Archive for October, 2013

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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Alcoholic drinks perfect solvents for polymerisation: Polymer Chemistry article featured in Chemistry World

Alcoholic drinksInternational researchers have gone through the contents of their liquor cabinets to see if alcoholic drinks make good solvents for single-electron transfer living radical polymerisation (SET-LRP). And the answer is an unequivocal yes.

‘Everything worked’, says David Haddleton, leader of the 26 person team at the University of Warwick in the UK. Pimm’s, Guinness, Ouzo and a homemade Romanian brandy were just some of the beverages tested with everyone contributing something from their homeland.

SET-LRP is a technique used for the ultrafast synthesis of certain linear polymers, in this case polymers of N-isopropylacrylamide (NIPAM). ‘Living radical polymerisation has seen impressive developments over the past few years – the most attractive features of these systems are the fact that the livingness, or end-functionality, remains very high to essentially full conversion, which has enabled synthesis of complex high-order multiblock copolymers in recent previous work, as well as the typically very high polymerisation rate,’ explains Per Zetterlund, a radical polymerisation expert from the University of New South Wales in Australia. Zetterlund says Haddleton’s findings further demonstrate the robustness and versatility of the technique. 

Interested to know more? Read the full article in Chemistry World here…

Absolut “copper catalyzation perfected”; robust living polymerization of NIPAM: Guinness is good for SET-LRP
David M. Haddleton et al.
Polym. Chem.,
2014, Advance Article
DOI: 10.1039/C3PY01075A, Communication

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

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Paper of the week: Healable supramolecular polymer nanocomposite films

Healable polymeric materials have received increasing interest in recent years with the ultimate aim of improving the resilience of safety-critical components. Two distinct classes of materials have been developed – autonomously healing systems that repair in response to the fracture damage itself and healable materials that require an external intervention to promote healing. One of the major deficiencies of many supramolecular materials is that, in order to achieve healing at accessible temperatures and within usable timeframes, the materials are frequently elastomeric in nature with glass transition temperature well below ambient. These properties preclude the use of most supramolecular materials as structural components in high-value engineering applications such as in the aerospace industry.

Graphical abstract: Molecular recognition between functionalized gold nanoparticles and healable, supramolecular polymer blends – a route to property enhancement

Inspired by the success of polymer-composite materials in replacing metals across a range of high value products, Hayes and co-workers have investigated the possibility of producing nanoparticle-reinforced, supramolecular, healable composites. The material comprises a blend of three components: a pyrene-functionalized polyamide, a polydiimide and pyrene-functionalized gold nanoparticles (P-AuNPs). The polymeric components interact by forming well-defined π–π stacked complexes between π-electron rich pyrenyl residues and π-electron deficient polydiimide residues. Complexation studies in solution demonstrate that the introduction of P-AuNPs results in more rapid formation of an insoluble supramolecular network when compared to control samples that did not contain the P-AuNPs. Films of the nanocomposite are tough and flexible, and contain a relatively homogeneous dispersion of P-AuNPs. Films containing P-AuNPs are stronger and stiffer than those cast from the same polymers but without P-AuNPs, and also than films containing AuNPs that lacked the pyrenyl motif. Healing studies using a classic break/heal test, followed by stress–strain analysis, showed that materials containing up to 10 wt% P-AuNPs can even exhibit healing efficiencies of more than 100%.

Molecular recognition between functionalized gold nanoparticles and healable, supramolecular polymer blends – a route to property enhancement by Rajendran Vaiyapuri, Barnaby W. Greenland, Howard M. Colquhoun, Joanne M. Elliott and Wayne Hayes, Polym. Chem. 2013, 4, 4902-4909.

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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Introducing Polymer Chemistry Associate Editor Christopher Barner-Kowollik

Christopher Barner-Kowollik completed a Dr. rer. nat. in Physical Chemistry at the University of Göttingen, before joining the Centre for Advanced Macromolecular Design (CAMD) at the University of New South Wales (Sydney), where he led a research team as full professor, after holding ranks from post-doctoral fellow to associate professor. He is currently a full professor of macromolecular chemistry at the Karlsruhe Institute of Technology (KIT). 

Christopher’s main research interests are situated at the interface of organic, polymer and bio-chemistry and focus on a wide range of polymer-related research fields such as the synthesis of complex macromolecular architectures with highly-defined functionality and composition via living/controlled polymerization protocols, advanced synthesis via polymer conjugation techniques and macromolecular transformations at ambient temperature including light triggered methodologies, fundamental investigations into polymerization mechanisms and kinetics as well as high resolution imaging and characterization of macromolecular chain structures. Applications include high definition surface modification and nano-engineering for targeted cell attachment, biomimetic materials ranging from adhesives to routes to self-folding polymer chains, surface and solution bonding/debonding on demand systems, supramolecular chemistry with polymer strands as well as advanced biosubstrate functionalization.

Christopher’s recent papers include:

Dual thermo- and photo-responsive micelles based on miktoarm star polymers
Eva Blasco, Bernhard V. K. J. Schmidt, Christopher Barner-Kowollik, Milagros Piñol and Luis Oriol  
Polym. Chem., 2013, 4, 4506-4514 DOI: 10.1039/C3PY00576C

Fast and catalyst-free hetero-Diels–Alder chemistry for on demand cyclable bonding/debonding materials
Kim K. Oehlenschlaeger, Nathalie K. Guimard, Josef Brandt, Jan O. Mueller, Ching Yeh Lin, Stefan Hilf, Albena Lederer, Michelle L. Coote, Friedrich G. Schmidt and Christopher Barner-Kowollik  
Polym. Chem., 2013, 4, 4348-4355 DOI: 10.1039/C3PY00476G

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, Review Article

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