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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 ▲]

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See detailMicroplastics contamination in three planktivorous and commercial fish species
Collard, France ULg; Das, Krishna ULg; Gilbert, Bernard ULg et al

Poster (2016, May)

In 2014, 311 million tonnes of plastics were produced worldwide while it is estimated that 10% ended up in the oceans. Plastics adsorb many pollutants, cause entanglements in many vertebrates and provoke ... [more ▼]

In 2014, 311 million tonnes of plastics were produced worldwide while it is estimated that 10% ended up in the oceans. Plastics adsorb many pollutants, cause entanglements in many vertebrates and provoke blockage of the digestive tract of marine mammals, birds and turtles. Plastics also fragment in smaller parts, forming microplastics (<5 mm). These microplastics have the same size than planktonic organisms and can thus be ingested by filter-feeders and planktivorous organisms including fish. Although planktivorous Clupeiforme species are the most fished species in the world (17 million tonnes in 2013), the possible impact of microplastic ingestion on this group has received little attention. The aim of this study was to quantify and to characterize the ingested anthropogenic particles (AP) in herrings (Clupea harengus), sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus). Twenty individuals of each species were sampled. Herrings and sardines were caught in the Channel and in the North Sea in January 2013 and in January 2014. Anchovies were sampled in July 2013. The stomach contents were digested by sodium hypochlorite to isolate AP and then they were analysed by Raman spectroscopy and measured. AP were constituted of microplastics (MP) and cellulose fibres, sometimes associated with dyes. We found several plastic families: polyethylene (PE), polypropylene (PP), polystyrene, polyacrylonitrile, polyethylene terephthalate, polyamide and poly(butyl methacrylate). MP occurred in 35%, 50% and 40% of stomach contents of anchovies, sardines and herrings, respectively. Anchovies ingested bigger AP (2 mm) than the two other species. MP was in majority PE followed by PP. Our study shows that highly commercial species are exposed to MP. Further research is needed as MP are transport medium for organic pollutants and their fate once in the organism is unknown. [less ▲]

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See detailUn manuscrit de l’entourage de Noël Bellemare sous le microscope : analyse du ms. W 29 de l’Université de Liège
Oger, Cécile ULg; L'Estrange, Elizabeth; Gilbert, Bernard ULg et al

Conference (2016, February 26)

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See detailComprehensive study of the thermo-reversibility of Diels-Alder based PCL polymer networks
Defize, Thomas ULg; Thomassin, Jean-Michel ULg; Alexandre, Michaël et al

in Polymer (2016), 84

Chemical crosslinking is an efficient tool to improve or impart new properties to conventional polymers. Especially, crosslinking imparts remarkable shapeememory properties to poly-ε-caprolactone (PCL ... [more ▼]

Chemical crosslinking is an efficient tool to improve or impart new properties to conventional polymers. Especially, crosslinking imparts remarkable shapeememory properties to poly-ε-caprolactone (PCL) materials. Nevertheless, the processing of networks is often tricky due to infusibility and insolubility of cross-linked chains. Therefore, the synthesis of PCL networks including thermo-reversible crosslinks based on (retro)-Diels-Alder (DA) reaction were developed to allowpreserving the melt-processing while keeping the required mechanical properties below the melting point. This paper aims at studying in depth, such thermo-dependent network formation and stability. Besides conventional swelling experi- ments, Raman spectroscopy was revealed as a powerful tool to follow the formation of the DA adduct during the crosslinking. In combination with rheological measurements, we were able to determine the most appropriate temperatures to form the network (DA crosslinking) and to process it (retro-DA re- action) without degradation of the material. [less ▲]

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See detailAnthropogenic particles in stomachs of anchovies (Engraulis encrasicolus) related to gill rakers morphology
Collard, France ULg; Das, Krishna ULg; Gilbert, Bernard ULg et al

in Proceedings of In the Wake of Plastics, Venice, October 13-15, 2015 (2015, October)

Anthropogenic debris (AB) contaminate oceans and affect marine organisms in several ways. Plastic production is constantly increasing and it is estimated that 10% of this production end in the seas. As a ... [more ▼]

