Polymer Chemistry Blog

2016 Polymer Chemistry Lectureship awarded to Feihe Huang

14 Mar 2016

It is with great pleasure that we announce Professor Feihe Huang (Zhejiang University) as the recipient of the 2016 Polymer Chemistry Lectureship award.

This award, now in its second year, honours an early-stage career researcher who has made significant contribution to the polymer chemistry field. The recipient is selected by the Polymer Chemistry Editorial Board from a list of candidates nominated by the community.

Read on to find out more about Feihe…

Feihe Huang was born in Shaodong, Hunan, China in February 1973. He obtained his Doctor of Philosophy in Chemistry during the spring of 2005 with the aid and guidance of Prof. Harry W. Gibson. He joined Prof. Peter J. Stang’s group in University of Utah as a postdoctoral fellow in March 2005. In December 2005, he became a professor of chemistry in Department of Chemistry at Zhejiang University. In March 2008, he became a Qiushi Chair Professor of Zhejiang University.

His current research interests are supramolecular polymers, amphiphiles, and pillararene supramolecular chemistry. Awards and honors he has received to date include the William Preston Award for a MS Thesis from VT, Chinese Government Award for Outstanding Self-Financed Students Abroad, The Sigma Xi Research Award for Ph.D. Degree Candidates from the VT Chapter of Sigma Xi Research Society, Outstanding Ph.D. Dissertation Award from VT, the Thieme Chemistry Journals Award, the Outstanding Recent Graduate Alumnus Award from VT, Humboldt Fellowship for Experienced Researchers from the Humboldt Foundation, The National Science Fund (China) for Distinguished Young Scholars winner, Fellow of the Royal Society of Chemistry, Asian Chemical Congress Asian Rising Star, the Chinese Chemical Society AkzoNobel Chemical Sciences Award, the Cram Lehn Pedersen Prize in Supramolecular Chemistry, and the 2016 Polymer Chemistry Lectureship award.

He has published more than 180 supramolecular chemistry papers in Nature Chem. (1), PNAS (2), J. Am. Chem. Soc. (23), Angew. Chem., Int. Ed. (5), Adv. Mater. (6), Nature Commun. (1), Chem. Soc. Rev. (5), Acc. Chem. Res. (4), Prog. Polym. Sci. (1), etc. His publications have been cited more than 11255 times. His h-index is 59. He has served as a guest editor for Chem. Soc. Rev., Acc. Chem. Res., Chem. Rev. and Chem. Commun.

He sits on the Advisory Boards of Chem. Soc. Rev., Chem. Commun., Acta Chim. Sinica, Macromolecules, ACS Macro Lett., and Polym. Chem. and Editorial Boards of Materials Chemistry Frontiers (2016-) and Acta Polymerica Sinica (2016-). The homepage of his research group is http://www.chem.zju.edu.cn/~huangfeihe/index.php

To learn more about Feihe’s research, please see the following for his recent work in Polymer Chemistry:

Facile construction of fluorescent polymeric aggregates with various morphologies by self-assembly of supramolecular amphiphilic graft copolymers
Xiaofan Ji, Yang Li, Hu Wang, Run Zhao, Guping Tang and Feihe Huang
Polym. Chem., 2015, 6, 5021-5025

A double supramolecular crosslinked polymer gel exhibiting macroscale expansion and contraction behavior and multistimuli responsiveness
Xiaofan Ji, Kecheng Jie, Steven C. Zimmerman and Feihe Huang
Polym. Chem., 2015, 6, 1912-1917

Construction of muscle-like metallo-supramolecular polymers from a pillar[5]arene-based [c2]daisy chain
Lingyan Gao, Zibin Zhang, Bo Zheng and Feihe Huang
Polym. Chem., 2014, 5, 5734-5739

Keep your eyes peeled for Feihe’s upcoming Polymer Chemistry article in honour of the Lectureship award.

We would like to thank everybody who nominated a candidate for the Lectureship; we received many excellent nominations, and the Editorial Board had a difficult task in choosing between some outstanding candidates.

