References of "Grignard, Bruno"
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See detailPhotocleavable stabilizer for the preparation of PHEMA nanogels by dispersion polymerization in supercritical carbon dioxide
Alaimo, David; Grignard, Bruno ULg; Kuppan, Chandrasekar et al

in Polymer Chemistry (in press)

A new photo-sensitive diblock copolymer composed of a hydrophilic sequence of poly(ethylene oxide) (PEO) linked to a CO2-philic sequence of poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) (PFDA) by a ... [more ▼]

A new photo-sensitive diblock copolymer composed of a hydrophilic sequence of poly(ethylene oxide) (PEO) linked to a CO2-philic sequence of poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) (PFDA) by a light sensitive o- nitrobenzyl group was successfully synthesized by RAFT polymerization and used as stabilizer for the free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in dispersion in ?,?,?-trifluorotoluene and supercritical carbon dioxide (scCO2). Thanks to this fluorinated stabilizer, well-defined particles of PHEMA down to 350 nm of diameter were produced in scCO2. Advantageously, the photocleavable group at the block junction of the stabilizer could be cleaved by exposing the particles to UV light so that the fluorinated block could be extracted in TFT or scCO2. As supported by X-ray photoelectron spectroscopy (XPS) analysis, up to 80 % of the fluorinated block of the stabilizer can be removed, leading to efficient swelling and dispersion of the resulting PHEMA nanogels in water. [less ▲]

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See detailPolyhydroxyurethane hydrogels: synthesis and characterizations
Gennen, Sandro ULg; Grignard, Bruno ULg; Thomassin, Jean-Michel ULg et al

in European Polymer Journal (in press)

Hydrogels based on polyurethane (PU) are promising (bio-) materials because of their bio- compatibility, biodegradation and excellent mechanical properties. In this publication, polyurethane hydrogels ... [more ▼]

Hydrogels based on polyurethane (PU) are promising (bio-) materials because of their bio- compatibility, biodegradation and excellent mechanical properties. In this publication, polyurethane hydrogels were produced for the first time by a non-isocyanate route by solvent-free step-growth copolymerization between a CO2-sourced hydrophilic polyethy- lene glycol bi-cyclic carbonate with diamines in the presence of a cross-linker. Kinetic of poly(hydroxyurethane) (PHU) synthesis was monitored by ATR-IR and the chemical cross-linking was confirmed by rheology and gel contents measurements. Hydrogels were obtained by immersion of PHUs in water and the influence of the diamine/cross-linker ratio and the nature of diamine on the water swelling and compression properties (compression modulus, strain and stress at break) of PHU hydrogels was evaluated. Additionally, the compression properties of the hydrogels were improved by the addition of Montmorillonite as nanofiller in the PHU formulation. This work opens new application fields for CO2-sourced PHUs. [less ▲]

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See detailOrganocatalytic coupling of CO2 with oxetane
Alves, Margot ULg; Grignard, Bruno ULg; Boyaval, Amélie ULg et al

in ChemSusChem (in press)

The organocatalytic coupling of CO2 with oxetanes is investigated under solvent-free conditions. The influence of the main reaction parameters (type of organocatalytic system, pressure and temperature) on ... [more ▼]

The organocatalytic coupling of CO2 with oxetanes is investigated under solvent-free conditions. The influence of the main reaction parameters (type of organocatalytic system, pressure and temperature) on the yield, the product formed and the selectivity of the reaction are discussed. An onium salt combined with a fluorinated alcohol promotes the efficient and selective organocatalytic synthesis of ?,?-hydroxyl oligocarbonates by coupling CO2 with oxetanes at 130°C and at a CO2 pressure as low as 2 MPa. NMR characterizations were correlated with MALDI-ToF analyses for elucidating the structure of the oligomers. Online FTIR studies under pressure, NMR titrations and DFT calculations allowed an in-depth understanding of the reaction mechanism. Finally, CO2- based poly(carbonate-co-urethane)s were synthesized by step- growth polymerization of hydroxyl telechelic oligocarbonates with MDI. The organocatalytic system described in this paper constitutes an innovative sustainable route to the selective preparation of hydroxyl telechelic carbonates, of high interest for many applications, notably for the polyurethane business, especially for coatings or foams. [less ▲]

