Focus on: Antimicrobial polymers

Antimicrobial agents kill or inhibit the growth of microorganisms, and can be sub-divided into several classes depending on the type of microorganism they target. Sub-divisions include, antibacterial, antifungal, antiviral and antiparasitic agents. In particular, antibacterial agents are incredibly important worldwide, with the emergence of multi-drug resistant bacteria. Antibiotic-resistant infections are becoming an increased health and economic burden on society. As such the development of new antibacterials continues to be paramount to limiting the spread of multi-drug resistant bacteria.

This month we focus on three articles published in Polymer Chemistry which have reported the use of antimicrobial polymers. In each case the polymers reported have antibacterial properties, and in one article polymers were also investigated for their antifungal properties.

 

 

1. Cationic peptidopolysaccharides synthesized by ‘click’ chemistry with enhanced broad-spectrum antimicrobial activities
Yajuan Su, Liang Tian, Meng Yu, Qiang Gao, Dehui Wang, Yuewei Xi, Peng Yang, Bo Lei, Peter X. Ma, Peng Li
Polym. Chem., 2017, 8, 3788-3800; DOI: 10.1039/C7PY00528H

Cationic peptidopolysaccharides were prepared through the grafting of ε-poly-L-lysine (EPL) to a chitosan (CS) backbone by thiol-ene “click” chemistry. The resulting CS-g-EPL polymers were assessed for their antimicrobial activity against Gram negative bacteria, Gram positive bacteria and fungi, which showed broad-spectrum antimicrobial activity. In addition the hemolytic activity of the polymers was determined, and the lead candidate was further investigated for it’s biocompatability.

2. Astaxanthin-based polymers as new antimicrobial compounds
S. Weintraub, T. Shpigel, L. G. Harris, R. Schuster, E. C. Lewis, D. Y. Lewitus
Polym. Chem., 2017, 8, 4182-4189; DOI: 10.1039/C7PY00663B

Astaxanthin (ATX) is an organic pigment produced by fungi and algae, possessing various therapeutic properties. Polyesters were prepared using carbodiimide-mediated coupling of ATX, which is a diol, with alkyl- and PEG-diacids. The diacid used influenced the resulting physico–chemical–mechanical properties of the polymers. Antibacterial activity was observed against three strains of bacteria, including MRSA, and the materials were found to be non-toxic in an in vivo wound healing model.

3. Bio-inspired peptide decorated dendrimers for a robust antibacterial coating on hydroxyapatite
Yaping Gou, Xiao Yang, Libang He, Xinyuan Xu, Yanpeng Liu, Yuebo Liu, Yuan Gao, Qin Huang, Kunneng Liang, Chunmei Ding, Jiyao Li, Changsheng Zhao, Jianshu Li
Polym. Chem., 2017, 8, 4264-4279; DOI: 10.1039/C7PY00811B

The authors report the use of a salivary statherin protein inspired dendrimer, for use as an antibacterial coating for implanted biomaterials. A peptide sequence was coupled to the surface of a G4 PAMAM dendrimer, by Michael addition. The materials showed adsorption to hydroxyapatite surfaces with sufficient binding strength to survive washing. The adsorbed dendrimers endowed antimicrobial properties observed by an inhibition of biofilm formation and through in vivo experiments.

 

Read these articles for free until September 10th


About the webwriterFiona Hatton

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. Find her on Twitter: @fi_hat

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Paper of the month: Acceleration and improved control of aqueous RAFT/MADIX polymerization of vinylphosphonic acid in the presence of alkali hydroxides

Seiler et al. report the acceleration and improved control of vinylphosphonic acid in the presence of alkali hydroxides during both conventional and RAFT/MADIX polymerization.

Phosphonic acid functionalized polymers find use in a wide range of applications such as metal protection, polymer electrolyte membranes flame retardancy and dentistry. This is thanks to their unique characteristics including their acidic nature, stability, proton conductivity and metal binding ability. Vinyl phosphonic acid (VPA) in particular is a structurally simple example of such monomers which is not only affordable but also provides with a polymer (PVPA) with phosphonic acid groups that are directly attached to the backbone.

