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Mes recherches se concentrent sur le développement, la synthèse et l'utilisation de liquides ioniques (d'origine biosourcée) et de solvants de type DES (Deep Eutectic Solvent).
Ces solvants ont de nombreuses applications dans le domaine de l'énergie, notamment pour le développement d'électrolytes utilisés dans les batteries et les cellules solaires. Ils sont également utilisés dans le prétraitement de biomasses.
Ma recherche se focalise plus particulièrement sur la chitine et ses dérivés tels que le chitosane, les nanocristaux et les fibres de chitine/chitosane, ainsi que sur la soie. J'étudie ces matériaux organiques en vue de leur application dans des domaines variés tels que l'agriculture, l'environnement et la biomédecine.
Biomasse, chitine, chitosane, nanocristaux, soie, liquide ionique, solvant DES
Effect of dicationic ionic Liquid: Trimethylene bis-methylimidazolium bromide ([M(CH2)3IM2+][2Br-]) on the structural, optical and morphological properties of ZnO nanoparticles |
Theoretical and experimental studies of chitin nanocrystals treated with ionic liquid or deep eutectic solvent to afford nanochitosan sheets |
Copper-uptake mediated by an ecofriendly zwitterionic ionic liquid: A new challenge for a cleaner bioeconomy |
Fundamental insight into the interaction between a lithium salt and an inorganic filler for ion mobility using a synergic theoretical-experimental approach |
IL versus DES: Impact on chitin pretreatment to afford high quality and highly functionalizable chitosan |
Hybrid Electrolytes Based on Optimized Ionic Liquid Quantity Tethered on ZrO2 Nanoparticles for Solid-State Lithium-Ion Conduction |
New biobased-zwitterionic ionic liquids: efficiency and biocompatibility for the development of sustainable biorefinery processes |
Conversion of Chitin in Ionic Liquids |
Straightforward extraction and selective bioconversion of high purity chitin from Bombyx eri larva: Toward an integrated insect biorefinery |
Synthesis of high molecular weight chitosan from chitin by mechanochemistry and aging |
Effect of standard light illumination on electrolyte’s stability of lithium-ion batteries based on ethylene and di-methyl carbonates |
Preparation of nucleoside derivative carrying an isothiazole or oxathiole cycle with an antiproliferative activity |
The influence of chloride and hydrogen sulfate anions in two polymerised ionic liquids based on the poly(1-(hydroxyethyl)-3-vinylimidazolium cation, synthesis, thermal and vibrational studies |
XRD and ATR/FTIR investigations of various montmorillonite clays modified by monocationic and dicationic imidazolium ionic liquids |
New iodide-based amino acid molecules for more sustainable electrolytes in dye-sensitized solar cells |
The effect of room temperature ionic liquids on the selective biocatalytic hydrolysis of chitin via sequential or simultaneous strategies |
Imidazolium-based titanium substrates against bacterial colonization |
Towards Renewable Iodide Sources for Electrolytes in Dye-Sensitized Solar Cells |
Consequences of Solid Electrolyte Interphase (SEI) Formation upon Aging on Charge-Transfer Processes in Dye-Sensitized Solar Cells |
SiO2/Ionic Liquid Hybrid Nanoparticles for Solid-State Lithium Ion Conduction |
Interface stability of a TiO(2)/3-methoxypropionitrile-based electrolyte: first evidence for solid electrolyte interphase formation and implications |
In this work, we make a comparative study between ZnO nanoparticles samples (NPs) synthesized by the conventional method (ZnO-S) and samples elaborated in an ionic liquid (IL) media (ZnO-IL) to see the effect of the latter on the structural, optical and morphological properties of these NPs. The results of this study are obtained using the following characterization methods: X-ray diffraction for the study of the structural properties of the different ZnO NPs samples, infrared spectroscopy (FTIR) to determine the nature of the different bonds present in our samples, UV–Visible spectrometry to determine the gap energy of zinc oxide. The results of Transmission Electron Microscopy have also been reported to show the effect of ionic liquid on the morphology of ZnO NPs. The XRD allowed us to see the effect of ionic liquid on the size of the crystallites manifested by a noticeable decrease. The curves of the UV–Vis show that the value of the gap energy is not the same for the two samples of ZnO-S and ZnO-IL, which implies that the latter has been influenced by the change in the reaction media. Transmission electron microscopy shows that the ionic liquid influences the size of the nanoparticles, there are two populations of nanoparticles, the first between (50 and 100 nm) as for ZnO-S NPs and a second in the order of 20 nm, which implies that the presence of the ionic liquid reduced the size of the NPs. We conclude that ionic liquid can be very useful to control the size of ZnO NPs and the appearance of novel properties.
