Archive for August, 2012

Paper of the week: Degradable copolymers by ring-opening and reverse addition–fragmentation chain transfer polymerization

Graphical abstract: Degradable graft copolymers by ring-opening and reverse addition–fragmentation chain transfer polymerization

Polymers with a diverse range of properties and applications can be prepared by tailoring polymer topology and composition. Among these polymer architectures, the preparation of graft copolymers has been intensely investigated. In this context, researchers at Warwick University reported on the synthesis and controlled ring-opening polymerization (ROP) of a six membered cyclic carbonate monomer with pendant reversible addition–fragmentation chain transfer (RAFT) functionality. The growth of fast propagating monomers (methyl acrylate, tetrahydropyran acrylate and N-isopropylacrylamide) from the obtained RAFT-functional poly(carbonate)s resulted in the formation of well-defined graft copolymers with a biodegradable backbone. Importantly, control of solution and thermal properties was achieved through variation of graft length, grafting density and grafting monomer. In addition, the preparation and self-assembly of a PNiPAm graft copolymer provided a convenient route to novel thermoresponsive biodegradable micelles.

Degradable graft copolymers by ring-opening and reverseaddition–fragmentation chain transfer polymerization by Rebecca J. Williams, Rachel K. O’Reilly and Andrew P. Dove Polym. Chem20123, 2156-2164.

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Paper of the week: water-dispersible silver-decorated polymer vesicles and micelles with antibacterial efficacy

Graphical abstract: Preparation of water-dispersible silver-decorated polymer vesicles and micelles with excellent antibacterial efficacy

It is well known that silver nanoparticles have excellent antibacterial activities. However, to prepare well-defined, water-dispersible and long-term stable silver nanoparticles still remains a challenge. Presented in this paper are the design and preparation of new water-dispersible silver-decorated polymer vesicles and micelles based on a new kind of amphiphilic block-statistical copolymer synthesized by ATRP: poly(ethylene oxide)-block-poly(2-(dimethylamino)ethyl methacrylate-stat-t-butyl acrylate) (PEO-b-P(DMA-stat-tBA)) and its partially hydrolyzed derivative, poly(ethylene oxide)-block-poly(2-(dimethylamino)ethyl methacrylate-stat-acrylic acid) (PEO-b-P(DMA-stat-AA)). Poly(DMA) is introduced for the coordination of Ag+ ions to form silver nanoparticles in situ upon reduction, whereas poly(AA) is designed to serve the scaffold for the silver nanoparticle formation in the micelle core by electrostatic interactions with Ag+ ions. Those water-dispersible silver-decorated polymer micelles and vesicles showed excellent antibacterial efficacy against Escherichia coli (E. coli) with quite low minimum inhibitory concentration and minimum bactericidal concentration.

Preparation of water-dispersible silver-decorated polymer vesicles and micelles with excellent antibacterial efficacy by Hang Lu, Lang Fan, Qiuming Liu, Jingren Wei, Tianbin Renand Jianzhong Du Polym. Chem. 2012, 3, 2217-2227.

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1st Polymer Chemistry International Symposium

1st Polymer Chemistry International Symposium

The 1st Polymer Chemistry International Symposium will take place in China this year. The purpose of RSC journal symposia is to bring together scientists in a stimulating and friendly environment that will foster collaborations between the researchers and the universities involved in the meetings.

The symposium will comprise of three one-day meetings held at three separate institutions. Each one day meeting will feature talks by Polymer Chemistry international speakers from the journal’s Editorial Board, in addition to a collection of local speakers. The symposium is organised by Polymer Chemistry, the Royal Society of Chemistry and the local host organisations. The meetings will take place at Tsinghua University (Beijing), Suzhou University and Fudan University (Shanghai). 

The symposium will appeal to academic and industrial scientists with an interest in all aspects of synthetic and biological macromolecules. Attendance at the symposium is free of charge and student participation is strongly encouraged. 

See list of speakers…

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Paper of the Week: Design of a platform for the preparation of libraries of functional polymer brushes

Graphical abstract: Synthesis and post-polymerization modification of poly(pentafluorophenyl methacrylate) brushes

Post-polymerization modification is a powerful strategy to endow polymers with functional groups that cannot be incorporated via direct polymerization. In this paper, Klok and co-workers explored the reversible addition–fragmentation chain transfer polymerization (RAFT) of pentafluorophenyl methacrylate (PFMA) to prepare active ester containing polymer brushes and investigated the feasibility and versatility of these reactive thin polymer films towards post-polymerization modification with a variety of amines. Except for the secondary amine diisopropylamine, the sterically demanding aminomethylanthracene and aniline, post-polymerization modification with all other investigated amines proceeded with near to quantitative conversion within 2–20 hours. The high reactivity towards a broad range of amines, combined with a good hydrolytic stability and solubility/swellability in a range of organic solvents makes the PPFMA brushes a very attractive platform for the rapid synthesis of diverse libraries of functional polymer brushes via post-polymerization modification.

