Correlation between Ionic Conductivity and Mechanical Properties of Solid-like PEO-based Polymer Electrolyte

Poly(ethylene glycol) methyl ether methacrylate polymer networks (PEO-based networks), with or without anionic bis(trifluoromethanesulfonyl)imide (TFSI)-grafted groups, are promising electrolytes for Li–metal all solid-state batteries. Nevertheless, there is a need to enhance our current understanding of the physicochemical characteristics of these polymer networks to meet the mechanical and ionic conductivity property requirements for Li battery electrolyte materials. To address this challenge, our goal is to investigate the impact of the cross-linking density of the PEO-based network and the ethylene oxide/lithium ratio on mechanical properties (such as glass transition temperature and storage modulus) and ionic conductivity. We have synthesized a series of cross-linked PEO-based polymers (si-SPE for single ion solid polymer electrolyte) via solvent-free radical copolymerization. These polymers are synthesized by using commercially available lithium 3-[(trifluoromethane)sulfonamidosulfonyl]propyl methacrylate (LiMTFSI), poly(ethylene glycol)methyl ether methacrylate (PEGM), and [poly(ethylene glycol) dimethacrylate] (PEGDM). In addition, we have synthesized a series of cross-linked PEO-based polymers (SPE for solid polymer electrolyte) using LiTFSI as the ionic species. Most of the resulting polymer films are amorphous, self-standing, flexible, homogeneous, and thermally stable. Interestingly, our research has revealed a correlation between ionic conductivity and mechanical properties in both the SPE and si-SPE series. Ionic conductivity increases as glass transition temperature, α relaxation temperature, and storage modulus decrease, suggesting that Li+ transport is influenced by polymer chain flexibility and Li+/EO interaction

Behavior of Tin-Based “Super-POSS” Incorporated in Different Bonding Situations in Hybrid Epoxy Resins

Hybrid organic–inorganic epoxies containing the heavier POSS homologue, <i>n</i>-butylstannoxane dodecamer, incorporated as an inert block, as a linear unit, and as a network junction were prepared. This nanometer-sized inorganic cage is especially attractive because of its chemical reactivity (besides mechanical matrix reinforcement). It can undergo oxidative cross-linking reactions with the matrix, or at elevated temperature in the absence of air, it can oligomerize to larger nanodomains, thus generating additional chemical cross-links. The influences of the bonding situation of the stannoxane cages on the hybrid resins’ morphology, mechanical properties, and on the cages’ chemical activity were studied. The highest reactivity was observed in the case of the linearly bonded cages, which also can achieve unusual short-range mobility in the matrix at high temperatures. This mobility was found to be a result of reversible oxonium ionic bonds to the linear units. The branching stannoxane units display a fair antioxidative reactivity in the matrix, which is nevertheless markedly smaller than in the case of the linear ones. On the other hand, the branching cage achieves the highest mechanical reinforcement of the matrix. The nonbonded stannoxane displays macroscopic phase separation at concentrations above 4 wt % and does not reinforce the matrix markedly, but at low concentrations, it is highly efficient in counteracting the oxidative degradation of the matrix. The effect of the stannoxane cages was also systematically compared with the effect of similarly incorporated POSS cages in the same matrix and in general

Ex Situ X‑ray Diffraction, X‑ray Absorption Near Edge Structure, Electron Spin Resonance, and Transmission Electron Microscopy Study of the Hydrothermal Crystallization of Vanadium Oxide Nanotubes: An Insight into the Mechanism of Formation

The nucleation and growth of vanadium oxide nanotubes (VO_<i>x</i>-NT) have been followed by a combination of numerous ex situ techniques along the hydrothermal process. Intermediate solid phases extracted at different reaction times have been characterized by powder X-ray diffraction, scanning and transmission electron microscopy, electron spin resonance, and V–K edge X-ray absorption near-edge structure spectroscopy. The supernatant vanadate solutions extracted during the hydrothermal treatment have been studied by liquid ⁵¹V NMR and flame spectroscopy. For short durations of the hydrothermal synthesis, the initial V₂O₅-surfactant intercalate is progressively transformed into VO_<i>x</i>-NT whose crystallization starts to be detected after a hydrothermal treatment of 24 h. Upon heating from 24 h to 7 days, VO_<i>x</i>-NT are obtained in larger amount and with an improved crystallinity. The detection of soluble amines and cyclic metavanadate [V₄O₁₂]^4– in the supernatant solution along the hydrothermal process suggests that VO_<i>x</i>-NT result from a dissolution–precipitation mechanism. Metavanadate species [V₄O₁₂]^4– could behave as molecular precursors in the polymerization reactions leading to VO_<i>x</i>-NT

Ex Situ X‑ray Diffraction, X‑ray Absorption Near Edge Structure, Electron Spin Resonance, and Transmission Electron Microscopy Study of the Hydrothermal Crystallization of Vanadium Oxide Nanotubes: An Insight into the Mechanism of Formation

