Archive for May, 2012

Paper of the Week: Copper mediated controlled radical polymerization in a continuous tubular reactor

Graphical abstract: Copper mediated controlled radical polymerization of methyl acrylate in the presence of ascorbic acid in a continuous tubular reactor

Single electron transfer-living radical polymerization (SET-LRP) has been recently proposed as a “variant” of the originally-developed atom transfer radical polymerization (ATRP). There has been very little research done, however, combining SET-LRP with reducing agents. In this view, Cunningham and co-workers reported an innovative design for a flow reactor for the continuous production of uniform polymer with high livingness using SET-LRP, improving upon the initial concept. Instead of using copper tubing to construct the entire reactor, a short copper coil was used to initiate polymerization and generate soluble copper species. The bulk of the reaction then took place in inert stainless steel tubing, using ascorbic acid as a reducing agent to drive the catalytic cycle and mediate the polymerization. Polymerizations were conducted at ambient temperature with 30 wt% DMSO as solvent, producing well defined living polymer at a steady state conversion of 78% for a residence time of 62 min. Chain extensions using outlet polymer solutions were well-controlled and proceeded to high conversion in a short period of time, with a final concentration of 10 ppm of residual copper. The results illustrate the significant potential of using a continuous tubular reactor with ascorbic acid as a reducing agent as an efficient means to scale-up production of well controlled polyacrylics and other multiblock copolymers.

Copper mediated controlled radical polymerization of methyl acrylate in the presence of ascorbic acid in a continuous tubular reactor by Nicky Chan, Michael F. Cunningham and Robin A. Hutchinson Polym. Chem., 20123, 1322-1333.

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Author of the Week: Youliang Zhao

Dr. Youliang Zhao was born in Shuangfeng County, Hunan Province, China, in September 1975. He received B.Sc. (1997) and M.Sc. (2000) degrees from Xiangtan University and Ph.D. in July 2003 at Institute of Chemistry, the Chinese Academy of Sciences with Prof. Fu Xi. He went to Tokyo Institute of Technology in November 2003 and worked as a JSPS Postdoctoral Fellow with Prof. Akira Hirao. From November 2005 to August 2007, he was a postdoctoral research fellow with Dr. Sébastien Perrier at University of Leeds. He became a full professor at College of Chemistry, Chemical Engineering and Materials Science, Soochow University since August 2007. He has published more than 50 peer reviewed research papers in scientific journals primarily on synthesis of complex macromolecular architectures, hybrid materials and nanocomposites by polymerization techniques such as controlled radical polymerization (CRP), ring-opening polymerization (ROP) and living anionic polymerization (LAP) and their combination with highly efficient coupling reactions. He has been invited to give lectures on his research work in international conferences as well as in some research institutions. His research interests include synthesis and properties of stimuli-responsive inorganic-organic hybrid materials, graphene-polymer nanocomposites, and functional polymers involving dendrimers, block, star, graft and hyperbranched polymers.

Please follow the link for further information on Zhao’s research group: http://www.polymer.cn/ss/zhaoyouliang/index.html or http://chemistry.suda.edu.cn/index.aspx?lanmuid=69&sublanmuid=603&id=65

What was your inspiration in becoming a chemist?

I become a chemist because of my strong interest in chemistry. Our chemistry teachers in high school always encouraged us to do some interesting chemistry experiments, which fully inspired my curiosity. The undergraduate and graduate studies further underlay my background in polymer science. I am so lucky to become a chemist that I am able to design and synthesize novel compounds and polymers, which may have potential applications in materials science and technology.

What was the motivation to write this article? (DOI:10.1039/C1PY00396H)

The motivation of this article was to develop a versatile method to prepare suprapure multicomponent block copolymers and recycle the functional solid supports. In our previous study, three types of methods comprising Z-supported RAFT graft polymerization, radical-induced chain exchange reaction, and combination of RAFT polymerization and coupling reactions were used to synthesize well-defined homopolymers and block copolymers grafted onto silica particles although the solid substrates were not recycled. In this continuous study, tandem RAFT process and CuAAC afforded better-defined block copolymer grafted silica, de-grafting process and postmodification gave access to highly pure block copolymers with terminal functionalities, and clickable silica particles were efficiently recovered until all the surface functionalities were vanished. Our study affords a versatile and general approach for surface modification, synthesis of high-purity block copolymers and recycle of clickable solid substrate, which is of great importance for “green” syntheses and development of renewable resources. We have extended this method for the fabrication of functional graphene-polymer nanocomposites.