Please join us in congratulating Feihe by adding your comments below!

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Focus on: Redox-Responsive Polymers

07 Mar 2016

By Fiona Hatton.

Stimuli-responsive polymers exhibit interesting changes in chemical and/or physical properties with exposure to external stimuli which has lead to considerable research into this area of polymer chemistry. Various types of stimuli reported include: light, temperature, pH, mechanical and redox environment. In some cases polymeric materials can be responsive to more than one of these stimuli and as such are dual or multi-responsive. Various redox-responsive polymers have been reported in Polymer Chemistry this month, highlighted below, with applications ranging from sensing, nanolithography and magnetic devices to drug delivery applications.

Table of contents figure: Redox-controlled upper critical solution temperature behaviour of a nitroxide containing polymer in alcohol–water mixtures

1. Redox-controlled upper critical solution temperature behaviour of a nitroxide containing polymer in alcohol–water mixtures, Olivier Bertrand, Alexandru Vlad, Richard Hoogenboom, Jean-François Gohy, Polym. Chem., 2016, 7, 1088-1095.

The authors present the synthesis of poly(TEMPO methacrylate) which exhibited UCST behaviour in water/alcohol mixtures. The UCST could be tuned through the water/alcohol ratio as well as which alcohol was used. Oxidation of the nitroxide radical to the oxoammonium cation could be achieved chemically or electrochemically and with increasing oxidation the UCST was decreased. The polymer shows promise for sensing applications.

2. One for all: cobalt-containing polymethacrylates for magnetic ceramics, block copolymerization, unexpected electrochemistry, and stimuli-responsiveness, C. Rüttiger, V. Pfeifer, V. Rittscher, D. Stock, D. Scheid, S. Vowinkel, F. Roth, H. Didzoleit, B. Stühn, J. Elbert, E. Ionescu, M. Gallei, Polym. Chem., 2016, 7, 1129-1137.

A cobalt containing methacrylate was prepared and polymerized by different techniques to form homopolymer and block copolymers. The homopolymers were heated under nitrogen to give magnetic cobalt oxide. The block copolymers were investigated for their reversible reduction and oxidation which lead to the formation of micelles with varying the oxidation state of the cobalt. The polymers have potential in nanolithography and magnetic devices based on soft polymer templates.

3. Oxidation and temperature dual responsive polymers based on phenylboronic acid and N-isopropylacrylamide motifs, Mei Zhang, Cheng-Cheng Song, Ran Ji, Zeng-Ying Qiao, Chao Yang, Fang-Yi Qiu, De-Hai Liang, Fu-Sheng Du, Zi-Chen Li, Polym. Chem., 2016, 7, 1494-1504.

NIPAM and a phenylboronic pinacol ester containing monomer were polymerised to give diblock copolymers, with tunable LCSTs. Triblock copolymers were also prepared with PEG which self-assembled into micelles at 37 °C. The micelles were loaded with doxorubicin and triggered release was achieved through oxidation and elimination of the phenylboronic acid unit. These dual-responsive micelles may have applications in the treatment of inflammation-related diseases or cancers.

Dr. Fiona Hatton is a Web Writer for Polymer Chemistry. She is currently a postdoctoral researcher at KTH Royal Institute of Technology, Sweden, having completed her PhD in the Rannard group at the University of Liverpool, UK. Visit her webpage for more information.

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Polymer Chemistry welcomes new Associate Editor Hong Chen and new Advisory Board members!

25 Feb 2016

By Hugh Cowley, Development Editor.

We are delighted to welcome Professor Hong Chen (Soochow University, China) to the PolymerChemistry Editorial Board as an Associate Editor, as well as our new Advisory Board members.

Leading the Macromolecules and Biointerface Lab (MacBio), a key laboratory at Soochow University, Hong’s research interests include surface modification and functionalisation of biomaterials, interactions between biomaterials and proteins or cells, the hemocompatibility of biomaterials, and biological detection.