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See detailNovel promising way to synthesize non-isocyanate polyurethanes (NIPUs) for innovative coating applications against corrosion protection of metal surfaces
Panchireddy, Satyannarayana ULg; Grignard, Bruno ULg; Thomassin, Jean-Michel ULg et al

Poster (2016, October 13)

Polyurethanes (PUs) are one of the most widely used polymeric materials with applications in automotive, as sealants, adhesives, decorative, aircraft topcoats, for coatings or as foams for thermal and/or ... [more ▼]

Polyurethanes (PUs) are one of the most widely used polymeric materials with applications in automotive, as sealants, adhesives, decorative, aircraft topcoats, for coatings or as foams for thermal and/or acoustic insulation. Industrially, PUs are produced by copolymerization between polyols and polyisocyanates. Because of the toxicity issues related to the use of isocyanates, there is a need to develop greener and safer route to produce such polymers. This study reports on the synthesis of new sustainable isocyanates-free PU (NIPU) coatings for aluminium anticorrosion. In a first step, bio- and CO2-sourced cyclic carbonates monomers were synthesized by coupling of epoxydized vegetable oils with CO2 using a new efficient bicomponent organocatalyst. In second step formulations including cyclic carbonates/amines/additives were optimized to produce highly adhesive cross-linked NIPU coatings that show good resistance against solvents and long-term barriers preventing the corrosion of the aluminiumsubstrate [less ▲]

Detailed reference viewed: 51 (3 ULg)
See detailSynthesis and characterization of non-isocyanate polyurethane (NIPU) hydrogels
Gennen, Sandro ULg; Grignard, Bruno ULg; Thomassin, Jean-Michel ULg et al

Poster (2016, October 13)

Due to its good biocompatibility, biodegradation and excellent mechanical properties, polyurethane (PU) is a material of choice for biomedical applications (gloves, tubing, artificial membranes…) and, as ... [more ▼]

Due to its good biocompatibility, biodegradation and excellent mechanical properties, polyurethane (PU) is a material of choice for biomedical applications (gloves, tubing, artificial membranes…) and, as hydrogels, it was used as wound dressing, soft contact lenses, drug delivery systems and scaffolds for tissue engineering. Classically, PU are synthesized by a step-growth polymerization between poly (di-)ols and poly (di-) isocyanates. Due to the toxicity of isocyanates, REACH regulations have changed and, today, there is a need to develop greener and safer route to produce isocyanate-free PUs. This contribution focus on the synthesis of NIPU hydrogels by copolymerizing a bifunctional CO2-sourced hydrophilic PEG bi-cyclic carbonate with diamines in presence of a cross- linker. The PEG bi-cyclic carbonates was prepared via a CO2/epoxide coupling reactions using a new efficient organocatalytic system based on the use of an ammonium salt (TBAI) in combination with a fluorinated alcohol. [less ▲]

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See detailSynthesis and characterizations of non-isocyanate polyurethane (NIPU) hydrogels
Gennen, Sandro ULg; Grignard, Bruno ULg; Thomassin, Jean-Michel ULg et al

Poster (2016, September 12)

Polyurethane (PU) is on of the most used polymers for the preparation of hydrogels due to its good biocompatibility, biodegradation and excellent mechanical properties. PU hydrogels are found in lot of ... [more ▼]

