Focus on: Photopolymerisation

Photochemistry is an incredibly useful field of chemistry which allows for temporal control of reactions through the presence of light. Specifically when applied in polymer chemistry, light can be used to achieve conformational changes, modify polymer chains and to polymerise monomers. This month, focusing on photopolymerisation, we take a look at three papers and a communication, featured in Polymer Chemistry, which utilise light to polymerise various monomers via different techniques, including: reversible-deactivation radical polymerisations and curing of coatings and bulk materials. The vast scope of these articles highlights the applicability of photochemistry as a versatile approach to polymer synthesis.

ToC

1. Room temperature synthesis of poly(poly(ethylene glycol) methyl ether methacrylate)-based diblock copolymer nano-objects via Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA), Jianbo Tan, Yuhao Bai, Xuechao Zhang, Li Zhang, Polym. Chem., 2016, 7, 2372-2380.

The authors describe the chain extension of a hydrophilic macromolecular chain transfer agent (macroCTA) with hydroxypropyl methacrylate, through a light-mediated PISA approach. A visible light LED (405 nm) was used and the aqueous photo-PISA reactions achieved high conversion within 30 min irradiation time. Nano-objects with various morphologies were realised and investigated for their thermoresponsive properties.

2. Extremely deep photopolymerization using upconversion particles as internal lamps, Ren Liu, Hao Chen, Zhiquan Li, Feng Shi, Xiaoya Liu, Polym. Chem., 2016, 7, 2457-2463

Photopolymerisation was reported through thick samples by using upconversion nanoparticle (UCNP) assisted photochemistry. Through near-infrared laser excitation, the UCNPs produce visible light, which is adsorbed by a photo-initiator and causes curing of the material. Using this technique 60% conversion of double bonds has been achieved through a sample depth of 13.7 cm, and shows promise for ultra-high density data storage and preparation of functional composites.

3. Towards mussel-like on-demand coatings: light-triggered polymerization of dopamine through a photoinduced pH jump, David Perrot, Céline Croutxé-Barghorn, Xavier Allonas, Polym. Chem., 2016, 7, 2635-2638.

In this communication, the authors present a light triggered polymerisation of dopamine to give highly adhesive coatings. The irradiation of quaternary ammonium salts of phenylglyoxylic acid acted as photobase generators. This release of a strong base in water causes the polymerisation of dopamine through a self-oxidative polymerisation process. The presented methodology shows potential as a one-pot on-demand approach for the polymerisation of dopamine on various substrates.

4. Efficient multiblock star polymer synthesis from photo-induced copper-mediated polymerization with up to 21 arms, B. Wenn, A. C. Martens, Y.-M. Chuang, J. Gruber, T. Junkers, Polym. Chem., 2016, 7, 2720-2727

Here, utilising different multi-functional initiators, various star copolymers have been prepared via a photo-induced copper mediated polymerisation technique. Using a UV-microflow reactor, various multiarm-multiblock star-copolymers were prepared with varying acrylic block copolymer compositions, with low dispersities. Through post-polymerisation hydrolysis amphiphilic materials were prepared which showed pH-responsiveness and complex self-assembly in solution.


Dr. Fiona Hatton is a Web Writer for Polymer Chemistry. She is currently a postdoctoral researcher in the Armes group at the University of Sheffield, UK.

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Top 10 most-read Polymer Chemistry articles – Q1 2016

This month sees the following articles in Polymer Chemistry that are in the top 10 most accessed from January – March 2016:

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers
Furkan H. Isikgor and C. Remzi Becer
Polym. Chem., 2015, 6, 4497-4559
DOI: 10.1039/C5PY00263J

Flame retardancy of polylactide: an overview
Serge Bourbigot and Gaëlle Fontaine
Polym. Chem., 2010, 1, 1413-1422
DOI: 10.1039/C0PY00106F

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

A rapid crosslinking injectable hydrogel for stem cell delivery, from multifunctional hyperbranched polymers via RAFT homopolymerization of PEGDA
Yixiao Dong, Yue Qin, Marie Dubaa, John Killion, Yongsheng Gao, Tianyu Zhao, Dezhong Zhou, Dominik Duscher, Luke Geever, Geoffrey C. Gurtner and Wenxin Wang
Polym. Chem., 2015, 6, 6182-6192
DOI: 10.1039/C5PY00678C

