Oligomeric Ionic Liquids Research Articles

In Ukrainian

Due to the variety of their forms and properties, silver nanoparticles (AgNPs) are promising for obtaining nanomaterials with various functional applications. Today, regardless of the method of obtaining AgNPs, there is a problem of stabilizing their surface to prevent aggregation, which significantly reduces their activity and prevents uniform distribution during the preparation of nanomaterials. The aim of this work was the synthesis of silver nanoparticles using an oligomeric ionic liquid (OIL) and the study of their structure and antimicrobial properties. In this work, for the first time, an anionic OIL with a hyperbranched structure developed by us was used as a surface stabilizer in the synthesis of AgNPs. The synthesis of AgNPs was carried out by the reduction of Ag ions in the composition of AgNO3 with trisodium citrate in the presence of this OIL. Using the methods ofUV-vis and FTIR spectroscopy, X-ray analysis, electron microscopy and the disc-diffusion method, the peculiarities of the structural organization of AgNPs and their antimicrobial properties were studied. UV-visible spectroscopy data indicate the formation of silver nanoparticles and their spherical or quasi-spherical shape. It was found that there are adsorbed ionic and carbonyl groups on the surface of the formed AgNPs, and the formation of host-guest complexes between OIL and silver ions was revealed using FTIR. The formation of AgNPs and complexes between OIL and silver ions is also confirmed by X-ray diffraction. According to electron microscopy, the size of the synthesized nanoparticles varies from 5 to 16 nm, with an average value of 10.2 nm. This average value is very close to the value of 9.3 nm obtained from the results of X-ray analysis. The synthesized silver nanoparticles showed a very high antimicrobial activity against C. albicans fungi, while the width of the inhibition zone (d) was 34 mm. Also, the AgNPs powder shows very high activity against gram-positive bacteria S. aureus (d = 30 mm) and gram-negative bacteria E. coli (d = 12 mm). The approach developed by us to the synthesis of AgNPs in the presence of OIL as a surface stabilizer with certain functionalization of the latter opens up new opportunities in the synthesis of AgNPs and the preparation of highly dispersed related systems, including functionalized nanocomposite polymer materials with antimicrobial properties.

Does the method of combining individual components affect the structure of heteroconjugated oligomeric ionic liquids?

In this study, we proved that the structure of heteroconjugated oligomeric ionic liquids (HOILs) depends on the specific properties of the constituents rather than the preparation method used. To establish this fact, 6 functional HOILs were obtained with a natural (choline), natural-derived (decyl betainate) and fully synthetic (didecyldimethylammonium) cation, as well as oligomeric anions derived from the popular herbicides (MCPA and dicamba). Based on the results of spectral analysis (1H NMR, 13C NMR, FT-IR) of the HOILs obtained, it was possible to confirm that neither the cation structure, nor the chosen synthetic route has any effect on the definitive structure of the obtained systems, as MCPA occurred in the protonated form in all the HOILs studied. This result was further confirmed by the analysis of molecular geometry as well as the physicochemical properties (phase transition temperatures, refractive index) of the HOILs obtained. Therefore, the data acquired provide important guidance for the design of novel active ingredients according to the oligomeric IL concept and the development of methods for their efficient preparation.

Exploring the potential of naturally-derived ionic liquids for sustainable vegetable oil deacidification

This work investigated two different approaches for vegetable oil deacidification using an ionic liquid (IL), composed of cholinium cation ([Ch]) and oleate anion ([OLE]), as a solvent to form oligomeric ILs (OILs) potentially, and reactive extraction to form multicomponent ILs (MILs) from different acids. The OIL approach (adding an excess acid into the IL through hydrogen bonding) removed oleic acid (∼80%) from a commercial vegetable soybean oil, previously acidified, possibly due to high intermolecular interactions. Through MIL approach, the FFA removal was up to 85%. In this case, the MIL formation occurred concomitant to deacidification as a driving force. Both strategies were evaluated in crude vegetable oil, and the high removal indexes were maintained. Concerning the oil loss, the MIL and OIL approaches result in a significantly lower oil loss (up to 5%) than conventional chemical processes (up to 50%). Finally, envisioning integrated processes, MIL was reused in a new deacidification process, achieving good results (removal of FFA up to 85%). Alternatively, reused MILs and OILs were employed in the β-carotene and astaxanthin recovery from P. rhodozyma wet biomass, indicating that the obtained IL-based systems could be further used as green solvents for other sustainable extraction processes.