Polyurethane (PU) is on of the most used polymers for the preparation of hydrogels due to its good biocompatibility, biodegradation and excellent mechanical properties. PU hydrogels are found in lot of applications such as wound dressing, soft contact lenses, drug delivery and scaffolds for tissue engineering. Classicaly, PU is produced by a step-growth polymerization between diols and diisocyanates. However, in order to avoid the use of harmful isocyanates compounds and because of regulations which tend to ban the use of isocyanates, we developed hydrogels based on a non-isocyanate polyurethane (NIPU) chemistry by valorizing CO2-sourced cyclic carbonates and amines. Precisely, NIPU hydrogels were prepared by a solvent-free copolymerization between bifunctional hydrophilic polyethylene glycol cyclic carbonates and diamines in presence of a triamine as a crosslinker, followed by a water swelling of the obtained cross-linked gel. Parameters such as the cross-linking ratio and diamine’s nature were optimized. Different clay contents (cloiste 30B) as nanofiller were dispersed in the ideal cyclic carbonate/diamine/triamine formulation prior polymerization in order to reinforce the compression properties of NIPU hydrogels. Finaly, we were able to prepare NIPU hydrogels with water content up to 80 % and good compression properties using low clay content. [less ▲]

Detailed reference viewed: 64 (4 ULg)
See detailValorization of CO2 for the preparation of advanced materials
Gennen, Sandro ULg; Grignard, Bruno ULg; Thomassin, Jean-Michel ULg et al

Conference (2016, July 07)

Detailed reference viewed: 12 (2 ULg)
See detailMerging carbon dioxide utilisation, bioresources and CO2-based process for sustainable low carbon footprints polyurethanes
Alves, Margot ULg; Grignard, Bruno ULg; Gennen, Sandro ULg et al

Poster (2016, June 29)

Making plastics more sustainable by valorizing waste CO2 as a cheap, inexhaustible and renewable feedstock is an early stage technology with strong innovation potential that imposes itself as a strategic ... [more ▼]

Making plastics more sustainable by valorizing waste CO2 as a cheap, inexhaustible and renewable feedstock is an early stage technology with strong innovation potential that imposes itself as a strategic driver for developing future low carbon footprints materials and technologies. With a global production estimated to 18 million tons for 2016, polyurethane (PU) is one of the most important polymers in our everyday life with applications in automotive, in building and construction, in coating, in the medical field, as flexible and rigid foams for thermal and/or acoustic insulation. Industrially, PU is produced by step-growth polymerization between di- or polyisocyanates and di- or polyols. However, isocyanates are extremely toxic compounds and made from even more toxic and explosive phosgene. Prolonged exposure to isocyanates vapour results in serious health damages such as skin irritation, asthma or DNA mutation whereas phosgene causes death. Because of the toxicity issues of these compounds associated to drastic changes in the REACH regulations limiting/banning the use of isocyanates, there is a need today to develop new greener and safer alternatives to produce PU. Valorising CO2 as C1 feedstock for producing precursors entering in the synthesis of polyurethanes by a non-isocyanate route (NIPU) is a promising route to solve this challenge the polyurethane sector is facing. Through its global objective focussing on the synthesis of isocyanate-free low carbon footprint foamed materials for thermal insulation this research highlights benefits of merging bio-resources with carbon dioxide transformation and “physical” utilization. The success of the project relies on 3 key steps involving: i) The synthesis of bio- and CO2-sourced cyclic carbonates using new highly efficient organocatalysts: Due to the low reactivity of CO2 versus epoxides, addition of catalysts in the reaction medium is necessary. If lot of catalysts have been developed, their use generally suffers from some drawbacks. Indeed, most of the metal-based catalysts are highly sensitive to hydrolysis and oxidation or/and poorly selective and additionally, some of them are toxic whereas less/non-toxic and eco-friendly organocatalysts such as ionic liquids and halide salts are generally only efficient at very high temperature and pressure, so favouring the decomposition of catalyst. To overcome these limitations, we developed a new highly-efficient bicomponent homogeneous organocatalyst that showed unexpected catalytic activity for the fast (within a few minutes) and selective addition of CO2 onto model epoxides and epoxidized vegetable oils under solvent-free and mild experimental conditions. The use of this powerful dual organocatalyst was further extended to the first organocatalytic coupling of CO2 with less reactive oxetanes to produce hydroxyl telechelic oligocarbonate entering the synthesis of CO2-sourced conventional PUs. ii) The synthesis of sustainable non-isocyanate polyurethanes: Sustainable NIPUs were produced by step-growth polymerization between the so-produced bio- and CO2-sourced cyclic carbonates and biosourced amino-telechelic comonomers derived from linseed fatty acids according to a process compatible with existing industrial infrastructures (extrusion). iii) The foaming of NIPUs: Sustainable foams with thermal insulation were produced by the supercritical CO2 assisted foaming technology. Due to its solubility in polymers, CO2 can replace conventional flammable VOCs and ozone depletion chemical or physical blowing agents such as diazo compounds, hydrocarbons (pentane, isopentane…) or inert gases (nitrogen…) to produce (ultra)lightweight microcellular foams. By finely choosing the CO2 impregnation and the foaming conditions, foams with a thermal conductivity as low as 0.052 Wm-1K-1 were produced. Our study shows that CO2 is not only sequestered in the material for long-term application, but is also valorized as a blowing agent in the production of sustainable thermally insulating NIPU foams. Such low carbon footprints materials will contribute to energy conservation and savings by reducing CO2 emissions [less ▲]

