les breves innovation n° 114
Transcription
les breves innovation n° 114
GROUPE FRANÇAIS D'ÉTUDES ET D'APPLICATIONS DES POLYMÈRES Août 2015 LES BREVES INNOVATION N° 114 Informations rassemblées et compilées par A. Momtaz Pour lire l’article, cliquer sur le titre 1. Nouveaux PRODUITS, nouveaux Matériaux SMU Chemist Receives NSF CAREER Award for Funding Research into New Methods of Creating Polymers 2. Techniques de synthèse: matières premières, procédés, outils Production de graphène en Pologne 3. Techniques de MISE en ŒUVRE et ADDITIFS de formulation Graphene: A wonder material struggles to find commercial applications Effects of Nanoparticles on Polymeric Blends 4. Polymères biosourcés, biopolymères, biocarburant R.A.S. 5. APPLICATIONS des Polymères a. Systèmes intelligents New fluorescent polymer makes deformation visible ii Août 2015 Color-changing polymer may signal traumatic brain injuries in soldiers, athletes Deux fibres intelligentes Nouveaux exemples de biomimétisme dans les matériaux b. Polymères pour l’électronique Transparent, electrically conductive network of encapsulated silver nanowires: A novel electrode for optoelectronics c. Revêtement de surface R.A.S. d. Energie Flexible dielectric polymer can stand the heat Roll-to-roll fabrication of fullerene-free organic solar cells e. Transport R.A.S. f. Bâtiment, construction R.A.S. g. Textile R.A.S. h. Médical, santé Des valves cardiaques en plastique pourraient sauver des millions de vies iii Août 2015 6. Techniques d'ANALYSE de calcul et de CARACTERISATION, études TOXICOLOGIQUES R.A.S. 7. RECYCLAGE, ENVIRONNEMENT, REGLEMENTATIONS R.A.S. 8. Enseignement et Recherche Top 25 ChemComm articles April–June 2015 9. ECHOS de l'INDUSTRIE BioAmber opens world's largest succinic acid plant in Sarnia GROUPE FRANÇAIS D'ÉTUDES ET D'APPLICATIONS DES POLYMÈRES Août 2015 LES BREVES INNOVATION N° 114 Informations rassemblées et compilées par A. Momtaz 1. Nouveaux PRODUITS, nouveaux MATERIAUX SMU Chemist Receives NSF CAREER Award for Funding Research into New Methods of Creating Polymers SMU chemist Nicolay (Nick) Tsarevsky has received a prestigious National Science Foundation CAREER Award, expected to total $650,000 over five years, to fund his research into new methods of creating polymers - whose uses range from fluorescent materials to drug carriers, to everyday technologies. NSF CAREER Awards are given to tenure-track faculty members who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research in American colleges and universities. Tsarevsky, an assistant professor in the Department of Chemistry in SMU's Dedman College of Humanities and Science, is a polymer chemist and the adviser to seven doctoral students who assist in his research. Polymers are molecules that can be found in just about anything and include both natural and synthetic materials. DNA and proteins are natural polymers, as is the cellulose found in wood and paper. Plastics are a group of synthetic polymers, as are many of the materials used in modern electronic technology. As Tsarevsky says in his web site's slogan, "It's a polymer world..." Prior to 20 years ago, the lab techniques used to make polymers with any precision approaching that of nature were very limited or didn't exist. The Tsarevsky group specializes in developing methods to make large polymeric molecules in a lab with desired shapes, sizes, and functionalities. "We try to provide the tools, which can be used to prepare a vast number of complex functional materials," says Tsarevsky, who, in a nod toward history's Stone, Bronze, and Iron Ages, refers to our era as the 'Polymer Age.' 2 Août 2015 "We make polymers that have the ability to kill bacteria on contact, and self-healing materials that you could break and that would heal by themselves," Tsarevsky adds. "I like to think of our work as trying to design and control the architecture of very large molecules." To make complex macromolecules, Tsarevsky took advantage of the special behavior (reactivity) of a group of compounds that contain hypervalent chemical bonds. These bonds are weaker than other "classical" chemical bonds, and can be broken in two different ways as well as reconstructed. The atoms they connect can be "swapped" or exchanged -- think building with Legos instead of permanent glue -- enabling the construction of new materials that couldn't be made otherwise. Several elements in the Periodic Table are able to form hypervalent bonds, but Tsarevsky feels iodine is one of the most attractive, in part because it's less toxic than many alternatives. Many of the current methods for making polymers use toxic heavy metals. The toxic impurities present in the final materials must be removed at potentially significant expense. The hypervalent iodine compounds Tsarevsky is employing aren't just less toxic, they also allow for processes to be carried out using fewer steps than traditional methods to yield the final functional products. Another chemical element that also is promising for its diverse chemistry (including ability to form hypervalent bonds) and lack of toxicity is bismuth, which Tsarevsky would like to explore in his future research. "The NSF CAREER funding is absolutely essential," Tsarevsky says. "Some of the money will go to support doctoral students conducting the research, some will go support supplies or equipment. Without this support, it would be extremely difficult or impossible to do these studies." Tsarevsky's long-term educational goal is to increase interest in chemistry, a subject he says too many students are intimidated by. "It's only scary when you know nothing about it or when you had a bad teacher in school who made chemistry torture," Tsarevsky says. "Without chemistry, we wouldn't have pharmaceuticals or materials like plastics. We wouldn't have many pigments or paints. Chemistry is not scary - it is beautiful and inspiring and allows you to be creative and make useful things nobody has seen before." Tsarevsky joined SMU in 2010. He was a Chief Science officer at ATRP Solutions, Inc., from 2007-10 and a visiting assistant professor at Carnegie Mellon University from 2005-07. Tsarevsky received a Ph.D. in Chemistry from Carnegie Mellon University in 2005 and a Bachelor and Master of Science in Theoretical Chemistry and Chemical Physics from the University of Sofia, Bulgaria, in 1999. Source : http://www.azonano.com/news.aspx?newsID=33466 3 Août 2015 2. Techniques de synthèse: matières premières, procédés, outils Production de graphène en Pologne La Pologne est en passe de parvenir à produire du graphène de qualité industrielle à grande échelle d’ici à la fin de l’année 2015, concurrençant de cette façon les leaders actuels du domaine que sont la Corée du Sud et les Etats-Unis. Deux méthodes différentes, mises au point respectivement par l’Institut des matériaux et technologies pour l’électronique (ITME) de Varsovie et l’Université Polytechnique de Lodz ont su bénéficier des moyens exceptionnels investis par la Pologne pour mettre en place des moyens de production et des produits à base de graphène à l’échelle industrielle. Lire la suite: http://www.diplomatie.gouv.fr/fr/politique-etrangere-de-lafrance/diplomatie-scientifique/veille-scientifique-ettechnologique/pologne/article/production-de-graphene-en-pologne 3. Techniques de MISE en ŒUVRE et ADDITIFS de formulation Graphene: A wonder material struggles to find commercial applications Back in the 1990s, as a young journalist working for a chemical engineering magazine, I recall writing an article on Buckminsterfullerene (C60), otherwise known as Buckyballs. It was going to be the next biggest thing in materials according to many observers, finding applications in lubricants, high-temperature superconductors, reaction catalysts, and "disintegrating polymers" as I put it at the time. Graphene nanoplatelets sell for $450/kg (industrial grade) and are hard to disperse throughout polymer matrices. Their potential would appear to be limited. Photo: Cheap Tubes Inc. Well guess what? 23 years on from that "groundbreaking article," Buckminsterfullerene still remains pretty much a laboratory curiosity, with no apparent commercial applications. Could the latest wonder material, graphene, specifically the graphene nanoplatelet (GNP) genre, be heading down that same road? One consultant seems to think so. You can read more on the rationale behind Lux Research's pessimistic outlook for GNP here. To boot, the analyst is also doubtful about the potential of multi-walled carbon nanotubes (MWNTs). Lux says that despite billions of dollars being poured into GNP R&D and production 4 Août 2015 plants by the private and public sectors, most developers of graphene applications are long shots with unproven technical value and business execution. The key hurdle, as is the case with MWNTs and other nanomaterials, is to maintain the performance of GNP when the material is dispersed in a matrix. What's more, says Lux, agglomeration and viscosity issues limit the practical loading of GNP as a primary reinforcement or additive in many applications. As a consequence, companies are finding it difficult to exploit the inherent characteristics of GNP in the final product, be it a composite part, battery, supercapacitor, or transparent conductive film. And lest one forgets, as any new market entry, not only do GNP-based products have to prove themselves on performance, but they need be compelling enough to justify their higher upfront price tags. But it's not all bad news. "While GNP developers indeed appear poised to repeat the trajectory of their older MWNT cousins, it would be a disservice to graphene film developers to entirely lump them in with their GNP peers," notes Lux. There may be opportunities for this material in the sensor field and as heat sinks in electronic devices, for example. Nevertheless, the initial hype surrounding GNP-based products such as composites and conductive compounds does appear to be receding rapidly. Source: http://www.plasticstoday.com/blogs/graphene-wonder-material-strugglesfind-commercial-application-20150730a?cid=nl.plas06.20150805 Effects of Nanoparticles on Polymeric Blends Results of the research can help the design and optimum production of polymeric nanocomposites and they can reduce the production cost. The presence of nanoparticles significantly affects the dynamic behavior of polymeric systems. For example, the presence of these nanoparticles can reduce or increase the viscosity or change the glassy transfer temperature in polymers depending on the size of particles or the interaction between the particles and the polymer. The composite of polystyrene/polyethylene nanoparticles was produced in this research and its rheological behavior was studied. Dendrimer polyethylene nanoparticles are completely hydrophobic and they are soluble in normal organic solvents, including tetrahydrofuran and chloroform contrary to linear samples. These nanoparticles are synthesized in one step and they are about 30 nanometers in size. In addition, they have much lower bulk viscosity than linear polymers. Polyethylene nanoparticles can have various applications in different aspects, but they have mostly been used and studied as drug carriers so far. This research studied the effects of the presence of the ultrafine nanoparticles on rheological properties of polystyrene blends. The tests showed that the viscosity of the system was lower than that of the pure polystyrene in all nanocomposites. The decrease in viscosity could not be explained by any of the existing theories. Therefore, the researchers tried to suggest probable mechanisms to explain the reason. 