SYNTHESIS OF SILVER NANOPARTICLES IN THE PRESENCE OF HYPERBRANCHED OLIGOMERIC IONIC LIQUID AS THEIR SURFACE STABILIZER

A method for synthesis of silver nanoparticles (AgNPs) in the presence of proposed by us protic anionic oligomeric ionic liquid (OIL) of hyperbranched structure as a stabilizer of their surface was developed. Reduction of Ag(I) silver cations was carried out with trisodium citrate in an aqueous environment at temperature of 100°C for an hour. The OIL proposed and used by us as a surface stabilizer of colloidal AgNPs is a product of exhaustive acylation of hyperbranched oligoester polyol of the 3rd generation (contains 32 terminal primary aliphatic hydroxyl groups) with cyclic 2-sulfobenzoic anhydride and subsequent neutralization of the resulting sulfonic compound with N-methylimidazole. The synthesized AgNPs stabilized with the OIL are powders soluble in water that opens up wide possibilities of using the developed AgNPs to obtain nanodisperse systems, in particular hydrosols and nanocomposite functional polymer materials. The formation of «guest-host» type complexes between the OIL and silver ions Ag(I) and the adsorption of carbonyl and ionic (their cationic component) groups on the surface of the formed AgNPs were established by FTIR. According to FTIR data trisodium citrate is also partially adsorbed on the surface of the formed silver nanoparticles and takes part in complex formation. The formation of AgNPs was also confirmed by X-ray analysis. The X-ray diffractograms of the obtained AgNPs show reflections at 38.0, 44.2, 64.4 and 77.3°, which are correspondingly related to (111), (200), (220) and (311) reflections of crystal planes and indicates the formation of silver nanoparticles with a face-centered cubic structure. It should be noted that the intensity of the above-mentioned reflexes increases with an increase in amount of the OIL used in the synthesis that confirms the stabilizing effect of the OIL in relation to the AgNPs and favoring the formation of the last ones due to autoreduction of silver. X-ray data evidences presence of trisodium citrate in the composition of the AgNPs being absorbed on the surface or as the complex with silver ions. The formation of AgNPs is also confirmed by TEM data. The TEM micrograph shows nanosized spherical particles of the «core-shell» type, where according to FTIR and X-ray analys a reduced silver is the core, and the OIL and trisodium citrate forms the shell as a stabilizer. These nanoparticles form swarm-like structures. Analysis of the microphotograph showed that the obtained AgNPs are characterized by a narrow size distribution in the range of 5–10 nm. The synthesized AgNPs stabilized with OIL and trisodium citrate are powders soluble in water, which opens up wide possibilities of their use for obtaining highly dispersed systems, in particular hydrosols and nanocomposite functional polymer materials based on them.

Construction of Imatinib Controlled Release Film-Forming System Based on Drug Ion-Pair and Oligomeric Ionic Liquids for the Long Local Therapy of Cutaneous Melanoma.

An imatinib controlled release film-forming system (FFS) was developed based on the drug ion-pair and newly designed oligomeric ionic liquids (OILs) for the topical therapy of cutaneous melanoma, which avoided the systemic side-effect of oral administration and maintained a long local therapy effect. The OILs significantly improved the drug release capacity about 1.5-fold, and the formability and stability of FFSs (verified by AFM/PLM). The in vivo anti-tumor efficacy studies in melanoma tumor bearing mice showed that compared with the oral capsules, the topical application of the optimized imatinib FFS significantly (p < 0.01) increased tumor inhibition rate (67.54 ± 2.72%) and the amount of apoptotic cells. As confirmed by FT-IR and NMR, the partial protonation of OILs were demonstrated to have high hydrogen bond forming capacity, thus showing low polarity and good biocompatibility. More importantly, based on 13C-NMR study, OILs demonstrated higher hydrogen bond forming capacity, and formed bridge between drug ion-pair (O-H of counter-ion) and PVA (O-H), increased the molecular mobility of PVA, thus maintaining a long drug release capacity. Therefore, an imatinib FFS was developed with good therapeutic effect and the effect of drug ion-pair and OILs on increasing the drug skin retention and controlled release of imatinib FFS for topical therapy was clarified at the molecular level, which provided a safe and effective way for the treatment of cutaneous melanoma.

