Archive for the ‘Paper of the Week’ Category

Paper of the week: Efficient microencapsulation of a liquid isocyanate with in situ shell functionalization

Nguyen et al. outline the efficient microencapsulation of a liquid isocyanate with in situ shell functionalization.

Nguyen et al. report on a one-pot, facile approach for the encapsulation of the liquid hexamethylene diisocyanate isocyanurate trimer in polyurea microcapsules formed via the oil-in-water interfacial reaction of an uretonimine-modified diphenyl methane diisocyanate trimer with triaminopyrimidine; with in situ shell functionalization/modification using different types of hydrophobic agents. Remarkably, the use of hexamethylenedisilazane resulted in microcapsules of about 70 μm in diameter, with a smooth outer surface and a high isocyanate core content up to 85 wt% as determined by quantitative online FT-IR analysis of the extracted core. On the other hand, the use of an alkylamine, fluorinated aromatic amine and/or perfluoride amine provided microcapsules of approximately 100 to 150 μm in diameter containing around 65–75 wt% of the isocyanate core content, with the outer shell surface bearing pendant hydrophobic groups as confirmed by SEM-EDX. The effects of the functionalizing compound on the microcapsule properties such as shell morphology, size distribution and stability were assessed. After one day immersion in water, the initial isocyanate content of the microcapsules with a non-functionalized shell dropped rapidly from 49 to 15 wt%, whereas the ones with the modified shell structure maintained their core content, suggesting a significantly enhanced microcapsule stability.

Efficient microencapsulation of a liquid isocyanate with in situ shell functionalization by Le-Thu T. Nguyen, Xander K. D. Hillewaere, Roberto F. A. Teixeira, Otto van den Berg and Filip E. Du Prez, Polym. Chem., 2015, 6, 1159-1170.

Remzi Becer is a web-writer and Advisory Board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: Highly regioselective Pd/C-catalyzed direct arylation toward thiophene-based π-conjugated polymers

Hayashi et al. have successfully developed a highly regioselective Pd/C-catalysed direct arylation toward thiophene-based π-conjugated polymers.

Pd/C heterogeneous catalysts were used in the direct arylation polycondensation of thiophenes. The efficient and highly regioselective polycondensation of thiophene monomers was achieved under phosphine-free conditions to give linear π-conjugated alternating copolymers with high molecular weight in high yield.

Highly regioselective Pd/C-catalyzed direct arylation toward thiophene-based π-conjugated polymers by Shotaro Hayashi, Yoshihisa Kojima and Toshio Koizumi Polym. Chem., 2015,6, 881-885.

Remzi Becer is a web-writer and Advisory Board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: Novel polymer synthesis methodologies using combinations of thermally- and photochemically-induced nitroxide mediated polymerization

Guillaneuf and Gigmes and co-workers discuss novel polymer synthesis methodologies using combinations of thermally- and photochemically-induced nitroxide mediated polymerization

The combination of thermally- and photochemically-induced polymerization using light-sensitive alkoxyamines was investigated. The thermally driven polymerizations were performed via the cleavage of the alkoxyamine functionality, whereas the photochemically-induced polymerizations were carried out either by nitroxide mediated photo-polymerization (NMP2) or by a classical type II mechanism, depending on the structure of the light-sensitive alkoxyamine employed. Once the potential of the various structures as initiators of thermally- and photo-induced polymerizations was established, their use in combination for block copolymer syntheses was investigated. With each alkoxyamine investigated, block copolymers were successfully obtained and the system was applied to the post-modification of polymer coatings for application in patterning and photografting.

Novel polymer synthesis methodologies using combinations of thermally- and photochemically-induced nitroxide mediated polymerization by Jason Morris, Sofia Telitel, Kathryn E. Fairfull-Smith, Steven E. Bottle, Jacques Lalevée, Jean-Louis Clément, Yohann Guillaneuf and Didier Gigmes Polym. Chem., 2015,6, 754-763

Remzi Becer is a web-writer and Advisory Board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: The power of one-pot: a hexa-component system containing π–π stacking, Ugi reaction and RAFT polymerization for simple polymer conjugation on carbon nanotubes

Yang et al. have developed a one pot approach to prepare polymer-carbon nanotube conjugates.