Why did you choose Polymer Chemistry to publish your work?

Polymer Chemistry is an excellent journal which publishes high quality manuscripts in polymer science. It is natural for me to publish our best results in this journal due to its good visibility.

In which upcoming conferences may our readers meet you?

I will be in Changchun, China, during 2-6 June at the International Symposium on Polymer Chemistry (PC2012). I attend IUPAC International Conference on Novel Materials and Synthesis (NMS) & International Symposium on Fine Chemistry and Functional Polymers (FCFP) regularly and will attend NMS-VIII & FCFP-XXII to be held in Xi’An, China in October this year.

How do you spend your spare times?

When I am free, I like travelling and reading.

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

Chances are given, I may want to be a historian since the complex history always attracts me. I may also want to be a writer because of my strong interest in poem, essay and novel.

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Paper of the Week: Glycopolymer–peptide bioconjugates with antioxidant activity

Graphical abstract: Glycopolymer–peptide bioconjugates with antioxidant activity via RAFT polymerization

Peptide/protein–polymer bioconjugates have attracted increasing interest as they have numerous potential applications in biotherapeutics, biotechnology, and nanotechnology. In their paper, Liu and co-workers employed reversible addition–fragmentation chain transfer radical (RAFT) polymerization to design poly(2-(2,3,4,6-tetra-O-acetyl-b-D-glucosyloxy)ethyl
methacrylate) (PAcGlcEMA) polymers end-functionalized with the tripeptide reduced glutathione (GSH). The resulting PGlcEMA-GSH bioconjugate exhibited high affinity for Concanavalin A and significant antioxidant activity.
The specific recognition of targeting glucose moieties and antioxidant ability of GSH make peptide–glycopolymer bioconjugate PGlcEMA-GSH a suitable candidate for antioxidant delivery systems, biomimetics and biodetection.

Glycopolymer–peptide bioconjugates with antioxidant activity via RAFT polymerization by Haiting Shi, Li Liu, Xiaobei Wang and Jingyi Li Polym. Chem., 20123, 1182-1188.

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Author of the Week – Dr. Mihaela C. Stefan

Dr. Mihaela C. Stefan is an Assistant Professor in the Department of Chemistry at University of Texas at Dallas. She received a BS in Chemical Engineering, and MS and Ph.D. degrees in Chemistry from Politehnica University Bucharest, Romania. She worked as a Postdoctoral Researcher in Krzysztof Matyjaszewski’s and Richard McCullough’s research groups at Carnegie Mellon University. She joined the Department of Chemistry at the University of Texas at Dallas in August 2007.  Since 2007 she has attracted 9 graduate students, 31 undergraduate students, and 3 summer high school student into her research lab.  Currently, 6 graduate students and 6 undergraduate students are working in her lab. She has published more than 40 peer-reviewed papers out of which 19 were published after joining UTD.

She received the NS&M Outstanding Teacher Award in 2009 and the Inclusive Teaching Diversity Award in 2012.  She is aslo a recipient of the Faculty Early Career Development (CAREER) award from NSF, which is given to junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research. Her research group is developing novel polymeric materials for organic electronics and for drug delivery applications.  The common theme on both research directions is the interdisciplinary training of students at the interface between organic/polymer chemistry and materials science.

For more information see here: http://www.utdallas.edu/~mci071000/

What was your inspiration in becoming a chemist?

My parents were chemists and I started to visit their labs when I was only 5-6 years old. At the initial stage I was fascinated with the colors in the lab as my mom used to show me titrations. Sometimes my mom would take me to work on Saturdays because she could not take me to the kindergarten on weekends. Going to work with my mom was so much better than going to kindergarten. When I had to decide for college I choose to study chemical engineering because traditionally back in my home country when you study chemistry you prepare for a teaching career. At that time teaching was something I would have not considered as a career choice.  Now teaching is such an important part of my work and I can never imagine my life without going in the classroom to teach.

What was the motivation to write this review? (DOI: 10.1039/C1PY00453K)

I wrote the review as an invited paper for the themed issue on New Methods of Polymer Synthesis. The review describes the synthesis of block copolymers of polythiophene by Grignard metathesis (GRIM) polymerization.  My group works on the development of novel semiconducting polymers for organic electronics applications. Whenever possible we use Grignard metathesis method because it is a living polymerization which allows the control of the molecular weights and functional end groups of the semiconducting polymers.