 

 

Despite the popularity and applicability of this polymer, the polymerization of VPA is typically slow yielding incomplete conversions which necessitates the need for additional costly and time-consuming purification steps. Destarac, Harrisson and co-workers were capable to circumvent this by investigating the effect of adding various alkali hydroxides to the conventional (free radical) and reversible addition-fragmentation transfer polymerization/macromolecular design by interchange of xanthates (RAFT/MADIX) radical polymerizations. Both types of polymerizations were strongly affected by the addition of NaOH. The authors found that by adding 1 equivalent of NaOH they could significantly increase the rate of the polymerization and the final conversion for both conventional and RAFT/MADIX polymerizations while larger quantities led to retardation of the reaction. A wide range of alkali hydroxides were also studied including H+, Li+, K+ and NH4+. It was shown that the dispersity of the final polymer decreases as the ionic radius of the counterion increases (H+ > Li+> Na+ > K+ > NH4+) while the acceleration of the polymerization follows the order Na+ > K+ > NH4+> Li+ > H+). Overall, the fastest rates of polymerizations were obtained in the presence of 0.5 equivalent of NaOH, while the same concentration of KOH or NH4OH allowed for a moderate acceleration on the polymerization rate combined with an improved control over the molar masses. Thus, this simple and cost-effective strategy can significantly improve the efficiency of the polymerization of VPA by simultaneously enhancing the reaction rate and the control over the molar masses.

 

 

Tips/comments directly from the authors:

  1. Take care to control the temperature when neutralizing the VPA – the reaction is very exothermic!
  2. Use NaOH for the most significant acceleration of polymerization and NH4OH for the strongest reduction in dispersity of the polymer.
  3. PVPA homopolymer can be precipitated in MeOH, but many PVPA-containing DHBCs must be purified by dialysis due to the small difference in solubility between PVPA and VPA and the low volatility of VPA.

 

Read this exciting research for free until 10/09/2017 through a registered RSC account.

Acceleration and improved control of aqueous RAFT/MADIX polymerization of vinylphosphonic acid in the presence of alkali hydroxides
Polym. Chem., 2017, 8, 3825-3832, DOI: 10.1039/c7py00747g

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About the webwriterAthina Anastasaki

Dr. Athina Anastasaki is a web writer for Polymer Chemistry. She is currently a Global Marie Curie Fellow working alongside Professor Craig Hawker at the University of California, Santa Barbara (UCSB). Please visit this website for more

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8th Symposium on Controlled Radical Polymerization

American Chemical Society, Chemistry for Life ®

 

Polymer Chemistry is pleased to be sponsoring the 8th Symposium on Controlled Radical Polymerization, held during this year’s ACS Fall Meeting in Washington, DC and organised by Brent SumerlinHaifeng Gao, Krzysztof Matyjaszewski and Nicolay Tsarevsky.

The symposium, which will take place on Sunday 20 August, will also feature a talk from Polymer Chemistry 2017 Lectureship winner Dr Julien Nicolas, as well as sessions on:

  • New macromolecular architectures and new ATRP initiating systems
  • Kinetics of radical polymerizations deduced via SP-PLP-EPR
  • RAFT 20 years later: Elements of RAFT navigation
  • Ionic auxiliaries for stereocontrolled radical polymerization
  • Mechanistic studies of transition metal catalyzed radical termination
  • Living radical polymerization using organic catalysts: Synthesis and applications
  • Electrochemistry for ATRP
  • Iron mediated controlled radical polymerisation
  • Designer polymers from palladium-catalyzed cross-coupling reactions

Registration for this event is now open – please visit the ACS website to register.

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Welcoming our new Polymer Chemistry Editor-in-Chief

We are excited to welcome new Editor-in-Chief Christopher Barner-Kowollik (Queensland University of Technology) to the Polymer Chemistry Editorial Board

 

 

Prof. Barner-Kowollik

Christopher Barner-Kowollik is Professor of Materials Science and head of the Soft Matter Materials Laboratory at the Queensland University of Technology. He has published over 510 peer-reviewed studies and won several awards for his research, most recently the coveted Erwin-Schrödinger Award of the Helmholtz association (2016) and a Laureate Fellowship from the Australian Research Council (2017).

His main research interests are situated at the interface of organic, polymer and biochemistry and focus on a wide range of polymer-related research fields, such as the (photochemical) synthesis of complex macromolecular architectures with highly-defined functionality and composition, advanced synthesis via polymer ligation techniques and macromolecular transformations at ambient temperature in solution and on surfaces, with a strong focus on light-induced methodologies, advanced photolithographic processes, fundamental investigations into polymerization mechanisms and kinetics, as well as high resolution imaging and characterization of macromolecular chain structures via mass spectrometric methods in solution and on surfaces.

