Archive for April, 2016

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

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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