An experienced editor, Hong was previously a member of the Polymer Chemistry Advisory Board. She has made a significant contribution to the field and to the journal, and we are very excited to have her take a leading role in the Polymer Chemistry team!

As a Polymer Chemistry Associate Editor, Hong will be handling submissions to the journal. Why not submit your next paper to her Editorial Office?

To find out more about Hong’s research, take a look at her recent Polymer Chemistry papers:

Efficient cancer cell capturing SiNWAs prepared via surface-initiated SET-LRP and click chemistry
Lulu Xue, Zhonglin Lyu, Yafei Luan, Xinhong Xiong, Jingjing Pan, Gaojian Chen and Hong Chen
Polym. Chem., 2015, 6, 3708-3715

Facile synthesis, sequence-tuned thermoresponsive behaviours and reaction-induced reorganization of water-soluble keto-polymers
Xianghua Tang, Jie Han, Zhengguang Zhu, Xinhua Lu, Hong Chen and Yuanli Cai
Polym. Chem., 2014, 5, 4115-4123

Combining surface topography with polymer chemistry: exploring new interfacial biological phenomena
Dan Li, Qing Zheng, Yanwei Wang and Hong Chen
Polym. Chem., 2014, 5, 14-24

We also warmly welcome our new Advisory Board members to the Polymer Chemistry team:

Matthew Becker, University of Akron, USA
Xuesi Chen, Chinese Academy of Sciences, China
Didier Gigmes, Aix-Marseilles Université, CNRS, France
Sophie Guillaume, Institut des Sciences Chimiques de Rennes, France
Thomas Junkers, Hasselt University, Belgium
Toyoji Kakuchi, Hokkaido University, Japan
Jacques Lalevée, Institut de Science des Matériaux de Mulhouse, France
Guey-Sheng Liou, National Taiwan University, Taiwan
Ravin Narain, University of Alberta, Canada
Felix Schacher, Friedrich-Schiller-University Jena, Germany
Lei Tao, Tsinghua University, China
Yusuf Yagci, Istanbul Technical University, Turkey

The full Polymer Chemistry team can be found on our website.

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Paper of the month: pH-Sensitive nanogates based on poly(L-histidine) for controlled drug release from mesoporous silica nanoparticles.

18 Feb 2016

By Athina Anastasaki, Web Writer.

Bilalis et al. report the design and synthesis of novel pH-sensitive nanogates based on poly(L-histidine) from mesoporous silica nanoparticles.

The development of novel drug delivery materials necessitates the combination of the knowledge from different scientific fields, including organic and inorganic chemistry. Among the wide range of hybrid organic/inorganic materials, mesoporous silica nanoparticles (MSNs) have attracted considerable attention thanks to their unique characteristics such as high surface area, large specific volume, controllable pore diameter, facile surface functionalization and nontoxicity. On the other hand, polypeptide-coated silica-based systems, including poly(L-histidine) (PHis), have shown great promise in preventing untimely release of drugs and as such the combination of PHis and MSNs can provide an excellent template for the design of advanced drug delivery systems for controlled release applications. To this end, Iatrou, Bilalis and co-workers have exploited surface-initiated ring-opening polymerization (ROP) to synthesize novel pH-sensitive poly(L-histidine)-grafted mesoporous silica nanoparticles through an amino-functionalized MSN intermediate. The successful grafting of the homopolypeptide chains from the surface of MSNs was demonstrated by Fourier Transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) while size exclusion chromatography (SEC) confirmed the controlled character of the polymerization. Dynamic light scattering (DLS) and zeta potential analysis were also employed to ascertain the pH-responsive nature of the polypeptide-gated MSNs. In addition, drug loading and release studies were performed in order to verify the role of the grafted PHis chains as pH-sensitive nanogates for the MSN pores utilizing the model anticancer drug doxorubicin (DOX). DOX was efficiently loaded within the nanochannels of the hybrid MSN@PHis (~90%) and the drug entrapment and release pattern were proved to be pH-dependent with exert stability at physiological pH. The combination of the positive characteristics of MSNs and poly(L-histidine) enables the described materials as promising drug nanocarriers with potential in vitro and in vivo applications.

