References of "Grignard, Bruno"
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See detailSelf-foaming polymers: opportunities for the next generation of personal protective equipment
Monie, Florent ULiege; Vidil, Thomas; Grignard, Bruno ULiege et al

in Materials Science and Engineering: R: Reports (2021), 145

Polymeric foams merge the intrinsic lightness of porous materials with low thermal and electrical conductivity as well as good energy adsorption capabilities and filtration abilities, depending on their ... [more ▼]

Polymeric foams merge the intrinsic lightness of porous materials with low thermal and electrical conductivity as well as good energy adsorption capabilities and filtration abilities, depending on their morphology. Such com- binations explain their widespread use in many applications, including in the domain of personal protective equipment (PPE). Indeed, foams are the materials of choice to fulfill a series of essential protective functions, including: (i) insulation, (ii) dissipation, (iii) adsorption, (iv) filtration, (v) flotation and, of course, (vi) cush- ioning. Historically, foams were developed by iterative formulation works aiming at nucleating and stabilizing bubbles of gas in a polymer matrix. The foaming of polyurethanes is among the earliest – and today most mature – methodologies. Indeed, polyurethanes are obtained from isocyanate precursors that have the ability to partially decompose in gaseous CO2 in the presence of water. The gas, also referred to as the blowing agent (BA), is released concomitantly with the polymerization reaction to initiate the expansion of the growing polymer. Because the BA is primarily embedded in the molecular structure of the precursors of the polymer, this system is usually labelled as self-foaming. With the growing health and environmental awareness regarding the toxicity of isocyanates, a burgeoning number of self-foaming polymers and their precursors that circumvent the use of isocyanates are reported in the literature. They combine an interesting range of assets – from the typical ease of use of one-pack systems to the relative innocuity of their blowing gas (e.g., CO2, H2O, halogen-free alkanes) – that are very well suited to the large-scale production of foams in compliance with strict safety and environmental specifications. In this context, the present review is showcasing both historical and emerging self-foaming (pre)polymers that represent opportunities for the production of the next generation of safer and environmentally benign PPE. A special attention is dedicated to the self-foaming mechanisms – i.e., the chemical transformations of the (pre) polymers that result in the release of the blowing agent – and its interplay with the physicochemical processes resulting in the hardening of the (pre)polymers (e.g., sol-gel or rubber-glass transitions). A classification of those mechanisms – (i) thermolysis and (ii) condensation – is proposed for the first time. The properties of the resulting foams are also briefly discussed in terms of densities, cell morphology and mechanical response with the intention to guide the reader in selecting the best foaming process for the targeted polymer matrix and with a special [less ▲]

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See detailCarbon Dioxide for Producing Non-Isocyanate Polyurethane Foams, Adhesives, Hydrogels and—Much More!
Detrembleur, Christophe ULiege; Siragusa, Fabiana ULiege; Habets, Thomas ULiege et al

Conference (2021, April 19)

The recycling of carbon dioxide (CO2) by transforming this waste into value has become a major goal in contemporary science. Strategies are emerging to turn this renewable carbon feedstock into valuable ... [more ▼]

The recycling of carbon dioxide (CO2) by transforming this waste into value has become a major goal in contemporary science. Strategies are emerging to turn this renewable carbon feedstock into valuable engineering plastics while diversifying renewable resources for the sustainable production of consumer materials. Novel routes to efficiently turn CO2 into polymers are expected to accelerate and facilitate the transition from existing fossil-based to future generations of more sustainable materials while trying to meet the requirements of a circular economy for consumer plastics. In the first part of this talk, we will discuss how CO2 can be converted into monomers that are then involved in step-growth copolymerizations with diamines to produce non-isocyanate polyurethanes (NIPUs), greener variants of conventional polyurethanes that are commonly prepared by the toxic isocyanate chemistry. These monomers can be easily and quantitatively produced at the multi-kg scale under solvent-free conditions in our lab. We will show how they can be exploited to design some representative high performance NIPUs materials. We will first discuss how adhesives and coatings can be produced under solvent-free conditions, with adhesion performances on various substrates (aluminum, wood, stainless steel, glass) that compete to those of commercial products, provided that appropriate curing is applied. We will then report on an innovative robust and solvent-free process for the construction of flexible or rigid self-blown NIPU foams that offers the first realistic alternative to the traditional isocyanate route. In this process, the CO2-based monomer is not only exploited to construct the NIPU matrix but also for its self-blowing. If time permits, we will also show that NIPUs hydrogels can be produced in water at room temperature without any catalyst with impressive short gel times. These hydrogels can be easily reinforced by introducing natural polymers or clay in the formulations prior to curing. All these technologies can be easily scaled-up and are highly versatile, opening new opportunities in the design of more sustainable materials while valorizing CO2 as a renewable carbon feedstock. In the second part of the talk, we will describe an innovative approach for the facile preparation of new regioregular functional NIPUs (e.g. poly(oxo-urethane)s and poly(oxazolidone)s) at room temperature by using a novel family of monomers prepared by the CO2 chemistry. The special reactivity of these monomers will be discussed, and if time permits, we will show how they can be exploited for the facile construction of other relevant polymers (e.g. polycarbonates, sulfur-containing polymers) under mild operating conditions. [less ▲]