A hexa-component system has been successfully developed for simple polymer conjugation on carbon nanotubes. The well-known Ugi reaction has been recognized as a multicomponent click (MCC) reaction to efficiently collaborate with π–π stacking and RAFT polymerization to construct this delicate one-pot system. The CNT–(co)polymer composites inherit the properties of the conjugated polymers and can be well dispersed in both organic and aqueous solvents. As a simple and efficient method, this one-pot system might have the potential to become a general approach to prepare carbon-based composites.

The power of one-pot: a hexa-component system containing π–π stacking, Ugi reaction and RAFT polymerization for simple polymer conjugation on carbon nanotubes by Bin Yang, Yuan Zhao, Xu Ren, Xiaoyong Zhang, Changkui Fu, Yaling Zhang, Yen Wei and Lei Tao, Polym. Chem., 2015,6, 509-513.

Remzi Becer is a web-writer and Advisory Board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: Precise one-pot synthesis of fully conjugated end-functionalized star polymers containing poly(fluorene-2,7-vinylene) (PFV) arms

Nomura et al. present the one-pot synthesis of star shaped conjugated polymers.

A facile, precise one-pot synthesis of end-functionalized star (triarm) polymers consisting of poly(9,9-di-n-octylfluorene-2,7-vinylene)s (PFVs), the triblock copolymers [by incorporation of tri(2,5-dialkoxy-1,4-phenylene vinylene) or terthiophene units as the middle segment], has been achieved by olefin metathesis followed by Wittig-type coupling. Effects of the PFV conjugation length, the middle segment and the end groups on the emission properties have been studied.

Precise one-pot synthesis of fully conjugated end-functionalized star polymers containing poly(fluorene-2,7-vinylene) (PFV) arms by Kotohiro Nomura, Tahmina Haque, Tomohiro Miwata, Akiko Inagaki and Kenji Takamizu Polym. Chem., 2015,6, 380-388

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: Amphiphilic/fluorous random copolymers as a new class of non-cytotoxic polymeric materials for protein conjugation

Koda et al have developed amphiphilic/fluorous random copolymers bearing poly(ethylene glycol) (PEG) chains and perfluorinated alkane pendants as novel non-cytotoxic polymers for protein conjugation.

Three kinds of random copolymers with different initiating terminals (carboxylic acid, pyridyl disulfide, and N-hydroxysuccinimide ester) were prepared by reversible addition–fragmentation chain transfer (RAFT) copolymerization of a PEG methyl ether methacrylate and a perfluorinated alkane methacrylate with the corresponding functional chain transfer agents. All of the polymers were soluble in water to form nanostructures with perfluorinated compartments via fluorous interaction: large aggregates from the intermolecular multi-chain association and compact unimer micelles from the intramolecular single-chain folding. Such a PEGylated and perfluorinated random copolymer was non-cytotoxic to NIH 3T3 mouse embryonic fibroblast cells and human umbilical vein endothelial cells (HUVECs). Additionally, a random copolymer with a pyridyl disulfide terminal was also successfully conjugated with a thiolated lysozyme.

Amphiphilic/fluorous random copolymers as a new class of non-cytotoxic polymeric materials for protein conjugation by Yuta Koda, Takaya Terashima, Mitsuo Sawamoto and  Heather D. Maynard Polym. Chem., 2015,6, 240-247.

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: RAFT-prepared α-difunctional poly(2-vinyl-4,4-dimethylazlactone)s and their derivatives

Quek et al present the synthesis and effect of end-groups on aqueous inverse temperature solubility of these polymers

A series of five novel R-group di-functional phenyl dithiobenzoates have been prepared and utilized in the controlled reversible addition–fragmentation chain transfer (RAFT) radical polymerization of 2-vinyl-4,4-dimethylazlactone (VDMA), yielding a series of homopolymers of similar average degrees of polymerization but variable α-end group functionality. Each of the reactive polyVDMA homopolymers was reacted with four different small molecule amines: dimethylamine, diethylamine, N,N-diethylethylenediamine and tetrahydrofurfurylamine yielding a series of novel end-functional materials. The effect of the end-groups on the inverse temperature dependent aqueous solubility of the formally hydrophilic homopolymers was then measured and compared to similar materials prepared with benzylpropyltrithiocarbonate as the RAFT agent. In virtually all instances, the introduction of the twin α-end-groups resulted in overall more hydrophobic species that exhibited cloud points spanning the range 25.1–42.7 °C. Importantly, there was a strong influence on the nature of the end groups and the associated solubility characteristics with, in some cases, cloud point behaviour only being observed in polymers with twin end groups while those derived from benzylpropyltrithiocarbonate were fully soluble.

