Archive for January, 2016

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

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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Top 10 most-read Polymer Chemistry articles – Q4 2015

This month sees the following articles in Polymer Chemistry that are in the top 10 most accessed from October – December:

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

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

Supramolecular hydrogels assembled from nonionic poly(ethylene glycol)-b-polypeptide diblocks containing OEGylated poly-l-glutamate
Shusheng Zhang, Wenxin Fu and Zhibo Li
Polym. Chem., 2014,5, 3346-3351
DOI: 10.1039/C4PY00016A

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

Oxidant-induced dopamine polymerization for multifunctional coatings
Qiang Wei, Fulong Zhang, Jie Li, Beijia Li and Changsheng Zhao
Polym. Chem., 2010,1, 1430-1433
DOI: 10.1039/C0PY00215A

Scalable synthesis and derivation of functional polyesters bearing ene and epoxide side chains
Yunfeng Yan and Daniel J. Siegwart
Polym. Chem., 2014,5, 1362-1371
DOI: 10.1039/C3PY01474F

End group removal and modification of RAFT polymers
Helen Willcock and Rachel K. O’Reilly
Polym. Chem., 2010,1, 149-157
DOI: 10.1039/B9PY00340A

The power of light in polymer science: photochemical processes to manipulate polymer formation, structure, and properties
Shunsuke Chatani, Christopher J. Kloxin and Christopher N. Bowman
Polym. Chem., 2014,5, 2187-2201
DOI: 10.1039/C3PY01334K

Bringing d-limonene to the scene of bio-based thermoset coatings via free-radical thiol–ene chemistry: macromonomer synthesis, UV-curing and thermo-mechanical characterization
Mauro Claudino, Jeanne-Marie Mathevet, Mats Jonsson and Mats Johansson
Polym. Chem., 2014,5, 3245-3260
DOI: 10.1039/C3PY01302B

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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Focus on: Polymers in Catalysis

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.


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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