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See detailFunctional polyethylenes by organometallic-mediated radical polymerization of biobased carbonates
Scholten, Philip Benjamin Vincent ULiege; Cartigny, Grégory ULiege; Grignard, Bruno ULiege et al

in ACS Macro Letters (2021), 10(3), 313-320

Partly or fully renewable (co)polymers are gaining interest in both academia and industry. Polyethylene is a widely used polymer, classically derived from fossil fuels, with a high versatility stemming ... [more ▼]

Partly or fully renewable (co)polymers are gaining interest in both academia and industry. Polyethylene is a widely used polymer, classically derived from fossil fuels, with a high versatility stemming from the introduction of comonomers altering the mechanical properties. The introduction of renewable functionalities into this polymer is highly attractive to obtain functional, tunable, and at least partially renewable polyethylenes. We herein report the introduction of biosourced cyclic carbonates into polyethylene using organometallic-mediated radical polymerization under mild conditions. Molecular weights of up to 14 600 g mol−1 with dispersities as low as 1.19 were obtained, and the cyclic carbonate content could be easily tuned by the ethylene pressure during the polymerization. As a proof of concept, the hydrolysis of the cyclic carbonates of a representative copolymer was explored, and it provided polyethylene-bearing vicinal diols, with a hydrolysis degree of 71%. Given the multitude of chemoselective modifications possible on cyclic carbonates as well as the fact that many allylic- and alkylidene-type cyclic carbonates are accessible from renewable resources, this work opens up an avenue for the design of functional and more sustainable polyethylenes. [less ▲]

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See detailAccess to biorenewable and CO2‑based polycarbonates from exovinylene cyclic carbonates
Siragusa, Fabiana ULiege; Van Den Broeck, Elias; Ocando, Connie et al

in ACS Sustainable Chemistry and Engineering (2021), 9(4), 1714-1728

We investigate the scope of the organocatalyzed step-growth copolymerization of CO2-sourced exovinylene bicyclic carbonates with bio-based diols into polycarbonates. A series of regioregular poly(oxo ... [more ▼]

We investigate the scope of the organocatalyzed step-growth copolymerization of CO2-sourced exovinylene bicyclic carbonates with bio-based diols into polycarbonates. A series of regioregular poly(oxo-carbonate)s were prepared from sugar- (1,4-butanediol and isosorbide) or lignin-derived (1,4-benzenedimethanol and 1,4-cyclohexanediol) diols at 25 °C with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst, and their defect-free structure was confirmed by nuclear magnetic resonance spectroscopy studies. Their characterization by differential scanning calorimetry and wide-angle X-ray scattering showed that most of them were able to crystallize. When the polymerizations were carried out at 80 °C, some structural defects were introduced within the polycarbonate chains, which limited the polymer molar mass. Model reactions were carried out to understand the influence of the structure of alcohols, the temperature (25 or 80 °C), and the use of DBU on the rate of alcoholysis of the carbonate and on the product/linkage selectivity. A full mechanistic understanding was given by means of static- and dynamic-based density functional theory (DFT) calculations showing the determining role of DBU in the stability of intermediates, and its important role in the rate-determining steps is revealed. Furthermore, the origin of side reactions observed at 80 °C was discussed and rationalized by DFT modeling. As impressive diversified bio-based diols are accessible on a large scale and at low cost, this process of valorization of carbon dioxide gives new perspectives on the sustainable production of bioplastics under mild conditions. [less ▲]

