Interview with Christopher Barner-Kowollik

You may have seen our recent profile of Polymer Chemistry Associate Editor Christopher Barner-Kowollik. Here, we ask Christopher more about his career, research and the challenges polymer chemistry can solve.

Which projects are you working on at the moment?

We have a very broad portfolio of project areas in my team, divided into the research platforms ‘synthetic method development’, ‘advanced hybrid materials’, ‘underpinning mechanisms’ and ‘advanced polymer characterization’, with several parallel projects in each. Light driven surface encoding and recoding protocols with applications in cell guidance as well as targeted cell attachment are certainly an important activity, including the development of new photo-chemical reaction sequences. We continue to have a strong interest in biomaterials modification both in solution and the solid state and have not too long ago expanded our portfolio into biomimetic system ranging from universally adhesive bonding/debonding systems to bionspired self-folding single chains and nanoparticles. The design of new functional direct laser writing chemistries featuring reactive surfaces has recently moved into our centre of interest, too, as have supramolecular polymer systems with switchable property profiles. Although a smaller activity, the mechanistic study of photoinduced processes and polymerizations is still an important fundamental activity. For more information on all of our activities, please visit www.macroarc.de.

What motivated you to specialise in polymer chemistry?

I was trained as a physical chemist (albeit with a macromolecular touch) and became continuously more interested in synthetic polymer chemistry over the years. Polymer chemistry offers such a wide variety of research activities and requires knowledge from many chemical disciplines including organic, inorganic, physical and analytical chemistry that very much appeals to me. In addition, I always liked generating materials that can find applications as well as the interactions with industrial partners.
Nevertheless, there is ample room for fundamental research in polymer science and many unanswered questions and challenges exist, which require creativity and clever ideas.

What are the hot topics in polymer research at the moment?

In terms of general challenges that polymer chemistry can and must contribute to solutions for are efficient energy storage, conversion and handling as well as advanced materials for biomedical applications, from regenerative medicine to delivery systems. To address these broad challenges, we as synthetic polymer chemists have to provide solutions for the next step change in our ability to synthesize macromolecules, be it via the provision of precision surface design methodologies, controlling release from polymer systems, folding polymers, sequence controlled polymers or combining synthetic polymer chemistry with biomimetic approaches. Further, many solutions for applications require fine control over network properties, which is not yet available (e.g. monodisperse networks). Some very exciting work is currently also being done in the area of self-healing materials and sheet-like two dimensional polymers. In the materials research area, mimicking nature’s best materials such as nacre is an exciting topic. That said, the field is so diverse that one can identify many hot areas – there is rarely anything non-relevant. It all depends on one’s personal interests and views.

What current problem would you like to see science provide a solution to?

A cure for cancer would certainly be high on the list, but I believe the provision of clean drinking water to the world’s population would probably save even more lives.

What do you find to be the most rewarding aspect of your career?

Discussing and debating scientific questions (down to the details!) with my coworkers and colleagues as well as educating young scientists at all stages of their careers from undergraduate researcher to PhD student to junior group leader.
It is such a rewarding experience to solve a scientific problem and to see enthusiastic researchers mature into confident scientists.

What’s the secret to being a successful scientist?

Curiosity, creativity, very hard work and perseverance as well as the ability to enjoy and part-take in aspects of life that have nothing to do with science (e.g. music, theatre, literature, your family, friends).

Which scientist past or present do you most admire?

Charles Darwin for arguably providing the most influential theory (fact!) in the history of science.

If you weren’t a scientist, what would you be?

On the day of enrolling at university, I was still considering two options: Chemistry or History, both of which I love. No question, as an alternative to the natural sciences, I would have loved to study history – and maybe I will do some day! I have the highest respect for historians and find the works of contemporary historians such as Ian Kershaw absolutely fascinating reading.