Synthesis and post-polymerization modification of poly(pentafluorophenyl methacrylate) brushes by Kemal Arda Günay, Nicolas Schüwer and Harm-Anton Klok Polym. Chem. 20123, 2186-2192.

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Top 10 most-read Polymer Chemistry articles in June

This month sees the following articles in Polymer Chemistry that are in the top ten most accessed for June:

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

New methods of polymer synthesis 
Christopher Barner-Kowollik, Jean-François Lutz and Sébastien Perrier 
Polym. Chem., 2012, 3, 1677-1679 
DOI: 10.1039/C2PY90007F 

2-(2,3,4,5,6-Pentafluorophenyl)-1H-benzo[d]imidazole, a fluorine-rich building block for the preparation of conjugated polymer donors for organic solar cell applications 
Marios Neophytou, Heraklidia A. Ioannidou, Theodosia A. Ioannou, Christos L. Chochos, Solon P. Economopoulos, Panayiotis A. Koutentis, Grigorios Itskos and Stelios A. Choulis  
Polym. Chem., 2012, 3, 2236-2243 
DOI: 10.1039/C2PY20198D 

Supramolecular three-armed star polymers via cyclodextrin host–guest self-assembly  
Bernhard V. K. J. Schmidt, Tobias Rudolph, Martin Hetzer, Helmut Ritter, Felix H. Schacher and Christopher Barner-Kowollik  
Polym. Chem., 2012, Advance Article 
DOI: 10.1039/C2PY20293J 

UCST-driven self-assembly and crosslinking of diblock copolymer micelles  
Peter J. Roth, Thomas P. Davis and Andrew B. Lowe  
Polym. Chem., 2012, 3, 2228-2235 
DOI: 10.1039/C2PY20204B 

Three new conjugated polymers based on benzo[2,1-b:3,4-b′]dithiophene: synthesis, characterization, photoinduced charge transfer and theoretical calculation studies  
Shaojie Chen, Qiuyu Zhang, Hepeng Zhang, Junwei Gu, Mingliang Ma, Tiejun Xin, Yanyang Zhou, Jian Zhou and Qing Liu  
Polym. Chem., 2012, 3, 2244-2253 
DOI: 10.1039/C2PY20122D 

Diels–Alder “click” reactions: recent applications in polymer and material science  
Mehmet Atilla Tasdelen  
Polym. Chem., 2011, 2, 2133-2145 
DOI: 10.1039/C1PY00041A 

Single-chain polymer nanoparticles via reversible disulfide bridges  
Bryan T. Tuten, Danming Chao, Christopher K. Lyon and Erik B. Berda  
Polym. Chem., 2012, Advance Article 
DOI: 10.1039/C2PY20308A 

Fluorescence resonance energy transfer in recognition-mediated polymer-quantum dot assemblies  
Vikas Nandwana, Brian Fitzpatrick, Qian Liu, Kyril M. Solntsev, Xi Yu, Gülen Yesilbag Tonga, Serkan Eymur, Murat Tonga, Graeme Cooke and Vincent M. Rotello  
Polym. Chem., 2012, Advance Article 
DOI: 10.1039/C2PY20353G 

Photo-responsive systems and biomaterials: photochromic polymers, light-triggered self-assembly, surface modification, fluorescence modulation and beyond  
Francesca Ercole, Thomas P. Davis and Richard A. Evans  
Polym. Chem., 2010, 1, 37-54 
DOI: 10.1039/B9PY00300B 

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: Synthesis and charge-transporting properties of electron-deficient CN2–fluorene based D–A copolymers

Graphical abstract: Synthesis and charge-transporting properties of electron-deficient CN2–fluorene based D–A copolymers

The past decade has witnessed extensive concentration on the synthesis of conjugated polymers and their applications for organic electronic devices due to their low-cost, light-weight, and flexibility compared to their inorganic semiconductor counterparts. Donor–acceptor (D–A) copolymerization is a currently common strategy to design and synthesize potential semiconducting copolymers. In this study, Yao and co-workers reported on the synthesis of four D–A copolymers on the basis of a novel acceptor (A) unit of 9-fluorenylidene malononitrile (CN2–Fluorene) and four common donor (D) units of 9-alkylfluorene (P1), benzodithiophene (P2), bithiophene (P3), and dithienopyrrole (P4). These four copolymers exhibit a weak ICT absorption edge up to 800 nm. The HOMO energy levels of the copolymers are finely tuned by the donor units, while the LUMO energy levels of the copolymers are highly depressed and determined by the CN2–Fluorene unit. The hole mobility of P3 is measured as 1.43 x 10-3 cm2.V-1.s-1 under ambient conditions and that of P2 and P4 is on the order of 10-4 cm2.V-1.s-1. The results reveal that CN2–Fluorene is a new electron-acceptor unit and may be incorporated with proper electron-donors when designing semiconducting D–A copolymers.