GUANIDINIIUM-CONTAINING OLIGOMER CATIONIC PROTONIC IONIC LIQUIDS

By reacting a dian epoxy oligomer with guanidinium hydrochloride, a synthesis method of guanidinium-containing cationic proton oligomeric ionic liquids (OIL) capable of condensation reactions was developed. These compounds are characterized by an amphiphilic structure combining a flexible oligoether or hydroxyl-containing guanidinium oligoether block with terminal hydroxyl-containing guanidinium fragments. These compounds are capable of supramolecular organization due to the self-association of flexible oligoether blocks with terminal hydroxyl-containing guanidinium fragments from the outside of the formed cluster. They are characterized by two glass transition temperatures, which differ significantly in magnitude. The structure formed by the flexible oligoether component is determined by its segmental mobility with the glass transition temperature in the range (70–85 °C), and the terminal guanidinium fragments are responsible for the manifestation of the cohesive nature of the glass transition of the oligomer as a whole with the glass transition temperature in the range (-70)–(-60 °C), which characteristic of classical ionic liquids. The proton conductivity of the synthesized compounds in anhydrous conditions reaches a value of 1,94·10-3 S/cm at 120 °C and is determined not by the absolute value of the introduced protons, but by their specific number in relation to the MW oligomers. The synthesized OIL are of interest as electrolytes with an anhydrous conduction mechanism and starting reagents for the synthesis of ion-containing block copolymers of various functional purposes.

In search of sustainable alternatives for vegetable oils deacidification using oligomeric ionic liquid approach

Crude vegetable oils contain free fatty acids (FFAs) that can compromise the sensorial quality and oxidation stability, and thus, need to be removed by deacidification processes. However, conventional physical and chemical processes are related to neutral oil and nutraceutical loss, need of catalysts, and high energy consumption. The liquid-liquid extraction of these bioproducts using sustainable solvents, such as ionic liquids (ILs), seems to be interesting alternative over processes using bioethanol and organic solvents. In this work, the use of protic FA-based IL, such as diethanolammonium caprate ([H2EA][C10OO]) as solvent for deacidification of vegetable oils through the oligomeric IL approach was investigated. The liquid-liquid equilibria (LLE) data of systems containing [H2EA][C10OO], FA (palmitic, oleic and linoleic acids) and vegetable oil (palm olein, canola or soybean oils) were determined and modelled using NRTL model. IL presented good extraction efficiency of FFAs, presenting high distribution coefficient. Also, the NRTL model well described the LLE of such kind of systems. Moreover, solute-solvent affinity was evaluated by predictive COSMO model for a better comprehension of the results. Therefore, the results might indicate that protic FA-based ILs might have potential applicability as alternative solvents for deacidification of crude vegetable oils.

OLIGOMERIC GUANIDINE-CONTAINING PROTON CATIONIC IONIC LIQUID

Oligomeric ionic liquids occupy an intermediate position between low molecular weight and polymeric. They are promising as polymer electrolytes in electrochemical devices for various purposes, membranes for the separation of gas mixtures, in sensor technologies, and so on. Oligomeric guanidinium ionic liquids are practically not described in the literature. In terms of studying the effect of the structure of the epoxy component on the properties of oligomeric ionic liquids of this type, it is advisable to introduce into its composition an aliphatic oligoether component. The choice of aliphatic oligoepoxide for the synthesis of guanidinium oligomeric ionic liquids is based on the fact that it is structurally similar to poly - and oligoethylene oxides, which are known to be non-toxic, biodegradable, and reactive oligomeric ionic liquids at elevated temperatures. A new type of reactive oligomeric proton cationic ionic liquid was synthesized by the reaction of oligomeric aliphatic diepoxide with guanidine, followed by neutralization of the product with hydrochloric acid. In this study, the synthesis of proton cationic oligomeric ionic liquids was based on the introduction of guanidinium fragments as end groups of the oligoether aliphatic chain. This reaction is attractive because of the ease of opening the oxirane ring with such a strong nucleophile as guanidine.The reaction forms a fragment with an aliphatic C-N bond, which retains the high basicity of the nitrogen atom. Its structure is characterized by the presence of guanidinium groups at the ends of the aliphatic hydroxyl-containing oligoether chain. The chemical structure of this compound is characterized by IR -, 1H ,13 C NMR spectroscopy methods, and its molecular mass characteristics are determined.The average molecular weight of the synthesized oligomeric ionic liquids is 610 g / mol.The value of the coefficient of polydispersity of the synthesized oligomeric ionic liquids is equal to 1.2. Determination of the content of amino groups in the guanidine-containing oligomer in the basic form by titrometric method allowed to establish that the value found is close to the theoretically calculated value. The synthesized oligomeric proton ionic liquid is characterized by an amorphous structure with two glass transition temperatures. The first lies in the range -70 °C, the second in the region of 70 °C, and the beginning of thermal oxidative destruction is located in the region of 148 °C. The temperature dependence of the ionic conductivity for this compound is nonlinear in the Arrhenius coordinates, which indicates the realization of ionic conductivity mainly due to the free volume in the system. The proton conductivity of this compound is 6.4·10-5–1·10-2Cm/cmin the range of 20–100 °C. The obtained compound exhibits surface-active properties characteristic of classical surfactants, as evidenced by the value of the limiting surface activity – 2.8·102 Nm2 / kmol. The value of CCM is 1.8·10-2 mol/l., and the value of the minimum surface tension – 37.70 mN / m. The synthesized oligomeric ionic liquid is of interest as electrolytes operating under anhydrous conditions, surfactants, disinfectants, and starting reagents for the synthesis of ion-containing blockopolymers.