5 Août 2015 Results of the research will increase the production rate, decrease energy consumption, facilitate the production of complicated pieces and decrease the final price of the product. Results of the research have been published in Macromolecules, vol. 48, issue 10, 2015, pp. 3368-3375. Source: http://www.nanotech-now.com/news.cgi?story_id=52103 4. Polymères biosourcés, biopolymères, biocarburants R.A.S. 5. APPLICATIONS des Polymères a. Systèmes intelligents New fluorescent polymer makes deformation visible A new type of polymer can show that it has changed shape. After exposure to UV light, the chain-like molecules emit a different colour of light. This opens a new pathway for research into how viruses function in a cell and how minor damage in rubbers and plastics can accumulate and lead to rupture. The new polymers were developed by researchers at Wageningen University, who published an article on their findings in the Journal of the American Chemical Society on 12 August 2015. A polymer can be compared to a necklace of small molecules that are chemically linked together. Polymers are the basis of a huge variety of natural and artificial materials, from skin, hair and DNA, to the simplest and most advanced plastics. The properties of these polymer materials are largely determined by their spatial structure, also known as 'conformation'. Polymers can be as straight as uncooked spaghetti, but can also occur as a tangle of cooked spaghetti. Polymer chains resist changes to their conformation, for example when they are stretched. This spring-like effect provides elasticity to rubbers, flexibility to plastics and strength to the cytoskeleton of the cell. Therefore, to change the conformation of a polymer, force must be applied to the molecule. But figuring out the 6 Août 2015 exact conformation of a polymer is particularly difficult, especially if the polymers are surrounded by many other substances, such as in a cell. Fingerprint A team of researchers from the Physical Chemistry and Soft Matter Group of Wageningen University, led by Joris Sprakel, has designed a new kind of polymer that 'reports' its spatial configuration to the researchers through the light it emits. PhD candidate Hande Cingil carried out the work on the water-soluble semiconducting polymers, which the researchers have called conjugated polyelectrolytes (CPEs). Luminescent polymers have existed for some time. They change colour as their conformation changes. A special feature of the CPE polymers is that nuances can be observed in these colour changes. Following irradiation with UV light, the existing polymers emit a colour spectrum that looks like the profile of a mountain with a flat top. But the new polymers have their own 'fingerprint': they show specific peaks in the spectrum. In addition, these peaks shift as the spatial structure changes, for example, if the material in which they are incorporated is stretched. As a result, the novel polymers can detect very small forces on the nanoscale. Artificial virus In their publication in the prestigious Journal of the American Chemical Society, the Wageningen chemists demonstrate the functioning of their CPE polymers. For this purpose they used a protein that was designed by their colleagues in Wageningen, Renko de Vries and Martien Cohen Stuart. The protein is a highly simplified version of an artificial virus; like a biological virus, it binds to DNA and subsequently encapsulates it. Sprakel: "In our experiment, the CPE was encapsulated by the simplified artificial 7 Août 2015 virus protein, giving it a rigid layer, which caused the polymer to change shape. Using simple and non-invasive light spectroscopy, this encapsulation process can now be studied in detail." Rupture The novel polymers can be used for many purposes. Groups of molecules can be attached to the polymers for specific applications, such as the detection of proteins or toxins. Thanks to the discovery it is possible to study changes in conformation, also deep inside complex substances and materials, in an entirely new way. For example, it offers an improved method for determining exactly how viral proteins stretch and fold to encapsulate DNA, or how very minor damage to polymeric materials gradually accumulates and eventually causes the materials to rupture. The researchers are currently working on fundamental research that goes beyond showing whether a polymer chain has stretched: they aim to show exactly where in the chain this stretching occurred. Source: http://phys.org/news/2015-08-fluorescent-polymer-deformationvisible.html#jCp Color-changing polymer may signal traumatic brain injuries in soldiers, athletes A bomb blast or a rough tackle can inflict brain damage that destroys lives. Yet at the time of impact, these injuries are often invisible. To detect head trauma immediately, a team of researchers has developed a polymer-based material that changes colors depending on how hard it is hit. The goal is to someday incorporate this material into protective headgear, providing an obvious indication of injury. The team will describe their approach in one of more than 9,000 presentations at the 250th National Meeting & Exposition of the American Chemical Society (ACS). Recent research and media accounts have indicated that soldiers and professional athletes may suffer long-term complications—such as memory loss, headaches and dementia—stemming from past head trauma. In April, a lawsuit filed by a group of National Football League players was settled, requiring the organization to pay retired players with head injuries. And several professional hockey players are now suing the National Hockey League over the same issue. But even children playing contact sports may be at risk. There is no easy way to tell if someone has just sustained a brain injury, so soldiers and athletes may unknowingly continue to do the very activity that caused the damage and potentially cause more harm. But a force-responsive, color-changing patch could prevent additional injury, says Shu Yang, Ph.D. "If the force was large enough, and you could easily tell that, then you could immediately seek medical attention," she explains. 