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Paper of the week: DNA binding ability of macromolecular platinum-drugs

Cisplatin (cis-diamminedichloroplatinum(II) (CDDP)) is a well-known platinum anticancer drug effective to treat solid tumours in head and neck, non-small cell lung, ovarian and testicular cancers. However, the use of cisplatin also results in severe side effects as well as resistance against the drug. The next generation of platinum drugs had either different amine ligands to replace NH3 or a different leaving ligand to replace chloride to improve water-solubility and stability, and also to reduce side-effects. Meanwhile, Pt(IV) prodrugs were also developed to combat excessive toxicity but also to confer targeting ability for improved anticancer activity.

Graphical abstract: Macromolecular platinum-drugs based on statistical and block copolymer structures and their DNA binding ability

In this article, Stenzel and co-workers designed three different macromolecular Pt-drugs using Cu-click chemistry to attach a bidentate amino ligand to the polymer. Two statistical copolymers with different ligand densities were prepared, which were compared to the block copolymer. DNA binding studies revealed that the statistical copolymer with the highest density of Pt-drugs had the highest affinity to the DNA, due to a multivalent effect. Interestingly, when evaluating the cytotoxic effect of these macromolecular drugs using OVCAR-3 cells the activities of all three polymer architectures were similar. It can therefore be concluded that although DNA binding tests may give an initial indication on the ability of the structure to bind to the DNA, they cannot predict the outcome.

Macromolecular platinum-drugs based on statistical and block copolymer structures and their DNA binding ability by Khairil Juhanni Abd Karim, Sandra Binauld, Wei Scarano and Martina H. Stenzel Polym. Chem. 2013, 4, 5542-5554.

Julien Nicolas is a guest web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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Paper of the week: Multicomponent click chemistry from Biginelli reaction

Click chemistry, first described by Sharpless and co-workers, refers to a type of modular, atom-economic reaction that provides high yields in short reaction times with no or only inoffensive byproducts. A few reactions, such as the well-known copper-catalyzed azide–alkyne cycloaddition (CuAAC), thiol–ene/yne free-radical addition, (hetero) Diels–Alder reaction, hydroxyl/thiol-isocyanate coupling, etc., have been discovered to have these attractive ‘clickable’ features and have found important applications in many areas. Until now, almost all click reactions are two-component reactions. It could be very interesting if three or more reactive elements could be combined together to construct new click reactions, which might provide more choices and functional diversity. Multicomponent reactions (MCRs) seem to be possible candidates to address this point. MCRs are a type of modular and highly efficient reaction using at least three different reactants to achieve a single complex and functional product in one pot with negligible or no byproducts.

Graphical abstract: A new insight into the Biginelli reaction: the dawn of multicomponent click chemistry?

In this context, Tao, Wei and co-workers have revisited the Biginelli reaction as a potential tri-component click chemistry. Through the quick and efficient modification of polymer side groups and locking of two polymer chains, Biginelli-type homopolymers and Biginelli-locked copolymers can be facilely and quantitatively obtained. Moreover, the Biginelli reaction showed good compatibility with RAFT polymerization to construct a one-pot MCP system. Both reactions proceeded well without interference, and almost neat Biginelli functionalized homopolymers were successfully achieved in a one-pot fashion. More importantly, the Biginelli reaction can also be recognized as a ‘catalyst-free’ bioorthogonal-click reaction, through which a fluorescent probe can be covalently anchored onto cell membranes without external addition of a catalyst, implying the potential application of the Biginelli reaction in chemical biology.

A new insight into the Biginelli reaction: the dawn of multicomponent click chemistry? by Chongyu Zhu, Bin Yang, Yuan Zhao, Changkui Fu, Lei Tao and Yen Wei Polym. Chem. 2013, 4, 5395-5400.

Julien Nicolas is a guest web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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IPST2013: International Polymer Conference, Yogyakarta, Indonesia

The Innovation in Polymer Science and Technology 2013 (IPST2013) was held in Yogyakarta, Indonesia on October 7 – 10, 2013 and organised by the Indonesian Polymer Association (HPI). It was attended by more than 250 participants from over 20 countries; presenting about 200 paper works consisting of 102 oral and 108 poster presentations, including 7 plenary speakers, and 24 keynote speakers. To date, this event was the biggest international polymer conference, organised by the Indonesian Polymer Association.

