Ionic Liquid-modified Graphene Oxide Research Articles

Tribological performance of ionic liquid modified graphene oxide/silicone rubber composite and the correlation of properties using machine learning methods

AbstractThis study investigates and predicts the tribological properties of an imidazolium ionic liquid modified graphene oxide (ILGO) with silicone rubber (QM) composite. The pin on the disc tribometer was utilized to conduct experimental tribological property analysis, with load, sliding velocity, and temperature as changing parameters. Coefficient of friction (COF) of QMILGO1.5 was 42% lower than that of pure QM. Study found that ionic liquid serves as a self‐lubricating layer for graphene, establishing a solid graphene‐to‐ionic liquid interface bond with the rubber matrix. The experimental data were utilized for training artificial neural networks (ANNs), which were then used to predict the COF of the nanocomposites for values for which the experiment was not performed. The produced composite's predictions of friction coefficient utilizing the ANN technique were quite close to experimental results. The work's fundamental goal is to buy experimentation verifies the COF of functionalized graphene oxide (ILGO) with silicone rubber composite, use the actual experimental values to train a deep neural network using Multilayer perceptron, and then use the trained network to predict the values of COF for which obtaining the values by experimentation was difficult.

Tungstate supported on magnetic ionic liquid-modified graphene oxide as an efficient and recyclable catalyst for the selective oxidation of sulfides

An effective and recyclable catalyst based on tungstate ion immobilization on magnetic ionic liquid modified graphene oxide (WO4@Fe3O4/GO-IL) has been synthesized in this research. The catalyst was characterized by various techniques such as Raman spectroscopy, X-ray diffraction, thermogravimetric analysis, electron microscopy transmission and scanning, and vibrating sample magnetometer. Also, for the selective oxidation of sulfides to the corresponding sulfoxides, the as-synthesized catalyst was investigated. Additionally, the WO4@Fe3O4/GO hybrid was used to study the role of ionic liquid in this transformation and, the observed yield of methyl phenyl sulfoxide was remarkably inferior. Also, by using an external magnet, the catalyst can be quickly retrieved and recycled successfully in five following reaction cycles without any significant reduction in activity and selectivity of the catalyst.

Charge-driven interaction for adsorptive removal of organic dyes using ionic liquid-modified graphene oxide

A facile approach is presented to synthesize the ionic liquid-grafted graphene oxide (GO-ImOH) for fast and efficient adsorptive removal of cationic dyes. A coupling reaction between the hydroxyl terminal of imidazolium ionic liquid and the carboxylic group of GO, yielded the GO-ImOH hybrid material. The higher surface negative charge (−32 mV) and excellent dispersibility make the GO-ImOH an efficient adsorbent for cationic dyes. The GO-ImOH showed excellent removal efficiency for methylene blue (cationic dye), whereas it could adsorb only 22% methyl orange (anionic dye). The GO-ImOH displayed significantly higher adsorptive removal capacity for cationic dye compared to that of GO adsorbent. The chemical and structural features of GO-ImOH and spectroscopic analyses (FTIR and Raman) of pristine and recovered GO-ImOH adsorbent suggested multiple adsorptive interaction pathways (electrostatic, π-cation, π-π interactions, and hydrogen linkages) between the GO-ImOH adsorbent and the dye molecules. The work paves a new direction for the development of ionic liquids-modified 2D nanomaterials for efficient and fast adsorptive removal of organic pollutants, where the adsorptive sites on the surface of 2D nanomaterials can be tuned by selecting the desired functionalities from a diversified library of cations and anions of ionic liquids.

Effect of ionic liquid modified graphene oxide on mechanical and self-healing application of an ionic elastomer