Tips/comments directly from the authors:

It is really important to strictly maintain the reported time of reaction during the synthesis of MSNs using TEOS. Longer or less time of reaction will lead to larger or smaller nanoparticles, respectively.
It should be noted that the functionalization of the surface of MSNs with APTES was conducted before the removal of CTAB so as to avoid the grafting of PHis chains from the MSN nanopores.
When following the reported functionalization procedure, a LiOH solution must be used in order to remove HCl traces from the amino groups of MSNs after the removal of CTAB.
The loading procedure of DOX into the MSN nanopores should take place at acidic pH (3.0). In that way the maximum drug encapsulation is ensured, because the PHis nanogates are in an opened state (fully protonated and thus hydrophilic).

pH-Sensitive nanogates based on poly(L-histidine) for controlled drug release from mesoporous silica nanoparticles by P. Bilalis, L.-A. Tziveleka, S. Varlas and H. Iatrou, Polym. Chem., 2016, 7, 1475-1485, DOI: 10.1039/C5PY01841B

Dr. Athina Anastasaki is a Web Writer for Polymer Chemistry. She is currently an Elings fellow working alongside Professor Craig Hawker at the University of California, Santa Barbara (UCSB). Please, visit her webpage for more information.

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Focus on: Polymeric Composite Materials

28 Jan 2016

By Fiona Hatton.

A composite material contains two or more constituents which when combined afford significantly different material properties than the individual components. Well-known composites include concrete, plywood and fibre-reinforced plastics. With regard to polymeric composite materials, they usually consist of fillers dispersed in a polymer matrix to improve desired mechanical properties of the polymer material. Recently, research efforts have also focused on nanocomposites, where the filler has at least one dimension in the nano-scale, for example, nanoparticles, carbon nanotubes, 2D-sheets, such as graphene oxide, and nanofibres. These nano-fillers have shown huge improvements to material properties at low mass fractions, primarily due to the high surface area to volume ratio that nanomaterials possess. The increased interfacial area between the nanomaterial and continuous polymer matrix results in increased polymer-filler strength. Various applications have been proposed for nanocomposites: biomedical applications, waste water treatment, structural materials to name but a few.

Each of the highlighted articles this month report polymeric nanocomposites with improved properties such as increased strength, thermal stability, and desired adsorption behaviour when compared to the non-composite materials.

ToC image for article 1

1. Enhancement of the crosslink density, glass transition temperature, and strength of epoxy resin by using functionalized graphene oxide co-curing agents, Jin Won Yu, Jin Jung, Yong-Mun Choi, Jae Hun Choi, Jaesang Yu, Jae Kwan Lee, Nam-Ho You, Munju Goh, Polym. Chem., 2016, 7, 36-43.

Graphene oxide (GO) was incorporated into epoxy resins through functionalisation of the edge of the GO with amino groups, subsequently utilised for reaction with epoxy groups present in the polymer matrix. The incorporation of the modified GO into the resin improved the tensile strength and thermal properties of the materials. Higher crosslinking densities were also observed due to the covalent linking of the GO thanks to the amino groups introduced.

2. Tailored high performance shape memory epoxy–silica nanocomposites. Structure design, S. Ponyrko, R. K. Donato, L. Matějka, Polym. Chem., 2016, 7, 560-572.

The authors describe the preparation of epoxy resins containing silica nanoparticles and shape memory behavior of the materials was investigated. The materials were prepared through in situ generation of nanosilica within the epoxy resin. The stimuli utilized for the shape memory behavior was temperature, exploiting the visco-elastic behavior of the epoxy resin. The results contribute to improved understanding of this type of shape memory materials.