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See detailCatalytic transformation of CO2: from monomers to polymers
Alves, Margot ULg; Grignard, Bruno ULg; Boyaval, Amélie ULg et al

Conference (2016, May 24)

Valorising CO2 as a renewable C1 feedstock for producing added value building blocks is the scope of many academic and industrial researches. Carbon dioxide is a thermodynamically and kinetically stable ... [more ▼]

Valorising CO2 as a renewable C1 feedstock for producing added value building blocks is the scope of many academic and industrial researches. Carbon dioxide is a thermodynamically and kinetically stable molecule that can be converted into five membered cyclic carbonates by coupling with epoxides using organometallic complexes or organocatalysts. To date, the identification and development of highly efficient (organo)catalysts under mild experimental conditions still remains challenging. In particular, the synthesis of six membered cyclic carbonates by the CO2/oxetane coupling using such organocatalysts has never been reported to our knowledge. In this context, we developed a new highly efficient bicomponent homogeneous organocatalyst composed of an ammonium salt as the catalyst and fluorinated single or double hydrogen bond donor activators (HBD). First, the efficiency of this new organocatalyst for the fast and selective CO2/epoxide coupling was investigated through detailed kinetic studies by IR spectroscopy under pressure and results were compared with the most efficient organocatalysts reported in the literature. This study was completed by molecular modeling in order to elucidate the reaction mechanism. DFT calculations showed that the hexafluoroisopropanol functionalities of HBDs strengthened the proton donor capability and allowed a better stabilization by hydrogen bonding of the intermediates and transition states. Finally, the use of this dual organocatalyst was extended to the coupling of CO2 with less reactive oxetanes to produce hydroxyl telechelic oligocarbonates. [less ▲]

Detailed reference viewed: 74 (3 ULg)
See detailSynthesis of CO2-sourced hydrogels by using the non-isocyanate polyurethane (NIPU) chemistry
Gennen, Sandro ULg; Grignard, Bruno ULg; Thomassin, Jean-Michel ULg et al

Poster (2016, May 23)

Polyurethane (PUs) is one of the most important polymers and finds applications as elastomers, coatings, adhesives and sealants for automotive or construction. PU is also a material of choice in the ... [more ▼]

Polyurethane (PUs) is one of the most important polymers and finds applications as elastomers, coatings, adhesives and sealants for automotive or construction. PU is also a material of choice in the biomedical domain due to its good biocompatibility, biodegradation and mechanical properties. Especially, PUs hydrogels have been developed in the last years for biomedical applications such as soft contact lenses, wound dressing, drug delivery systems and scaffolds for tissue engineering. Traditionally, PUs are synthesized by a step-growth polymerization between diols and diisocyanates. Because of toxicity issues and a possible interdiction of isocyanates, we focused on developing new PU hydrogels using a non-isocyanate route (Figure 1). The polyurethanes formed by this route are called NIPU (for Non-Isocyanate PolyUrethane). Firstly, chemically cross-linked NIPU gels were synthesized by solvent-free polycondensation between a hydrophilic CO2-sourced polyethyleneglycol bi-cyclic carbonate and a diamine in the presence of a crosslinker. Then, NIPU gels were swelled in water till water equilibrium before characterization of their mechanical properties by compression tests. The influence of the cross-linking ratios (diamine/crosslinker ratio) and diamine structure on the swelling and the compression properties were studied. To reinforce the compression properties of NIPU hydrogel (increase in stress at break, strain at break and compression modulus), a nanofiller was dispersed in the cyclic carbonate/diamine/crosslinker formulation prior to polymerization. For the first time, nanocomposite NIPU hydrogels with high water contents (up to 80%) and good compression properties have been prepared by using low clay content. [less ▲]