IPST2013

The conference was officially opened by the representative of Indonesian government, the Ministry of Research and Technology of Indonesia. The Indonesian Polymer Association presented a 2013 HPI award to Dr. M. Sugandi (a former of the HPI’s chair) for her lifetime contributions in polymer research as well as in the polymer society in Indonesia. The best student posters were awarded to 5 students: Arum Patriati (Indonesia), Shih Ming Chang (Taiwan), Emiko Ohara (Japan), Ayami Nagayama (Japan), and Koay Seong Chun (Malaysia). Zainon Othman (Malaysia) and Firman Kurniawansyah (Indonesia) were awarded the best oral presentation prize.

The IPST2013 was officially closed by Ms. Eniya L. Dewi, the chair of the IPST2013 and ICFCHT2013. The next conference will take place in 2016 (IPST2016) and will be held in Padang, West Sumatera, Indonesia. We look forward to seeing you there!

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Author of the Week: Professor Parameswar K. Iyer

Professor Parameswar K. Iyer received his B.Sc. (Chemistry) in 1993 and his M.Sc. (Organic Chemistry) in 1995 at Bhavnagar University. He completed his Ph.D. in 1999 working at the Central Salt and Marine Chemicals Research Institute, Bhavnagar, India working on asymmetric catalysis. He worked as a postdoctoral fellow at Technion, Israel (1999-2001), University of California Santa Barbara (2001-2003) and at Case Western Reserve University, Cleveland (2003-2004). He then joined the Indian Institute of Technology Guwahati as an Assistant Professor in July 2004. In 2008 he was promoted as an Associate Professor and then a full Professor in January 2013. Professor Iyer currently leads a Research Group at the Department of Chemistry and Center for Nanotechnology at IIT Guwahati of ~10 people. His research interests involve the development of novel conjugated polymer and macromolecular structures, their application in optoelectronic devices, chemical and biological sensors and extension to therapeutics.

Group web-link: http://www.iitg.ernet.in/chemistry/fac/pki/

What was your inspiration in becoming a chemist?

As a high school student I had intense curiosity and found science practical, especially chemistry and biology, highly exciting and I used to look forward to it. This interest was further enhanced when I used to visit Central Salt and Marine Chemicals Research Institute (CSMCRI), Bhavnagar, India that used to be in close proximity to my home. Hence, I chose chemistry as my further line of study. I was also fortunate to work at this laboratory for my graduate (PhD) thesis work under the guidance of Dr. Rukhsana I. Kureshy that kindled my interest in chemistry. I realized with time that being a teacher along with being a chemist is much more interesting since this provided immense opportunities to interact with young bright minds.

What was the motivation to write your Polymer Chemistry article?

Over the years I observed that Polymer Chemistry publishes high quality work on several aspects of polymers and their interdisciplinary applications. We have been working for the past few years on the development of conjugated polymer systems with diverse applications in sensors and diagnosis and had an aim of extending these systems to therapeutics. We have developed a number of polymer and oligomer based systems that had diagnosis potential for neurological disorders. The key advantage of the system reported in the present article is that these materials can be prepared by an easy polymerization method, it is non toxic and it can bind toxic metals such as iron and iron containing metalloproteins at varying pH conditions in biological media at extremely low concentrations. This motivated us to use this system to probe metal traces in cerebrospinal fluid (CSF) having amyloid beta (Ab) that add to the toxicity enhancement. The binding of metal in CSF with the help of this new polymer based material disrupted the Ab instantly. With the low levels of detection that were possible with this polymer, the early diagnosis and therapeutic applications of this polymer for Alzheimer’s disease and other neurological disorders are huge.

Why did you choose Polymer Chemistry to publish your work?

Although Polymer Chemistry was a new journal, it has established itself as a top journal in polymer chemistry. I have known from colleagues that the reviewer comments received from Polymer Chemistry were very helpful and criticisms allowed improvement of the manuscript. I experienced the same as my colleagues, and found that this also encouraged me and my students to carry out the revisions with great enthusiasm, drawing praise from reviewers. I also found that the rapid review and publication time and wide readership were very helpful.