Why did you choose Polymer Chemistry to publish your work?

Polymer Chemistry is one of the leading journals in polymer science. This is my second paper to be published in Polymer Chemistry and both times I enjoyed the fast time to publication and the fair review process.

In which upcoming conferences may our readers meet you?

I will attend the International Conference on Science and Technology of Synthetic Metals ICSM 2012 which will be held on July 8-13 in Atlanta. I will also give an invited talk to the “Young Academic Investigators” Symposia organized by the Organic Division of ACS at the Fall 2012 ACS Meeting in Philadelphia.

How do you spend your spare times?

I do not have much spare time because we are trying to work hard to build a successful research group. However, when I have time to take a break from my work I like to read biographies. I love reading biographies of scientists and I always look to buy books. I also enjoy playing with my cats. In the future I hope to find some spare time to volunteer for a shelter as I love animals, especially cats.

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

I would probably have pursued a career as a cat veterinarian if I was not a scientist.

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Paper of the Week: Measurement platform for monomer reactivity ratios

Graphical abstract: A robust and high-throughput measurement platform for monomer reactivity ratios from surface-initiated polymerization
Knowledge of monomer reactivity ratios provides the necessary insight to control and predict the monomer sequence; however, these kinetic parameters are often time-consuming and difficult to accurately measure. In their study, Beers and co-workers reported a robust approach to measure monomer reactivity ratios using surface-initiated copolymerization and XPS as a synthesis and characterization toolset. For the range of monomer pairs investigated, reactivity ratios obtained from the non-linear least squares evaluation of XPS copolymer composition data are reproducible and are in good agreement with bulk reactivity ratios obtained by traditional NMR analysis. Additionally, they have developed and demonstrated a high-throughput approach to measure reactivity ratios using a single substrate exhibiting a gradient in copolymer brush composition. The high-throughput approach significantly reduces the time and effort required to generate reliable and reproducible point estimates of reactivity ratios, and these values are in good agreement with values obtained from both the discrete statistical copolymer brush and classical bulk analytical methods.

A robust and high-throughput measurement platform for monomer reactivity ratios from surface-initiated polymerization by Derek L. Patton, Kirt A. Page, Emily A. Hoff, Michael J. Fasolka and Kathryn L. Beers Polym. Chem., 20123, 1174-1181.

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Paper of the Week: Multifunctional nano-assemblies

Core–shell nanoassemblies made from amphiphilic block copolymers have shown potential for use as a drug delivery system. A great deal of work has been focused on the design of sophisticated stimuli-sensitive nanoassemblies in order to take advantage of the environment changes that occur in nature.
In this view, Aoyagi and co-workers reported an original method to prepare nanoassemblies with targetable and tunable shell functions by simply mixing three different block copolymers with a common temperature-responsive segment. The building blocks, acrylamide-type P(NIPAAm-coN-(hydroxymethyl)acrylamide (HMAAm))-b-P(NIPAAm-co-BMAAm), poly(ethylene oxide) (PEO)-b-P(NIPAAm-co-BMAAm), and methacrylate-type poly(2-lactobionamidoethyl methacrylate) (PLAMA)-b-P(NIPAAm-co-HMAAm)-b-P(NIPAAm-co-BMAAm), were successfully polymerized by reversible addition–fragmentation chain transfer (RAFT) polymerization. Regardless of the block copolymer types, they formed a stable core–shell assembly with the collapsed common segments by simple mixing in aqueous solutions. The flexibility of designing block copolymers with a favorable functional group and the simple mixing of the selected block copolymers make the present concept considerably advantageous over self-assembly of the one block copolymer system. This study could open up new possibilities toward effective and facile encapsulation, targeting, and triggered release of drugs.

A ‘smart’ approach towards the formation of multifunctional nano-assemblies by simple mixing of block copolymers having a common temperature sensitive by Yohei Kotsuchibashi, Mitsuhiro Ebara, Naokazu Idota, Ravin Narain and Takao Aoyagi Polym. Chem., 2012, 3, 1150-1157.