Anthropogenic debris (AB) contaminate oceans and affect marine organisms in several ways. Plastic production is constantly increasing and it is estimated that 10% of this production end in the seas. As a consequence, plastic is considered as an emerging contaminant and ingestions by organisms are increasingly reported. Microdebris (< 5mm) are available for a high range of organisms, including planktivorous fish, such as the European anchovy (Engraulis encrasicolus). Planktivorous fish have a particular gill basket, with long and tight gill rakers, related to their diet. Upon these gill rakers, small structures called denticles are present. These gill rakers act as a net to trap organic particles and AB. The aim of our study was to correlate sizes of AB ingested with the mesh constituted by the gill rakers and associated structures. Fifteen stomach contents were analyzed by Raman spectroscopy and particles were measured. Five gill arches were observed with a scanning electron microscope. Cellulose fibers and microplastics were the most AB ingested. Comparing to other Clupeiformes (pilchard and Atlantic herring), anchovies have more denticles on each gill rakers (personal data). AB ingestion by fish is poorly studied and impacts of AB are not much understood. Clupeiformes play a major role in marine ecosystems and is the most consumed order by humans. As the branchial basket constitutes a food selective apparatus, more morphological studies dealing with AB ingestion on Clupeiformes are needed. [less ▲]

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See detailNew efficient organocatalytic system for solvent-free chemical fixation of CO2 into epoxides
Panchireddy, Satyannarayana ULg; Gennen, Sandro ULg; Alves, Margot ULg et al

Poster (2015, September 11)

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide (CO2) into added-value products has gained interest in both academic and ... [more ▼]

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide (CO2) into added-value products has gained interest in both academic and industrial fields. To date, the chemical fixation of CO2 onto epoxides with the formation of cyclic carbonates (CC) is one of the most promising ways to valorise CO2 at an industrial scale. Indeed, CC are useful monomers for polycarbonate synthesis and they can react with primary amines to produce 2-hydroxyethylurethane. This reaction can be extrapolated to the synthesis of non-isocyanate polyurethanes (NIPUs) by a step growth polymerization between bifunctional CC and diamines. [less ▲]

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See detailDetection of anthropogenic particles in fish stomachs: an isolation method adapted to identification by Raman spectroscopy
Collard, France ULg; Gilbert, Bernard ULg; Eppe, Gauthier ULg et al

in Archives of Environmental Contamination & Toxicology (2015), 69

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See detailIsolation and identification of anthropogenic particles in fish stomachs by Raman spectroscopy: a new method
Collard, France ULg; Gilbert, Bernard ULg; Eppe, Gauthier ULg et al

in Organohalogen Compounds (2015, August)

Microplastic particles (MP) contaminate oceans and affect marine organisms in several ways. Ingestion combined with food intake is generally reported. However, data interpretation is often circumvented by ... [more ▼]

Microplastic particles (MP) contaminate oceans and affect marine organisms in several ways. Ingestion combined with food intake is generally reported. However, data interpretation is often circumvented by the difficulty to separate MP from bulk samples. Visual examination is often used as one or the only step to sort these particles. However, color, size and shape are insufficient and often unreliable criteria. Here we present an isolation method of MP specially adapted to a subsequent analysis by Raman spectroscopy. This method avoids fluorescence problems allowing the identification anthropogenic particles (AP) from stomach contents of fish by Raman spectroscopy. It was validated with commercial samples of microplastics and cotton along with stomach contents from three different Clupeiformes fishes: Clupea harengus, Sardina pilchardus and Engraulis encrasicolus. The optimized digestion and isolation protocol showed no visible impact on microplastics and cotton particles while the spectroscopic analysis allowed precise identification of microplastics and textile fibers. This approach allowed us to isolate 35 particles. These were analyzed by Raman spectroscopy: eleven were microplastics and thirteen were made of cellulose or lignin, or both (mostly fibers). Some particles were not identified but contained artificial colorants. This isolation protocol will help to assess the presence, quantity and composition of AP in planktivorous fish stomachs. [less ▲]

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See detailCO2-sourced non-isocyanate polyurethanes: from the monomer synthesis to the elaboration of polymeric materials
Gennen, Sandro ULg; Grignard, Bruno ULg; Gilbert, Bernard ULg et al