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See detailWater-borne isocyanate-free polyurethane hydrogels with adaptable functionality and behavior
Bourguignon, Maxime ULiege; Thomassin, Jean-Michel ULiege; Grignard, Bruno ULiege et al

in Macromolecular Rapid Communications (2021), 42(3), 2000482

Polyurethane hydrogels are attractive materials finding multiple applications in various sectors of prime importance; however, they are still prepared by the toxic isocyanate chemistry. Herein the facile ... [more ▼]

Polyurethane hydrogels are attractive materials finding multiple applications in various sectors of prime importance; however, they are still prepared by the toxic isocyanate chemistry. Herein the facile and direct preparation in water at room temperature of a large palette of anionic, cationic, or neutral polyurethane hydrogels by a non‐isocyanate route from readily available diamines and new hydrosoluble polymers bearing cyclic carbonates is reported. The latter are synthesized by free radical polymerization of glycerin carbonated methacrylate with water‐soluble comonomers. The hydrogel formation is studied at different pH and its influence on the gel time and storage modulus is investigated. Reinforced hydrogels are also constructed by adding CaCl2 to the formulation that in‐situ generates CaCO3 particles. Thermoresponsive hydrogels are also prepared from new thermoresponsive cyclic carbonate bearing polymers. This work demonstrates that a multitude of non‐isocyanate polyurethane hydrogels are easily accessible under mild conditions without any catalyst, opening new perspectives in the field. [less ▲]

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See detailSelf-blowing isocyanate free polyurethane foams
Detrembleur, Christophe ULiege; Thomassin, Jean-Michel ULiege; Grignard, Bruno ULiege et al

Patent (2021)

The present invention relates to a curable isocyanate-free formulation for preparing a polyurethane self-blowing foam comprising at least one multifunctional cyclic carbonate having at least two cyclic ... [more ▼]

The present invention relates to a curable isocyanate-free formulation for preparing a polyurethane self-blowing foam comprising at least one multifunctional cyclic carbonate having at least two cyclic carbonate groups at the end of the chain (compound A), at least one multifunctional amine (compound B), at least one multifunctional thiol (compound C) and at least one catalyst (compound D), to a process for preparing said foams and to the thus obtained foams. [less ▲]

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See detailSynergetic effect of dopamine and alkoxysilanes in sustainable non-isocyanate polyurethane adhesives
Gomez-Lopez, Alvaro; Grignard, Bruno ULiege; Calvo, Iñigo et al

in Macromolecular Rapid Communications (2021), 42

The preparation of non‐isocyanate polyurethanes (NIPUs) by polyaddition of (poly)cyclic carbonates to (poly)amines represents one of the most optimistic alternatives for replacing conventional ... [more ▼]

The preparation of non‐isocyanate polyurethanes (NIPUs) by polyaddition of (poly)cyclic carbonates to (poly)amines represents one of the most optimistic alternatives for replacing conventional polyurethanes prepared by the toxic isocyanate chemistry. However, the limited reactivity of conventional five membered cyclic carbonates even in the presence of catalysts restricts their industrial implementation. One way to mitigate this lack of reactivity is to combine with other chemistries to create hybrid‐NIPUs with superior performance. In this article the combination of the adhesive promoter, dopamine, and the fast‐curing promoter, an aminopropyl trimethoxysilane, is found to create a synergetic effect on the rheological and adhesive properties of NIPUs. After demonstrating the importance of adjusting soft/hard ratios to obtain lap‐shear strength adhesion values up to 21 MPa on stainless steel, these values are retained when adding dopamine and silane compounds. Importantly, the adhesive properties of NIPU are preserved at high temperature (T > 200 °C) for optimal compositions. Finally, adhesion tests on various substrates (polyamide, high density polyethylene, poly(methyl methacrylate), oak wood, and aluminum) show best performances on polar substrates confirming the strong interactions of hydroxyl groups of NIPU and dopamine. [less ▲]

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See detailA supercritical fluid technology for liposome production and comparison with the film hydration method
Penoy, Noémie ULiege; Grignard, Bruno ULiege; Evrard, Brigitte ULiege et al

in International Journal of Pharmaceutics (2021), 592

Liposomes were produced by an innovative method using supercritical carbon dioxide as a dispersing agent. A quality by design strategy was used to find optimal production conditions with specific ... [more ▼]