Synthesis and charge-transporting properties of electron-deficient CN2–fluorene based D–A copolymers by Jianhua Huang, Yan Zhao, Xunlei Ding, Hui Jia, Bo Jiang, Zhiguo Zhang, Chuanlang Zhan, Shenggui He, Qibing Pei, Yongfang Li, Yunqi Liu and Jiannian Yao Polym. Chem. 20123, 2170-2177.

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Author of the Week: Ulrica Edlund

 

Ulrica Edlund, associate professor and senior lecturer at Fibre and Polymer Technology, KTH, was rewarded a Ph.D. in Polymer Technology in 2000 followed by a post-doctoral fellowship at the University of Pennsylvania, Philadelphia, USA. Since 2002, she is affiliated with KTH at Fibre and Polymer Technology. Her expertise comprises synthesis, surface modification, and characterization of polymeric biomaterials, the design of controlled drug delivery matrices, and the development of functional formulations and materials from renewable resources.

She has contributed to inventing and developing a new, non-destructive, one-step technique for the covalent surface modification of biomaterials. She has also been very active in the design of renewable functional materials for a sustainable future including renewable films, coatings, microspheres, and hydrogel formulations based on more or less purified non-cellulosic oligo- and polysaccharide rich fractions generated in commercial wood processing operations such as pulping (2 patents, 1 pending application).

She has received several awards, including the Nobel Foundation scholarship, and was in 2002 selected as one of the “outstanding young European scientists forming the future European network” by the European Polymer Federation. Ulrica was in 2010 awarded KTHs Teaching Award for outstanding efforts in undergraduate education.

What was your inspiration in becoming a chemist?

Chemistry never fails to intrigue me. Chemical processes are everywhere, in everything and they are what makes us exist. The more you learn about the chemistry, the more you know about the world. Why macromolecular chemistry in particular? Allow me to quote Professor de Gennes (Nobel laurate in 1991) who expressed that so elegantly:

“…it is not only their applications that make polymers so fascinating. The greatest incentive for polymer science is life itself. All the answers to the mystery of life are connected with polymers in one way or another.”

What was the motivation to write your Polymer Chemistry article? (DOI: 10.1039/C2PY20421E)

Protein fouling is a critical problem for the vast majority of biomaterials in contact with biological milleu, in particular blood plasma. So far only polymer based carboxybetaines have successfully prevented this negative event. The development of new materials with non-fouling surfaces is urgently requested in the biomedical materials industry. However, hybrids of biological and synthetic non-fouling polymers require the use of polymerisation techniques accounting for control at the molecular and supramolecular level while avoiding the use of any toxic catalysts or harsh conditions. How, us four co-authors asked ourselves, do we accomplish this and at the same time acknowledge the growing need for green conditions and renewable resources when developing new chemistry?

We have worked for many years with the development of hemicellulose-rich functional materials derived from by-products of the wood processing industry. In addition to being a cheap and renewable bulk material, we have previously shown that hemicellulose can be converted to multi-site initiators that are able to initiate single electron transfer living radical polymerisation (SET-LRP) and produce vinyl-graft-glucopolymers with a molecular brush-like architecture. In the present work, we developed such a macroinitiator as well as the new betaine monomers and combined them to achieve a state-of-the-art SET-LRP of these carboxybetaine monomers in water at room temperature. The prepared grafted copolymers self-assembled in spheres with the antifouling polymer at the external layer. We were excited to find that the assembled copolymers are remarkably stable in water. There are a range of possible bioapplications where the interaction with proteins must be prevented.

Why did you choose Polymer Chemistry to publish your work?

Polymer Chemistry is a relatively new, yet already well established, forum with high quality papers that cover a large span of chemical aspects related to macromolecular systems. Our paper does not really fit into just one corner of polymer chemistry, but addresses new advancements in “living” radical polymerisation, polysaccharide chemistry, self-assembly, as well as the needs for non-fouling biomaterials and renewable functional materials. We felt Polymer Chemistry would be the perfect place to reach a broader audience in both academia and industry and we are excited to have our work published in this journal.

In which upcoming conferences may our readers meet you?

My co-author Ann-Christine Albertsson and I look very much forward to attending the upcoming 244th ACS National Meeting in Philadelphia, USA, August 19-24. Later this year, October 23-25, we will be in Helsinki, Finland, for the Nordic Wood Biorefinery Conference.

How do you spend your spare times?

I have 3 children, three boys (ages 9, 6 and 3) so I do not have one minute of boredom! I am very lucky to enjoy their everyday company and to share their activities and interests, whether it is soccer practice, reading stories, playing computer games, or LEGO constructions. Whenever I can find some time, I play the piano and I also enjoy baking (which is chemistry, really…). I do plenty of experimenting with cakes and cup cakes at home, with the kind and quite messy help of my sons.

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

Oh, there are so many aspects of Natural Science and technology that I would really enjoy digging into. Lately, thanks to my older sons, I read and studied a lot about minerals and rocks, and I find geology very interesting. They also made me discover the fascinating world of dinosaurs. Paleontology, perhaps? In some way, somehow, I think I would still be a scientist.

 

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