Conference (2015, July 07)

Due to problems related to the rarefaction of fossil resources and the global warming that comes from CO2 emissions, new carbon feedstocks that are abundant, renewable, non-toxic, inexpensive and ... [more ▼]

Due to problems related to the rarefaction of fossil resources and the global warming that comes from CO2 emissions, new carbon feedstocks that are abundant, renewable, non-toxic, inexpensive and environmentally friendly must be explored to produce chemicals. Besides the valorization of bio-based raw materials, the use of CO2 as a C1 carbon source into added-value products has gained interest in both academic and industrial fields. One promising way to valorize CO2 relies on its chemical fixation onto epoxides to produce cyclic carbonates that find applications as electrolytes in lithium ion batteries, as aprotic polar solvents or as useful intermediates for polycarbonates. Cyclic carbonates also react with primary amines to produce 2-hydroxyethylurethane. This reaction can be extrapolated to the synthesis of non-isocyanate polyurethanes (NIPU) by polyaddition of bifunctional cyclic carbonates with diamines.5 This study focusses on (i) the synthesis of cyclic carbonates using new highly efficient organocatalysts and (ii) their valorization as monomers to produce non-isocyanate polyurethanes. First, we have identified a bicomponent organocatalyst for the very fast synthesis of cyclic carbonates from CO2 and epoxides under very mild reaction conditions. Kinetics of reactions were followed by online Raman spectroscopy. NMR titrations were realized to evidence the mechanism of activation of this novel organocatalytic system that will be discussed in detail this talk. The second objective relies on the development of new efficient organocatalysts for the synthesis of high molar masses NIPUs in short reaction times. Organic compounds interacting with the cyclic carbonate by hydrogen bonding were identified and their catalytic activity was highlighted by a model reaction between ethylene carbonate and a primary amine before extrapolation to the synthesis of NIPUs that find applications as coatings or foamed materials. [less ▲]

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See detailFluorinated alcohols as activators for the solvent-free chemical fixation of carbon dioxide onto epoxides
Gennen, Sandro ULg; Alves, Margot ULg; Méreau, Raphaël et al

in ChemSusChem (2015), 8(11), 1845-1849

The addition of fluorinated alcohols to onium salts provides highly efficient organocatalysts for the chemical fixation of CO2 onto epoxides under mild experimental conditions. The combination of online ... [more ▼]

The addition of fluorinated alcohols to onium salts provides highly efficient organocatalysts for the chemical fixation of CO2 onto epoxides under mild experimental conditions. The combination of online kinetic studies, NMR titrations and DFT calculations allows understanding this synergistic effect that provides an active organocatalyst for CO2/epoxides coupling. [less ▲]

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See detailNon-isocyanate polyurethane: from the monomer synthesis to foamed materials
Gennen, Sandro ULg; Alves, Margot ULg; Tassaing, Thierry et al

Poster (2015, May 18)

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 ... [more ▼]

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... Classically, PUs are produced by a step-growth polymerization between diols and diisocyanates. However, isocyanates are harmful upon prolonged exposure to vapours which can lead to health issues such as asthma and skin irritation. In addition, isocyanates are produced from even more toxic and explosive phosgene. Due to these problems in combination with increasing regulatory scrutiny, there is today a need to develop isocyanate- and phosgene free- PU synthesis, also called non-isocyanate polyurethane or NIPUs. One of the most promising alternatives to the conventional synthesis of PU relies on the step-growth polymerization between bicyclic carbonate monomers and diamines, but until now, obtaining high molar mass NIPUs in a short time still remains a challenge. This study will be focused on three objectives: 1) The synthesis of CO2-sourced biscyclic carbonates by CO2/epoxide coupling using new highly efficient bicomponent organocatalysts allowing the fast conversion of epoxides into the corresponding cyclic carbonates under mild and solvent-free conditions. 2) The synthesis of high molar mass NIPUs from CO2-sourced monomers and diamines thanks to the use of efficient organocatalysts. A series of organic compounds interacting with cyclic carbonates by hydrogen bonding were first identified and their catalytic activity was highlighted by a model reaction between ethylene carbonate and a primary amine before extrapolation to NIPU synthesis. 3) The scCO2-assisted foaming of CO2-sourced NIPUs with production of potential carbon zero-emission materials with low thermal conductivity [less ▲]