 

Christopher has been an Associate Editor for Polymer Chemistry since 2009, and we are delighted that he has agreed to become our new Editor-in-Chief! Welcome to the new position!

Christopher takes over from Professor David Haddleton, who has led the journal since its launch in 2009. We would like to thank Professor Haddleton for his excellent work as Editor-in-Chief and will be delighted to continue working with him as an Advisory Board member.

As Polymer Chemistry Editor-in-Chief, Christopher will be handling submissions to the journal. Why not submit your next paper to his Editorial Office?

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Paper of the month: Structure/property relationships in copolymers comprising renewable isosorbide, glucarodilactone, and 2,5-bis(hydroxymethyl)furan subunits

Lillie et al. report the synthesis of linear carbohydrate derived polyesters and their effect on mechanical properties.

Polyesters obtained from bio-derived monomers are often used as building blocks with the ultimate aim of meeting consumer demands for high-performance and sustainable materials. To this end, Reineke, Tolman, and Lillie sought to establish how changing the ratio of the sustainable D-glucaro-1,4:6,3-dilactone containing α, ω-diene (GDLU) and isosorbide undecanoate (IU) may influence the thermal, chemical and mechanical properties of the acyclic diene metathesis (ADMET)-derived polymers. The authors synthesized a series of random copolymers consisting of a range of GDLU and IU compositions and fully characterized them by uniaxial tensile testing, small-amplitude oscillatory shear rheology, X-ray scattering, and hydrolytic degradation testing.

 

It was found that small compositional changes have a detrimental impact on their mechanical performance and degradability. In addition, the authors investigated which carbohydrate-based building block was most important in promoting the elasticity and shape-memory abilities of this class of materials. To address this issue, GDL or isosorbide were replaced with a different sustainable diol, 2,5-bis(hydroxymethyl) furan. Studies of the resulting copolymers indicated that GDLU is responsible for imparting both elasticity and shape memory properties. Further, more economical and environmentally-friendly routes for the synthesis of GDLU and IU feedstocks were also explored.

 

Tips/comments directly from the authors:

  1. Acetonitrile appears to be the essential solvent for the scandium triflate-catalyzed esterification of GDL with 10-undecenoic acid anhydride.
  2. 10-Undecenoic acid anhydride can rapidly degrade on wet silica gel. To prevent this, oven dry (120 °C) the silica gel prior to its use and minimize the excess 10-undecenoic acid anhydride used in the reaction.
  3. Due to the hydrolytic instability of GDL and GDL-containing polymers, they should be stored in a vacuum desiccator to protected from moisture to prevent degradation between uses.

 

Read this exciting research for free until 13/08/2017 through a registered RSC account.

 

Structure/property relationships in copolymers comprising renewable isosorbide, glucarodilactone, and 2,5-bis(hydroxymethyl)furan subunits
Polym. Chem., 2017, 8, 3746-3754, DOI: 10.1039/c7py00575j

 

 

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About the webwriterAthina Anastasaki

Dr. Athina Anastasaki is a web writer for Polymer Chemistry. She is currently a Global Marie Curie Fellow working alongside Professor Craig Hawker at the University of California, Santa Barbara (UCSB). Please visit this website for more

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European Polymer Federation – Australian European Workshop

At this year’s European Polymer Federation Congress, Polymer Chemistry is pleased to sponsor the Australian-European Polymer Symposium, which will take place on Tuesday 4 July. The workshop will include 12 lectures (six from Australia, six from Europe) to illustrate connections, interactions and collaborations between European and Australian polymer researchers and will also include the presentation of Polymer Chemistry and Soft Matter poster prizes.