In which upcoming conferences may our readers meet you?

I am planning to attend http://www.kjf-icomep2013.org and http://www.icsm2014.fi/ conferences. I am also organizing the 3rd International Conference on ‘Advanced Nanomaterials and Nanotechnology” (ICANN-2013) at the Indian Institute of Technology Guwahati (IITG), India, which will take plade between December 1-3, 2013.

http://www.iitg.ernet.in/icann2013/

How do you spend your spare time?

When I am not at work, I am either at the athletics track or at basketball courts which helps me stay fit physically and mentally. Besides sports, I love cooking, gardening and photography.

Which profession would you choose if you were not a scientist?

It’s easier to tell what I would not have become than what I would have. As an undergraduate student, I was inclined to join Air force due to my NCC activities. Being a sports coach would also have been a good career option.

A rapid and sensitive detection of ferritin at a nanomolar level and disruption of amyloid β fibrils using fluorescent conjugated polymer
B. Muthuraj, Sameer Hussain and Parameswar Krishnan Iyer  
Polym. Chem., 2013, 4, 5096-5107 DOI: 10.1039/C3PY00680H

Professor Iyer’s peper was recently featured as the Paper of the Week.

To keep up-to-date with all the latest research, sign-up to our RSS feed or Table of contents alert.

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Paper of the week: Direct heteroarylation of β-protected dithienosilole and dithienogermole monomers

Conjugated polymers have been used extensively in organic electronic devices such as bulk heterojunction solar cells (BHJ-SCs), light emitting diodes (LEDs), field effect transistors (FETs), etc. Typical synthetic protocols involve conventional aryl carbon–carbon bond forming reactions, including Stille, Suzuki, Negishi, etc., where a (hetero)aryl halide is coupled with a (hetero)aryl organometallic reagent. Although widely utilized, these commonly utilized reactions are hampered by stoichiometric amounts of organometallic waste as well as unstable monomers. A greener alternative is direct (hetero)arylation, which has been used extensively in the preparation of small molecules, and involves the coupling of an aryl halide directly with another arene through activation of a C–H bond. However, this reaction is not selective and more than one type of C–H bond may react, which, during polymerization reactions, can lead to cross-linked materials.

Graphical abstract: Direct heteroarylation of β-protected dithienosilole and dithienogermole monomers with thieno[3,4-c]pyrrole-4,6-dione and furo[3,4-c]pyrrole-4,6-dione

In their paper, Leclerc and co-workers reported the preparation of N-octylthieno[3,4-c]pyrrole-4,6-dione with 4,4-bis(2-ethylhexyl)-dithieno[3,2-b:2′,3′-d]silole (PDTSiTPD) and 4,4-bis(2-ethylhexyl)-dithieno[3,2-b:2′,3′-d]germole (PDTGeTPD), which have exhibited high efficiencies in organic solar cells, using direct (hetero)arylation polymerization methodologies. In order to circumvent side reactions leading to cross-linked polymers, a number of new dithieno[3,2-b:2′,3′-d]silole (DTSi) monomers were prepared where the β-positions were blocked with alkyl chains and the alkyl groups on the heteroatom were modified. Co-polymers were synthesized with N-alkylthieno[3,4-c]pyrrole-4,6-dione (TPD) and the oxygen congener, N-alkylfuro[3,4-c]pyrrole-4,6-dione (FPD).

Direct heteroarylation of β-protected dithienosilole and dithienogermole monomers with thieno[3,4-c]pyrrole-4,6-dione and furo[3,4-c]pyrrole-4,6-dione by Lauren G. Mercier, Badrou Réda Aïch, Ahmed Najari, Serge Beaupré, Philippe Berrouard, Agnieszka Pron, Amélie Robitaille, Ye Tao and Mario Leclerc Polym. Chem. 2013, 4, 5252-5260.

This article is part of the Polymer Chemistry themed collection on Conjugated polymers.

Julien Nicolas is a guest web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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Best Student Poster Prize at IPST2013

Congratulations to Koay Seong Chun for being awarded the Polymer Chemistry Best Student Poster Prize at IPST2013!