3. A core–shell structure of polyaniline coated protonic titanate nanobelt composites for both Cr(VI) and humic acid removal, Tao Wen, Qiaohui Fan, Xiaoli Tan, Yuantao Chen, Changlun Chen, Anwu Xu, Xiangke Wang, Polym. Chem., 2016, 7, 785-794.

Core-shell polyaniline/hydrogen titanate nanobelt composites were prepared through in situ oxidative polymerisation which showed excellent absorption of Cr(VI) and humic acid for waste water treatment applications. The mechanisms of the Cr(VI) and humic acid removal were investigated as well as regeneration performance and reusability. The industrial implications on the composites appear promising; showing efficient and cost effective waste water treatment.

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Paper of the month: Lights on! A significant photoenhancement effect on ATRP by ambient laboratory light

25 Jan 2016

By Athina Anastasaki, Web Writer.

Zhang et. al. report a significant photoenhancement effect on classical ATRP and ATRP derivatives by ambient laboratory light.

Since the introduction of atom transfer radical polymerisation (ATRP) by Matyjaszewski and Sawamoto, a large diversity of other copper adjuncts have attracted considerable interest including activator regenerated by electron transfer (ARGET)-ATRP, activator generated by electron transfer (AGET)-ATRP, initiators for continuous activator regeneration (ICAR)-ATRP and single electron transfer living radical polymerisation (SET-LRP). Recently photoinduced copper radical polymerization has also drawn significant attention as CuBr₂, typically referred to as deactivating species, can be reduced in situ generating the active CuBr species in the presence of UV or visible light. In this contribution, Jordan and co-workers investigated on whether the typical laboratory light would have any considerable impact on standard ATRP reactions. Interestingly, the vast majority of the ATRP techniques (with the exception of ARGET-ATRP) demonstrated a remarkable photoenhancement effect by ambient light, originated from common fluorescent lamps. It was observed that when less copper complex is utilized for the polymerizations, a stronger influence of the ambient light in the monomer conversion is evident and this effect was significant even in the presence of additional reducing agents. As a general rule, it was concluded that the slower the polymerization is, the more pronounced the effect of the ambient laboratory light can be. As it was proved that it makes a difference if one is performing an ATRP reaction with the hoods on and off, the effect of the laboratory light on the polymerization can no longer be neglected and the authors encourage the report of the light conditions in typical ATRP experiments in order to ensure the reproducibility.

Tips/comments directly from the authors:

Comments:
In this study, we provide conclusive evidence that common laboratory light especially originating from fluorescence lamps has a significant impact on ATRP. This is most probably one main reason why reproducibility of ATRP reactions are not as it should be which impairs further development of controlled radical polymerization techniques. As shown, the impact of light is different for the different ATRP recipes and will also strongly vary with the:

1. Type of complex formed regarding the metal and the ligands;
2. Quantity/concentration of metal complex formed and surely;
3. Type of illumination (natural light, type of fluorescent lamps installed in the laboratory and light intensity in the reaction vial). Strong influence were found for the “hood light illumination” (see Fig. 1 for description and Fig. 2 for experimental data) which was also very surprising for us. We therefore suggest to check the type of light bulbs/source of light, consider their emission spectra and resulting intensity at the location of the reaction and possibly provide these details in the experimental section to ensure reproducibility.

Tips:
1. The various metal complexes used in ATRP are most probably photosensitive but to a different extent. Thus, the influence of laboratory light will vary.
2. Perform the ATRP reactions always under the same light settings with the same light source and provide details (type of lamp, light intensity at each location of the reaction) in the experimental section.
3. Especially modern fluorescent lamps have a higher emission in the blue range and thus may have a stronger/other influence upon conversion/kinetics of the ATRP. Check the emission spectra of the lamps installed in the laboratory and especially in the chemical fume hoods.

