Paper of the month: Poly(ethylene glycol)-b-poly(vinyl acetate) block copolymer particles with various morphologies via RAFT/MADIX aqueous emulsion PISA

D’Agosto, Lansalot and co-workers report the synthesis of nanoparticles with various shapes through the RAFT/MADIX PISA polymerization of vinyl acetate.

 

 

Polymerization-induced self-assembly (PISA) is a widely used technique that allows access to the formation of a range of polymeric nanoparticles including spheres, worms and vesicles. Although this methodology has been very successful with dispersion polymerizations, emulsion polymerization systems are mostly limited to the preparation of spherical particles. Poly(vinyl acetate) latexes are obtained by emulsion polymerization and find use in many industrial applications but yet, the preparation of higher ordered morphologies remains challenging. D’Agosto, Lansalot and co-workers were able to circumvent this by conducting the emulsion polymerization of vinyl acetate at higher temperatures anticipating that this would not only lead to much faster reaction kinetics but also to the softening of the polymeric nanoparticles allowing for increased flexibility and rearrangements. Indeed, the aqueous macromolecular design via interchange of xanthate (MADIX)-mediated emulsion polymerization of vinyl acetate from a poly(ethylene glycol) with a xanthate chain-end macro-CTA led to well-controlled polymerizations with high blocking efficiency accompanied with the formation of stable latexes. By judiciously adjusting the targeted degree of polymerization, the authors triggered for the first time the morphological transformation from spherical to higher ordered morphologies and observed the formation of vesicles (with different sizes) as well as worm-like nanoparticles. In particular, the worm-like morphology could alternatively be observed by increasing the solid content from 10 to 15 wt%. The data was supported by very nice cryo-TEM images which depicted all the discussed morphologies. The range of obtained shapes were attributed to the high water solubility of vinyl acetate combined with the low Tg of PVAc. The presented elegant findings enhance our fundamental understanding on emulsion PISA systems where polymerization temperature and solid content significantly affect the resulting morphology.

 

 

Tips/comments directly from the authors:

 

  1. The polymerization takes place above the Tg of the forming PVAc block, which seems to be key for accessing non spherical morphologies in VAc PISA.
  2. PEG-b-PVAc block copolymers are obtained in very short times.
  3. This system provides an interesting medium for investigating the impact of several parameters on the morphologies obtained through PISA processes.
  4. Extension of this strategy to other non-activated monomers, for instance in the copolymerization of vinyl acetate and ethylene, seems accessible.

 

 

Citation to the paper: Poly(ethylene glycol)-b-poly(vinyl acetate) block copolymer particles with various morphologies via RAFT/MADIX aqueous emulsion PISA, Polym. Chem., 2020, 11, 3922-3930, DOI: 10.1039/d0py00467g

 

Link to the paper:

https://pubs.rsc.org/en/content/articlepdf/2020/py/d0py00467g

 

Read more papers on PISA in our Polymerisation-Induced Self Assembly themed collection here!

 

About the web writer:

Professor Athina AnastasakiDr. Athina Anastasaki is an Editorial Board Member and a Web Writer for Polymer Chemistry. Since January 2019, she joined the Materials Department of ETH Zurich as an Assistant Professor to establish her independent research group.

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Polymer Chemistry Author of the Month: Nicholas J. Warren

Nick WarrenNick Warren  is a University Academic Fellow within the School of Chemical and Process Engineering at the University of Leeds. He was awarded an Masters in Chemistry from the University of Bristol in 2005 following which he conducted two years industrial research. He then moved to the University of Sheffield where he studied for a PhD in Polymer Chemistry within Prof Steve Armes’ research group where he focussed on synthesis of biocompatible block copolymers. Following his PhD, he continued as a postdoctoral researcher in Sheffield working in the area of polymerisation-induced self-assembly (PISA) until 2016, when he moved to Leeds to start his independent research career. His current research aims to exploit the latest advances in polymerisation techniques, combined with new reactor technologies for the design and discovery of controlled-structure polymers.

What was your inspiration in becoming a polymer chemist?

During my undergraduate masters project, I worked on development on combining pH responsive microgels with photo-responsive surfactants. I was fascinated by the ability to use chemical composition as a means of tuning physical characteristics of a material and imparting responsive behaviour. This brought on a specific interest in synthetic polymer chemistry, where there are so many synthetic routes to generating responsive materials. This was the focus of my PhD, where I gained expertise in ATRP and RAFT polymerisation which provided a convenient tool-box allowing me to design and synthesise pH responsive block copolymers.

What was the motivation behind your most recent Polymer Chemistry article?