Thiol–ene “click” reactions and recent applications in polymer and materials synthesis: a first update
Andrew B. Lowe
Polym. Chem., 2014, 5, 4820-4870
DOI: 10.1039/C4PY00339J

Investigation into thiol-(meth)acrylate Michael addition reactions using amine and phosphine catalysts
Guang-Zhao Li, Rajan K. Randev, Alexander H. Soeriyadi, Gregory Rees, Cyrille Boyer, Zhen Tong, Thomas P. Davis, C. Remzi Becer and David M. Haddleton
Polym. Chem., 2010, 1, 1196-1204
DOI: 10.1039/C0PY00100G

Cu(0)-mediated living radical polymerization: recent highlights and applications; a perspective
Athina Anastasaki, Vasiliki Nikolaou and David M. Haddleton
Polym. Chem., 2016, 7, 1002-1026
DOI: 10.1039/C5PY01916H

Toughening of photo-curable polymer networks: a review
Samuel Clark Ligon-Auer, Martin Schwentenwein, Christian Gorsche, Jürgen Stampfl and Robert Liska
Polym. Chem., 2016, 7, 257-286
DOI: 10.1039/C5PY01631B

Synthesis of polymeric janus nanoparticles and their application in surfactant-free emulsion polymerizations
Binh T. T. Pham, Chris H. Such and Brian S. Hawkett
Polym. Chem., 2015, 6, 426-435
DOI: 10.1039/C4PY01125B

Design of thiol- and light-sensitive degradable hydrogels using Michael-type addition reactions
Prathamesh M. Kharkar, Kristi L. Kiick and April M. Kloxin
Polym. Chem., 2015, 6, 5565-5574
DOI: 10.1039/C5PY00750J

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 month: Rapidly-cured isosorbide-based cross-linked polycarbonate elastomers

Kristufek et al. report the synthesis of rapidly-cured isosorbide-based cross-linked polycarbonate elastomers.

Inexpensive starting materials from natural products (such as isosorbide, isomannide etc.) can allow for natural material to begin to compete with and (why not?) eventually replace petrochemicals as a source of monomers. Isosorbide-based materials in particular have attracted considerable attention due to both the rigidity of their fused ring systems and the easily-modifiable dual hydroxyl functionalities. However, the utility of isosorbide-based materials for elastomers is perhaps more limited. As such, in the current article, Wooley and co-workers aim to produce rapidly-photo-cross-linked isosorbide-based elastomers via thiol-ene chemistry that will have the additional potential to hydrolytically break down into their original building blocks.

This novel cross-linked network system was elegantly synthesized using a naturally-derived monomer, isosorbide dialloc (IDA) and cross linked with tri-methylpropane tris(3-mercaptopropionate) (TMPTMP) yielding IDA-co-TMPTMP, an optically transparent elastomer. All the IDA-co-TMPTMP networks were obtained by environmentally friendly methods including solvent-free conditions, low catalyst loading and UV irradiation. Importantly, a study of a constant UV cure time (1 minute) and variation of the thermal curing times led to the conclusion that this material is near its optimal thermal and mechanical properties without requiring post-cure heating.

The thermal decomposition temperature of the networks were consistent (320 °C) while the glass transition temperature remained below room temperature for all samples with a % elongation of 220-340%. The hydrolytic degradation of the material was also evaluated and found to afford 8.3±3.5% and 97.7±0.3% mass remaining after 60 days under accelerated basic and physiological neutral buffer conditions respectively. Finally, a cell viability assay and fluorescence imaging with adherent cells were also reported in order to show the potential of this material as a biomedical substrate. In conclusion, the rapid synthesis of this optically transparent flexible elastomer presented very interesting properties that could be very useful in biomedical applications or as environmentally-friendly materials.

Tips/comments directly from the authors:

  1. Because DMPA dissolves slowly in the reaction mixture, it is important to keep it in the dark while mixing and allow it to fully dissolve, resulting in the most uniform materials.
  2. Glass slides were used as the molds to maximize the light exposure to the reaction mixture of the two monomers, ensuring the rapid curing time.
  3. During the degradation study, it is important to change the solution at short (ca. 2 days), constant intervals to provide consistent results.