Lights on! A significant photoenhancement effect on ATRP by ambient laboratory light by Tao Zhang Dan Gieseler and Rainer Jordan, Polym. Chem., 2016, 7, 775-779

Dr. Athina Anastasaki is a Web Writer for Polymer Chemistry. She is currently an Elings Fellow working alongside Professor Craig Hawker at the University of California, Santa Barbara (UCSB).Visit her webpage for more information.

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Focus on: Polymers in Catalysis

05 Jan 2016

By Fiona Hatton.

This month, focussing on polymers in catalysis, we look at three articles where catalytic activity has been inferred to a polymer chain through functionalisation of the polymer, or through using the polymer as a support for another catalyst.

In the body, reactions are usually catalysed by enzymes. Mimicking enzyme activity with synthetic polymers has been investigated for several types of enzymes, here, in the first article a polymer was prepared mimicking the activity of S-adenosyl methionine synthetase.

Transition metal catalysis is widely used in the preparation of polymers as well as organic molecules, one major disadvantage is the removal of the catalyst after completion of the reaction. The second article describes a proposed solution to this problem through a thermoresponsive catalytic polymer. In the third article a porous polymer support containing in situ generated gold nanoparticles highlights another route to circumvent the issues with removal of catalytic residues, by utilising solid supported catalysts.

ToC image for article

1. Synthetic polymeric variant of S-adenosyl methionine synthetase, Lakshmi Priya Datta, Binoy Maiti, Priyadarsi De, Polym. Chem., 2015, 6, 7796-7800.

The authors describe the synthesis of a polymer via RAFT and subsequent functionalisation with methionine moeities which mimicked the activity of the enzyme S-adenosyl methionine synthetase. Methionine plays major roles in the biosynthesis of proteins and DNA methylation. The resulting polymer was shown to methylate cytosine in the absence of a methyltransferase enzyme, highlighting the enzyme-like activity of the polymer.

2. A thermoresponsive polymer supporter for concerted catalysis of ferrocene with a ruthenium catalyst in living radical polymerization: high activity and efficient removal of metal residues, Kojiro Fujimura, Makoto Ouchi, Mitsuo Sawamoto, Polym. Chem., 2015, 6, 7821-7826.

With the aim to achieve the efficient removal of metal residues from ruthenium-ferrocene concerted catalysed living radical polymerisation, a thermoresponsive polymer support was prepared containing ruthenium as a catalyst and ferrocene as a cocatalyst. This was used to catalyse the polymerisation of MMA in toluene, and subsequent aqueous washing resulted in the almost quantitative removal of Ru (99.8% removal) and Fe (98.5% removal), showing promise for practical applications.

3. “Clickable” thiol-functionalized nanoporous polymers: from their synthesis to further adsorption of gold nanoparticles and subsequent use as efficient catalytic supports, Benjamin Le Droumaguet, Romain Poupart, Daniel Grande, Polym. Chem., 2015, 6, 8105-8111.

A porous polymeric material was prepared through a channel die processing technique, consisting of PS-b-PLA, where the two blocks were connected through a disulphide linkage. After removal of the PLA block, the remaining thiol groups were utilised in both post-modification “click” reaction and in situ gold nanoparticle (GNP) generation. The porous polymer GNP hybrid catalysed the reduction of 4-nitrophenol to 4-aminophenol with a yield of 68%, and retained this efficiency over 5 runs.

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Paper of the month: Solvent-free mechanochemical synthesis of a bicyclononyne tosylate: a fast route towards bioorthogonal clickable poly(2-oxazoline)s

23 Dec 2015

By Athina Anastasaki, Web Writer.

Glassner et. al. report a new solvent-free mechanochemical synthesis of a bicyclononyne tosylate.

