salt matrix [poly(vinyl chloride) (PVC) (30 wt%) / poly(ethyl methacrylate) (PEMA) (70 wt%): 30 wt% zinc triflate Zn(CF₃SO₃)₂] containing different concentrations of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIMTFSI) ionic liquid has been prepared by simple solution casting technique. The prepared films of gel polymer membranes have been characterized utilizing complex impedance spectroscopy, differential scanning calorimetry (DSC), thermogravimetric (TG), and cyclic voltammetry (CV) analyses. The dielectric constant and ionic conductivity pursue similar trend with increasing EMIMTFSI concentration. The addition of ionic liquid in varied amounts into the optimized polymer blend-salt system effectively reduces the glass transition temperature (T_g) of the film as revealed from differential scanning calorimetry results. The origin of an improved thermal stability and feasible cyclic performance in respect of the best conducting sample of the resultant gel polymer electrolytes was also examined by utilizing thermogravimetric and cyclic voltammetry measurements.     

Effect of monocationic ionic liquids as electrolyte additives on the electrochemical and thermal properties of Li-ion batteries

The conventional electrolyte system has been compared with the ionic liquid (IL) additive containing electrolyte system at room temperature as well as elevated temperature. In this work, two types of monocationic ILs such as 1-butyl-3-methylpyrrolidinium hexafluorophosphate (Pyr IL) and 1-ethyl-3-methylimidazolium hexafluorophosphate (IMI IL) are added as an additive at two different weight ratios in 1.15 M LiPF₆ (EC/EMC = 3/7 v/v) electrolyte solution, the structural, electrochemical and thermal characteristics of LiNi_0.80Co_0.15Al_0.05O₂ (NCA)/carbon full-cell in different electrolyte formulations have been reconnoitered. X-ray diffraction (XRD) studies have proved that IL as an electrolyte additive does not alter the structural stability of cathode materials after cycling. Under room temperature, Pyr IL additives at 1 wt% and 3 wt% deliver better cycleability than others, with the retention ratios of 93.62% and 92.8%, respectively. At elevated temperature, only 1 wt% Pyr IL additive is giving stable capacity retention ratio of 80.74%. Ionic conductivity and self-extinguishing time (SET) values are increasing with respect to the amount of additive added to the electrolyte. Thermal studies reveal that 3 wt% Pyr IL is favorable regarding the safety of the battery as it shows shifting of peak to higher temperature of 272.10 °C. Among the IL additives evaluated in this study, addition of 1 wt% Pyr IL is the most desirable additive for achieving the best cycling performance as well as thermal behavior of Li-ion batteries.     

Hydrodynamic sono-voltammetry of ferrocene in [Tf2N] based ionic liquid media

The present work deals with the hydrodynamic behavior of several room-temperature ionic liquids presenting the same bis(trifluoromethanesulfonyles)imide anion, associated with four different cations: 1-butyl-3-methylimidazolium, 1-octyl-3-methylimidazolium, N-trimethyl-N-propylammonium and 1-butyl-1-methylpyrrolidinium cations. Steady state voltammetry was used as an electrochemical technique to characterize mass transfer in both silent and sonicated conditions, using a rotating disk electrode. Results obtained in RTILs media are compared to those acquired in synthetic solutions of controlled viscosity, in order to develop a better understanding of the phenomena involved in such media.     

Ultrasound-assisted green synthesis of nanocrystalline ZnO in the ionic liquid [hmim][NTf2

For the first time, zinc oxide nanoparticles have been synthesized by the sonochemical method in an ionic liquid, 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, liquid [hmim][NTf(2)] as a solvent. The morphology and structure of ZnO nanoparticles have been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A possible mechanism is proposed to explain the formation of ZnO nanostructures.     