Liposomes were produced by an innovative method using supercritical carbon dioxide as a dispersing agent. A quality by design strategy was used to find optimal production conditions with specific parameters (lipid concentration, dispersion volume, agitation rate, temperature and pressure) allowing the production of liposomes with predicted physicochemical characteristics (particles size and PdI). Two conditions were determined with specific production parameters. It was shown that these two conditions allowed the production of liposomes of different compositions and that most of the liposome formulations had size and dispersity in accordance with the prediction values. The condition involving the higher lipid concentration showed a higher variability in terms of size and dispersity. However, this variability remained acceptable. This innovative supercritical method allowed the production of liposomes with physicochemical characteristics similar to those obtained by the conventional thin film hydration method. This new supercritical carbon dioxide method easily scalable in GMP conditions is a one-step production method contrarily to conventional methods which generally need an additional step as extrusion to homogenize the size of liposomes. [less ▲]

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See detailChemo- and regio-selective additions of nucleophiles to cyclic carbonates for the preparation of self-blowing non-isocyanate polyurethane foams
Monie, Florent ULiege; Grignard, Bruno ULiege; Thomassin, Jean-Michel ULiege et al

in Angewandte Chemie International Edition (2020), 59(39), 17033-17041

Polyurethane (PU) foams are indisputably daily essential materials found in many applications, notably for comfort (e.g. matrasses) or energy saving (e.g. thermal insulation). Today, greener routes for ... [more ▼]

Polyurethane (PU) foams are indisputably daily essential materials found in many applications, notably for comfort (e.g. matrasses) or energy saving (e.g. thermal insulation). Today, greener routes for their production are intensively searched for avoiding the use of toxic isocyanates. We now describe an easily scalable process for the simple construction of self-blown isocyanate-free PU foams by exploiting the organocatalyzed chemo- and regio-selective additions of amines and thiols to easily accessible cyclic carbonates. These reactions are first validated on model compounds and rationalized by DFT calculations. Various foams are then prepared and characterized in terms of morphology and mechanical properties, and the scope of the process is illustrated by modulating the composition of the reactive formulation. Due to the impressive diversity and accessibility of the main components of the formulations, this new robust and solvent- free process is opening avenues for constructing more sustainable PU foams, and offers the first realistic alternative to the traditional isocyanate route. Introduction [less ▲]

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See detailAdvancing the synthesis of isocyanate-free poly(oxazolidones)s: scope and limitations
Habets, Thomas ULiege; Siragusa, Fabiana ULiege; Grignard, Bruno ULiege et al

in Macromolecules (2020), 53(15), 6393-6408

Poly(oxazolidone) is an emerging class of polyur- ethanes (PUs) that is easily accessible by an isocyanate-free pathway via the step-growth copolymerization of CO2-based monomers (bis(α-alkylidene cyclic ... [more ▼]

Poly(oxazolidone) is an emerging class of polyur- ethanes (PUs) that is easily accessible by an isocyanate-free pathway via the step-growth copolymerization of CO2-based monomers (bis(α-alkylidene cyclic carbonate)s) with primary diamines at room temperature. Here, we explore the scope and limitation of this process by investigating the influence of the diamine and the reaction conditions on the structure and macromolecular parameters of the polymer. Less hindered diamines (aliphatic and benzylic) provide selectively poly- (hydroxyoxazolidone)s, whereas the bulkier ones (cycloaliphatic) furnish polymer chains bearing two types of linkages, oxo- urethane and hydroxyoxazolidone ones. The increase of the reaction temperature or the addition of DBU as a catalyst enables to accelerate the polymerizations. The quantitative polymer dehydration is also achieved by refluxing in acetic acid, providing a new class of unsaturated poly(oxazolidone)s composed of α-alkylidene oxazolidone linkages (for hindered polymers) or a mixture of α- and β-alkylidene oxazolidone linkages (for the less hindered ones). These unsaturated poly(oxazolidone)s present a high glass transition temperature (90 °C ≤ Tg ≤ 130 °C) and a remarkable thermal stability (Td > 360 °C), rendering these polymers attractive for applications requiring high temperatures. This work is therefore opening an avenue to novel functional isocyanate-free PUs, with the pendant hydroxyl or olefin groups that are expected to be easily derivatized. [less ▲]