Koay Seong Chun (left) is a PhD student working in Professor Salmah Husseinsyah and Dr. Hakimah Osman's group at the School of Materials Engineering, Universiti Malaysia Perlis, Malaysia.

Koay Seong Chun (left) is a PhD student working in Professor Salmah Husseinsyah and Dr. Hakimah Osman's group at the School of Materials Engineering, Universiti Malaysia Perlis, Malaysia.

He received his RSC prize at the International Conference on the Innovation in Polymer Science and Technology 2013 (IPST2013) which was held in Yogyakarta, Indonesia, from October 7 – 10, 2013. The poster, titled “Infuence of Methacrylic Acid Modification on Tensile Properties of Polypropylene/Cocoa Pod Husk Biocomposites”, was presented alongside 54 other student poster presentations and achieved the highest collective score from the judges.

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Paper of the week: Sensitive detection of ferritin and disruption of amyloid β fibrils using fluorescent conjugated polymer

Enhanced levels of toxic metals, especially iron, from the labile iron pool in the brain are primarily responsible for the pathogenesis of several neurological disorders, such as Alzheimer’s disease (AD). These metals are a major source for generating highly toxic reactive oxygen species, accelerating amyloid b (Ab) peptide aggregation in the brains of AD patients. Ab has high affinity for iron, resulting in its accumulation and localization in brain plaques enhancing neurotoxic H2O2, oxidative stress and free radical formation. Hence, controlling neurotoxicity would also involve regulation of the redox active metals present, along with the Ab.

Graphical abstract: A rapid and sensitive detection of ferritin at a nanomolar level and disruption of amyloid β fibrils using fluorescent conjugated polymer

In their study, Iyer and co-workers synthesized a non toxic conjugated polymer, poly(1,4-bis-(8-(8-hydroxyquinoline)-octyloxy)-benzene) (PHQ), able to bind iron containing heme and non-heme proteins, such as ferritin, at nanomolar levels with the highest known selectivity in cerebrospinal fluid (CSF). It has been employed to interact with the bound iron, including non-heme ferritin, in the Ab protofibril aggregates and to diminish their accumulation. The anti-AD activity of PHQ was confirmed via in vitro control studies by doping CSF of healthy individuals with Ab(1–40) with and without iron using a Thioflavin-T binding assay test and electron microscopy analysis. This new strategy to clear the cerebral deposits using conjugated polymers enables the toxic aggregated Ab peptide fibrils present in the CSF to be successfully disrupted under physiological conditions.

A rapid and sensitive detection of ferritin at a nanomolar level and disruption of amyloid β fibrils using fluorescent conjugated polymer by B. Muthuraj, Sameer Hussain and Parameswar Krishnan Iyer, Polym. Chem. 2013, 4, 5096-5107 .

Julien Nicolas is a guest web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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Top 10 most-read Polymer Chemistry articles – Q3 2013

This month sees the following articles in Polymer Chemistry that are in the top 10 most accessed from July – September.

Thiol-ene “click” reactions and recent applications in polymer and materials synthesis
Andrew B. Lowe
Polym. Chem., 2010,1, 17-36
DOI: 10.1039/B9PY00216B

Low band-gap benzothiadiazole conjugated microporous polymers
Shijie Ren, Robert Dawson, Dave J. Adams and Andrew I. Cooper
Polym. Chem., 2013,4, 5585-5590
DOI: 10.1039/C3PY00690E

Diels–Alder reactions for carbon material synthesis and surface functionalization
Nicolas Zydziak, Basit Yameen and Christopher Barner-Kowollik
Polym. Chem., 2013,4, 4072-4086
DOI: 10.1039/C3PY00232B

End-functional stereoregular poly(methyl methacrylate) with clickable C?C bonds: facile synthesis and thiol–ene reaction
Yasuhiro Kohsaka, Takashi Kurata and Tatsuki Kitayama
Polym. Chem., 2013,4, 5043-5047
DOI: 10.1039/C3PY00799E