Thermo-reversible supramolecular crosslinking reactions such as Diels Alder reactions, disulfide metathesis reactions, imine bond formation, metal–ligand interactions, host–guest interactions, hydrogen bonds, and ionic interactions are broadly used for self-healing purposes. Herein, we have studied the ionic supramolecular interactions in miscellaneous nature, which benefit a strong and self-repairing carboxylate nitrile rubber by introducing a low cost and commercially available materials. The excellent mechanical and healing performance were combined by initiating the ionic liquid (IL) and ionic liquid modified graphene oxide (GO) with zinc oxide containing compounds into XNBR rubber. The healing performance and mechanical properties of various rubber composites essentially depend on the dispersion of ionic charges of ionic liquids via graphene oxide and the ionic network structures (zinc-carboxylate network). Graphene oxide and ionic liquid grafted graphene oxide were successfully synthesized. XRD, Raman spectroscopy, SEM, and TEM analysis were conducted for in-depth characterization of the ingredients and composite materials. Differential scanning calorimetry, rubber process analyzer, and thermogravimetric studies exhibit various thermal transitions present in the ionic crosslinked XNBR rubber. The ionic crosslinked XNBR rubber with 3 phr of ionic liquid grafted graphene oxide, and ionic liquid grafted graphene oxide with zinc oxide containing compounds exhibits very good tensile strength (3.1 ± 0.2 and 6.1 ± 0.6 MPa respectively) with excellent healing efficiency of 77.4 and 85.2% respectively, which is much greater than the utmost reported non-covalent supramolecular ionic crosslinked elastomers.

Ionic liquid modified graphene oxide for enhanced flame retardancy and mechanical properties of epoxy resin

AbstractIn this work, to improve its dispersion and flame retardancy, graphene oxide (GO) was functionalized by silane coupling agent KH550 and 1‐butyl‐3‐methylimidazole hexafluorophosphate (PF6‐ILs), and characteristics of the PF6‐ILs@GO was obtained by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). Then, the synergistic flame retardant of GO or PF6‐ILs@GO and melamine pyrophosphate (MPP) were applied for epoxy resin (EP) materials. Specifically, the limiting oxygen index (LOI) value of EP with 0.1 wt% PF6‐ILs@GO was increased to 29.2% from 27.5% of EP/MPP composites, and the UL‐94 test reached the V‐0 rating. The CCT results showed that the total heat release (THR) and total smoke release (TSP) of EP/MPP/PF6‐ILs@GO composites were significantly 24.4% and 53.4% lower than that of EP/MPP composites. Besides, the thermal behavior investigated by TGA indicated that the char‐forming effect of GO and PF6‐ILs@GO was great, the residual char of EP/MPP/PF6‐ILs@GO composites was as high as 19.5% at 700°C, and its thermal stability was higher than that of EP/MPP composites. On the other hand, the tensile strength of EP/MPP/GO and EP/MPP/PF6‐ILs@GO composites were increased by 15.6% and 28.3% compared with EP/MPP composites. According to SEM analysis, the EP/MPP/GO composites formed a good protective char layer, which can effectively improve flame retardancy of EP. This research represents a new method of flame retardant modified GO to improve the flame retardancy and mechanical properties of polymers.

Ionic liquid modified graphene oxide supported Mo-complex: A novel, efficient and highly stable catalyst

A novel ionic liquid modified graphene oxide supported Mo-complex [GO@IL/MoO2(acac)2] was successfully prepared, characterized and its catalytic application was investigated. The GO@IL/MoO2(acac)2 catalyst was prepared through the surface modification of graphene oxide with alkyl imidazolium chloride followed by treatment with molybdenyl acetylacetonate. The GO@IL/MoO2(acac)2 catalyst was characterized by using FT-IR, PXRD, TGA, EDX, and SEM analyses. This catalyst showed high activity in the green production of pyrazolo[b]phthalazine dione derivatives under ultrasonic conditions. The designed catalyst was effectively recovered and successfully reused at least eight times without significant loss in its efficiency.

Ionic liquid-modified graphene oxide sponge for hexavalent chromium removal from water

Chromium pollution in groundwater is a major cause of concern due to significant health risks of hexavalent chromium (Cr(VI)) ions. Graphene oxide (GO) covalently modified with 1-aminopropyl-3-methylimidazolium bromide (mimNH2) and freeze-dried to give 1-aminopropyl-3-methylimidazolium bromide functionalized graphene oxide sponge (mimGO sponge). mimGO sponge effectively adsorbed hexavalent chromium (Cr(VI), toxic) by electrostatic interactions and reduced Cr(VI) to trivalent chromium (Cr(III), less toxic) by an indirect mechanism with the contribution of delocalized π-electrons on the six-membered aromatic ring of mimGO sponge. The change in contact time, adsorbent loading, initial Cr(VI) solution concentration, and different types of adsorbents were investigated. The experimental data were fitted to the pseudo-second order kinetic model, which showed hydro-chromate adsorption on mimGO sponge was surface adsorption with chemical interaction. The adsorption process was well-defined by the Langmuir isotherm model, and equilibrium adsorption capacity was 208.3 mg/g at 23 ℃ in an acidic environment. The electrostatic interaction between the chromate ions and mimGO sponge also caused a reduction of Cr(VI) to less benign Cr(III) on the adsorbent surface. Thus, mimGO sponge has a green adsorbent that showed the potential for Cr(VI) removal from water.