The strain promoted azide-alkyne cycloaddition of cyclooctynes (SPAAC) is a popular bioorthogonal reaction that enables the tracking of biomacromolecules in living systems. Among the various cylooctynes that have been developed for SPAAC reactions, derivatives of bicyclo[6.1.0]non-4-yne (BCN) have attracted considerable interest for a number of reasons including their low hydrophobicity and ability to undergo fast cycloadditions not only with azides but also with nitrones. At the same time, poly(2-oxazoline)s (PAOx) represent a promising class of polymers for biomedical applications that can easily incorporate clickable end-groups by employing functional initiators or terminators. In this paper, Hoogenboom and co-workers present the first mechanochemical synthesis of a BCN tosylate (BCN-OTs) initiator via solvent-free reaction conditions utilizing high speed vibration milling instead of manual grinding. The BCN-OTs was subsequently used for the cationic ring opening polymerization (CROP) of 2-ethyl-2-oxazoline (EtOx) yielding a well-defined polymer and demonstrating controlled/living polymerization features such as narrow molecular weight distributions and high chain end fidelity. This represents a rapid route to prepare defined BCN functionalized PEtOx that can be used for bioorthogonal strain-promoted conjugation reactions. This was successfully demonstrated for the synthesis of a PS-b-PEtOx copolymer and a PEtOx-protein conjugate. As such, BCN-OTs may find potential applications as intermediate in the synthesis of functional BCN derivatives and BCN-PAOx. In addition, the ball-milling methodology utilized for this study is a promising tool for the synthesis of other unstable/highly reactive tosylates.

Tips/comments directly from the authors:

1) KOH and K₂CO₃ should be finely grounded and dried in a vacuum oven prior to use.

2) During the synthesis of BCN-OTs, removal of solvents has to be performed at ambient temperature (turn of the heating bath of the rotary evaporator).

3) BCN-OTs has to be used immediately for the next step because of its limited stability at ambient conditions.

Solvent-free mechanochemical synthesis of a bicyclononyne tosylate: a fast route towards bioorthogonal clickable poly(2-oxazoline)s by M. Glassner, S. Maji, V. de la Rosa, N. Vanparijs, K. Ryskulova, B. De Geest and R. Hoogenboom, Polym. Chem., 2015, 6, 8354-8359

Dr. Athina Anastasaki is a Web Writer for Polymer Chemistry. She is currently a Warwick (UK)/ Monash (Australia) research fellow working under the Monash Alliance. Visit http://haddleton.org/group-members for more information.

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Editorial Board’s Top Picks: Emily Pentzer

04 Dec 2015

By Alice Jensen, Development Editor.

Emily Pentzer is an Associate Editor for Polymer Chemistry and an Assistant Professor of Chemistry at Case Western Reserve University, USA. Her research addresses application-based materials problems in the areas of energy harvesting, management, and storage. She uses synthetic chemistry to tailor molecular design and control self-assembly for the preparation and study of novel conductive materials with controlled domain sizes and interfaces.

You can find all Editorial Board’s Top Picks papers in our web collection.

Focus on PAH building blocks for electronically active and porous polymers (Associate Editor: Prof Emily Pentzer Case Western Reserve University, USA)

Polyaromatic hydrocarbons (PAHs) are attractive building blocks for electronically active and porous organic polymers. For these applications, the preparation and isolation of appropriate polymeric structures is needed to provide the desired properties. PAHs are typically incorporated into conjugated polymers by transition metal-catalyzed cross-coupling reactions, and their solubility and solution processability is ensured by substitution with alkyl groups; recent interest has focused on accessing reduced band gap structures. Alternatively, for the preparation of porous organic polymers, the tendency of PAHs to aggregate through p-p interactions must be overcome, and alkyl groups are disadvantageous for gas adsorption/storage. Recent advances in the design and synthesis of PAH-containing polymers have helped expand the usefulness of these heteroatom-free systems.

1. Anthanthrene as a large PAH building block for the synthesis of conjugated polymers
Antoine Lafleur-Lambert,Jean-Benoît Giguère and Jean-Francois Morin
Polym. Chem., 2015, 6, 4859-4863

Aromatic anthanthrene is readily available from the common dye vat orange 3 and can be used to prepare PAH-containing polymers. Morin and coworkers report the preparation of a series of anthanthrene-based conjugated polymers. The anthanthrene unit has branched alkyl substituents to control solubility and was copolymerized with electron rich and electron poor aryl comonomers. The absorption spectra of these polymers range from 450 to 850 nm, depending on the constituent materials. The series of novel polymers all showed similar LUMO levels, and variation of the HOMO levels show no trends based on the comonomer identity. These results indicate that both the HOMO and the LUMO orbitals are located on the anthanthrene units, and are not heavily influenced by the comonomer identity.