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See detailA catalytic domino approach towards oxo-alkyl carbonates and polycarbonates from CO2, propargylic alcohols and (mono- and di-) alcohols
Ngassam Tounzoua, Charlène ULiege; Grignard, Bruno ULiege; Brege, Antoine ULiege et al

in ACS Sustainable Chemistry and Engineering (2020), 8(26), 9698-9710

We have explored the domino reaction between propargylic alcohols, carbon dioxide and various alcohols with the double objective to prepare oxo-alkylcarbonates with a high yield and selectivity under mild ... [more ▼]

We have explored the domino reaction between propargylic alcohols, carbon dioxide and various alcohols with the double objective to prepare oxo-alkylcarbonates with a high yield and selectivity under mild conditions and to extend the process to the synthesis of phosgene-free polycarbonates. We first searched for a common catalytic system that was highly selective for the two reactions involved in the domino process, i.e. the cycloaddition of CO2 to propargylic alcohol to yield α-alkylidene cyclic carbonate (αCC), and the alcoholysis of αCC to furnish the oxo-alkylcarbonate. Kinetics studies monitored by operando IR spectroscopy and supported by 1H-NMR analyses and DFT modeling have permitted to identify an efficient binary catalytic system composed of a combination of tetrabutylammonium phenolate [TBA][OPh] and silver iodide (AgI) (or copper iodide (CuI)) and to understand its action mode. The [TBA][OPh]/AgI catalytic system (5 mol%) was then successfully implemented for the selective preparation of a range of oxo-alkylcarbonates by the domino reaction with alcohols and propargylic alcohols of different structures. Most of these oxo-alkylcarbonates were produced at a high yield (≧ 97 %) under mild operating conditions, i.e. at 60 °C and 1 bar of CO2. The one-pot synthesis of various poly(β-oxocarbonate)s from bis(propargylic alcohol)s, diols and CO2 was finally investigated and the best operating conditions ([TBA][OPh]/AgI (10 mol%), 60 °C, 15 bar) afforded polycarbonate oligomers with weight-average molar masses of 4,300 g/mol. Although the system should be optimized to produce longer polymer chains, this process offers a new phosgene-free alternative to the synthesis of functional polycarbonates (poly(oxo-carbonate)s) under mild conditions. [less ▲]

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See detailImpregnation of mesoporous silica with poor aqueous soluble molecule using pressurized carbon dioxide: is the solubility in the supercritical and subcritical phase a critical parameter?
Koch, Nathan ULiege; Jennotte, Olivier ULiege; Grignard, Bruno ULiege et al

in European Journal of Pharmaceutical Sciences (2020), 150

Recently, mesoporous silica (MS) has been used as a material able to maintain amorphous state of active compounds and therefore, enhance the oral bioavailability of BCSII drugs. Among impregnation methods ... [more ▼]

Recently, mesoporous silica (MS) has been used as a material able to maintain amorphous state of active compounds and therefore, enhance the oral bioavailability of BCSII drugs. Among impregnation methods of MS, techniques using supercritical carbon dioxide (sc-CO2) are promising tools. Solubility of compounds in sc-CO2 is reported as one of the most critical parameters, which usually limits its use in drug formulation. Indeed, most of compounds have poor solubility in sc-CO2. The aim of this work is to compare different MS and to study alternative processes using pressurized CO2 for insoluble molecule in sc-CO2. By using high pressure reactor, DSC, HPLC and in vitro dissolution tests, the crystallinity and dissolution profiles of MS with different pore size (6.6 nm, 25.0 nm and 2.5 nm) impregnated with fenofibrate (FF) under sc-CO2 were compared to select the most appropriate carrier. Then, the selected MS has been impregnated under supercritical, subcritical and atmospheric conditions. We have shown that the MS pore size of 6.6 nm provides the higher amorphous drug loading capacity as well as the faster and higher drug dissolution. In addition, FF-MS formulations produced with pressurized CO2 as fusion medium, both in subcritical and supercritical conditions; give similar crystallinity and dissolution results compared to those produced with supercritical fluids as solvent. Through this study, we show new possibilities of using CO2 for insoluble compounds in this fluid. [less ▲]