RAFT-prepared α-difunctional poly(2-vinyl-4,4-dimethylazlactone)s and their derivatives: synthesis and effect of end-groups on aqueous inverse temperature solubility by Jing Yang Quek, Xuechao Liu, Thomas P. Davis, Peter J. Roth and Andrew B. Lowe Polym. Chem., 2015,6, 118-127

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: Pristine and thermally rearranged gas separation membranes

Ma et al present the pristine and thermally rearranged gas separation membranes.

A novel o-hydroxyl-functionalized spirobifluorene-based diamine monomer, 2,2′-dihydroxyl-9,9′-spirobifluorene-3,3′-diamine (HSBF), was successfully prepared by a universal synthetic method. Two o-hydroxyl-containing polyimides, denoted as 6FDA-HSBF and SPDA-HSBF, were synthesized and characterized. The BET surface areas of 6FDA-HSBF and SPDA-HSBF are 70 and 464 m2 g−1, respectively. To date, SPDA-HSBF exhibits the highest CO2 permeability (568 Barrer) among all hydroxyl-containing polyimides. The HSBF-based polyimides exhibited higher CO2/CH4 selectivity than their spirobifluorene (SBF) analogues (42 for 6FDA-HSBF vs. 27 for 6FDA-SBF) due to an increase in their diffusivity selectivity. Polybenzoxazole (PBO) membranes obtained from HSBF-based polyimide precursors by thermal rearrangement showed enhanced permeability but at the cost of significantly decreased selectivity.

Pristine and thermally-rearranged gas separation membranes from novel o-hydroxyl-functionalized spirobifluorene-based polyimides by Xiaohua Ma, Octavio Salinas, Eric Litwiller and Ingo Pinnau Polym. Chem., 2014,5, 6914-6922.

DOI: 10.1039/C4PY01221F

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: Oximes as reversible links in polymer chemistry

Mukherjee et al presented the preparation of dynamic star shaped polymers using oximes as reversible links.


Summerlin and his co-workers have demonstrated the formation of oxime-functional macromolecular stars that are able to dissociate and reconstruct themselves upon application of a stimulus. The reversible nature of the oxime bond in the presence of externally added alkoxyamines or carbonyl compounds enables reconfiguration via competitive exchange. Reversible addition–fragmentation chain transfer (RAFT) polymerization was utilized to prepare well-defined amphiphilic block copolymers in which a hydrophobic keto-functional block allowed self-assembly into micelles in water. Adding a difunctional alkoxyamine small molecule to these solutions resulted in crosslinking of the micelles to yield macromolecular stars. The reversible nature of the O-alkyl oxime linkages was demonstrated via competitive exchange with excess of carbonyl compounds or monofunctional alkoxyamine under acidic conditions and at elevated temperatures to result in dissociation of the stars to unimolecular oxime-functional polymer chains.

Oximes as reversible links in polymer chemistry: dynamic macromolecular stars by Soma Mukherjee, Abhijeet P. Bapat, Megan R. Hill and  Brent S. Sumerlin Polym. Chem., 2014,5, 6923-6931.

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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Paper of the week: Fluorescent PEGylation agent by a thiolactone-based one-pot reaction

One pot preparation of fluorescent PEGylated proteins by a thiolactone reaction to be used in theranostic applications has been reported by Zhao et al.

Theranostic combinations usually contain an imaging, a therapeutic and a cloaking component to simultaneously fulfil diagnostic and therapeutic functions. Using upgraded PEGylation technology, a straightforward one-pot strategy based on thiolactone ring-opening has been developed to facilely synthesize a multifunctional PEGylation agent, fluorescent protein-reactive poly(ethylene glycol) (PEG), which can subsequently react with a model therapeutic protein to form a fluorescent PEGylated protein as a model of sophisticated theranostic combinations.

Fluorescent PEGylation agent by a thiolactone-based one-pot reaction: a new strategy for theranostic combinations by Yuan Zhao, Bin Yang, Yaling Zhang, Shiqi Wang, Changkui Fu, Yen Wei and   Lei Tao Polym. Chem., 2014,5, 6656-6661

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

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