Formation of stoichiometric and non-stoichiometric ionic liquid and cocrystal multicomponent phases of lidocaine with azelaic acid by changing counterion ratios

Tuning of physicochemical properties of ionic liquids and crystalline materials is a challenge that opens up unlimited possibilities for expanding applications and controlling biological activity of pharmaceutical multicomponent phases incorporating active pharmaceutical ingredients (APIs) with counterions or coformers. In this work we have investigated the effect of changing lidocaine (LID) and azelaic acid (AZE) ratios on the physicochemical properties of their corresponding multicomponent systems using a thermodynamics-based approach. Microscopy, X-ray diffraction analysis, infrared spectroscopy, nuclear magnetic resonance, and thermogravimetric analysis provided complimentary characterisation. Mechanochemical synthesis of LID:AZE systems at a range of stoichiometries yielded at least two distinct liquid phases and two distinct crystalline phases, one of which involved a unique 2:3 LID:counterion composition not observed previously. Furthermore, to the best of our knowledge the formation of oligomeric ionic liquids involving dicarboxylic acids is also being reported for the first time. This work highlights the need for a careful characterisation of multicomponent systems, especially for pharmaceutical applications.

Tunable naturally-derived oligomeric ionic liquids: phase behavior and liquid crystal profile

Ionic liquid crystals (ILCs) derived from functional compounds obtained from natural sources, such as fatty acids (FAs), are promising compounds due to their sustainable appeal, low cost, and nutritional value. To expand the application of naturally-derived ILCs, this work discloses the use of the oligomeric approach to tune the LC and melting profiles of ILCs derived from FAs (stearic and oleic acids) and choline by mixing them to their parent FA. The oligomeric systems were investigated through the characterization of the solid-[liquid crystal]-liquid (S-LC-L) thermodynamic equilibrium. S-LC transitions were modelled using Margules and Margules-UNIFAC approaches, with the former presenting better results. The systems presented melting profiles similar to eutectic mixtures with a nonideal behavior and formation of solid solutions. The reduction of the melting point and the LC temperature window was related to the concentration and presence of unsaturation in the molecular structure of the components. The LC mesophases were formed at a wide temperature and FA concentration range. Oleic acid-based system presented lower melting points and a broader LC temperature domain with possibly two types of mesophases (lamellar and inverted hexagonal). Therefore, the oligomeric approach promoted the tunability of the LC and melting profiles of naturally-derived ILCs, which might expand their industrial applicability as lubricants, solvents and reaction media for low or high temperature processes, or as structuring agents (e.g. melting profile modifier) for the design of natural-based products.

Self-assembly, phase behaviour and ion-conducting property of pyridinium-based ionic liquid-crystalline oligomers

ABSTRACT Series of oligomeric ionic liquid crystals (OILCs) based on various anions including bromide (Br−), tetrafluoroborate (BF4 −), dodecylbenzenesulphonate (A-SO3 −) and (+)-10-camphorsulphonate (D-SO3 −) are synthesised by use of pyridine-containing monomers, terminal bromo-substituted alkanes and anion replacement reagents. The effect of anions on the chemical structure, liquid-crystalline behaviour, and ionic conductivity is investigated. The OILCs show various mesophases including smectic, hexagonal columnar and bicontinuous cubic phase due to the change in anions. These mesophase types are determined by two incompatible segments derived from ionic mesogens and flexible alkyl chains in the microstructure. For the OILCs based on A-SO3 − and D-SO3 − anions, a curvature of the interfaces between the layers arises due to the increased size of one segment, resulting in columnar and cubic mesophases. The ionic conductivity is investigated in the way that a lithium ion solution passing through the oriented OILC films at room temperature. For the OILC films with various anions, ionic conductivities of the measuring system increase a little in the order A-SO3 − > D-SO3 − > BF4 −> Br−. The values based on A-SO3− anion films show nearly twofold increase compared with those based on Br- anions, which can be attributed to the effects of both ion migration and ionic channels in the microstructures.