Detailed reference viewed: 129 (2 ULg)
See detailCyclic and oligo-carbonates by organocatalytic coupling of CO2 with epoxides or oxetanes
Alves, Margot ULg; Grignard, Bruno ULg; Boyaval, Amélie ULg et al

Conference (2016, April 20)

Valorising CO2 as a renewable C1 feedstock for producing added value building blocks is the scope of many academic and industrial researches. Carbon dioxide is a thermodynamically and kinetically stable ... [more ▼]

Valorising CO2 as a renewable C1 feedstock for producing added value building blocks is the scope of many academic and industrial researches. Carbon dioxide is a thermodynamically and kinetically stable molecule that can be converted into five and six membered cyclic carbonates by coupling with epoxides or oxetanes, respectively, using appropriate catalysts. Although transition metal catalysts are efficient under atmospheric pressure and ambient temperature, most of them are poorly selective, sensitive to hydrolysis and/or oxidation and/or toxic whereas less/non-toxic and eco-friendly organocatalysts such as ionic liquids and halide salts are generally only efficient at very high temperature and pressure favouring their thermal degradation. To overcome these limitations, we developed a new highly efficient bicomponent homogeneous organocatalyst composed of an ammonium salt as the catalyst and fluorinated single or double hydrogen bond donor activators. Through online FTIR kinetic studies, we demonstrated that this new organocatalyst showed unexpected catalytic activity for the fast and selective addition of CO2 onto epoxides under solvent-free and mild experimental conditions. The use of this dual catalyst was then extended to the coupling of CO2 with less reactive oxetanes to produce hydroxyl telechelic oligocarbonates. In the first part of this talk, based on kinetics of reactions followed by online FTIR under pressure, we will describe the reaction conditions required for the organocatalytic coupling of CO2 with epoxides and oxetanes. In the second part, the mechanism of the reaction will be approached and discussed based on DFT calculations. Finally, we will compare and discuss the efficiency of various organocatalytic systems for this type of reaction. [less ▲]

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See detailCO2-blown microcellular non-isocyanate polyurethane (NIPU) foams: from bio- and CO2-sourced monomers to potentially thermal insulating materials
Grignard, Bruno ULg; Thomassin, Jean-Michel ULg; Gennen, Sandro ULg et al

in Green Chemistry (2016), 18(7), 2206-2215

Bio- and CO2-sourced non-isocyanate polyurethane (NIPU) microcellular foams were prepared using supercritical carbon dioxide (scCO2) foaming technology. These low-density foams offer low thermal ... [more ▼]

Bio- and CO2-sourced non-isocyanate polyurethane (NIPU) microcellular foams were prepared using supercritical carbon dioxide (scCO2) foaming technology. These low-density foams offer low thermal conductivity and have an impressive potential for use in insulating materials. They constitute attractive alternatives to conventional polyurethane foams. We investigated CO2’s ability to synthesize the cyclic carbonates that are used in the preparation of NIPU by melt step-growth polymerization with a bio-sourced amino-telechelic oligoamide and for NIPU foaming. Our study shows that CO2 is not only sequestered in the material for long-term application, but is also valorized as a blowing agent in the production of NIPU foams. Such foams will contribute to energy conservation and savings by reducing CO2 emissions. [less ▲]

Detailed reference viewed: 128 (25 ULg)
See detailCO2-based sustainable polymers: from CO2-sourced monomers to low CO2 emission foamed materials
Grignard, Bruno ULg; Gennen, Sandro ULg; Alves, Margot ULg et al

