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Toward a Green Polymerization of Lignin‐Derived Monomers in Ethyl Lactate Solution or Aqueous Emulsion
No full textInternational audienceABSTRACT Novel biobased polymers based on lignin building blocks are synthesized and systematically characterized. The three prominent aromatic aldehydes that can be obtained from oxidative degradation of lignin, namely p‐hydroxybenzaldehyde (H), vanillin (V), and syringaldehyde (S), are chemically modified into radically polymerizable styrenic monomers presenting either a methoxy or butoxy (‐OBu) group at the para‐position. The transformation of these molecules is accomplished and optimized individually on each compound. Subsequently, polymers are successfully prepared by free radical polymerization in homogeneous conditions (in solution using ethyl lactate as green solvent) and in heterogeneous conditions (in aqueous emulsion using a biosourced surfactant). Novel polymeric materials with high thermal stability and a glass transition temperature (Tg) tunable between 40°C and 110°C are obtained, depending on the monomer used
Aerobic Mukaiyama-type oxidation of essential oil of ortanic tangor from Reunion Island: an applied example of valorization on terpenes using salophen complexes
No full textInternational audienceThe work described in this comprehensive study is based on valorising essential oils from citrus originated from Réunion Island, ortanic tangor, using Mukaiyama-type aerobic oxidation of terpenes, in particular limonene. This innovative work combines extraction, fractionation and catalytic oxidation to transform an agricultural residue into valuable compounds, while respecting the principles of green chemistry. The research highlights the use of metal salophen complexes based on cheap and abundant transition metals to achieve mild epoxidation at room temperature. In addition, a theoretical study using DFT provided a better understanding of the mechanism of this reaction for the best catalyst (molybdenum containing), suggesting that the activator could be a molybdenum oxo-cis-{MoVIO2} species resulting from the evolution of the initial catalyst
Porous NaTi<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub>-PVDF Composite Granules as Negolyte Boosters for Sodium-Based Redox-Targeting Flow Batteries
No full textInternational audienceRedox-Targeting Flow Batteries (RTFBs) are promising alternatives to classical vanadium-based batteries for large-scale and stationary energy storage. Typically, RTFBs are marked by higher energy densities thanks to the addition of solid boosters within aqueous systems, taking care to limit the use of critical raw materials. This work subsequently investigates the case of sodium titanium phosphate (NTP, NaTi2(PO4)3, 132.8 mAh/g) as a potential booster material for the negolyte side of aqueous RTFBs. Pure NTP and carbon-coated NTP (C-NTP) particles were synthesized and characterized by various techniques (X-ray, TEM, TGA, Raman). So-obtained NTP and C-NTP particles were found to be suitable for creating innovative porous composite boosters formed as centimeter-sized granules by dry processing. Porous composite granules with an open porosity of 65% and 50 wt % of immobilized NTP or C-NTP were successfully produced by an extrusion–dissolution process using a regular PVDF binder and PEO as a porogen agent. Subsequently, intensive electrochemical tests were performed using an innovative dual-mediator reaction system (Fe-Tiron and 2,7-AQDS). High NTP reactivity, with booster utilization rates of up to 84% of its theoretical capacity, can be achieved under flow conditions, with an increase in volumetric capacity by a factor of 1.5, from 4 Ah L–1 to 6 Ah L–1. The mediator concentration (10 – 100 mM) and the mediator/booster ratio (0.5 – 1) play key roles in NTP reactivity. The fundamental work also highlights the benefit of C-NTP, allowing higher reactivity at low mediator concentrations. The study consequently validates the potential of NTP as an interesting booster material in future RTFB applications, with its scalable extrusion–dissolution technique to create innovative porous booster granules
Nanoarchitectonics of Pro-Degradative Coating to Enhance Iron Corrosion Behavior and Biosafety for Bioresorbable Cardiovascular Stents
No full textInternational audienceControlling both the resorption rate and the formation of reactive oxygen species (ROS) of biodegradable iron (Fe) remains a central challenge for bioresorbable cardiovascular stents. Here, we introduce an innovative, nanoengineered surface coating strategy to simultaneously accelerate Fe corrosion and suppress ROS generation without altering the bulk Fe materials. Aryl-diazonium salt chemistry (4-cyanobenzene diazonium tetrafluoroborate, DCN) was used to creates robust polyaryl interphases that can immobilize gold nanoparticles (Au NPs) on Fe, establishing nanoscale microgalvanic and catalytic sites. Electrochemical analysis reveals that the coating increases the overall Fe corrosion rate while biasing cathodic oxygen reduction reaction towards the four-electron pathway, thereby reducing peroxide/OH• formation. This mechanism is supported by the remarkably reduced OH• content detected by terephthalateprobe assay. Corrosion metrics show a pronounced, controllable rate enhancement relative to bare Fe, and the post-corrosion exposure interfacial spectroscopy/microscopy verify the persistence of Au NPs, attributed to atomic Fe-FeO-Au interactions and anchoring by the DCN-derived polyaryl layer. Endothelial cells culture indicates favorable adhesion and viability, supporting cytocompatibility of the modified surface. This surface-chemistry-driven mechanism establishes a general interfacial principle for rate-and pathway-control of iron biodegradation, offering a concise route to safer, faster-resorbing Fe-based stents