Continuous-flow techniques are well utilised in small molecule synthesis and are now becoming commonplace in polymer chemistry. In my research group, we aim to use flow-chemistry to conduct polymer synthesis and try and exploit its characteristics to develop new materials, streamline methods for optimising polymerisation processes; or for detailed online monitoring. We have already published some work conducting PISA in flow, which combined my existing expertise in PISA, with my growing interest in reactor technologies, but it became apparent that the relatively long timescales for the reactions meant that there were limited advantages over batch synthesis. We therefore looked to speed up the process, which was relatively straight-forward since our all-acrylamide PISA system was ideally suited to Seb Perrier’s ‘ultrafast’ RAFT technology. By using flow-reactors equipped with online monitoring, we were not only able to synthesise a wide range of PISA nanoparticles on short timescales, but also obtain kinetic data despite the short reaction time.

Which polymer scientist are you most inspired by?

From a synthetic perspective, the work being undertaken in Prof Brent Sumerlin’s group encompasses many of the areas I have a keen interest. I am also inspired by Prof Tanja Junkersresearch, since she is at the forefront of work into applying automation and flow chemistry to polymer synthesis.

How do you spend your spare time?

I now have two children under 3, so I spend most of my time running around after them! We spend quite a lot of time hiking in the Peak District and I also like to cook, which has recently expanded into bread making (to varying degrees of success).

What profession would you choose if you weren’t a scientist?

I’d be a barista with a small coffee shop somewhere sunny.

Read Nick’s full article now for FREE

And if you are interested in reading more about PISA then check out our recent themed collection here


Rapid production of block copolymer nano-objects via continuous-flow ultrafast RAFT dispersion polymerisation

 

graphical abstract

Ultrafast RAFT polymerisation is exploited under dispersion polymerisation conditions for the synthesis of poly(dimethylacrylamide)-b-poly(diacetoneacrylamide) (PDMAmxb-PDAAmy) diblock copolymer nanoparticles. This process is conducted within continuous-flow reactors, which are well suited to fast reactions and can easily dissipate exotherms making the process potentially scalable. Transient kinetic profiles obtained in-line via low-field flow nuclear magnetic resonance spectroscopy (flow-NMR) confirmed the rapid rate of polymerisation whilst still maintaining pseudo first order kinetics. Gel permeation chromatography (GPC) reported molar mass dispersities, Đ < 1.3 for a series of PDMAmxb-PDAAmy diblock copolymers (x = 46, or 113; y = 50, 75, 100, 150 and 200) confirming control over molecular weight was maintained. Particle characterisation by dynamic light scattering (DLS) and transmission electron microscopy (TEM) indicated successful preparation of spheres and a majority worm phase at 90 °C but the formation of vesicular morphologies was only possible at 70 °C. To maintain the rapid rate of reaction at this lower temperature, initiator concentration was increased which was also required to overcome the gradual ingress of oxygen into the PFA tubing which was quenching the reaction at low radical concentrations. Ill-defined morphologies observed at PDAAm DPs close to the worm-vesicle boundary, combined with a peak in molar mass dispersity suggested poor mixing prevented an efficient morphological transition for these samples. However, by targeting higher PDAAm DPs, the additional monomer present during the transition plasticises the chains to facilitate formation of vesicles at PDAAm DPs of ≥300.


About the Webwriter

Simon HarrissonSimon Harrisson is a Chargé de Recherche at the Centre National de la Recherche Scientifique (CNRS), based at the Laboratoire de la Chimie des Polymères Organiques (LCPO) in Bordeaux, France. His research seeks to apply a fundamental understanding of polymerization kinetics and mechanisms to the development of new materials. He is an Advisory Board member for Polymer Chemistry. Follow him on Twitter @polyharrisson

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Paper of the month: A general method to greatly enhance ultrasound-responsiveness for common polymeric assemblies

Dou and co-workers report a new way to improve ultrasound responsiveness in polymeric self-assemblies.

Image describing the work presented

Polymer assemblies or nanoparticles hold great potential to improve diagnosis and treatment of diseases by encapsulating chemotherapeutic or imaging agents with masked toxicity and triggerring release at target sites. To release encapsulated agents, polymer assemblies are often composed of specific stimuli-responsive polymers that can change their properties upon response to external stimuli such as pH, temperature, light, redox, magnetic, and ultrasound. However, this approach limits the components of polymer nanoparticles to stimuli-responsive polymers. In this work, Chen and co-workers elegantly crosslink a common non-responsive diblock copolymer using an ultrasound-responsive crosslinker, followed by the preparation of polymer assemblies that can dissociate under gentle ultrasound treatment. In particular, the photodimerization of coumarin groups under UV irradiation (365 nm) triggered the crosslinking, and a subsequent ultrasound treatment (5 min treatment by the ultrasound of 20-25 kHz at 32.5 W) dissociated the resultant polymer nanoparticles. Interestingly, this strategy could be successfully applied to not only spherical micelles but also worms and vesicles. The use of ultrasound-responsive crosslinker reported in this work paves the way for synthesizing ultrasound-responsive polymer nanoparticles from any block copolymer (not limited to a few ultrasound-responsive copolymers), thus representing a major step forward in the synthesis of smart polymer nanoparticles for biological science and technology.