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Author of the Week: Christophe Boisson

Christophe Boisson studied chemistry at the Ecole Nationale Supérieure de Chimie de Montpellier (France). He received his PhD in Organic Chemistry from the University of Paris-Sud 11 in 1996 for investigations of the chemistry of f-metal amide complexes. The same year, he became research associate at the French National Center for Scientific Research (CNRS) and he joined the group of Dr Roger Spitz at CPE-Lyon where he developed research in the field of copolymerization of ethylene with butadiene. In 2008, he was appointed CNRS research director at the laboratory Chemistry, Catalysis, Polymers and Processes (UMR 5265 – CNRS, CPE Lyon, University Lyon 1). His research interests are focused on homogeneous and heterogeneous catalysts for the polymerization of olefins.

 

 

Details of his research activities can be found at: http://c2p2-cpe.com/index.php

 

What was your inspiration in becoming a chemist?

When I was a young student, chemistry was the scientific disciplines I succeeded best. This was at first a good reason to start learning chemistry but very rapidly I was fascinating by the arrangement of atoms to make molecules and the infinite possibilities of structure creation offered by chemistry.

What was the motivation behind the research in your recent Polymer Chemistry paper (DOI: 10.1039/C2PY20063E)?

Synthetic rubbers in the tyre industry are principally based on homo- and co-polymers of butadiene. Our group has a long standing interest in the polymerization of butadiene. We have developed neodymium catalysts for stereospecific polymerization of butadiene but especially for the design of new elastomers named EBR (ethylene-butadiene rubber) bearing unique microstructures. More recently, we focused on nickel catalysts for butadiene polymerization since these complexes are less sensitive to functional groups than neodymium systems and provide opportunities to prepare new materials. In the present paper, an investigation of the activation of nickel(0) and nickel(II) precursors using a range of activators is reported and several new efficient catalysts are described. These investigations permit us to rationalize the formation of the actives species in the case of the industrial catalysts Ni(O2CR)2/BF3.OEt2/AlEt3.

Why did you choose Polymer Chemistry to publish your work?

In the editorial of the first issue of this young journal, Prof. David Haddleton wished that “the next generation of polymer chemists see Polymer Chemistry as their own journal representing what they need from their top journal”. I think it is the case and it is a very good reason to publish my works in this journal.

In which upcoming conferences may our readers meet you?

4th International Conference on Polyolefin Characterization (Houston – October 21-24, 2012)

International Conference on the Reaction Engineering of Polyolefins (Ferrara, Italy, June 17-20 2013 internet site :  www.incorep.org)

How do you spend your spare time?

I think it is very important to save time for family in spite of our very exiting but also time consuming research work. Playing with my children, cooking and running are my favourite spare time hobbies.

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

My father was a chef, I will certainly enjoy creating my own dishes which I could taste contrary to chemicals.

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Sébastien Perrier joins the Polymer Chemistry Editorial Board

Professor Sébastien Perrier We are delighted to announce that Professor Sébastien Perrier (University of Sydney, Australia) has joined the Polymer Chemistry Editorial Board.

Professor Perrier expressed his pleasure at becoming a member of the Editorial Board saying: “I am excited to join the Editorial Board of Polymer Chemistry. In a very short time, Polymer Chemistry has had a major impact in the field, through the variety and excellent quality of the articles it publishes – I am not surprised it is already so well cited. As a researcher, I am also very impressed by how fast a submission is processed, from submission to publication – this is becoming an important element in our field, and Polymer Chemistry is definitely leading the pack!”

Professor Sébastien Perrier graduated with his PhD in 2002 from the University of Warwick, England, in polymer chemistry. After one year as a postdoctoral fellow at the University of New South Wales, Australia, he was appointed as lecturer at the University of Leeds, UK. In October 2007, he moved to the University of Sydney and was appointed as director of the Key Centre for Polymers & Colloids. Sébastien leads a team of 15-20 researchers working on the design of a wide range of state-of-the-art functional polymeric materials by careful manipulation of their molecular structure. He is a member of the editorial boards of the journals Soft Matter, Macromolecules, European Polymer Journal and Polymer Chemistry, a member of the RACI Polymer Division executive committee (2011 Chair), and was appointed on the Australian Research Council College of Experts in 2011. Awards include the Macro Group UK Young Researcher Award (2006), the Young Tall Poppy Science Award (2009), the Rennie Memorial Medal (2009), and the David Sangster Polymer Science and Technology Award (2009).