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See detailMonocomponent non-isocyanate polyurethane adhesives based on a sol-gel process
Gomez-Lopez, Alvaro; Grignard, Bruno ULiege; Calvo, Iñigo et al

in ACS Applied Polymer Materials (2020), 2(5), 1839-1847

In the context of replacement of toxic conventional polyurethanes, non-isocyanates polyurethanes (NIPUs) based on 5-membered cyclic carbonates have emerged as the most promising alternatives. The low ... [more ▼]

In the context of replacement of toxic conventional polyurethanes, non-isocyanates polyurethanes (NIPUs) based on 5-membered cyclic carbonates have emerged as the most promising alternatives. The low reactivity of conventional 5-membered cyclic carbonates has limited the preparation of one pot-based systems due to long curing times. This work focuses in the improvement and application of these materials as adhesives by the combination of the NIPU chemistry with the sol-gel process able to cure in the presence of humidity. Thus, NIPU prepolymers are functionalized with (3-aminopropyl)triethoxysilane (APTES) and their curing behaviour as well as their adhesion performance are investigated by rheology and lap-shear test respectively. In spite of the ability of alkoxysilane to cure under ambient conditions, our results show that to have better adhesion properties, catalyst and temperature must be used to speed up the curing process. Hence, it is demonstrated that the fastest curing and the best performance are achieved at 100°C when acetic acid is employed as catalyst. Finally we demonstrate the importance of the soft (poly(propylene glycol) dicarbonate) to hard (resorcinol dicarbonate) ratio to achieve superior cohesion and adhesion properties in NIPUs adhesives. [less ▲]

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See detailThe coupling of CO2 with diols promoted by organic dual systems: Towards products divergence via benchmarking of the performance metrics
Brege, Antoine ULiege; Méreau, Raphaël; McGehee, K et al

in Journal of CO2 Utilization (2020), 38

Herein, we propose a critical study balancing two metal-free dual activating systems, namely DBU/EtBr and TEA/TsCl, for the coupling of CO2 with 1,x-diols to afford (a)cyclic carbonates. In-situ ATR-IR ... [more ▼]

Herein, we propose a critical study balancing two metal-free dual activating systems, namely DBU/EtBr and TEA/TsCl, for the coupling of CO2 with 1,x-diols to afford (a)cyclic carbonates. In-situ ATR-IR monitoring cor- related with DFT calculations led to mechanism propositions for the model formation of propylene carbonate from propylene glycol. Kinetics upon various experimental conditions were established for the first time, leading to an optimized synthetic protocol. The substrates scope was then investigated and selectivities toward the formation of cyclic or linear carbonates were correlated to the dual activating system and the diol structure. By choosing the suitable organic dual activating system, one is able to control the product selectivity to substituted ethylene- or trimethylene carbonate and/or acyclic compounds, providing a powerful tool to synthesize CO2- based precursors that are highly relevant for organic and polymer chemistry from ubiquitous building blocks. [less ▲]

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See detailInfluence of the cyclic vs. linear carbonate segments in the properties and performance of CO2-sourced polymer electrolytes for lithium batteries
Ouhib, Farid ULiege; Meabe, Leire; Mahmoud, Abdelfattah ULiege et al

in ACS Applied Polymer Materials (2020), 2(2), 922-931

Polycarbonates bearing linear carbonate linkages and polyether segments have demonstrated to be highly attractive solid electrolyte candidates for the design of safe energy storage devices, e.g. lithium ... [more ▼]