Invited speakers include:

Emmanuel P. Giannelis (Cornell University, USA)
Gaetano Guerra
(Università degli Studi di Salerno, Italy)
Dave Haddleton
(University of Warwick)
Tanja Junkers
(Universiteit Hasselt, Belgium)
Simon Harrisson
(Université de Toulouse III Paul Sabatier, France)
Felix Schacher
(Friedrich Schiller University Jena, Germany)
Hans Heuts
(Technische Universiteit Eindhoven, Netherlands)
Leonie Barner
(Queensland University of Technology, Australia)
Holger Schönherr 
(Universität Siegen, Germany)
Neil Cameron
(Monash University, Australia)
Markus Muellner
(University of Sydney, Australia)
Greg Qiao
(University of Melbourne, Australia)

EPF 2017 will be held from 2-7 July at the Lyon Convention Center and will focus on the latest trends in the polymer science and technology industry, including macromolecular chemistry; physics of polymers and polymer materials; modelling and simulation and polymer characterisation.

To register now, click here or visit the EPF website for more details on the speaker list and other workshops.

 

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Paper of the month: Block copolymer synthesis in one shot: concurrent metal-free ATRP and ROP processes under sunlight

Aydogan et al. report the.facile synthesis of block copolymers consisting of different monomer familes via successfully combining ATRP and ROP strategies.

Block copolymers are of a great interest to the polymer chemistry community as they provide intermediate physicochemical properties when compared to the respective homopolymers. Sequential monomer addition, mechanistic transformation and coupling of different segments are three of the most popular approaches to obtain block copolymers. However, all these approaches suffer from several drawbacks such as being limited to monomers that can be polymerized only under the same polymerization mechanism or requiring extreme experimental precautions and elongated purification steps.



In order to address the latter challenge, Yagci, Yilmaz and co-workers developed the first metal free example of block copolymer formation in which they concurrently polymerize structurally different monomers from a junction point serving as two functional groups for each polymerization. Since atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP) are not expected to interfere with each other and as such could be the ideal candidates for such a system. In order to test this hypothesis, a specifically designed initiator was synthesized possessing a tertiary bromine at one end (capable of initiating an ATRP reaction) and a hydroxyl functionality at the other end (capable for initiating a ROP reaction). Under carefully optimized conditions and in the presence of both the ATRP and ROP catalysts both methyl methacrylate (MMA) and ε- caprolactone could be simultaneously polymerized yielding a diblock copolymer with good agreement between theoretical and experimental value sand low dispersity values. Interestingly, the reaction took place on the roof of the chemistry department at Istanbul technical university utilizing natural sunlight as the light source. The applicability of this technique was further demonstrated by the simultaneous polymerization of different sets of monomers including n butyl acrylate- ε- caprolactone and methyl methacrylate-lactide combinations. As such, the successful combination of ATRP with ROP in the same reaction media allows for the facile one pot synthesis of block copolymers which can find use in further applications where excess of metals or inorganic residues would be undesirable.

Tips/comments directly from the authors:

1. All chemicals should be added into the reaction tube under nitrogen atmosphere in dark (perhaps by covering the outside of the tube with an aluminium foil) to avoid any premature light induced polymerization.
2. ROP polymerization can take place even in dark. Therefore, the ROP catalyst should be added last, and afterwards, the reaction tube should be exposed to sunlight as soon as possible. This way, one can provide the optimum conditions for the polymerizations to be realized simultaneously.
3. The method is best applicable in sunny days. Sunlight was deliberately selected as the most natural and simple way of light exposure. However, various other irradiation sources that emit in the wavelength regions matching with the absorption of appropriate sensitizers can also be used.

Read this exciting research for free until 17/07/2017 through a registered RSC account.

 

Block copolymer synthesis in one shot: concurrent metal-free ATRP and ROP processes under sunlight
Polym. Chem., 2017, 8, 2899-2903, DOI: 10.1039/c7py00069c

 

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About the webwriterAthina Anastasaki

Dr. Athina Anastasaki is a web writer for Polymer Chemistry. She is currently a Global Marie Curie Fellow working alongside Professor Craig Hawker at the University of California, Santa Barbara (UCSB). Please visit this website for more

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Focus on: Naturally Occurring Polymers

This month we focus on 3 articles published in Polymer Chemistry which report the use of naturally occurring polymers. As opposed to synthetic polymers, naturally occurring polymers are produced by living organisms in nature. Classes of naturally occurring polymers include proteins, polynucleotides, polyisoprenes, lignin and polysaccharides. These polymers can be extracted and utilised in various applications. In particular, polysaccharides such as cellulose and chitosan are cheap and abundant, biodegradable and are being used increasingly due to growing environmental concerns. Here, chitosan and/or celluose are utilised for the preparation of hydrogels, cellulose modification, and with thermo-conductive carbon nanotubes, exemplifying the broad versatility of these naturally occurring polymers.