Blends of hexanoyl chitosan/epoxidized natural rubber doped with EMImTFSI

Hexanoyl chitosan soluble in THF is prepared by acyl modification of chitosan. Epoxidation natural rubber (ENR25) (25 mol%) is chosen to blend with hexanoyl chitosan. Films of hexanoyl chitosan/ENR25 blends containing lithium bis(trifluoromethanesulfonyl)imide (LiN(CF₃SO₂)₂) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) are prepared by solution casting technique. FTIR results suggested that LiN(CF₃SO₂)₂ salt interacted with hexanoyl chitosan, ENR25, and EMImTFSI. EMImTFSI interacted with hexanoyl chitosan and ENR25 to form EMIm⁺-hexanoyl chitosan and EMIm⁺-ENR25 complexes, respectively. The effect of EMImTFSI on the morphology and thermal properties of the blends is investigated by polarized optical microscopy (POM) and differential scanning calorimetry (DSC), respectively. The ionic conductivity of the electrolytes is measured by electrochemical impedance spectroscopy (EIS). Upon addition of 12 wt% EMImTFSI, a maximum conductivity of 1.3 × 10^?6 S cm^?1 is achieved. Methods based on impedance spectroscopy and FTIR are employed to study the transport properties of the prepared polymer electrolytes. The ac conductivity was found to obey universal law, σ(ω)?=?σ _dc ?+?Aω ^S . The temperature dependence of exponent s is interpreted by the small polaron hopping (SPH) model.     

ESR studies on the pressure and temperature dependence of electron self-exchange kinetics between tetrathiafulvalene (TTF) and its radical cation in ionic liquids and organic solvents

The question whether chemical reactions and diffusion processes in ionic liquids are comparable with those taking place in classical organic liquids is a current issue in the literature. Pressure- and temperature-dependent investigations on simple electron self-exchange reactions between the two partners of a redox couple are good tools to get a better understanding of how the solvent influences such reactions. The electron self-exchange reaction between tetrathiafulvalene (TTF) and its radical cation has been investigated in two ionic liquids and two organic solvents using electron spin resonance (ESR) line broadening experiments at variable temperature and pressure. Rate constants are reported for the ionic liquids 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim⁺][Tf₂N^?]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim⁺][Tf₂N^?]) within a temperature range of 298 K ≤ T ≤ 368 K and a pressure range of 0.1 MPa ≤ p ≤ 100 MPa. The self-exchange reaction of the redox couple [TTF/TTF^?+] has been found to be diffusion-controlled in the used ionic liquids over the entire temperature range. The observed rate constants in ionic liquids at higher pressures are larger than those predicted by common diffusion, and suggest that the electron transfer takes place within a solvent cage. Also, the self-exchange reaction of the [TTF/TTF^?+] redox couple in classical solvents (dimethylphthalate (DMP) and acetonitrile) was investigated and compared to the results with those obtained in ionic liquids. The high viscosity of the ionic liquids makes it difficult to extract the electron transfer rate constants reliably, making interpretation within the framework of the Marcus Theory impossible.     

A thermal and electrochemical properties research on gel polymer electrolyte membrane of lithium ion battery

N-methyl-N-propyl-piperidin-bis(trifluoromethylsulfonyl)imide/bis(trifluoromethylsulfonyl) imide lithium base/polymethyl methacrylate(PP₁₃TFSI/LiTFSI/PMMA) gel polymer electrolyte (GPE) membrane was prepared by in situ polymerization. The physical and chemical properties were comprehensively discussed. The decomposition characteristics were emphasized by thermogravimetric (TG-DTG) method in the nitrogen atmosphere at the different heating rates of 5, 10, 15 and 20 °C min⁻¹, respectively. The activation energy was calculated with the iso-conversional methods of Ozawa and Kissinger, Friedman, respectively, and the Coats-Redfern methods were adopted to employ the detailed mechanism of the electrolyte membrane. The equation f(α)=3/2[(1−α)^1/3−1] was quite an appropriate kinetic mechanisms to describe the thermal decomposition process with an activation energy (E_α) of 184 kJ/mol and a pre-exponential factor (A) of 1.894×10¹¹ were obtained.     