8 Août 2015 Read more at: http://phys.org/news/2015-08-color-changing-polymer-traumaticbrain-injuries.html#jCp Deux fibres intelligentes Une fibre recouverte de graphène pour l'électronique wearable; une fibre lumineuse composée de cellules polymères électrochimiques. Une fibre recouverte de graphène pour l'électronique wearable Des chercheurs ont réussi à transférer une monocouche de graphène sur des fibres couramment utilisées dans l'industrie textile. Ce matériau conducteur et extensible pourrait avoir un grand potentiel dans les textiles intelligents. L'intérêt d'utiliser du graphène monocouche est sa flexibilité, sa résistance mécanique et sa conductivité électrique. Le matériau est obtenu par un dépôt chimique en phase vapeur (CVD) de graphène sur une feuille de cuivre suivi d'un transfert sur des fibres de polypropylène. Le processus consiste à spin-coater le substrat graphène / cuivre avec un film mince de polyméthacrylate de méthyle (PMMA) avant d'effectuer l'attaque chimique du cuivre, puis le transfert du graphène sur les fibres. Le PMMA est ensuite éliminé par lavage à chaud à l'acétone. Le projet est porté par l'Université d'Exeter (UK), Centexbel (BE), l'Institut INESC-MN (PT) et les universités de Lisbonne et Aveiro (PT). Une fibre lumineuse Des chercheurs de l'Université Fudan - Shanghai ont développé une fibre innovante pour textiles lumineux. Elle est composée de cellules polymères électrochimiques émettrices de lumière ou PLEC (Polymer light-emitting electrochemical cell). 9 Août 2015 Ces cellules sont formées d'un fil d'inox formant une anode recouvert par trempage d'une couche épaisse de nanoparticules de ZnO puis d'une couche de polymères électroluminescents (PF-B, ETT-15, LiTf). Le tout est entouré lentement de nanotubes de carbone alignés qui forment la cathode. L'épaisseur totale est de 1 mm. Lorsqu'une tension est appliquée, les fibres émettent une lumière dont la couleur varie en fonction de la nature du polymère. Les PLEC ont l'avantage de fonctionner à des tensions plus basses que les OLED et d'avoir un meilleur rendement énergétique. Les scientifiques ont pu mettre au point des fibres longues de plusieurs centimètres, conservant 90% de leurs propriétés lumineuses même après 100 cycles de flexion avec un rayon de 6 mm. De nombreux obstacles restent à surmonter en termes de robustesse, de stabilité et de durée de vie mais la technique de fabrication est simple et facile à industrialiser. Les applications seraient à trouver dans les textiles intelligents, par exemple pour le biomédical. Sources : Sirris (21-08-2015), http://europepmc.Org, http://www.nature.com Nouveaux exemples de biomimétisme dans les matériaux Des protections solaires inspirées du poisson zèbre, des muscles artificiels issus de pelures d'oignon, des surfaces anti-reflets inspirées d'un papillon transparent, des vêtements de confort sur le principe de la fourrure de l'ours polaire. 10 Août 2015 Des protections solaires inspirées du poisson zèbre Une exposition prolongée au soleil provoque un vieillissement cellulaire prématuré. Comme les humains, les animaux et les plantes doivent se protéger de ces effets néfastes. Les algues, les coraux et certains invertébrés fabriquent, grâce à des enzymes spécifiques, des molécules anti-UV appelées MAAs. Jusqu'ici, les chercheurs pensaient que les vertébrés les trouvaient dans leur alimentation. Récemment cependant, des biologistes de l'Université de l'Oregon ont découvert que le poisson-zèbre (Danio rerio) synthétisait lui-même sa propre protéine protectrice, le gadusol (C8H12O6), différent des MAAs. Ils ont même observé que le gène entrant dans la fabrication de cette molécule était déjà présent chez les embryons. Ils ont été en mesure de recréer le processus de biosynthèse en transférant les gènes du poisson à de la levure. Les scientifiques ont recherché ce gène dans d'autres espèces et l'ont trouvé chez les amphibiens, les reptiles et les oiseaux. Reste à voir s'ils fabriquent eux aussi le gadusol anti-UV. La découverte de la biosynthèse du gadusol pourrait inspirer les fabricants de protections solaires : un composé du gadusol pourrait être efficace comme protection solaire par ingestion plutôt que comme traitement de la peau. Des muscles artificiels avec une structure de peau d'oignon Les muscles artificiels sont intéressants dans nombre d'applications, par exemple dans la robotique ou les prothèses. Il s'agit par exemple d'élastomères électroactifs ou d'oxyde de vanadium. Mais, sous l'effet d'une stimulation externe, ces actuateurs souples peuvent fléchir ou se contracter/s'expanser, mais pas accomplir les deux actions simultanément. Des chercheurs de l'Université nationale de Taiwan se sont inspirés de la structure des oignons pour aller plus loin. 11 Août 2015 Ils ont étudié les cellules de la membrane translucide située juste en dessous de leur peau extérieure. Ce qui les intéressent est que ces cellules forment une seule couche et sont disposées en treillis. Un échantillon de l'épiderme de l'oignon a été traité à l'acide pour éliminer l'hémicellulose, la protéine qui maintient rigides les parois. La membrane a été revêtue ensuite d'une mince couche d'or sur les deux faces – l'une plus épaisse que l'autre pour obtenir un gradient de rigidité. Quand une tension électrique est appliquée sur le matériau, les couches d'or fonctionnent comme des électrodes. Lorsqu'elle est faible (0-50 V), les cellules s'expansent et le matériau fléchit de -30 µm, du côté de la couche épaisse. Lorsqu'elle est plus élevée (50-1000 V), les cellules se contractent et le matériau fléchit de 1 mm du côté de la couche mince. La force maximale est de 20 μN à 1000 V. Afin de démontrer la technologie, les chercheurs ont combiné deux de ces muscles artificiels pour former une pince qui a pu être utilisée pour ramasser une boule de coton. 