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See detailCarbon dioxide, a cheap bio-sourced building block for cyclic carbonates and non-isocyanate polyurethanes
Gennen, Sandro ULg; Alves, Margot ULg; Tassaing, Thierry et al

Poster (2015, May 03)

Due to concerns about global warming combined with the decrease of fossil resources, new carbon feedstocks that are abundant, renewable, non-toxic, inexpensive and environmentally friendly must be ... [more ▼]

Due to concerns about global warming combined with the decrease of fossil resources, new carbon feedstocks that are abundant, renewable, non-toxic, inexpensive and environmentally friendly must be explored to produce chemicals. Besides the valorization of bio-based raw materials, the chemical transformation of carbon dioxide into added-value products has gained interest in both academia and industry. To date, the chemical fixation of CO2 onto epoxides with the formation of cyclic carbonates is one of the most promising ways to valorize CO2 at an industrial scale. Indeed, cyclic carbonates find applications as electrolytes in lithium ion batteries, as aprotic polar solvents or as useful intermediates for polycarbonates. Cyclic carbonates also react with primary amines to produce 2-hydroxyethylurethane. This reaction can be extrapolated to the synthesis of non-isocyanate polyurethanes (NIPU) by polyaddition of bifunctional cyclic carbonates with diamines.5 This study aims (i) at developing a new highly efficient organocatalyst for the synthesis of cyclic carbonates under mild experimental conditions and (ii) their valorization as monomers to produce non-isocyanate polyurethanes. First, we have identified a bicomponent organocatalyst, composed of a judicious combination of an organocatalyst and an activator, for the very fast synthesis of cyclic carbonates from CO2 and epoxides under very mild reaction conditions. Kinetics of reactions were followed by online Raman spectroscopy measurements under pressure. NMR titrations were realized to evidence the mechanism of activation of this novel organocatalytic system that will be discussed in detail in this talk. The second objective relies on the development of new efficient organocatalysts for the synthesis of high molar masses NIPUs in short reaction times. Organic compounds interacting with the cyclic carbonate by hydrogen bonding were identified and their catalytic activity was demonstrated for model compounds. [less ▲]

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See detailWhen microplastic is not plastic: the ingestion of artificial cellulose fibers by macrofauna living in seagrass macro-phytodetritus.
Remy, François ULg; Collard, France ULg; Gilbert, Bernard ULg et al

in Environmental Science & Technology (2015), 49

Dead leaves of the Neptune grass, Posidonia oceanica (L.) Delile, in the Mediterranean coastal zone, are colonized by an abundant “detritivorous” invertebrate community that is heavily predated by fishes ... [more ▼]

Dead leaves of the Neptune grass, Posidonia oceanica (L.) Delile, in the Mediterranean coastal zone, are colonized by an abundant “detritivorous” invertebrate community that is heavily predated by fishes. This community was sampled in August 2011, November 2011 and March 2012 at two different sites in the Calvi Bay (Corsica). Ingested artificial fibers (AFs) of various sizes and colors were found in 27.6% of the digestive tracts of the nine dominant species regardless of their trophic level or taxon. No seasonal, spatial, size or species-specific significant differences were revealed; suggesting that invertebrates ingest AFs at constant rates. Results showed that, in the gut contents of invertebrates, varying by trophic level, and across trophic levels, the overall ingestion of AFs was low (approximately 1 fiber per organism). Raman spectroscopy revealed that the ingested AFs were composed of viscose, an artificial, cellulose-based polymer. Most of these AFs also appeared to have been colored by industrial dyes. Two dyes were identified: Direct Blue 22 and Direct Red 28. The latter is known for being carcinogenic for vertebrates, potentially causing environmental problems for the P. oceanica litter community. Techniques such as Raman spectroscopy are necessary to investigate the particles composition, instead of relying on fragment size or color to identify the particles ingested by animals. [less ▲]