Revealing the role of functional binder PEDOT:PSSTFSI in cathode-electrolyte interphase formation on LiFe<sub>0.4</sub>Mn<sub>0.6</sub>PO<sub>4</sub> electrodes of Li-ion battery
No full textInternational audienceThe stability of the cathode–electrolyte interphase (CEI) plays a critical role in determining the long-term performance of Li-ion batteries, particularly under high-voltage operation. This work investigates CEI formation and evolution in LiFe0.4Mn0.6PO4 (LFMP) composite positive electrodes using PEDOT:PSSTFSI, a conductive polymer that replaces both carbon black and polyvinylidene fluoride (PVDF) binder in the electrode formulation. Electrochemical tests, XRD, and XPS confirm PEDOT:PSSTFSI's electrochemical stability up to 4.5 V vs. Li+/Li and non-reactivity towards the active material. Reversible redox activity is observed in XPS, but it does not affect long-term structural or electrochemical stability. XPS analysis of C 1s, O 1s, P 2p, and F 1s spectra across different charge states reveals that PEDOT:PSSTFSI promotes a thinner, more stable CEI without altering its composition compared to carbon-containing references. This reduced interfacial degradation corresponds with improved performance at higher voltages during extended cycling. The results underscore PEDOT:PSSTFSI's promise as a multifunctional binder offering conductivity, stability, and interfacial control for advanced Li-ion positive electrodes.</p
Experimental study on triaxial fatigue properties of mudstone interlayers in CAES under synergistic effects of stress amplitude and time interval
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From Molecule to Material: How Support Changes Heterobimetallic Catalysts in Lactide Polymerization
No full textInternational audienceSustainable production of polylactide demands catalysts that are both recoverable and capable of delivering precise molar mass and stereocontrol. A series of heterobimetallic complexes [(THF)NaFe(OtBu)3]2 , [(THF)2KFe(OtBu)3]2, [KZn(OtBu)3]2, [(THF)KCu(OtBu)3]∞ and [(THF)KCo(OtBu)3]2 was evaluated as precursors for heterogeneous catalysts by grafting onto dehydroxylated silica. All complexes demonstrated activity in the ring‐opening polymerization of lactide. Notably, the silica‐supported [(THF)KFe(OtBu)2]/SiO2‐700 and [(THF)NaFe(OtBu)2]/SiO2‐700 systems exhibited high efficiency, promising recyclability, and afforded predictable molar masses (Mn,exp close to Mn,th) with narrow dispersities. These findings highlight new opportunities for designing recyclable catalysts for sustainable PLA synthesis
Di‐tert‐Butyl‐Peroxide–CuI Promoted Radical Hydrogermylation of Alkenes
No full textInternational audienceA new protocol for alkene hydrogermylation with hydrogermanes involving a radical chain‐transfer mechanism initiated by di‐ tert ‐butyl peroxide (DTBP) and CuI in methyl tert ‐butyl ether (MTBE) is disclosed. The method has good generality regarding both appropriate alkene substrate‐types and hydrogermanes, and compares well to other existing protocols, sometimes improving them, while being easy‐to‐implement. The developed system is particularly well‐suited for indenes and allows for the preparation of original 2‐germylated indanes through a previously unexplored approach
Lipid droplet-based passive tracking to probe tissue dynamics in lymph node slices
No full textInternational audienceThis protocol describes a method to measure the microrheological properties of lymph node tissue. Lymph nodes, the primary organs of adaptive immune responses, remodel across multiple spatio temporal scales: at the cellular (and minute) scale through immune cell motility, such as that of B and T lymphocytes and dendritic cells, and at the organ (and day) scale through cell proliferation and restructuring of the fibroblastic stromal network.By tracking exogenous lipid droplets (used as passive tracers) in live lymph node slice explants, across different regions and conditions, we infer local tissue activity, immune cell motility, and the functional state of the organ. This approach offers a powerful tool for probing lymph node biomechanics at the scale of individual cells and provides a framework for studying the interplay between tissue mechanics and immune function
Mitigating structural deterioration via partial substitution with Fe in Mn-based Prussian white cathodes for Na-ion batteries
No full textInternational audiencePrussian white (PW) is a promising cathode material for sodium-ion batteries (SIBs), which offers high theoretical capacity at low cost while being composed of abundant elements. However, Fe-based PW suffers from relatively low average voltage, and while substitution of one Fe with Mn can increase the voltage, it introduces structural instabilities supposedly due to the Jahn–Teller distortion of Mn3+, resulting in poor capacity retention. In this work, we investigate the effect of partial substitution of Mn by Fe in Mn-based PW on electrochemical and structural stability. Two samples, Na1.82Mn[Fe(CN)6]0.96·2.0H2O and Na1.82Mn0.62Fe0.38[Fe(CN)6]0.96·2.1H2O, were synthesized by coprecipitation and characterized via a multimodal approach combining laboratory and synchrotron-based techniques. We demonstrate that partial Mn substitution by Fe does not eliminate Jahn–Teller distortion but mitigates its negative effects by suppressing the distorted phase formation occurring near end of charge, thereby significantly enhancing capacity retention without sacrificing overall capacity. These results provide fundamental insight into the interplay between redox activity and structural stability in mixed-metal PW and establish partial Mn substitution by Fe as an effective strategy to improve long-term cyclability of PW cathodes for SIBs