Archive for March, 2016

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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