1. Highly cost-effective and high-strength hydrogels as dye adsorbents from natural polymers: chitosan and cellulose
Hu Tu, Yi Yu, Jiajia Chen, Xiaowen Shi, Jialin Zhou, Hongbing Deng, Yumin Du
Polym. Chem., 2017, 8, 2913-2921; DOI: 10.1039/C7PY00223H

The authors decribe the preparation of composite hydrogels comprising chitosan, cellulose and rectorite for use as adsorbents for waste water treatment. The hydrogels had good elasticity and strength with the ability to restore their shape after compression. The adsorption efficiency was demonstrated with a dye molecule, which was adsorbed from solution. In addition these materials show promise as adsorbents for heavy metals.

2. Tandem modification of amphiphilic cellulose ethers for amorphous solid dispersion via olefin cross-metathesis and thiol-Michael addition
Yifan Dong, Laura I. Mosquera-Giraldo, Lynne S. Taylor, Kevin J. Edgar
Polym. Chem., 2017, 8, 3129-3139; DOI: 10.1039/C7PY00228A

The combination of olefin cross-metathesis and thiol-Michael addition chemistries have been used to functionalise cellulose derivatives. This methodology allowed for the design of certain cellulose-based polymers for potential use in amorphous solid dispersion, which can enhance the bioavailability of a poorly soluble drug. Mild reaction conditions and functional group tolerance make this strategy appealing for use with other polysaccharides.

3. Thermo conductive carbon nanotube-framed membranes for skin heat signal-responsive transdermal drug delivery
Ji-Hye Kang, Han-Sem Kim, Ueon Sang Shin
Polym. Chem., 2017, 8, 3154-3163; DOI: 10.1039/C7PY00570A

Smart carbon nanotube (CNT)-framed membranes were prepared from CNTs, chitosan and a thermoresponsive polymer, with an LCST around body temperature. The chitosan was used as a biocompatible adhesive to give cohesion to the CNTs. The loading and release of bovine serum albumin (BSA) was investigated and a high loading capacity was found, with temperature-dependent release of the BSA. The hybrid memberanes show potential as patch type transdermal drug delivery devices.

Read these articles for free until July 17th


About the webwriterFiona Hatton

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. Find her on Twitter: @fi_hat

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Polymer Chemistry Lectureship Award Julien Nicolas at APME 2017

Dr. Julien Nicolas (Université Paris Sud, France) was presented the 2017 Polymer Chemistry Lectureship at APME 17 – Advanced Polymers via Macromolecular Engineering in Ghent

Dr Julien Nicolas (Université Paris Sud, France) was presented the 2017 Polymer Chemistry Lectureship award at APME 17 – Advanced Polymers via Macromolecular Engineering in Ghent. The prize was awarded by Polymer Chemistry Associate Editor Prof. Dr. Christopher Barner-Kowollik from Queensland University of Technology and Karlsruhe Institute of Technology.

 
APME 2017 (Advanced Polymers via Macromolecular Engineering) took place in Ghent, Belgium on May 21-25, 2017.  The focus of the APME2017 meeting was on macromolecular engineering for the design of advanced polymeric structures, in connection to their characterisation and recent applications.

 

Dr. Julien Nicolas (left) holding the Polymer Chemistry prize awarded by Prof. Dr. Christopher Barner-Kowollik (right)

 

 

Congratulations to Julien on his award!

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International Symposium on Ionic Polymerization – IP 2017

The 12th International Symposium on Ionic Polymerization (IP 2017) will be held at Durham University, UK from 17 – 22 September, organised and hosted by the Durham Centre for Soft Matter. 

The focus of IP 2017 will be on academic and industrial research in the areas of anionic, cationic and ring-opening polymerization mechanisms. Contributions related to other methods of living/controlled polymerization (catalytic, controlled free-radical, and step-growth polymerizations) will also be covered.

IP 2017 will feature also feature number of international leading invited speakers, as well as oral presentations, short talks for younger researchers and a poster session, supported by Polymer Chemistry, which will provide participants the opportunity to highlight their recent work. Submission deadlines for all abstracts is 31 May.

If you would like to attend, please register before 1 August in order to claim the early-bird rate. You can also read more about the symposium on the IP 2017 website.

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