12 Août 2015 Dans cette étude, les scientifiques ont prouvé qu'une simple structure en treillis peut générer un mode d'actionnement unique et créé un muscle artificiel inédit. Les travaux se poursuivent pour réduire le voltage appliqué et augmenter la force d'actuation. Des verres anti-reflets inspirés d'un papillon transparent Un écran de verre plat - celui d'une tablette ou d'un GSM - réfléchit entre 8 et 100 % de la lumière qui tombe sur lui, rendant la lecture difficile surtout sous la lumière directe du soleil. Des chercheurs de l'Institut de Technologie de Karlsruhe (KIT) étudient la façon de le rendre moins réfléchissant. Des solutions ont été trouvées en s'inspirant des yeux des papillons de nuit, mais seulement lorsque l'angle de vue est perpendiculaire à la surface. Les scientifiques du KIT se sont inspirés des ailes du papillon Greta Oto qui ont la particularité d'être transparentes et de ne réfléchir que 2-5 % de la lumière, quel que soit l'angle de vision de l'observateur, et ce dans le visible, l'infrarouge et l'ultraviolet. 13 Août 2015 Cette caractéristique rend les papillons plus difficiles à suivre en vol : ils peuvent ainsi échapper à ses prédateurs. Alors que les surfaces transparentes peu réfléchissantes dans la nature sont formées de nanostructures régulières en forme de piliers, celles des ailes du papillon sont variables en taille (400 - 600 nm) et espacées de façon aléatoire (100 - 140 nm). Les chercheurs ont modélisé cet arrangement irrégulier et les résultats des calculs sont conformes avec le comportement observé à la lumière. Ces nanostructures chaotiques pourraient donc être à la base du développement de surfaces moins réfléchissantes dans toutes les directions pour les écrans ou les lentilles. Des vêtements qui régulent les échanges de chaleur La fourrure de l'ours polaire (Ursus maritimus), épaisse de quelques centimètres seulement, est capable de maintenir le corps de l'animal à 37°C par des températures extérieures de -40°C. 14 Août 2015 Les stylistes de HotSquash (UK) s'en sont inspirés pour créer une ligne de vêtements pratiques qui régulent les échanges de chaleur. La collection est composée de robes, de jupes, de vestes réalisés avec des textiles qui gardent chaud en hiver et froid en été, à l'instar de la fourrure de l'ours polaire. La gamme d'été est créé à partir d'un tissu appelé CoolFresh composé de fibres creuses multicanaux qui minimisent l'humidité et permettent à la transpiration de sécher deux fois plus vite que le coton ou la laine. La Warm Collection d'hiver joue sur l'isolation procurée par l'emprisonnement de l'air dans les fibres creuses. Sources : Sirris (28-08-2015), http://elifesciences.org, http://scitation.aip.org, http://www.researchgate.net, http://www.hotsquash.com b. Polymères pour l’électronique Transparent, electrically conductive network of encapsulated silver nanowires: A novel electrode for optoelectronics Mesh of silver nanowires Manuela Göbelt on the team of Prof. Silke Christiansen has now developed an elegant new solution using only a fraction of the silver and entirely devoid of indium to produce a technologically intriguing electrode. The doctoral student initially made a suspension of silver nanowires in ethanol using wet-chemistry techniques. She then transferred this suspension with a pipette onto a substrate, in this case a silicon solar cell. As the solvent is evaporated, the silver nanowires organise themselves into a loose mesh that remains transparent, yet dense enough to form uninterrupted current paths. Encapsulation by AZO crystals Subsequently, Göbelt used an atomic layer deposition technique to gradually apply a coating of a highly doped wide bandgap semiconductor known as AZO. AZO consists of zinc oxide that is doped with aluminium. It is much less expensive than ITO and just as transparent, but not quite as electrically conductive. This process caused tiny AZO crystals to form on the silver nanowires, enveloped them completely, and finally filled in the interstices. The silver nanowires, measuring about 120 nanometres in diameter, were covered with a layer of about 100 nanometres of AZO and encapsulated by this process. Quality map calculated Measurements of the electrical conductivity showed that the newly developed composite electrode is comparable to a conventional silver grid electrode. However, its performance depends on how well the nanowires are interconnected, which is a function of the wire lengths and the concentration of silver nanowires in the suspension. 15 Août 2015 The scientists were able to specify the degree of networking in advance with computers. Using specially developed image analysis algorithms, they could evaluate images taken with a scanning electron microscope and predict the electrical conductivity of the electrodes from them. "We are investigating where a given continuous conductive path of nanowires is interrupted to see where the network is not yet optimum", explains Ralf Keding. Even with high-performance computers, it still initially took nearly five days to calculate a good "quality map" of the electrode. The software is now being optimised to reduce the computation time. "The image analysis has given us valuable clues about where we need to concentrate our efforts to increase the performance of the electrode, such as increased networking to improve areas of poor coverage by changing the wire lengths or the wire concentration in solution", says Göbelt. Practical aternative to conventional electrodes "We have developed a practical, cost-effective alternative to conventional screen-printed grid