Read this article for FREE until 15th July!

Citation to the paper: A general method to greatly enhance ultrasound-responsiveness for common polymeric assemblies, Polym. Chem., 2020, 11, 3296-3304, DOI: 10.1039/d0py00254b

You can read the paper here.

About the web writer

Professor Athina AnastasakiDr. Athina Anastasaki is an Editorial Board Member and a Web Writer for Polymer Chemistry. Since January 2019, she joined the Materials Department of ETH Zurich as an Assistant Professor to establish her independent research group.

 

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Paper of the month: A polymerization-induced self-assembly process for all-styrenic nano-objects using the living anionic polymerization mechanism

Wang and co-workers report an anionic polymerization combined with polymerization-induced self-assembly.

Schematic of LAP PISA process based on these all styrenic diblock copolymers and example TEM images on nano-objects

Polymerization-induced self-assembly (PISA) is arguably one of the most versatile and robust self-assembly methodologies and has been extensively evolved over the last decade to produce nanomaterials of various shapes. However, the vast majority of reported PISA methods employ a controlled radical polymerization strategy such as reversible addition–fragmentation chain transfer (RAFT) polymerization while low activated monomers such as styrenics are not frequently utilized. In this work, Wang and co-workers elegantly combine living anionic polymerization (LAP) with PISA to afford the facile and quantitative synthesis of spherical and worm-like nanoparticles. In particular, poly(p-tert-butylstyrene)-b-polystyrene was used as a model diblock copolymer and the polymerization was performed in heptane, a good solvent for the first block and a poorer solvent for the polystyrene segment. This formulation allowed the first monomer to polymerize in a homogenous system while the formation of the second block was performed under heterogeneous conditions. Importantly, all diblock copolymers synthesized exhibited narrow molecular weight distributions thus demonstrating excellent control over the polymerization. By adjusting the solid content and the molecular weight of each block, the authors were able to attain spheres, vesicles and worms at relatively high purity. To increase reproducibility, the authors also constructed a detailed phase diagram, where the exact location of each morphology was shown. Overall, it was demonstrated that LAP can be successfully combined with PISA therefore expanding PISA formulations beyond controlled radical polymerization.

Tips/comments directly from the authors:

  1. All-styrenic monomers with relatively low activity were firstly introduced into the PISA system and can be completely converted in the LAP PISA system with a rapid polymerization rate.
  2. The typical self-assembled morphologies, such as the spherical, worm-like and vesicular micelles, can also be captured in the LAP PISA system.
  3. Due to the excellent control on the molecular weight and structure of polymers in the LAP process, the nano-objects formed in the LAP PISA process were featuring with uniform sizes and morphologies.
  4. The molecular weights of each block and solids content have important influence on the LAP PISA process.
  5. The LAP PISA process can be performed in a large scale, and the potential industrial application is hoped to be explored for some novel nanomaterials in the future.

Read this article for FREE until 11th June!

Citation to the paper: A polymerization-induced self-assembly process for all-styrenic nano-objects using the living anionic polymerization mechanism, Polym. Chem., 2020, 11, 2635-2639, DOI: 10.1039/d0py00296h

Link to the paper:

https://pubs.rsc.org/en/content/articlepdf/2020/py/d0py00296h

About the web writer

Athina AnastasakiDr. Athina Anastasaki is an Editorial Board Member and a Web Writer for Polymer Chemistry. Since January 2019, she joined the Materials Department of ETH Zurich as an Assistant Professor to establish her independent research group.

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Paper of the month: Organocatalyzed atom transfer radical polymerization (ATRP) using triarylsulfonium hexafluorophosphate salt (THS) as a photocatalyst

Lei and co-workers report an inexpensive organocatalyzed atom transfer radical polymerization.