Electrochemically deposition of ionic liquid modified graphene oxide for circulated headspace in-tube solid phase microextraction of naphthalene from honey samples followed by on-line liquid chromatography analysis.

In this work, an inexpensive, fast, and selective ionic liquid modified graphene oxide (GO-IL) was synthesized and electrochemically deposited on the inner surface of a stainless-steel tube. Then, it was applied for circulated headspace in-tube solid-phase microextraction (CHS-IT-SPME) of naphthalene from honey samples. Next, the coated tube was replaced with the sample loop of a six-port injection valve for on-line desorption and further HPLC-UV analysis of naphthalene. The sorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDX). Different parameters affecting the procedure efficiency, including extraction temperature, extraction time, salt concentration, and sample volume were optimized by central composite design and response surface methodology. Under the optimum conditions, the calibration curve was linear within the range of 0.3-200 ng mL-1, with a regression coefficient of 0.9972. The limits of detection (LOD) and quantification (LOQ) were found to be 0.1 ng mL-1 and 0.3 ng mL-1, respectively. Intra-day and inter-day RSDs% for three replicate measurements of naphthalene at the concentration of 10 ng mL-1 were obtained 3.9% and 5.0%, respectively. Also, good tube-to-tube reproducibility of 5.3% was achieved. Finally, the method was successfully applied for measuring trace amounts of naphthalene in honey samples. Relative recoveries were calculated within the range of 90.0-106.5%, indicating excellent efficiency of the proposed method.

Ultra-trace sensing of cadmium and lead by square wave anodic stripping voltammetry using ionic liquid modified graphene oxide

The detection of Cd (II) and Pb (II) ions have been done by modifying the glassy carbon electrode (GCE) with graphene oxide (GO) mixed ionic liquid (IL) (BMIM-PF₆) and nafion binder. The developed nanocomposite film combines the advantages of graphene and ionic liquid for enhanced detection. The estimated sensitivity for Cd (II) was 0.0711 µA/ppb and limit of detection found to be 0.33 ppb in the concentration range of 2.4–70 ppb. The effect of deposition potential (Dp), deposition time (Dt) and stirring speed(S) have been carried out for the response of Cd (II) current signal. The estimated sensitivity for Pb (II) was 0.0371 µA/ppb and limit of detection value of 0.42 ppb found in the linear calibration range of 5–15 ppb. Further the study of interaction effect of independent parameters (Dp, Dt, S) has also been studied by designing the experiment based on Box-Behnken design. The RSM modeling and optimization of process parameters for Cd (II) current response by IL/GO/GCE electrode was carried out with suitable empirical model. This developed sensor exhibited selective, good stability and reproducibility that could be explored for environmental, food and pharmaceutical analysis.

Amine-terminated ionic liquid modified graphene oxide/copper nanocomposite toward efficient lubrication

How to make full use of the synergistic effect between nanomaterials is of great significance for designing high-performance lubricating materials. Here, novel amine-terminated ionic liquid-modified graphene oxide (GO)/copper nanocomposite (IL-GO/Cu) is synthesized by facile liquid-phase method in which GO nanosheets and Cu nanoparticles are linked by 1-aminoethyl-3-methyl imidazolium nitrate ionic liquid through covalently grafting and electrostatic interaction. Of what interest is the homogeneous distribution of Cu nanoparticles on IL-GO plane/interlayers, possibly being endowed to excellent lubrication function. Results demonstrate that IL-GO/Cu nanocomposite with 0.08 wt% addition amount into polyethylene glycol (PEG 200) improves friction and wear resistance by up to 40.1% and 47%, respectively. Such performance characteristics mainly depend on the synergistic lubrication, including not only the boundary lubrication film composed of adsorbed/transfer/tribo-chemical film, but also the “third body” from the additive and its wear debris with Fe/Cu nanocrystals-embedded graphene-like structure. This paper offers an attractive strategy for fabricating graphene-based nanocomposite toward real-world application in tribology. • IL-GO/Cu composite with a sandwich-like structure is prepared via interlinkage of GO and reduced-Cu NPs by amine-terminated ILs. • Cu NPs with a diameter of 15~20 nm are evenly distributed across basal plane/interlayers. • As-prepared composite possesses high thermal-stability, good dispersion and excellent mechanical properties. • IL-GO/Cu composite as a high-performance lubricant depends on the synergies of boundary lubrication film and wear debris with sandwich-like structure.