electrodes and to the common ITO type that is threatened however by material bottlenecks", says Christiansen, who heads the Institute of Nanoarchitectures for Energy Conversion at HZB and additionally directs a project team at the Max Planck Institute for the Science of Light (MPL). Only a fraction of silver, nearly no shadow effects The new electrodes can actually be made using only 0.3 grams of silver per square metre, while conventional silver grid electrodes require closer to between 15 and 20 grams of silver. In addition, the new electrode casts a considerably smaller shadow on the solar cell. "The network of silver nanowires is so fine that almost no light for solar energy conversion is lost in the cell due to the shadow", explains Göbelt. On the contrary, she hopes "it might even be possible for the silver nanowires to scatter light into the solar cell absorbers in a controlled fashion through what are known as plasmonic effects." Source: http://www.nanotech-now.com/news.cgi?story_id=52023 c. Revêtement de surface R.A.S. d. Energie Flexible dielectric polymer can stand the heat Easily manufactured, low cost, lightweight, flexible dielectric polymers that can operate at high temperatures may be the solution to energy storage and power conversion in electric vehicles and other high temperature applications, according to a team of Penn State 16 Août 2015 engineers. "Ceramics are usually the choice for energy storage dielectrics for high temperature applications, but they are heavy, weight is a consideration and they are often also brittle," said Qing Wang, professor of materials science and engineering, Penn State. "Polymers have a low working temperature and so you need to add a cooling system, increasing the volume so system efficiency decreases and so does reliability." Dielectrics are materials that do not conduct electricity, but when exposed to an electric field, store electricity. They can release energy very quickly to satisfy engine start-ups or to convert the direct current in batteries to the alternating current needed to drive motors. Applications like hybrid and electric vehicles, aerospace power electronics and underground gas and oil exploration equipment require materials to withstand high temperatures. The researchers developed a cross-linked polymer nanocomposite containing boron nitride nanosheets. This material has high-voltage capacity for energy storage at elevated temperatures and can also be photo patterned and is flexible. The researchers report their results in a recent issue of Nature. This boron nitride polymer composite can withstand temperatures of more than 480 degrees Fahrenheit under the application of high voltages. The material is easily manufactured by mixing the polymer and the nanosheets and then curing the polymer either with heat or light to create crosslinks. Because the nanosheets are tiny -- about 2 nanometers in thickness and 400 nanometers in lateral size, the material remains flexible, but the combination provides unique dielectric properties, which include higher voltage capability, heat resistance and bendability. Source: http://www.nanotech-now.com/news.cgi?story_id=52058 Roll-to-roll fabrication of fullerene-free organic solar cells A new paper by Cheng et al., recently published in Advanced Science, introduces a new fabrication method for fullerene-free organic solar cells which aims to help address some of the limitations of these cells and to improve production efficiency. Cheng et al. avoid the use of fullerenes due to their absorption limitations and lower long-term stability, and instead focus on fullerene-free organic solar cells. To date, these have only been manufactured on a very small scale, as they are not yet able to be easily fabricated over a large area in the same way as those containing fullerenes. 17 Août 2015 Roll Coated Solar Cell Structure The development of efficient and stable solar cells is critical for the renewable energy industry and to reduce carbon emissions. Traditional silicon-based solar cells, while efficient, require an expensive and complex manufacturing method. In response to the disadvantages of silicon-based solar cells, new alternatives have been sought, such as polymer-based, organic solar cells. These alternatives offer a cheaper and easier manufacturing process, but have previously been hindered by stability and efficiency limitations. Roll-to-roll fabrication has been suggested as a potential method for advancing the industrial production of fullerene-free organic solar cells as it is fast and able to produce large, flexible and stable solar cells in favorable conditions. Using the roll-to-roll method the authors successfully fabricated a fullerene-free organic solar cell with a polymer donor of PBDTTT-C-T and a non-fullerene small molecule acceptor of DC-IDT2T. They found that their best power conversion efficiency value of 1.019% was achieved with a device area of over 1 cm2 and a flexible substrate, in conjunction with the vacuum-free, ambient and (ITO)-free conditions provided by rollto-roll fabrication. Thermal annealing and the use of a chlorobenzene processing solvent produced the best results. When comparing fullerene-based and fullerene-free examples the authors found that the fullerene-free solar cell was the most stable, indicating the potential of this type of cell to become a viable alternative to traditional solar cells. Source: http://www.materialsviews.com/roll-roll-fabrication-fullerene-free-organicsolar-cells/ e. Transport R.A.S. f. Bâtiment, construction R.A.S. 18 Août 2015 g. Textile R.A.S. h. Médical, santé Des valves cardiaques en plastique pourraient sauver des millions de vies Presque cinquante ans après la première greffe du coeur réalisée par le Professeur Barnad, l’Université de Cape Town (UCT) gagne à nouveau la reconnaissance internationale, cette