The nucleation and growth of vanadium oxide nanotubes (VO_<i>x</i>-NT) have been followed by a combination of numerous ex situ techniques along the hydrothermal process. Intermediate solid phases extracted at different reaction times have been characterized by powder X-ray diffraction, scanning and transmission electron microscopy, electron spin resonance, and V–K edge X-ray absorption near-edge structure spectroscopy. The supernatant vanadate solutions extracted during the hydrothermal treatment have been studied by liquid ⁵¹V NMR and flame spectroscopy. For short durations of the hydrothermal synthesis, the initial V₂O₅-surfactant intercalate is progressively transformed into VO_<i>x</i>-NT whose crystallization starts to be detected after a hydrothermal treatment of 24 h. Upon heating from 24 h to 7 days, VO_<i>x</i>-NT are obtained in larger amount and with an improved crystallinity. The detection of soluble amines and cyclic metavanadate [V₄O₁₂]^4– in the supernatant solution along the hydrothermal process suggests that VO_<i>x</i>-NT result from a dissolution–precipitation mechanism. Metavanadate species [V₄O₁₂]^4– could behave as molecular precursors in the polymerization reactions leading to VO_<i>x</i>-NT

Solvent-free Preparation of Ru/Al₂O₃ Catalysts for CO₂ Methanation: An Example of Frugal Innovation

To reduce the environmental impact of supported catalyst production in compliance with the recommendations of the UN’s 12th objective, which encourages more sustainable consumption and production patterns, we propose to revisit sol–gel chemistry in a more frugal mode. The principle of frugal innovation is to simplify products and processes, eliminate complexities to make solutions easier to understand and use, and reduce production costs. By this way, the synthesis of ruthenium-based catalysts supported on γ-AlOOH and γ-Al2O3 is revised via solvent-free sol–gel chemistry. Such catalysts are successfully prepared in one-pot preparation of the active phase and the support using Ru(acac)3/Al alkoxide that requires no sacrificial organic pore-generating agent, no washing, and no filtration and produces no liquid waste. The mixed Ru/Al precursor is hydrolyzed with a stoichiometric amount of water without any solvent. The obtained materials containing 1 and 3% Ru/Al molar ratios have high specific surface areas, from 300 to 690 m2·g–1 and exhibit well dispersed NPs of 1–4 nm on γ-AlOOH with interesting CO2 methanation activity and 100% CH4 selectivity. This proves that a frugal synthesis approach can do as well as traditional synthesis methods while having a much lower environmental impact (cE-factor, water consumption, and energy consumption are 24, 69, and 24 to 42 times lower, respectively) than the standard multistep protocol.

Solvent-free Preparation of Ru/Al₂O₃ Catalysts for CO₂ Methanation: An Example of Frugal Innovation

To reduce the environmental impact of supported catalyst production in compliance with the recommendations of the UN’s 12th objective, which encourages more sustainable consumption and production patterns, we propose to revisit sol–gel chemistry in a more frugal mode. The principle of frugal innovation is to simplify products and processes, eliminate complexities to make solutions easier to understand and use, and reduce production costs. By this way, the synthesis of ruthenium-based catalysts supported on γ-AlOOH and γ-Al2O3 is revised via solvent-free sol–gel chemistry. Such catalysts are successfully prepared in one-pot preparation of the active phase and the support using Ru(acac)3/Al alkoxide that requires no sacrificial organic pore-generating agent, no washing, and no filtration and produces no liquid waste. The mixed Ru/Al precursor is hydrolyzed with a stoichiometric amount of water without any solvent. The obtained materials containing 1 and 3% Ru/Al molar ratios have high specific surface areas, from 300 to 690 m2·g–1 and exhibit well dispersed NPs of 1–4 nm on γ-AlOOH with interesting CO2 methanation activity and 100% CH4 selectivity. This proves that a frugal synthesis approach can do as well as traditional synthesis methods while having a much lower environmental impact (cE-factor, water consumption, and energy consumption are 24, 69, and 24 to 42 times lower, respectively) than the standard multistep protocol.

Nanoparticles of Low-Valence Vanadium Oxyhydroxides: Reaction Mechanisms and Polymorphism Control by Low-Temperature Aqueous Chemistry

An aqueous synthetic route at 95 °C is developed to reach selectively three scarcely reported vanadium oxyhydroxides. Häggite V₂O₃(OH)₂, Duttonite VO­(OH)₂, and Gain’s hydrate V₂O₄(H₂O)₂ are obtained as nanowires, nanorods, and nanoribbons, with sizes 1 order of magnitude smaller than previously reported. X-ray absorption spectroscopy provides evidence that vanadium in these phases is V^+IV. Combined with FTIR, XRD, and electron microscopy, it yields the first insights into formation mechanisms, especially for Häggite and Gain’s hydrate. This study opens the way for further investigations of the properties of novel V^+IV (oxyhydr)­oxides nanostructures