Ultrasound assisted dispersive solid phase extraction of triazole fungicides by using an N-heterocyclic carbene copper complex supported on ionic liquid-modified graphene oxide as a sorbent.

An ultrasound-assisted method is described for dispersive solid phase extraction of trace levels of triazole fungicides. A sorbent was prepared from an N-heterocyclic carbene copper complex that was supported on ionic liquid-modified graphene oxide. The sorbent was characterized by scanning electron microscopy, transmission electron microscopy, Raman and FT-IR spectroscopy, energy-dispersive X-ray spectroscopy and elemental mapping. The capability of sorption and extraction is mainly based on complexation with Cu (I) ions. The variables affecting extraction were optimized. Following desorption with ethanol, the fungicides were quantified by corona discharge ion mobility spectrometry. Under optimized conditions (solution pH value: 7.0; amount of sorbent: 10mg; extraction time: 3min; desorption agent: ethanol), the technique provides good linearity (>0.994), repeatability (RSD < 4.1%), low limits of detection (0.18ng.mL-1), excellent preconcentration factors (468-476) and high recoveries from spiked environmental water samples (92-94%). The sorbent can be reused over five cycles without significant loss of its activity. Graphical abstract Schematic presentation of design and synthesis of the N-heterocyclic carbene copper complex supported on ionic liquid-modified graphene oxide as a sorbent for triazole fungicides and its application in ultrasound-assisted dispersive solid phase extraction with ion mobility spectrometric detection.

Electrochemical Sensor Based on Nanocomposite of Ionic Liquid Modified Graphene Oxide – Chitosan and its Application for Flow Injection Detection of Anticancer Thiopurine Drugs

AbstractElectrochemical activity of carbositall electrodes (CSEs) covered with polymeric films of Chitosan (Chit) containing different types of graphene oxide (GO) dispersed in a room temperature ionic liquid (IL) was comparatively investigated by using cyclic voltammetry of [Fe(CN)6]3−/4− as a model redox probe. It was recognized that the nanocomposite film with in situ electrochemically reduced GO (ERGO) provided an improved electrochemical activity, including increased peak current and electron‐transfer efficiency, compared to the initial GO nanosheets and chemically reduced GO (RGO). The novel electrochemical sensor ERGO‐IL‐Chit/CSE showed enhanced electrochemical response characteristics towards the antimetabolic thiopurines such as 6‐thioguanine, 6‐mercaptopurine and azathioprine which play a significant role in medicinal chemistry and cancer therapy. The diagnostic characteristics of the voltammetric signals for all investigated compounds in neutral aqueous media were established and the nature of the corresponding redox‐reactions was discussed. The developed sensor was incorporated into a flow injection amperometric system for the automatic dissolution testing of thiopurine anticancer drugs with a sampling rate of 60 h−1.

N-Heterocyclic carbene–copper complex supported on ionic liquid-modified graphene oxide: versatile catalyst for synthesis of (i) 1,2,3-triazole and (ii) propargylamine derivatives

A N-heterocyclic carbene–copper complex grafted on graphene oxide with an ionic liquid framework was prepared. The synthesis of (i) 1,2,3-triazole derivatives by ‘Click reaction’ and (ii) propargylamine derivatives by ‘A3 coupling reaction’ in aqueous media by this new catalyst were all successfully accomplished. The catalyst is characterized using infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and elemental analysis. The catalyst is reused in the ten reaction cycles without considerable loss of catalytic activity.

Effective Removal of Hexavalent Chromium from Aqueous Solutions Using Ionic Liquid Modified Graphene Oxide Sorbent

Effective Removal of Hexavalent Chromium from Aqueous Solutions Using Ionic Liquid Modified Graphene Oxide Sorbent

Imidazolium Ionic Liquid Modified Graphene Oxide: As a Reinforcing Filler and Catalyst in Epoxy Resin.