Organocatalyzed atom transfer radical polymerization (ATRP), also referred to as metal-free ATRP, has emerged over the last few years as an alternative to copper mediated ATRP in order to address the issue of metal contamination on the final polymers. In their current contribution, Lei and co-workers introduce triarylsulfonium hexafluorophosphate salt (THS) as an organic and inexpensive photocatalyst for ATRP of methacrylic monomers. The authors demonstrate exceptional temporal control with the polymerization completely stopping during the dark periods. Importantly, by adding sodium hydroxide, a significant acceleration over the polymerization rate was observed reaching relatively high conversions and narrow molecular weight distributions (Đ = 1.26–1.32). Block-copolymers were also possible, thus demonstrating high end-group fidelity. Last but not least, polymer brushes could also be prepared in an efficient manner on silicon wafer by utilizing surface-initiated ATRP in the presence of THS as a photocatalyst. Overall, the presented strategy is particularly attractive owing to the use of inexpensive compounds, the absence of metals and the mild temperatures employed. As the authors remark in the conclusions, such metal-free polymers may find interesting applications in the pharmaceutical, biomedical and food industries.

Tips/comments directly from the authors:

  1. This organocatalyzed-ATRP system is easy to operate. It does not need to undergo freeze-pump-thaw cycles.
  2. Temperature is an important factor for this organocatalyzed-ATRP system. Polymerization rate will be higher in summer and lower in winter unless you use an oil bath to have the temperature fixed.
  3. Due to the poor solubility of THS in water, aqueous media cannot be used as a solvent for this organocatalyzed-ATRP.
  4. When polymers with high molecular weights were synthesized by this system, the molecular weights were often lower than the theoretic values.
  5. In order to more effectively neutralize the free H+ generated by the rearrangement of triarylsulfonium hexafluorophosphate salt (THS), the use of powdered sodium hydroxide (NaOH) is a good choice.

Read this article for FREE until 12th May!

Citation to the paper: Organocatalyzed atom transfer radical polymerization (ATRP) using triarylsulfonium hexafluorophosphate salt (THS) as a photocatalyst, Polym. Chem., 2020, 11, 2222-2229, DOI: 10.1039/c9py01742a

Link to the paper:

https://pubs.rsc.org/en/content/articlepdf/2020/py/c9py01742a

About the web writer

Professor Athina AnastasakiDr. Athina Anastasaki is an Editorial Board Member and a Web Writer for Polymer Chemistry. Since January 2019, she joined the Materials Department of ETH Zurich as an Assistant Professor to establish her independent research group.

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2019 Polymer Chemistry Outstanding Student Paper Award Winner

We are pleased to introduce the Polymer Chemistry Outstanding Student Paper Award. This new annual award recognises outstanding work published in the journal, for which a substantial component of the research was conducted by a student. Read below for more information.

Our 2019 Winner

The inaugural recipient of the 2019 Polymer Chemistry Outstanding Student Paper award is Ms Evelina Liarou, currently a PhD student within the Haddleton group at the University of Warwick, for her contributions towards the paper titled ‘Ultra-low volume oxygen tolerant photoinduced Cu-RDRP’ (DOI: 10.1039/C8PY01720D).

Article imageIn this paper the authors introduce the first example of an oxygen-tolerant, ultra-low volume, photo-induced copper-RDRP method. A range of hydrophobic, hydrophilic and semi-fluorinated monomers are readily polymerized, achieving low dispersity values and quantitative monomer conversions in the absence of any conventional deoxygenation method. Notably, the reported conditions are compatible with extremely low volumes (as low as 5 μL total reaction volume), but can also be applied to larger scale polymerizations (up to 0.5 L). A further highlight of the paper is the use of an oxygen probe that allows for online monitoring of oxygen consumption, which significantly enhances the fundamental understanding of such polymerization protocols. Such an approach allows even non-experts to synthesise a range of materials with minimal effort and training.

Read the full article here now!

Eligibility

In order to be eligible for this award, the nominee must:

  • Have been a student at the time the research was conducted.
  • Be first author of a research article published in 2019 in Polymer Chemistry.

Selection Process

In order to choose the winner of the 2019 Outstanding Student Paper Award, a shortlist of articles that were published throughout the year, was selected by the editorial office and then subsequently assessed by the journal’s Editorial Board members. The winner was selected based upon the significance, impact and quality of the research.

Prize

The winner of the Outstanding Student Paper Award will receive an engraved plaque and a travel bursary of £500 to use towards a meeting of their choice.

 ***

To have your paper considered for the 2020 Polymer Chemistry Outstanding Student Award, simply indicate upon submission if the first author of the paper fulfils this criteria.