Polycarbonates bearing linear carbonate linkages and polyether segments have demonstrated to be highly attractive solid electrolyte candidates for the design of safe energy storage devices, e.g. lithium metal batteries. In this contribution, we are studying the influence of the introduction of some cyclic carbonate linkages within the polymer backbone on the electrolyte properties. We first describe the synthesis of polycarbonates/polyethers containing different contents of both linear and cyclic carbonate linkages within the chain by the copolymerization of a highly reactive CO2-based monomer (bis(-alkylidene cyclic carbonate)) with poly(ethylene glycol) diol and a dithiol at room temperature. We then explore the influence of the content of the cyclic carbonates and the loading of the polymer by lithium bis(trifluoromethane) sulfonimide (LiTFSI) on the electrolyte properties (glass transition and melting temperatures, ion conductivity and diffusivity). The best electrolyte candidate is characterized by a linear/cyclic carbonate linkage ratio of 82/18 when loaded with 30 wt% LiTFSI. It exhibits an ion conductivity of 5.6 10-5 S cm-1 at 25°C (7.9 10-4 S cm-1 at 60 °C), which surpasses by 150 % (424 % at 60 °C) the conductivity measured for a similar polymers bearing linear carbonate linkages only. It is also characterized by a high oxidation stability up to 5.6 V (vs. Li/Li+). A self-standing membrane is then constructed by impregnating a glass fiber filter by this optimal polymer, LiTFSI and a small amount of a plasticizer (tetraglyme). Cells are then assembled by sandwiching the membrane between a C-coated LiFePO4 (LFP) as the cathode and lithium as the anode and counter electrode. The cycling performances are evaluated at 0.1 C at 60 °C and room temperature for 40 cycles. Excellent cycling performances are noted with 100 % of the theoretical capacity (170 mAh g-1) at 60 °C, and 73.5 % of the theoretical capacity (125 mAh g-1) at 25 °C. [less ▲]

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See detailPlein gaz : enjeux et perspectives de la valorisation du CO2
Léonard, Grégoire ULiege; Evrard, Brigitte ULiege; Grignard, Bruno ULiege et al

Conference given outside the academic context (2019)

Detailed reference viewed: 93 (19 ULiège)
See detailDual activation catalysts for the selective conversion of CO2 into alkylidene cyclic carbonates and oxoalkyl carbonates
Ngassam Tounzoua, Charlène ULiege; Grignard, Bruno ULiege; Jérôme, Christine ULiege et al

Conference (2019, September 24)

Carbon dioxide (CO2) is a greenhouse gas responsible for global warming. In the last decades, efforts have been put towards the valorization of this abundant, nontoxic inexhaustible C1 source for the ... [more ▼]

Carbon dioxide (CO2) is a greenhouse gas responsible for global warming. In the last decades, efforts have been put towards the valorization of this abundant, nontoxic inexhaustible C1 source for the synthesis of useful commodity chemicals. The synthesis of cyclic carbonates is attracting much interest due to its 100% atom efficiency reaction and its large potential scope for the design of complex organic molecules or novel functional polymers (polycarbonates, polyurethanes, etc.). 5-membered cyclic carbonates can be obtained by the coupling of CO2 with diols, epoxides and lastly, alkynols. The latter have the advantage of affording cyclic carbonates that are activated by the presence of an exocyclic vinylic bond, making them reactive towards alcohols and amines. In addition, their ring-opening is regio-selective affording β -oxo-carbonate by reaction with alcohols, β-oxo-urethanes with secondary amines or β-hydroxy-oxazolidones with primary amines. Due to the inertness and high thermodynamic stability of CO2, a catalyst is required to transform alkynols into alkylidene cyclic carbonates. Bases, ionic liquids), carbenes, metal salts, have been shown to promote the cyclisation of CO2 with alkynols. Although full conversions are obtained in certain cases, the selectivity remains an issue. Also, harsh conditions and/or excessive amounts of base are often used. In this work, we designed novel, cheap, highly efficient organocatalysts for the synthesis of α-alkylidene cyclic carbonates from CO2 and alkynols. Several organocatalysts, based on ammonium cations and basic anions were screened, and kinetic studies were performed by Raman spectroscopy to identify the best anion/cation couple. We further optimized our catalytic system by developing cooperative catalysts providing conditions for the selective formation of α-alkylidene cyclic carbonates and oxoalkylcarbonates under mild experimental conditions and short reaction times at low catalyst loading. [less ▲]

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See detailCO2-based monomers: a detailed investigation of the carbonation reaction over diols for the synthesis of (a)cyclic carbonates promoted by organic dual systems
Brege, Antoine ULiege; Méreau, Raphaël; Grignard, Bruno ULiege et al

Poster (2019, September 23)

The present research aims at investigating in details the reaction between carbon dioxide and a diol to afford cyclic and acyclic carbonates in moderate to good yields. Thanks to its chemical structure ... [more ▼]