Ultrasonication an intensifying tool for preparation of stable nanofluids and study the time influence on distinct properties of graphene nanofluids – A systematic overview

Optimum ultrasonication time will lead to the better performance for heat transfer in addition to preparation methods and thermal properties of the nanofluids. Nano particles are dispersed in base fluids like water (water-based fluids), glycols (glycol base fluids) &oils at different mass or volume fraction by using different preparation techniques. Significant preparation technique can enhance the stability, effects various parameters & thermo-physical properties of fluids. Agglomeration of the dispersed nano particles will lead to declined thermal performance, thermal conductivity, and viscosity. For better dispersion and breaking down the clusters, Ultrasonication method is the highly influential approach. Sonication hour is unique for different nano fluids depending on their response to several considerations. In this review, systematic investigations showing effect on various physical and thermal properties based on ultrasonication/ sonication time are illustrated. In this analysis it is found that increased power or time of ideal sonication increases the dispersion, leading to higher stable fluids, decreased particle size, higher thermal conductivity, and lower viscosity values. Employing the ultrasonic probe is substantially more effective than ultrasonic bath devices. Low ultrasonication power and time provides best outcome. Various sonication time periods by various research are summarized with respect to the different thermophysical properties. This is first review explaining sonication period influence on thermophysical properties of graphene nanofluids.     

Impacts of ultrasonication time and surfactants on stability and optical properties of CuO,Fe3O4, and CNTs/water nanofluids for spectrum selective applications

The prime objective of the present experimental work is to evaluate the impact of ultrasonication time and surfactants on the optical characteristics (transmittance and absorbance) and stability of CuO/water, CNTs/water, and Fe₃O₄/water nanofluids to be used in spectrum selective applications. Two-step method with various ultrasonication times (30 min, 60 min, and 90 min) was employed to prepare nanofluids (having volume fractions of 0.004 % and 0.0004 %). Furthermore, various surfactants (anionic, cationic, and polymer) were added to the base fluid. The study results revealed that surfactants have a significant effect on the stability of nanofluids over ultrasonication time. The nanofluids prepared using sodium dodecylbenzene sulfonate (SDBS) have the highest zeta potential values than other surfactants used in the experimentation. The increase in transmittance of nanofluid was more prominent for lower concentration (0.0004 %) after one week of preparation. The concentration of nanoparticles, ultrasonication time, temperature, and surfactants influenced the optical characteristics of nanofluids. The most stabled CNTs nanofluid with 0.004 % concentration and 90 min of ultrasonication obtained an average of 67.6 % and 74.6 % higher absorbance than stabled CuO and Fe₃O₄ nanofluids, respectively. The irradiance transmitted through nanofluid was strongly dependent on the concentration and type of nanoparticles.     

High-intensity ultrasonication impact on the chlorothalonil fungicide and its reduction pathway in spinach juice

Among different novel technologies, sonochemistry is a sustainable emerging technology for food processing, preservation, and pesticide removal. The study aimed to probe the impact of high-intensity ultrasonication on chlorothalonil fungicide degradation, reduction pathway, and bioactive availability of spinach juice. The chlorothalonil fungicide-immersed spinach juice was treated with sonication at 360 W, 480 W, and 600 W, 40 kHz, for 30 and 40 min at 30 ± 1 °C. The highest reduction of chlorothalonil fungicide residues was observed at 40 min sonication at 600 W. HPLC-MS (high-performance liquid chromatography-mass spectroscopy) analysis revealed the degradation pathway of chlorothalonil and the formation of m-phthalonitrile, 3-cyno-2,4,5,6-tetrachlorobenamide, 4-dichloroisophthalonitrile, trichloroisophtalonitrile, 4-hydoxychlorothalonil, and 2,3,4,6-tetrachlorochlorobenzonitrile as degradation products. High-intensity sonication treatments also significantly increased the bioavailability of phenolic, chlorophyll, and anthocyanins and the antioxidant activity of spinach juice. Our results proposed that sonication technology has excellent potential in degrading pesticides through free radical reactions formation and pyrolysis. Considering future perspectives, ultrasonication could be employed industrially to reduce pesticide residues from agricultural products and enhance the quality of spinach juice.     