Chitin nanocrystals have gained growing interest due to their many excellent properties, however the higher crystallinity of these nano-rod-shaped particles is a major hindering factor in preparation of nanochitosans with low degree of acetylation (DA). Here we studied the effect of the ionic liquid 1-ethyl-3-methylimidazolium acetate (IL) and deep eutectic solvent (choline chloride:lactic acid) (DES) pretreatments of chitin nanocrystals (NCChits) before the deacetylation step using both experimental and theoretical approaches. The results showed that the ionic liquid pretreatment was able to partially disrupt the crystalline structure leading to a lower DA (18.2 %) after two cycles of deacetylation reaction. DES pretreatment, however, was unable to disturb the intra- and intermolecular hydrogen bonds, resulting in a DA of 73.6 % similar to that of unpretreated chitin nanocrystals (73.2 %). SEM images of chitin nanocrystals pretreated with ionic liquid showed that the crystals can rearrange into sheets. Molecular simulations reveal the detailed mechanism of chitin nanocrystal dissociation, in which the combination of a net molecular charge and hydrogen-bonding groups on a single scaffold (as is the case for [C2mim] and [OAc]) plays a paramount role. These results can open the way to afford controlled nanochitosan sheets from chitin nanocrystals.
This study aims to investigate the ability of an imidazolium biobased Zwitterionic Ionic Liquids (ZILs) in enhancing the phytoavailability of copper from garden (G) and vineyard (V) soils using the model plant ryegrass. Uncontaminated and artificially contaminated CuSO4 soils, unamended and ZIL-amended soil modalities were designed. The copper/ZIL molar ratio (1/4) introduced was rationally established based on molecular modeling and on the maximal copper concentration in artificially contaminated soil. Higher accumulation of copper in the shoots was detected for the uncontaminated and copper contaminated ZIL amended V soils (18.9 and 23.3 mg.kg−1, respectively) contrary to G soils together with a ZIL concentration of around 3% w/w detected by LC-MS analyses. These data evidenced a Cu-accumulation improvement of 38 and 66% compared to non-amended V soils (13.6 and 13.9 mg.kg−1 respectively). ZIL would be mainly present under Cu(II)-ZIL4 complexes in the shoots. The impact on the chemical composition of shoot were also studied. The results show that depending on the soils modalitity, the presence of free copper and/or ZIL led to different chemical compositions in lignin and monomeric sugar contents. In the biorefinery context, performances of enzymatic hydrolysis of shoots were also related to the presence of both ZIL and copper under free or complex forms. Ecotoxicity assessment of the vineyard soil samples indicated that the quantity of copper and ZIL remaining in the soils had no significant toxicity. ZIL amendment in a copper-contaminated soil was demonstrated as being a promising way to promote the valorization of phytoremediation plants.
The present paper aims at providing a fundamental insight into the interaction between a lithium salt and an inorganic filler in a perspective of lithium mobility. Through a synergistic approach, coupling experimental results and molecular dynamics simulations, the influence of the surface chemical state of the nanosilica Stöber-type on the dissociation of LiTFSI and its impact on the lithium conduction properties are studied. For this purpose, the surface modification of silica nanoparticles was performed by different methods such as calcination, lithiation and capping with organosilane. The impact of the surface modification on the dissociation of the lithium salt is further investigated by electrochemical impedance spectroscopy after impregnation of the material with a defined amount of lithium salt. The combined experimental and in silico analyses of the results, performed for the first time on such systems, allow a detailed understanding of the interaction between the salt and the support and should prove itself useful for the future design of hybrid polymer electrolytes in new generation batteries.