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Paper of the Week: Redox-sensitive shell cross-linked PEG–polypeptide hybrid micelles for controlled drug release

Recently, shell cross-linked polymeric micelles have attracted tremendous interest as drug carriers due to their remarkable benefits. In their paper, Zhang and co-workers designed a novel PEG-polypeptide hybrid copolymer, poly(ethylene glycol)-b-poly(L-cysteine)-b-poly(L-phenylalanine) (PEG-b-PCys-b-PPhe), able to: i) self-assemble in aqueous solutions into highly stable core–shell–corona micelles and ii) self-cross-link by the oxidation of thiol groups in the PCys segments. It was shown that these nanoconstructs could be helpful to reduce the drug loss in the extracellular environment and that they could be easily uptaken by HeLa cells, suggesting they may have great potential in intracellular drug delivery.

Redox-sensitive shell cross-linked PEG–polypeptide hybrid micelles for controlled drug release by Kang Wang, Guo-Feng Luo, Yun Liu, Cao Li, Si-Xue Cheng, Ren-Xi Zhuo and Xian-Zheng Zhang Polym. Chem. 20123, 1084-1090.

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Author of the Week: Takuya Yamamoto

Takuya Yamamoto received his PhD in 2004 from the University of Utah where he worked with Prof. Peter J. Stang.  He joined JST ERATO Aida Nanospace Project as a researcher in 2005.  Since 2008, he has been an assistant professor of the Department of Organic and Polymeric Materials, Tokyo Institute of Technology.  He received the Tokyo Tech Young Investigator Engineering Award from Tokyo Institute of technology in 2010, Award for Encouragement of Research in Polymer Science from the Society of Polymer Science, Japan in 2011, and Challenging Research President’s Honorary Award from Tokyo Institute of Technology in 2011.  His current research interests include the synthesis and self-assembly of cyclic polymers for the development of functional materials.

For more information, see: http://www.op.titech.ac.jp/lab/tezuka/ytsite/Japanese/Members/yamamoto.html and http://www.op.titech.ac.jp/lab/tezuka/ytsite/English/Members/yamamoto.html

 

 

What was your inspiration in becoming a chemist?

Many of my relatives are related to scientific professions, and some of them are in chemistry.  Since I was small, I have had opportunity to be exposed to the state-of-the-art technology of the field, which inspired me to pursue my career in chemistry.

What was the motivation behind the research in your recent Polymer Chemistry paper? (DOI: 10.1039/C1PY00475A)

Cyclic polymers are gaining growing interest due to the distinctiveness from linear and branched counterparts by the absence of chain ends, and their unique properties often rely on the particular topology.  Furthermore, cyclic block copolymers constructed by the combination of incompatible segments may provide novel properties and functions upon self-assembly giving rise to the amplification of “topology effects”.  We previously reported that a micelle formed from a poly(butyl acrylate)-b-poly(ethylene oxide) cyclic amphiphile exhibits significantly enhanced thermal stability in comparison with one from a linear counterpart (J. Am. Chem. Soc. 2010, 132, 10251).  This finding is regarded as the first example of an amplified topology effect by a synthetic cyclic polymer upon self-assembly.

To promote further studies on the subject, the development of synthetic process for amphiphilic cyclic polymers is inevitable to provide a variety of cyclic block copolymers having the programmed combination of segment components with narrow PDIs.  In particular, amphiphilic block copolymers with polystyrene segments are of an importance due to their universality and extensive studies on self-assembled structures from linear polystyrene-b-poly(ethylene oxide).  Hence, we expected that relevant cyclic polystyrene-b-poly(ethylene oxide) counterparts could provide unique opportunities to reveal novel topology effects upon self-assembly.

Why did you choose Polymer Chemistry to publish your work?

We were invited to write a review in Polymer Chemistry (“Topological polymer chemistry: a cyclic approach toward novel polymer properties and functions”, Polym. Chem. 2011, 2, 1930), which was selected as one of the top ten most-read articles twice.  To publicize more of our research from the journal, we submitted the original paper.

In which upcoming conferences may our readers meet you?

I will attend the 61st SPSJ Annual Meeting (May 29-31 in Yokohama, Japan), Warwick 2012 (July 9-12 in Warwick, UK), and the 61st Symposium on Macromolecules, SPSJ (Sept. 19-21 in Nagoya, Japan).

How do you spend your spare times?

I jog on weekends and sometimes hang out with my friends.

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

I haven’t thought much about it.  Probably, an ordinary corporate employee.

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