2. Dicyclopenta[cd,jk]pyrene based acceptors in conjugated polymers
Sambasiva R. Bheemireddy and Kyle N. Plunkett
Polym. Chem., 2016, Advance Article

In this study, Plunkett and Bheemireddy report the use of the PAH dicyclopentapyrene, as an acceptor unit in conjugated polymers. This alkylated monomer was copolymerized with various electron donor comonomers including thiophene, bithiophene, and diethynyl benzene. In the thin film, these polymers show broad absorption profiles, from ~320-720 nm, corresponding to band gaps of ~1.7 eV. The identity of the comonomer with the PAH had little influence on the HOMO and LUMO levels, inconsistent with traditional donor-acceptor theory for reduced bandgap materials. In fact, DFT calculations show the LUMO orbital distribution across the series is essentially unchanged and mostly located on the PAH unit (as expected), but surprisingly, the HOMO orbitals are also localized to the PAH unit for the thiophene and bithiophene polymers.

3. Di(naphthalen-2-yl)-1,2-diphenylethene-based conjugated polymers: aggregation-enhanced emission and explosive detection
Mengxia Gao, Yue Wu, Bin Chen, Bairong He, Han Nie, Tingyan Li, Fupeng Wu, Wenjun Zhou, Jian Zhou and Zujin Zhao
Polym. Chem., 2015, 6, 7641-7645

Di(naphthalene-2-yl)-1,2-diphenylethene is used as a building block by Zhao and coworkers to prepare fluorescent conjugated polymers which show aggregation induced emission. Addition of the poor solvent water to these polymers in THF causes them to aggregate and essentially turns on the fluorescence of the materials by preventing non-radiative excited state decay. DFT calculations show the HOMO and LUMO orbitals are significantly distributed over both comonomers, as well as the pendant naphthyl groups, indicating good intramolecular orbital overlap. These materials further show potential to detect explosives under aqueous conditions, as the fluorescence is quenched in the presence of picric acid.

4. Facile approach for preparing porous organic polymers through Bergman cyclization
Xian-Mei Zhang, Xuesong Ding, Aiguo Hu and Bao-Hang Han
Polym. Chem., 2015, 6, 4734-4741

The Bergman cyclization reaction was used to prepare microporous polymers from a triphenylene-based monomer that contains three ene-diyne moieties. This catalyst-free and thermally induced intramolecular cyclization produces three 1,4-benzene biradical per monomer that undergo intermolecular coupling to yield the porous polymer. Although the monomers themselves are planar, they link together in a non-planar fashion to give a porous, high surface area material. Han and coworkers then demonstrate that the novel micorporous polymers show high adsorption capacity for both hydrogen and carbon dioxide.

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Polymer Chemistry Blog

2016 Polymer Chemistry Lectureship awarded to Feihe Huang

Focus on: Redox-Responsive Polymers

Polymer Chemistry welcomes new Associate Editor Hong Chen and new Advisory Board members!

Paper of the month: pH-Sensitive nanogates based on poly(L-histidine) for controlled drug release from mesoporous silica nanoparticles.

Focus on: Polymeric Composite Materials

Paper of the month: Lights on! A significant photoenhancement effect on ATRP by ambient laboratory light

Top 10 most-read Polymer Chemistry articles – Q4 2015

Focus on: Polymers in Catalysis

Paper of the month: Solvent-free mechanochemical synthesis of a bicyclononyne tosylate: a fast route towards bioorthogonal clickable poly(2-oxazoline)s

Editorial Board’s Top Picks: Emily Pentzer

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