Chitin is mainly extracted from crustaceans, but this resource is seasonally dependent and can represent a major drawback to satisfy the traceability criterion for high valuable applications. Insect resources are valuable alternatives due to their lower mineral content. However, the deacetylation of chitin into chitosan is still an expensive process. Therefore, we herein compare the impact of both DES/IL-pretreatments on the efficiency of the chemical deacetylation of chitin carried out over two insect sources (Bombyx eri, BE and Hermetia illucens, HI) and shrimp shells (S). The results showed that chitosans obtained from IL-pretreated chitins from BE larva, present lower acetylation degrees (13–17%) than DES-pretreated samples (18–27%). A selective N-acylation reaction with oleic acid has also been performed on the purest and most deacetylated chitosans leading to high substitution degrees (up to 27%). The overall approach validates the proper chitin source and processing methodology to achieve high quality and highly functionalizable chitosan.
This paper describes the simple, highly reproducible, and robust synthesis of a new solid organic/inorganic electrolyte based on the ionic liquid (IL) 1-butyl-3-(carboxyundecyl)imidazolium bis(trifluoromethylsulfonyl)imide tethered to zirconia nanoparticles (15–25 nm) by coordination and named ZrO2@IL. The IL monolayer formation, ensured by two-dimensional solid-state NMR, at the nanoparticles’ surface considerably reduces both the IL’s consumption and the IL amount at the ZrO2 surface compared to the IL-based hybrid electrolytes reported in the literature. After LiTFSI, used as a lithium source, content optimization (26 wt %), the hybrid exhibits unprecedented stable conductivity passing from 0.6 × 10–4 S.cm–1 to 0.15 × 10–4 S.cm–1, respectively, from 85 °C to room temperature (25 °C). Unlike silica which is commonly adopted for this type of hybrid material, zirconia makes it possible to produce more impact-resistant pellets that are easier to compact, thus being favorable for accurate conductivity studies and battery development by electrode/composite/solid electrolyte layer stacking. The ZrO2@IL/LiTFSI solid hybrid electrolyte’s thermal stability (up to 300 °C) and performance make this electrolyte suitable for lithium conduction in all-solid-state batteries.
A new family of biobased-zwitterionic ionic liquids (ZILs) have been synthesized starting from the renewable resource l-histidine natural amino acid and varying the lengths of the alkyl chains. These ZIL derivatives were firstly studied for their biocompatibility with different microorganisms including bacteria, molds and yeast. The obtained MIC values indicated that all the microorganisms were 5 to 25 times more tolerant to ZIL derivatives than the robust 1-ethyl-3-methylimidazolium acetate [C2mim][OAc] used as a reference. Modeling studies also revealed that the presence of the cation and the anion on the same skeleton together with the length of the N-alkyl chain would govern the biocompatibility of these neoteric solvents. Among the different synthesized ZILs, the N,N′-diethyl derivative has been demonstrated to be a suitable eco-alternative to the classically used [C2mim][OAc] for efficient pretreatment of harwood sawdust leading to a significant improvement of enzymatic saccharification. In addition, with up to a 5% w/v concentration in the culture medium, ZILs did not induce deleterious effects on fermentative yeast growth nor ethanol production.
Chitins of different purity grades (45%, 89.7% and 93.3%) were efficiently extracted from Bombyx eri larva and fully physico-chemically characterized. Compared to commercially available and extracted α-chitin from shrimp shell, the collected data showed that insect chitins had similar characteristics in terms of crystallographic structures (α-chitin), thermal stability and degree of acetylation (>87%). The major differences lay in the crystallinity indexes (66% vs 75% for shrimp chitin) and in the morphological structures. Furthermore, low ash contents were determined for the insect chitins (1.90% vs 21.73% for shrimp chitin), making this chitin extraction and purification easier, which is highly valuable for an industrial application. Indeed, after only one step (deproteinization), the obtained chitin from Bombyx eri showed higher purity grade than the one extracted from shrimp shells under the same conditions. Insect chitins were then subjected to room temperature ionic liquid (RTIL) pretreatment prior to enzymatic degradation and presented a higher enzymatic digestibility compared to commercial one whatever their purity grade and would be thus a more relevant source for the selective production of N-acetyl-D-glucosamine (899.2 mg/g of chitin-2 steps vs 760 mg/g of chitin com). Moreover, for the first time, the fermentescibility of chitin hydrolysates was demonstrated with Scheffersomyces stipitis used as ethanologenic microorganism.