Surface modification of graphene oxide (GO) is one of the most important issues to produce high performance GO/epoxy composites. In this paper, the imidazole ionic liquid (IMD-Si) was introduced onto the surface of GO sheets by a cheap and simple method, to prepare a reinforcing filler, as well as a catalyst in epoxy resin. The interlayer spacing of GO sheets was obviously increased by the intercalation of IMD-Si, which strongly facilitated the dispersibility of graphene oxide in organic solvents and epoxy matrix. The addition of 0.4 wt % imidazolium ionic liquid modified graphene oxide (IMD-Si@GO), yielded a 12% increase in flexural strength (141.3 MPa), a 26% increase in flexural modulus (4.69 GPa), and a 52% increase in impact strength (18.7 kJ/m2), compared to the neat epoxy. Additionally the IMD-Si@GO sheets could catalyze the curing reaction of epoxy resin-anhydride system significantly. Moreover, the improved thermal conductivities and thermal stabilities of epoxy composites filled with IMD-Si@GO were also demonstrated.

Dispersive solid phase micro-extraction of mercury(II) from environmental water and vegetable samples with ionic liquid modified graphene oxide nanoparticles

A new dispersive solid phase micro-extraction (dispersive-SPME) method for separation and preconcentration of mercury(II) using ionic liquid modified magnetic reduced graphene oxide (IL-MrGO) nanoparticles, prior to the measurement by cold vapour atomic absorption spectrometry (CV-AAS) has been developed. The IL-MrGO composite was characterized by Brunauer? Emmett?Teller method (BET) for adsorption-desorption measurement, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The method is based on the sorption of mercury( II) on IL-MrGO nanoparticles due to electrostatic interaction and complex formation of ionic liquid part of IL-MrGO with mercury(II). The effect of experimental parameters for preconcentration of mercury(II), such as solution type, concentration and volume of the eluent, pH, time of the sorption and desorption, amount of the sorbent and coexisting ion concentration have been optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.08?10 ng mL-1 with a determination coefficient of 0.9995. The limit of detection (LOD) of the method at a signal to noise ratio of 3 was 0.01 ng mL-1. Intra-day and inter-day precisions were obtained equal to 3.4 and 4.5 %, respectively. The dispersive solid phase micro-extraction of mercury(II) on IL-MrGO nanoparticles coupled with cold vapour atomic absorption spectrometry was successfully used for extraction and determination of mercury(II) in water and vegetable samples.

Amino-terminated ionic liquid modified graphene oxide coated silica composite stationary phase for hydrophilic interaction chromatography

IL@GO@SiO2 composite was synthesized and revealed good separation for three kinds of strong polar and hydrophilic compounds in HILIC mode.

Gold nanoparticle supported on ionic liquid-modified graphene oxide as an efficient and recyclable catalyst for one-pot oxidative A3-coupling reaction of benzyl alcohols

A novel gold nanoparticle supported on graphene oxide with ionic liquid framework was used as a highly active and recyclable catalyst for novel domino oxidative A3-coupling reaction.

N-Heterocyclic carbene palladium complex supported on ionic liquid-modified graphene oxide as an efficient and recyclable catalyst for Suzuki reaction

An N-heterocyclic carbene Pd complex immobilized on GO with an ionic liquid framework synthesized by the modification of GO through a silylation reaction displayed a high catalytic activity in the Suzuki reaction.

Structure, thermal conductivity, and thermal stability of bromobutyl rubber nanocomposites with ionic liquid modified graphene oxide

In this report, we demonstrate that both the thermal stability and the thermal conductivity of bromobutyl rubber (BIIR) nanocomposites could be improved by incorporating the ionic liquids (ILs) modified graphene oxide (GO-ILs) using a solution compounding method. The structure, thermal stability and thermal conductivity of this newly modified BIIR nanocomposites were systematically analyzed and studied. The X-ray diffraction (XRD) analysis of GO-ILs showed that ILs had been effectively intercalated into the interlayer of GO, which was found to be able to raise the exfoliation degree of GO. The increased exfoliation degree facilitated a good dispersion of GO-ILs in the BIIR matrix, as revealed by the scanning electron microscope (SEM) images. The glass transition temperatures (Tg) of the GO-ILs/BIIR nanocomposites were also raised by the addition of GO-ILs, which indicates the strong interfacial adhesion between GO-ILs and the rubber. Most importantly, the incorporation of GO-ILs in the BIIR matrix could effectively improve the thermal stability of the rubber nanocomposites according to our thermogravimetric analysis (TGA). The activation energy (Ea) of thermal decomposition of GO-ILs/BIIR nanocomposites increases with the addition of GO-ILs. Besides, the thermal conductivity of GO-ILs/BIIR nanocomposite with 4 wt% of GO-ILs had 1.3-fold improvement compared to that of unfilled BIIR.