Specific Features of the Rheological Behavior of a Protic Oligomeric Ionic Liquid of Cationic Type with Basic Sites of Two Types in the Region of the Solid–Liquid Transition

The structure and rheological behavior of a reactive oligomeric ionic liquid (OIL) have been studied. The OIL has a linear structure and contains ionic fragments of two types at both ends of oligo(ethylene oxide) chain. The ionic fragments are represented by secondary amino groups and nitrogen-containing heterocycles protonated with ethane sulfonic acid. The results obtained using rotational rheometry in different dynamic regimes indicate that, in the linear region of deformation at temperatures T G '). The boundary, which is located at nearly 30°C, is characterized by equality between G ' and G '' in a wide range of strain amplitudes. The structural transformations induced by thermal and mechanical energies have been explained using a hypothesis of the existence of micellar structures and a “normal micelle–reverse micelle” transition in the OIL, as well as changes in micelle shapes. The analysis of the temperature dependences for the viscoelastic characteristics and scattered light intensity, as well as the data of DSC and optical microscopy, has led to the hypothesis that at, T = 21–28°C, the OIL may occur in an ordered state similar to the liquid-crystalline one.

Polymeric organic-inorganic proton-exchange membranes based on anionic oligomeric ionic liquid of hyperbranched structure

Polymeric organic-inorganic proton-exchange membranes based on anionic oligomeric ionic liquid of hyperbranched structure

Reactive Oligomeric Protic Cationic Linear Ionic Liquids with Different Types of Nitrogen Centers

Reactive linear oligo(ethylene oxides) containing terminal secondary hydroxyl groups and secondary amino groups combined with nitrogen heterocyclic fragments are synthesized by the reaction of oligo(oxyethylene glycol) α,ω-diglycidyl ether (М = 1.0 × 103) with 1-(3-aminopropyl)imidazole, 2-aminopyridine, or 2-amino-3-methylpyridine. Protonation of the synthesized compounds by ethanesulfonic acid and p-toluenesulfonic acid at their different ratios is studied. This process makes it possible to obtain oligomeric linear protic cationic ionic liquids capable of condensation. The proton conductivity of oligomeric ionic liquids is investigated under anhydrous conditions in the temperature range of 40–120°С. The highest conductivity (1.36 × 10–3 S/cm) is attained in the case of methylpyridinium ethanesulfonate oligomeric ionic liquid at 120°С. These compounds are thermally stable to a temperature of 250–290°С. They show promise for the synthesis of polymeric analogs of block ionic liquids suitable in the production of electrochemical devices for various purposes.

Electrochemical Behavior of Nanoporous Supercapacitors with Oligomeric Ionic Liquids

According to a recent study [Matsumoto, M. ; J. Am. Chem. Soc. 2017, 139, 16072−16075], an oligomeric ionic liquid (OIL) may exhibit a wide electrochemical window and an exceptionally high capacita...

Sulfonate aprotic oligomeric ionic liquid of hyperbranched structure

Sulfonate aprotic oligomeric ionic liquid of hyperbranched structure

Exceptionally High Electric Double Layer Capacitances of Oligomeric Ionic Liquids.

Electric double layer (EDL) capacitors are promising as next-generation energy accumulators if their capacitances and operation voltages are both high. However, only few electrolytes can simultaneously fulfill these two requisites. Here we report that an oligomeric ionic liquid such as IL4TFSI with four imidazolium ion units in its structure provides a wide electrochemical window of ∼5.0 V, similar to monomeric ionic liquids. Furthermore, electrochemical impedance measurements using Au working electrodes demonstrated that IL4TFSI exhibits an exceptionally high EDL capacitance of ∼66 μF/cm2, which is ∼6 times as high as those of monomeric ionic liquids so far reported. We also found that an EDL-based field effect transistor (FET) using IL4TFSI as a gate dielectric material and SrTiO3 as a channel material displays a very sharp transfer curve with an enhanced carrier accumulation capability of ∼64 μF/cm2, as determined by Hall-effect measurements.