Chitosan can be obtained from the deacetylation of chitin. This process is however difficult and usually accompanied by depolymerization, affording low molecular weight chitosan. We report a novel path, relying on the combination of mechanochemistry and aging, to yield high molecular weight chitosan with minimal use of energy and solvent. This method is versatile and applicable to a number of chitin sources, including crude crustacean and insect shells, yielding deacetylation up to 98% and remarkably high molecular weights. Chitin deacetylation was studied by magic angle spinning nuclear magnetic resonance and molecular weight was estimated by viscometry. This process affords chitosan in a safer fashion and with less materials and energy usage compared to the classic hydrothermal one.
The chemical reaction of 2-chloroethanol with 1-vinylimidazol as precursor led to the corresponding compound 1-hydroxyethyl-3-vinylimidazolium chloride [EtOHVIM+] [Cl−]. In the next step, treatment of [EtOHVIM+][Cl−] with 2,2-azobisisobutyronitril (AIBN) afforded the poly1-(hydroxyethyl)-3-vinylimidazolium chloride (poly[EtOHVIM+][Cl−]), Finally, the reaction of (poly[EtOHVIM+][Cl−]) and sulfuric acid led to poly 1-(hydroxyethyl)-3-vinylimidazolium hydrogen sulfate (poly[EtOHVIM+][HSO4−]) by replacing the [Cl−] halide by an [HSO4−] anion. The structure of these compounds was identified by 1H NMR, 13C NMR as preliminary spectroscopic characterization. To obtain information on the structure and vibrational behavior in these compounds, vibrational spectroscopy measurements were investigated by Fourier Transform-Infrared-Attenuated Total Reflectance and Fourier Transform Raman spectroscopy in the spectral range 600–4000 cm−1 and 4000–500 cm−1, respectively. The Polymerization of IL gave rise to specific marks in the Raman and IR spectra and enhanced its vibrational property. Also, in order to understand the thermal stability in these compounds, the results concerning the melting point, glass transition and decomposition were determined by thermogravimetric analysis (TGA), differential thermal (DTG), and differential scanning calorimetry (DSC). The results indicated that the poly [EtOHVIM+][HSO4−] compound showed interesting thermal properties like high temperature of degradation and low temperature of glass transition compared to poly[EtOHVIM+][Cl−].
Three different montmorillonites (Mts) labeled K10, KSF and SWy-3 were analyzed by X-ray diffraction and ATR/FTIR spectroscopy. The XRD results enabled validation of the purification process of the studied clays. In the spectral regions 3800–2600 and 1800-1300 cm-1, the study of different intensity ratios of peaks assigned to the OH bending and stretching modes displayed the specific vibrational behavior of SWy-3 which is certainly influenced by a greater proportion of Na+ in its structure. Before analyzing the clays modified by ionic liquids, we characterized two imidazolium based ionic liquids (ILs) with anion I-: [EMIM+] [I−] monocationic ionic liquid and [M(CH₂) IM2+] [2I−] dicationic ionic liquid. The passage from [EMIM+] [I−] to [M(CH₂) IM2+] [2I−] reveals significant vibrational changes through various modes: ν(NH), rings ν(CC), rings ν(CN), ν(CH2(N)), ν(CH3(N)) in addition to anion interaction modes. When purified, these ionic liquids modify clays, the XRD analysis shows that the studied modified clays exhibited higher d-value increase with respect to the purified Mts, and the reflection peaks 2θ (°) of plane (001) were displaced towards lower values as a consequence of the ionic liquid intercalation process. ATR/FTIR spectra recorded in the spectral zone 4000-600 cm-1 indicated the appearance of new peaks and a significant intensity variation between clays in relation to the type of chosen ionic liquid. These vibrational changes are directly connected to the presence of ionic liquids in clays. XRD and ATR/FTIR investigations show a stronger effect of the [M(CH2) IM2+] [2I−] dicationic ionic liquid on the Mts than the monocationic ionic liquid and the SWy-3 Mt is more sensitive to monocationic and dicationic ionic liquids than K10 and KSF Mts.