Rapidly-cured isosorbide-based cross-linked polycarbonate elastomers by T.S. Kristufek, S.L. Kristufek, L.A. Link, A.C. Weems, S. Khan, S.M. Lim, A.T. Lonnecker, J.E. Raymond, D.J. Maitland and K.L. Wooley, Polym. Chem., 2016, 7, 2045-2056, DOI: 10.1039/C5PY01659B


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  http://www.haddleton.org/users/athina-anastasaki for more information.

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3D printing enters the next dimension

Written by Polly Wilson

Scientists in the US have added a new dimension to 3D printing with a strategy that controls the chemical composition of printed features, as well as their three-dimensional position.

The University of Miami team's setup allows controlling both 3D position and monomer composition of a photopolymerisable mixture

With 3D printing systems becoming more mainstream, platforms that overcome their current limitations are increasingly relevant. Ideally, they should print different polymers close together, independently control their position and be compatible with delicate organic and biologically active materials.

To read the full article please visit Chemistry World.

Optimization of 4D polymer printing within a massively parallel flow-through photochemical microreactor
Xiaoming Liu, Yeting Zheng, Samuel R. Peurifoy, Ezan A. Kothari and Adam B. Braunschweig �
Polym. Chem., 2016, Advance Article
DOI: 10.1039/C6PY00283H, Paper

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Paper of the month: Thermoresponsive gels based on ABC triblock copolymers: effect of the length of the PEG side group.

Constantinou & Georgiou report the synthesis of thermoresponsive triblock copolymers using group transfer polymerisation.

Thermoresponsive polymers can find use in a wide range of applications including tissue engineering and 3-D printing. For the successful synthesis of thermoresponsive gels several criteria need to be taken into account such as the composition, the molar mass, the concentration and the architecture. Georgiou’s group elegantly demonstrate the facile synthesis of such materials through group transfer polymerisation (GTP) thanks to its unique characteristics including scalability and faster reaction rates in comparison to conventional radical polymerisations. Different copolymers were targeted based on the ionic hydrophilic pH and thermoresponsive 2-(dimethylamino)ethyl methacrylate (DMAEMA), the non-ionic poly(ethylene glycol) (PEG)-based methacrylate (methoxy di-, penta-, and nona(ethylene glycol) methacrylate, DEGMA, PEGMA, and NEGMA), and the hydrophobic BuMA. The effect of the PEG side chain length and different compositions were systematically varied in order to investigate their effects on the thermoresponsive behaviour of the copolymers. Micelle formation was observed for all the terpolymers and the effective pKas were affected by the hydrophobic BuMA content and the architecture. Interestingly, the cloud points were affected by both the composition (BuMA content) and the PEG side group length and increase as the hydrophilic content and the PEG length increased. The gel points were investigated over a wide range of temperatures and concentrations and found to be influenced by both the composition and the PEG side chain length. Stable gels were formed by the most hydrophobic and with the shortest PEG length macromonomers. In summary, it was demonstrated that the sol–gel transition can be tailored by varying both the PEG length as well as the composition of the polymers.

Tips/comments directly from the authors:

  1. It is really important to monitor the temperature between additions during the one-pot synthesis. GTP is exothermic so when all monomer has converted to the polymer the temperature will drop back down so the next monomer can be added.
  2. Since each addition/polymerisation step takes about 10-15 the reaction can be monitored in real time by gel permeation chromatography, if necessary.
  3. Even though ideally all monomers have to be distilled this is not necessary when the GTP reaction is scaled up as long as the monomers are dry.
  4. Gelation is also influenced by ionic strength so if salt is added to the polymer solutions the solution will gel at lower temperatures and concentrations.

Thermoresponsive gels based on ABC triblock copolymers: effect of the length of the PEG side group by A. P. Constantinou and T. K. Georgiou , Polym. Chem., 2016, 7, 2045-2056


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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2016 Polymer Chemistry Lectureship awarded to Feihe Huang

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

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

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!

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.

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:

  1. 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.
  2. 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.
  3. 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.
  4. 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

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.


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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