Conference (2016, April)

Due to concerns about the climate change combined with the decrease of fossil resources, the use of CO2 as a C1 feedstock for producing added value chemicals and materials has become a huge challenge in ... [more ▼]

Due to concerns about the climate change combined with the decrease of fossil resources, the use of CO2 as a C1 feedstock for producing added value chemicals and materials has become a huge challenge in academic laboratories and in industry. The coupling of CO2 with epoxide has emerged as one of the most promising way to convert CO2 into cyclic carbonates finding application as green solvents or electrolyte for batteries. Interestingly, these cyclic carbonates can also be valorised as monomers to produce new non-isocyanate polyurethanes by step-growth polymerization with amines. Polyurethane (PU) is one of the most important polymers in our everyday life with numerous applications such as thermosets, thermoplastics, elastomers, adhesives, sealants, coatings, rigid and flexible foams for wellness or acoustic and/or thermal insulation. In this talk, we will discuss the preparation of all green bio- and CO2-sourced non-isocyanate polyurethane (NIPU) microcellular foams with thermal insulation properties by using an eco-efficient process based on the supercritical carbon dioxide (scCO2) foaming technology. This talk will be divided in three sections: The synthesis of CO2-sourced cyclic carbonates by coupling CO2 with epoxides using a new highly-efficient bicomponent homogeneous organocatalyst combining the use of an ammonium salt as the catalyst and a fluorinated hydrogen bond donor activator that allows the fast and solvent-free coupling of CO2 with (biosourced) epoxides under mild experimental conditions. The synthesis of (bio- and) CO2-sourced isocyanates-free PUs by melt step-growth copolymerization, eliminating the toxicological issues associated to the conventional synthesis of polyurethanes from diols and isocyanates. The foaming of NIPUs by exploiting the scCO2 foaming technology. By finely choosing the appropriate CO2 impregnation and foaming conditions, thermally insulating CO2-blown microcellular NIPUs foams were produced. [less ▲]

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See detailNon-isocyanate polyurethanes from carbonated soybean oil Using monomeric or oligomeric diamines To achieve thermosets or thermoplastics
Poussard, Loïc; Mariage, J.; Grignard, Bruno ULg et al

in Macromolecules (2016), 49(6), 2162-2171

Fully bio- and CO2-sourced non-isocyanate polyurethanes (NIPUs) were synthesized by reaction of carbonated soybean oil (CSBO) either with biobased short diamines or amino-telechelic oligoamides derived ... [more ▼]

Fully bio- and CO2-sourced non-isocyanate polyurethanes (NIPUs) were synthesized by reaction of carbonated soybean oil (CSBO) either with biobased short diamines or amino-telechelic oligoamides derived from fatty acids to achieve respectively thermoset or thermoplastic NIPUs. Biobased carbonated vegetable oils were first obtained by metal-free coupling reactions of CO2 with epoxidized soybean oils under supercritical conditions (120 °C, 100 bar) before complete characterization by FTIR, 1H NMR, and electrospray ionization mass spectroscopy (ESI-MS). In a second step, biobased NIPUs were produced by melt-blending of the so-produced cyclocarbonated oil with the biobased aminated derivatives. The thermal and mechanical properties of resulting polymers were found to be depending on the cyclocarbonated vegetable oil/amine ratio. More precisely, short diamines and CSBO led to the formation of cross-linked NIPUs, and the resulting tensile and thermal properties were poor. In contrast, elastomeric NIPUs derived from oligoamides and CSBO exhibited a better rigidity, an improved elongation at break (εr up to 400%), and a higher thermal stability (T95 wt% > 350 °C) than those of starting oligoamides. These results are impressive and highlight the potentiality of this environmental friendly approach to prepare renewable NIPU materials of high performances. [less ▲]

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See detailTheoretical study of the organocatalyzed synthesis of NIPUs
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

Poster (2016, March)

Detailed reference viewed: 12 (3 ULg)