Ionic conductance of composite electrolytes based on network polymer with ceramic powder

Effects of ceramic fillers (α-Al₂O₃, γ-Al₂O₃ and BaTiO₃) have been investigated on the ionic conductance of polymeric complexes consisting of poly(ethylene oxide)-modified poly(methacrylate) (PEO-PMA) and lithium bis(trifluoromethylsulfonyl)imide, Li(CF₃SO₂)₂N, and ceramic powder. The addition of ceramic powder increased the ionic conductivity over an ambient temperature range. Conductivity of 4.9 × 10^− 5 S cm^− 1 at 333 K (60 °C) was obtained for the composite containing 15 wt.% α-Al₂O₃ prepared by photo-polymerization. The optimum content of Al₂O₃ was different among the methods of polymerization. The highest conductivity was obtained for the composite containing 5 wt.% of α-, or γ-Al₂O₃ prepared by thermal polymerization. The addition of the ceramic filler scarcely influenced the thermal properties of the polymer matrix. XRD and NMR experiments showed that the ionic mobility could be enhanced in the composites by addition of α-Al₂O₃. The addition of small amounts of ferroelectric BaTiO₃ also increased the ionic conductivity of the polymeric complex, but its extent was smaller than the case of the Al₂O₃ addition.     

Investigation of biosourced carboxymethyl cellulose-ionic liquid polymer electrolytes for potential application in electrochemical devices

Biosourced carboxymethyl cellulose polymer electrolytes have been studied for potential application in electrochemical devices. The carboxymethyl cellulose was obtained by reacting cellulose derived from kenaf fibre with monochloroacetic acid. Films of the biosourced polymer electrolytes were prepared by solution-casting technique using ammonium acetate salt and (1-butyl)trimethyl ammonium bis(trifluoromethylsulfonyl)imide ionic liquid as charge carrier contributor and plasticizer, respectively. The shift of peak of carboxyl stretching in the Fourier transform infrared spectra confirmed the interactions between the host biosourced polymer with the ionic liquid. Scanning electron microscopy indicated that the incorporation of ionic liquid changed the morphology of the electrolyte films. The room temperature conductivity determined using impedance spectroscopic technique for the film without ionic liquid was 6.31 × 10^?4 S cm^?1 while the highest conductivity of 2.18 × 10^?3 S cm^?1 was achieved by the film integrated with 20 wt% (1-butyl)trimethylammonium bis(trifluoromethanesulfonyl) imide. This proved that the incorporation of ionic liquid into the salted system improved the conductivity. The improvement in conductivity was due to an increase in ion mobility. The results of linear sweep voltammetry showed that the electrolyte was electrochemically stable up to 3.07 V.     

Quasi-solid state polymer electrolytes for dye-sensitized solar cells: Effect of the electrolyte components variation on the triiodide ion diffusion properties and charge-transfer resistance at platinum electrode

Quasi-solid state polymer electrolytes have been prepared from poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) as gelator for 1-ethyl-3-methylimidazolium based ionic liquids (with anions like trifluoromethanesulfonate [EMIM][TfO], bis(trifluoromethanesulfonyl)imide [EMIM][Tf₂N]) and polyacrylonitrile (PAN) for gelation of 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA] as well as I⁻/I₃⁻ as the redox couple. All electrolytes exhibit high ionic conductivity in the range of 10^− 3 S/cm. The effect of gelation, redox couple concentration, I⁻/I₃⁻ ratio, choice of cations and additives on the triiodide diffusion and charge-transfer resistance of the platinum/electrolyte interface (R_ct) were studied. The apparent diffusion coefficient of triiodide ion (D(I₃⁻)) at various iodide/triiodide ratios in liquid and gelified electrolytes has been calculated from measurements of the diffusion limited current (I_lim) in electrochemical cell resembling the set-up of a dye-sensitized solar cell. The charge-transfer resistance of the platinum/electrolyte interface as well as the capacitance of the electrical double layer (C_dl) have been calculated from impedance measurements. Electrolytes with reduced content of polymer (2.5 wt.%) were doped with Al₂O₃ particles of different sizes (50 nm, 300 nm, 1 μm). The dispersion of the particles proceeds by speedy stirring of the hot electrolyte and the addition of PAN provides a homogeneous suspension. The addition of Al₂O₃ particles causes a slight increase of the triiodide diffusion constants. Furthermore the suggested enhancement of the charge transfer rate shows a dependence on the size of the particles.