fois dans le domaine de la recherche sur les valves cardiaques. La solution développée par la start-up Strait Access Technologies (SAT), établie à UCT, a été conçue spécifiquement pour répondre aux besoins des 62 à 78 millions d’individus dans le monde touchés par les rhumatismes cardiaques, en particulier les enfants des pays en voie de développement (en comparaison, on estime à 33 millions le nombre de personnes vivant avec le VIH). Sans traitement adéquat, cette pathologie causée par les angines bactériennes mal soignées peut causer des lésions irréversibles des valves cardiaques. Le seul traitement possible est alors la chirurgie de remplacement de la valve, sans laquelle la survie moyenne du patient est estimée à 3 ans. Depuis 2002, il est possible d’éviter les opérations risquées de chirurgie à coeur ouvert, grâce à une technique appelée Transcatheter Aortic Valve Implantation, ou TAVI. L’opération mini-invasive consiste à implanter une prothèse biologique pour remplacer la valve défaillante, au moyen d’une sonde introduite par une artère du patient. La nouvelle valve, fixée sur un ballonnet à la pointe d’un cathéter, est acheminée jusqu’au coeur et gonflée pour prendre la place de la valve native. Il ne reste plus au médecin qu’à retirer le cathéter et à refermer l’endroit de l’incision. Si la technique présente de nombreux avantages, dont celui d’éviter une incision du thorax et de s’abstenir de l’utilisation d’une machine coeur-poumon, les risques dus à l’absence de contrôle du passage du sang à l’intérieur des cavités cardiaques lors de l’opération persistent. L’innovation de l’équipe du Dr Peter Zilla, chef du département de chirurgie cardiothoracique de UCT et directeur du SAT, permet de s’affranchir de ces potentielles complications. L’invention réside dans le système de déploiement de la valve de remplacement : le ballon du cathéter est creux, permettant au sang de circuler continuellement vers l’aorte durant la pose de la prothèse valvulaire. En outre, il contient une valve synthétique temporaire, qui prévient les risques de reflux de sang vers le coeur. L’appareil est enfin doté d’un ballon de pré-dilatation, pouvant être utilisé pour repousser la valve défectueuse contre la paroi vasculaire avant la pose de la nouvelle valve. Pour offrir une technologie accessible aux hôpitaux les plus pauvres, l’équipe de 19 Août 2015 recherche a également réétudié la composition de la valve. La première génération de valves en tissu biologique animal (péricarde) sera en effet bientôt suivie d’une version synthétique en polymère bio-stable (polyuréthane), entièrement développée au sein des laboratoires du SAT. La valve pourrait ainsi être commercialisée pour moins de 1000$ aux pays en voie de développement, soit trente fois moins que les produits disponibles sur le marché actuel. Source: http://www.diplomatie.gouv.fr/fr/politique-etrangere-de-la-france/diplomatiescientifique/veille-scientifique-et-technologique/afrique-du-sud/article/des-valvescardiaques-en-plastique-pourraient-sauver-des-millions-de-vies 6. Techniques d'ANALYSE de calcul et de CARACTERISATION, études TOXICOLOGIQUES R.A.S. 7. RECYCLAGE, ENVIRONNEMENT, REGLEMENTATIONS R.A.S. 8. Enseignement et Recherche Top 25 ChemComm articles April–June 2015 The 25 most-downloaded ChemComm articles in the second quarter of 2015 were as follows: A power-free microfluidic chip for SNP genotyping using graphene oxide and a DNA intercalating dye Jing Li, Yan Huang, Dongfang Wang, Bo Song, Zhenhua Li, Shiping Song, Lihua Wang, Bowei Jiang, Xingchun Zhao, Juan Yan, Rui Liu, Dannong He and Chunhai Fan DOI: 10.1039/C3CC40680F, Communication A novel one-pot method for the synthesis of substituted furopyridines: iodinemediated oxidation of enaminones by tandem metal-free cyclization Rulong Yan, Xiaoni Li, Xiaodong Yang, Xing Kang, Likui Xiang and Guosheng Huang DOI: 10.1039/C4CC08834D, Communication Perovskite solar cells prepared by flash evaporation Giulia Longo, Lidón Gil-Escrig, Maarten J. Degen, Michele Sessolo and Henk J. Bolink DOI: 10.1039/C5CC01103E, Communication 20 Août 2015 Bio-inspired CO2 conversion by iron sulfide catalysts under sustainable conditions A. Roldan, N. Hollingsworth, A. Roffey, H.-U. Islam, J. B. M. Goodall, C. R. A. Catlow, J. A. Darr, W. Bras, G. Sankar, K. B. Holt, G. Hogarth and N. H. de Leeuw DOI: 10.1039/C5CC02078F, Communication Heterostructured magnetic nanoparticles: their versatility and high performance capabilities Young-wook Jun, Jin-sil Choi and Jinwoo Cheon DOI: 10.1039/B614735F, Feature Article Multifunctional catalysis by Pd-polyoxometalate: one-step conversion of acetone to methyl isobutyl ketone Robert D. Hetterley, Elena F. Kozhevnikova and Ivan V. Kozhevnikov DOI: 10.1039/B515325E, Communication Selective guest sorption in an interdigitated porous framework with hydrophobic pore surfaces Satoshi Horike, Daisuke Tanaka, Keiji Nakagawa and Susumu Kitagawa DOI: 10.1039/B703502K, Communication Layer-by-layer assembly of graphene and gold nanoparticles by vacuum filtration and spontaneous reduction of gold ions Byung-Seon Kong, Jianxin Geng and Hee-Tae Jung DOI: 10.1039/B821920F, Communication Asymmetric catalysis activated by visible light Eric Meggers DOI: 10.1039/C4CC09268F, Feature Article The surface chemistry of metal–organic frameworks Christina V. McGuire and Ross S. Forgan DOI: 10.1039/C4CC04458D, Feature Article From themed collection 2015 Emerging Investigators Graphene quantum dots: emergent nanolights for bioimaging, sensors, catalysis and photovoltaic devices Jianhua Shen, Yihua Zhu, Xiaoling Yang and Chunzhong Li DOI: 10.1039/C2CC00110A, Feature Article Nanostructured electrochromic smart windows: traditional materials and NIR- 21 Août 2015 selective plasmonic nanocrystals Evan L. Runnerstrom, Anna Llordés, Sebastien D. Lounis and Delia J. Milliron DOI: 