The electrolyte is the second key component governing at once power conversion performances and stability of dye-sensitized solar cells. Towards the integration of more sustainable materials, we focused in the replacement of the major constituent of the electrolyte, namely the 1,3 di-alkyl imidazolium iodide. We synthesized two new iodide molecules derived from natural amino acid family (L-proline): (S)-2-(methoxycarbonyl)-1,1-dimethylpyrrolidinium iodide (PMeI) and (S)-2-(ethoxycarbonyl)-1,1-ethylpyrrolidinium iodide (PEtI). In combination with the C106 polypyridyl ruthenium(+II) sensitizer, power conversion efficiencies of 7.1% for PMeI and 6.5% for PEtI were obtained under standard Air Mass 1.5G conditions in conjunction with low-volatile 3-methoxypropionitrile-based solvent. The relationship between these new iodide molecules, the power conversion efficiency and interfacial charge transfer processes is herein discussed and systematically compared to the best standard 1,3 di-methylimidazolium iodide.
An efficient conversion of chitin, the second most abundant renewable polymer on the Earth, into N-acetylglucosamine and N,N[prime or minute]-diacetylchitobiose, using room temperature ionic liquids (RTILs) and commercially available chitinases is described for the first time. The sequential strategy consists of the use of RTILs to pretreat chitin under mild conditions as a first step before enzymatic hydrolysis. [C2mim][OAc] (1-ethyl-3-methyl imidazolium) pretreatment provides an efficient production of N-acetylglucosamine (185.0 +/- 4.0 mg per g chitin) or N,N[prime or minute]-diacetylchitobiose (667.60 +/- 20.71 mg per g chitin) catalyzed by chitinase from Trichoderma viride or Streptomyces griseus, respectively. A thorough investigation of the structural changes of chitin induced by RTIL pretreatment suggested an increase in enzymes' accessibility to the chitin substrate. Alternatively, a one-pot enzymatic hydrolysis of chitin in [C2mim][OAc]-aqueous medium constitutes a promising simultaneous route to selectively generate N-acetylglucosamine or N,N[prime or minute]-diacetylchitobiose by decreasing the required [C2mim][OAc] amount and the number of steps. Finally, the combination of the two chitinases from T. viride and S. griseus was shown to be very relevant to considerably increase the production of N-acetylglucosamine up to 760.0 +/- 0.1 mg per g chitin.
Nosocomial infections are often induced by the presence of pathogenic organisms on the surface of medical devices or hospital equipment. Chemical modifications of the surface are recognized as efficient strategies to prevent bacterial adhesion but they may have a negative impact on the material's interaction with living tissues. Here we have developed a photoactivated method for the modification of titanium substrates. A photoinduced technique employing a grafting-onto process has been successfully performed to covalently anchor an imidazolium-derivative siloxane onto titanium surfaces. Imidazolium surfaces showed higher bacteria-repellency performances than native titanium substrates, achieving more than 98% anti-adhesion efficiency against Escherichia coli after 24 h of incubation. In addition, these surfaces allowed for the adhesion and viability of osteoblasts cells without evidence of cytotoxicity.
Solid electrolyte interphase (SEI) layers form on sensitized-TiO2 photoanodes and platinum counter electrodes when dye-sensitized solar cells (DSSCs) are subjected to an accelerated aging protocol (e.g., heating at 85 °C in the dark for 500 h). To understand how this impacts device operation, we conducted an electrochemical impedance spectroscopy study and found that the SEI induces an additional electron-transfer process from the TiO2 to the electrolyte. This is materialized by the onset of a new charge-transfer semicircle at higher frequencies, predominantly visible under bias voltages similar to and greater than the open-circuit voltage. Our results emphasize the detrimental role of SEI formation on device performance and lifetime. Additionally, nanosecond transient absorption spectroscopy showed that SEI formation reduced the rate of oxidized dye regeneration. We also found that a proportion of the photogenerated holes on the dyes were transferred to the SEI itself. A prolonged aging duration led to the electrode’s mesoporosity network being entirely clogged by the SEI, thus impeding efficient transport of the electrolyte redox couple and being responsible for a further decline in photovoltaic performances.
We report the physical and electrical characterization of a series of substituted imidazolium-based ionic liquids grafted on Stöber-type SiO2. This hybrid architecture affords an increase of the lithium transference to 0.56 by hindering TFSI? (bis(trifluoromethane)sulfonimide) mobility to the total ionic conductivity. When doped with 16 wt % wt LiTFSI, the resulting hybrid organic/inorganic solid material exhibits a lithium diffusion coefficient of 2 ? 10?12 m2/s at 87 °C and a conductivity of ca. 10?6 S/cm at room temperature and 10?4 S/cm at 65 °C with an activation energy barrier of 0.89 eV.