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See detailCombining mesoporosity and Ti-doping in hematite films for water splitting
Toussaint, Caroline ULg; Tran, Hoang Son ULg; Colson, Pierre ULg et al

in Journal of Physical Chemistry C (2015), 119(4), 1642-1650

(Graph Presented). In this study, we report the synthesis of Ti-doped mesoporous hematite films by soft-templating for application as photoanodes in the photoelectrolysis of water (water splitting ... [more ▼]

(Graph Presented). In this study, we report the synthesis of Ti-doped mesoporous hematite films by soft-templating for application as photoanodes in the photoelectrolysis of water (water splitting). Because the activation of the dopant requires a heat treatment at high temperature (≥800°C), it usually results in the collapse of the mesostructure. We have overcome this obstacle by using a temporary SiO2 scaffold to hinder crystallite growth and thereby maintain the mesoporosity. The beneficial effect of the activated dopant has been confirmed by comparing the photocurrent of doped and undoped films treated at different temperatures. The role of the mesostructure was investigated by comparing dense, collapsed, and mesoporous films heated at different temperatures and characterized under front and back illumination. It turns out that the preservation of the mesotructure enables a better penetration of the electrolyte into the film and therefore reduces the distance that the photogenerated holes have to travel to reach the electrolyte. As a result, we found that mesoporous films with dopant activation at 850°C perform better than comparable dense and collapsed films. [less ▲]

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See detailWhen microplastic is not microplastic: ingestion of artificial cellulose fibers by macrofauna living in seagrass macrophytodetritus
Collard, France ULg; Remy, François ULg; Gilbert, Bernard ULg et al

Poster (2014, December 12)

Vagile macroinvertebrates associated with Posidonia oceanica exported litter were sampled in August 2011, November 2011 and March 2012 in the Calvi Bay (Corsica), near the STARESO oceanographic station ... [more ▼]

Vagile macroinvertebrates associated with Posidonia oceanica exported litter were sampled in August 2011, November 2011 and March 2012 in the Calvi Bay (Corsica), near the STARESO oceanographic station. Contents of digestive tracts were analyzed and fibers of various sizes and colors were found. Fibers were found in 27.6% of the digestive tracts in the nine dominant species. No correlation was found between number of fibers and taxonomic or trophic level. There were no seasonal or spatial preferences and thus we hypothesize that the organisms ingest these fibers randomly throughout the year. Analyses performed with a Raman spectroscope showed that these fibers were composed of cellulose associated with a coloring agent following the fiber color. Red fibers were dyed with the Direct Red 28, blue fibers were dyed with Direct Blue 22. Analyses by a scanning electron microscope (SEM) showed that cellulose fibers had the particular morphology of artificial cellulose fibers called: viscose. Our SEM analyses were compared to literature. This comparison assessed that fibers found in digestive tracts were made of viscose. In a first approach, viscose fibers looked like microplastic fibers because of their color and shape. However, it appeared that these fibers were made of artificial cellulose which is very different than plastic in terms of impacts and fate in the organisms. This study highlights the importance of physico-chemical analyses such as Raman spectroscopy and SEM to certainly identify the composition of particles ingested by organisms. From an ecological point of view, the red coloring agent is known to be carcinogenic in mammals and fish. Consequently, this pollution could provoke an environmental problem for the P. oceanica litter vagile macrofauna. [less ▲]

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See detailBiodegradable polyester-based microcarriers with modified surface tailored for tissue engineering
Grandfils, Christian ULg; Privalova, A.; Sevrin, Chantal ULg et al

Conference (2014, October 23)

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See detailA facile and fast electrochemical route to produce functional few-layer graphene sheets for lithium battery anode application
Ouhib, Farid ULg; Aqil, Abdelhafid ULg; Thomassin, Jean-Michel ULg et al

in Journal of Materials Chemistry A (2014), 2(37), 15298-15302

A simple approach for the production of polymer functionalized graphene nanosheets is reported. The resulting polyacrylonitrile chemisorbed on graphene sheets is made of 1 to 2 layers, with a large ... [more ▼]

A simple approach for the production of polymer functionalized graphene nanosheets is reported. The resulting polyacrylonitrile chemisorbed on graphene sheets is made of 1 to 2 layers, with a large majority of graphene single-layers. This novel functionalized graphene exhibits good cycling stability as an anode in Li-ion batteries without a conductive additive or binder. [less ▲]

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