The present research aims at investigating in details the reaction between carbon dioxide and a diol to afford cyclic and acyclic carbonates in moderate to good yields. Thanks to its chemical structure, CO2 has been identified as a promising reagent for the synthesis of organic carbonates as it is non-toxic, cheap and an abundant C1 renewable feedstock, and could potentially replace phosgene based carbonates produced industrially. Prior research has been focused on the epoxide/CO2 coupling to afford cyclic carbonates in good yields. Yet, this coupling suffers from limitations such as restricted substrates and exclusive synthesis of 5-membered cyclic carbonates. In order to extend the products availability through Carbon Dioxide Utilization, more recent research has been carried out with new substrates such as the use of diols. Thus, efforts are still needed to identify cheaper and more efficient protocols for the selective synthesis of cyclic and acyclic carbonates from the coupling of CO2 with diols. In this context, the use of organic bases/alkylating agent dual system as promoters and low pressure and temperature conditions (P<1MPa, r.t) seem to be a good alternative to afford organic carbonates. Thanks to an in-situ ATR-IR spectroscopy monitoring, a detailed understanding of the synthesis of propylene carbonate from propylene glycol and CO2 promoted by organic bases and the addition of co-reagents is proposed. Reaction intermediates are identified, and kinetic profiles determined for various parameters (pressure, temperature, solvent…). Two dual systems, one combining DBU and an alkyl halide (e.g Bromoethane), and another one with TEA and TsCl were compared. Different substrates were also tested such as 1,x diols (2 ≤ x ≤ 4) and Isosorbide. The selectivity toward the cyclic carbonate or the side products is discussed. Density Functional Theory (DFT) was also performed in this work to understand and validate the reaction pathways proposed via ATR-IR monitoring. Structures of transition states were optimized and comparisons between several reagents and/or paths were calculated, giving capital information about further enhancement of the CO2-diol conversion into carbonates. [less ▲]

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See detailOptimizing support properties of heterogeneous catalysts for the coupling of carbon dioxide with epoxides
Léonard, Géraldine L.-M.; Pirard, Sophie ULiege; Belet, Artium ULiege et al

in Chemical Engineering Journal (2019), 371

The study deals with the catalytic cyclocarbonation of epoxides to produce monomers used in the synthesis of polyurethane. A benchmark study of the textural properties of silica-based, doped or not ... [more ▼]

The study deals with the catalytic cyclocarbonation of epoxides to produce monomers used in the synthesis of polyurethane. A benchmark study of the textural properties of silica-based, doped or not, supports enabling the identification and optimization of the key parameters affecting the catalytic activity is reported. The results reveal that ammonium catalysts immobilized onto mesostructured supports with high surface area and low aggregation show better catalytic performances than analogue catalysts grafted onto microstuctured ones. While a high external surface area favours the grafting of ammonium salt, pore size must be large enough to enhance the accessibility of both carbon dioxide and epoxides to the catalytic sites. The activity of heterogeneous cat- alysts was evaluated for a model coupling reaction between carbon dioxide and propylene glycol diglycidylether. Using appropriated supports, cyclocarbonation yields are found to be higher in the presence of the hetero- geneous catalyst in comparison with the homogeneous one. These results allow to confirm the beneficial effect of the presence of residual OH silanol groups at the surface of the support, which activate epoxide through forming of hydrogen bonds. [less ▲]

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See detailAdvances in the use of CO2 as a renewable feedstock for the synthesis of polymers
Grignard, Bruno ULiege; Gennen, Sandro; Jérôme, Christine ULiege et al

in Chemical Society Reviews (2019), 48(16), 4466-4514

Carbon dioxide offers an accessible, cheap and renewable carbon feedstock for synthesis. Current interest in the area of carbon dioxide valorisation aims at new, emerging technologies that are able to ... [more ▼]

Carbon dioxide offers an accessible, cheap and renewable carbon feedstock for synthesis. Current interest in the area of carbon dioxide valorisation aims at new, emerging technologies that are able to provide new opportunities to turn a waste into value. Polymers are among the most widely produced chemicals in the world greatly affecting the quality of life. However, there are growing concerns about the lack of reuse of the majority of the consumer plastics and their after-life disposal resulting in an increasing demand for sustainable alternatives. New monomers and polymers that can address these issues are therefore warranted, and merging polymer synthesis with the recycling of carbon dioxide offers a tangible route to transition towards a circular economy. Here, an overview of the most relevant and recent approaches to CO2-based monomers and polymers are highlighted with particular emphasis on the transformation routes used and their involved manifolds. [less ▲]

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