Synthesis of multi-responsive polymeric nanocarriers for controlled release of bioactive agents
Xiaohong Wang, Guohua Jiang, Xia Li, Bolin Tang, Zhen Wei and Caiyi Mai
Polym. Chem., 2013,4, 4574-4577
DOI: 10.1039/C3PY00746D

Selective CO2 capture in an imine linked porphyrin porous polymer
Venkata S. Pavan K. Neti, Xiaofei Wu, Shuguang Deng and Luis Echegoyen
Polym. Chem., 2013,4, 4566-4569
DOI: 10.1039/C3PY00798G

Main-chain photoresponsive polymers with controlled location of light-cleavable units: from synthetic strategies to structural engineering
Qiang Yan, Dehui Han and Yue Zhao
Polym. Chem., 2013,4, 5026-5037
DOI: 10.1039/C3PY00804E

Autonomous self-healing of poly(acrylic acid) hydrogels induced by the migration of ferric ions
Zengjiang Wei, Jie He, Tony Liang, Hyuntaek Oh, Jasmin Athas, Zhen Tong, Chaoyang Wang and Zhihong Nie
Polym. Chem., 2013,4, 4601-4605
DOI: 10.1039/C3PY00692A

One pot synthesis of a poly(3-hexylthiophene)-b-poly(quinoxaline-2,3-diyl) rod–rod diblock copolymer and its tunable light emission properties
Zong-Quan Wu, Deng-Feng Liu, Ying Wang, Na Liu, Jun Yin, Yuan-Yuan Zhu, Long-Zhen Qiu and Yun-Sheng Ding
Polym. Chem., 2013,4, 4588-4595
DOI: 10.1039/C3PY00708A

Highly stretchable and resilient hydrogels from the copolymerization of acrylamide and a polymerizable macromolecular surfactant
Mei Tan, Tingting Zhao, He Huang and Mingyu Guo
Polym. Chem., 2013,4, 5570-5576
DOI: 10.1039/C3PY00745F

Why not take a look at the articles today and blog your thoughts and comments below.

Fancy submitting an article to Polymer Chemistry? Then why not submit to us today!

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Paper of the week: Internally structured nanoparticles and micelles

Block copolymers (BCPs) have the unique ability to form a rich array of self-assembled nanostructures in the bulk and in solution. In the bulk, complex phase diagrams have been mapped and morphologies including lamellar, cylindrical, and bicontinuous (gyroid) self-assembled structures have been identified. Similarly, a variety of structures can be accessed in solution from vesicles to spherical and cylindrical micelles. Recently it has been reported that bulk-type morphologies can be accessed in solution processing of BCPs. However, despite the potential of supramolecular chemistry to dictate the solution self-assembly of hydrophobic BCPs, systematic design rules to control nanostructures on demand are still limited.

Graphical abstract: Supramolecular guests in solvent driven block copolymer assembly: from internally structured nanoparticles to micelles

In the present study, Connal and co-workers established a versatile strategy to prepare a diverse range of self-assembled colloidal nanostructures from the same hydrophobic BCP.  Polymer nanoparticles with well-ordered phase separated morphology were accessed from the solution self-assembly of a hydrophobic polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) BCP. However, the introduction of a hydrophilic guest capable of hydrogen bonding with the pyridine block resulted in an amphiphilic BCP, thus drastically altering the self-assembly behavior and leading to traditional spherical micelles in water. Furthermore, a hydrophobic guest was incorporated into the BCP which formed internally nanostructured assemblies in water with the hydrophobic guest entrapped within the nanoparticle. Their methodology can be used to engineer new systems that incorporate and release guests upon triggered disruption of the supramolecular bonds. Furthermore, the diversity of nanostructures that can be tuned by the incorporation of different guests enables opportunities for outstanding control of the nanoparticle properties.

Supramolecular guests in solvent driven block copolymer assembly: from internally structured nanoparticles to micelles by Daniel Klinger, Maxwell J. Robb, Jason M. Spruell, Nathaniel A. Lynd, Craig J. Hawker and Luke A. Connal, Polym. Chem. 2013, 4, 5038-5042.

Julien Nicolas is a guest web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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