Synthesis and Characterization of Oligomeric Ionic Liquid/Heteropoly Acid Composite as a New Heterogeneous Catalyst through Anion-Exchange Method for Selective Cyclohexane Oxidation with Molecular Oxygen under Solvent-Free Conditions

In this work, we investigated solvent-free oxidation of cyclohexane using oligomeric ionic liquid (OIL)/heteropoly acid (HPA) composite with molecular oxygen under solvent-free conditions. OIL has six imidazolium cores which synthesized in three successive stages and was anion-exchanged by phosphomolybdic acid (H3PMo12O40, PMo) to synthesize OIL/HPA composite. OIL and OIL/HPA composite were characterized by different techniques such as, FT-IR, UV, BET, TGA, XRD, FESEM, EDX, and TEM. Optimal reaction conditions were obtained by evaluating the effective parameters on the reaction including temperature, time, oxygen pressure, and amount of the catalyst. The main product of the reaction in the presence of 20 mg of catalyst and 5 mL of cyclohexane was cyclohexanone by 21% conversion and 75% selectivity at 110 °C and 20 bar oxygen pressure after 5 h. The OIL/HPA showed good stability under reaction conditions and maintained its catalytic activity up to five cycles with little decrease in reaction conversion.

(Invited) New Lithium-Conducting Ionic Liquids and Their Polymer Electrolytes

In PEM Fuel Cells, Ionic liquids i.e. Proton-conducting Ionic Liquids, PILs, behave as proton-conducting materials to increase PEMFC operating temperature. Based on primary, secondary or tertiary ammoniums, they are ‘self-sufficient’ i.e. they don´t require any additional acids to perform the electrochemical reactions. Thus macroporous membranes have been successfully filled by PILs. Alternatively, PILs can be too associated to proton-conducting ionomers e.g. Nafion® or high performance based ionomers beforehand turned into their ammonium form in order to avoid molecular acid release. In the first case, high mechanical strength can be obtained while the swelling of PFSA ionomers by PILs increase markedly the proton-conductivity at the anhydrous state but strongly decrease the membrane mechanical strength. While PILs are self-sufficient in electrochemical conversion (FC), usual Li-ion battery ILs based on quaternary ammonium require conversely adding a lithium salt. The well-known advantages of ILs vs liquid solvents e.g. high Fp and high sub-ambient conductivities are partly compensated by the compulsory addition of the salt, which increases the viscosity and also the electrolyte cost. Oligoethers i.e. oligo(oxyethylene) or oligo-PEO) end-capped by 1, 2 or 3 salt moieties doesn’t match the performances of classical ionic liquids, in terms of sub-ambient conductivities but they both provide the lithium salt function and a solvating ability. This presentation will focus on new lithium-conducting oligomeric ionic liquids consisting of several oligoether chain lengths end-capped by organic perfluorinated anions. Their intrinsic ionic conductivities and those of related POE blends will be reported as well as their cationic transference numbers. Both classical ILs and oligomeric lithium-conducting ionic liquids degrading the electrolyte mechanical performances, they don´t allow thinning the polymer electrolyte films. A special attention will be paid to the reinforcement of ILs based polymer electrolytes.

Heterogenization of a Green Homogeneous Catalyst: Synthesis and Characterization of Imidazolium Ionene/Br–Cl–@SiO2 as an Efficient Catalyst for the Cycloaddition of CO2 with Epoxides

A promising new strategy for immobilizing a water-soluble oligomeric ionic liquid by coating the ionic liquid with mesoporous silica was established. The immobilized ionic liquid (IL@SiO2) exhibited a good catalytic activity for the production of cyclic carbonates through the cycloaddition of different epoxides with CO2 under solvent-free conditions. The IL@SiO2 catalyst was characterized by different techniques such as FTIR spectroscopy, XRD, TG analysis, FESEM-EDX spectroscopy, map analysis, BET analysis, and TEM. Use of 30 mg of the IL@SiO2 catalyst, which contained 0.023 mmol of the oligomeric ionic liquid IL-3, resulted in a yield of cyclic carbonate with styrene oxide of greater than 95% and a selectivity to the cyclocarbonate of almost 100%. We realized that the hydroxyl groups on the surface of silica could play an important role in the reaction through the hydrogen-bonding interactions between the epoxides and the hydroxyl groups. Moreover, the prepared catalyst was very stable under the reaction...