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
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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
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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.'
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"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
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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
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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.
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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
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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
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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
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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