10.1039/C4CC03109A, Feature Article The rechargeable aluminum-ion battery N. Jayaprakash, S. K. Das and L. A. Archer DOI: 10.1039/C1CC15779E, Communication Aggregation-induced emission: phenomenon, mechanism and applications Yuning Hong, Jacky W. Y. Lam and Ben Zhong Tang DOI: 10.1039/B904665H, Feature Article Smart surface of water-induced superhydrophobicity Xing Wang, Guangyan Qing, Lei Jiang, Harald Fuchs and Taolei Sun DOI: 10.1039/B902360G, Communication A highly selective fluorescent sensor for glucosamine Tam Minh Tran, Yuksel Alan and Timothy Edward Glass DOI: 10.1039/C5CC00415B, Communication Reduction of graphene oxide viaL-ascorbic acid Jiali Zhang, Haijun Yang, Guangxia Shen, Ping Cheng, Jingyan Zhang and Shouwu Guo DOI: 10.1039/B917705A, Communication Self-assembled sorbitol-derived supramolecular hydrogels for the controlled encapsulation and release of active pharmaceutical ingredients Edward J. Howe, Babatunde O. Okesola and David K. Smith DOI: 10.1039/C5CC01868D, Communication Pro-fragrant ionic liquids with stable hemiacetal motifs: water-triggered release of fragrances H. Q. Nimal Gunaratne, Peter Nockemann and Kenneth R. Seddon DOI: 10.1039/C5CC00099H, Communication Aromatic donor–acceptor interactions in non-polar environments Giles M. Prentice, Sofia I. Pascu, Sorin V. Filip, Kevin R. West and G. Dan Pantos DOI: 10.1039/C5CC00507H, Communication Wet chemical synthesis of silver nanorods and nanowires of controllable aspect 22 Août 2015 ratio Nikhil R. Jana, Latha Gearheart and Catherine J. Murphy DOI: 10.1039/B100521I, Communication Palladium-catalyzed ring opening of norbornene: efficient synthesis of methylenecyclopentane derivatives Xin-Xing Wu, Yi Shen, Wen-Long Chen, Si Chen, Xin-Hua Hao, Yu Xia, Peng-Fei Xu and Yong-Min Liang DOI: 10.1039/C5CC02246K, Communication A facile solvothermal growth of single crystal mixed halide perovskite CH3NH3Pb(Br1-xClx)3 Taiyang Zhang, Mengjin Yang, Eric E. Benson, Zijian Li, Jao van de Lagemaat, Joseph M. Luther, Yanfa Yan, Kai Zhu and Yixin Zhao DOI: 10.1039/C5CC01835H, Communication Microfluidic synthesis of chitosan-based nanoparticles for fuel cell applications Fatemeh Sadat Majedi, Mohammad Mahdi Hasani-Sadrabadi, Shahriar Hojjati Emami, Mojtaba Taghipoor, Erfan Dashtimoghadam, Arnaud Bertsch, Homayoun Moaddel and Philippe Renaud DOI: 10.1039/C2CC33253A, Communication Conversion of a metal–organic framework to N-doped porous carbon incorporating Co and CoO nanoparticles: direct oxidation of alcohols to esters Yu-Xiao Zhou, Yu-Zhen Chen, Lina Cao, Junling Lu and Hai-Long Jiang DOI: 10.1039/C5CC01588J, Communication http://blogs.rsc.org/cc/2015/08/04/top-25-chemcomm-articles-april-june-2015/ 9. ECHOS de l'INDUSTRIE BioAmber opens world's largest succinic acid plant in Sarnia Montreal-based BioAmber Inc., a leader in renewable chemistry, recently celebrated the opening of its BioAmber Sarnia plant, a project that was jointly realized with partner Mitsui & Co., Ltd. The BioAmber Sarnia plant is the world's largest succinic acid production facility and will be globally competitive while making chemicals more sustainably; according to BioAmber, the Sarnia plant will reduce greenhouse gas emissions by over 210,000 tons per year relative to the petroleum-derived process, the equivalent of taking 45,000 cars off the road. 23 Août 2015 The $141.5-million plant will annually produce 30,000 tons of succinic acid based on glucose from agricultural sugars, principally derived from southern Ontario’s agricultural community. Succinic acid is a “building block chemical” with common applications in the automotive and electronics industries, biodegradable plastics, paints and coatings, lubricants and as well as food-grade certified products. The demand for such renewable building block chemicals in large global markets is increasing steadily; in fact, over 50% of the production of the Sarnia plant has already been sold under take or pay contracts, and the remainder is committed to various customers under supply agreements. "We're excited that our renewable chemicals made from sugars are making everyday applications around the world more sustainable,” said BioAmber CEO Jean-François Huc. “We believe our disruptive biotechnology is going to profitably deliver benefits for the environment, our customers, our shareholders and the Sarnia Lambton community." BioAmber Sarnia is a fully integrated participant in the growing bio-industrial cluster in Sarnia Lambton and has received support from the Government of Canada and the Government of Ontario through the Ontario Ministry of Economic Development, Employment and Infrastructure's Strategic Jobs and Investment Fund. At the inauguration of the new plant, Brad Duguid, Member of Provincial Parliament Scarborough-Centre, Minister of Economic Development, Employment and Infrastructure said: "The opening of the BioAmber Sarnia facility is key to the development of Sarnia's very unique bio-industrial complex, delivering good jobs, significant exports, and diverse markets for Ontario farmers with the full support of the Government of Ontario. The production and development of sustainable chemicals by BioAmber, working from within the existing chemistry cluster in Sarnia, is an economic and environmental win for the community and the province." BioAmber is also grateful for the support of Bioindustrial Innovation Canada and the Sarnia Lambton community. For Sarnia Lambton, BioAmber is a jobs and export story with the potential to attract other manufacturers here to co-locate. Approximately 300 construction and 60 full-time jobs were created by the BioAmber Sarnia project and approximately 18 of the plant operators are graduates of nearby Lambton College. Source: http://www.plasticstoday.com/articles/bioamber-opens-worlds-largestsuccinic-acid-plant-in-sarnia-150807?cid=nl.plas08.20150811