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Polymer Chemistry Author of the Month: Suhrit Ghosh

Suhrit Ghosh was born in 1976 in India. After the completion of his undergraduate education (Chemistry major) at the Presidency College (now University), Kolkata, he was admitted to the integrated PhD program (Chemical Science) at the Indian Institute of Science, Bangalore in 1997. He received his MS degree (Chemistry) in 2000 and continued for PhD until 2005 under the supervision of Professor S. Ramakrishnan. Then he moved to the group of Professor S. Thayumanavan at the University of Massachusetts, Amherst, USA, for postdoctoral studies (2005-2007). Subsequently he worked as an Alexander von Humboldt postdoctoral fellow (2007-2008) with Professor Frank Würthner at the University of Würzburg, Germany. In 2008 he joined the Indian Association for the Cultivation of Science (IACS), Kolkata, India, as an Assistant Professor where he currently holds the position of Professor and Chair of the School of Applied and Interdisciplinary Sciences.

Research interests of his group include supramolecular polymerization of donor-acceptor π-systems, H-bonding driven directional assembly of amphiphilic π-systems/macromolecules and biologically relevant stimuli responsive aggregation of amphiphilic polymers (polydisulfides, polyurethanes). He has about 100 publications in peer reviewed journals and ten PhD students have graduated from his group. He is the recipient of the B. M. Birla Science Prize in Chemistry (2014), JSPS Invitation Fellowship (long term) Japan (2014), SwarnaJayanti Fellowship (2015) from the Department of Science and Technology, Government of India, K. Kishore Memorial Award (2016) from the Society of Polymer Science, India and the Bronze medal (2017) from the Chemical Research Society of India. He has been serving as an Associate Editor for the journal RSC Advances since 2015.

What was your inspiration in becoming a polymer chemist?

I was introduced to Polymer Chemistry by two captivating teachers (Professor Manas Chanda and Professor S. Ramakrishnan) during my Master’s Degree course work in the Indian Institute of Science, Bangalore. Subsequently I had an opportunity to carry out a year-long MS project on Polymer Chemistry under the supervision of Professor S. Ramakrishnan when I started learning more about the subject. From group discussions and seminars in the department, I learnt about the emerging topics (of the time) in Polymer Chemistry such as foldamers, molecular imprinting, conjugated polymers, helical polymers, amphiphilic polymers, supramolecular polymers and so on. I was greatly inspired by such diversity in the field and its interdisciplinary nature connecting chemistry with biology and materials science.

What was the motivation behind your most recent Polymer Chemistry article?

Poly(disulfide)s (PDS), although known for long time, lacked structural diversity in the absence of any generally applicable synthetic methodology. Recently we had established a mild step-growth polymerization approach to make linear functional PDS by a facile thiol-disulfide exchange reaction between commercially available 2,2′-dipyridyldisulfide and a di-thiol.  By taking a stoichiometric excess of the first monomer, telechelic PDS could be prepared with the reactive pyridyl-disulfide groups at the chain terminal which could be further functionalized by a functional thiol without disturbing the backbone disulfide groups. This motivated us to extend this approach for the synthesis of hyperbranched PDS, particularly considering the possibility of decorating such hyperbranched polymers with multiple reactive pyridyl-disulfide groups at the periphery for post-polymerization functionalization to produce a range of functional hyperbranched polymers with a fully bio-reducible disulfide backbone. We have exactly demonstrated this in our recent Polymer Chemistry paper and envisage that it might allow the screening of structurally diverse amphiphilic hyperbranched PDS for biological applications such as drug delivery.

Which polymer scientist are you most inspired by?

I am most inspired by Professor E. W. Meijer (Eindhoven University of Technology, The Netherlands), especially because of his pioneering fundamental contribution in the field of supramolecular polymers by connecting supramolecular chemistry and polymer chemistry.

How do you spend your spare time?

I like to cook, spend time with my 10-year-old daughter and socialize with like-minded people.

What profession would you choose if you weren’t a scientist?

Practising literature and creative writing.

Read Suhrit’s full article now for FREE until 8th May!


Hyperbranched polydisulfides

Disulfide containing polymers have been extensively studied as responsive materials for biomedical applications such as drug delivery, gene delivery, bio-sensing and receptor-mediated cellular uptake due to the possibility of cleaving the disulfide linkage with glutathione (GSH), a tri-peptide overexpressed in cancer cells. While linear and branched polymers containing disulfide groups have been already studied and more recently polydisulfides (PDS) have come to the fore, hyperbranched polydisulfides (HBPDS) were not known. This manuscript for the first time reports a generally applicable methodology for the synthesis of HBPDS by an A2 + B3 condensation approach. The B3 monomer contains three pyridyl-disulfide (Py–Ds) groups while a di-thiol compound serves as the A2 monomer. A polycondensation reaction under very mild reaction conditions produces HBPDS (Mw = 14300 g mol−1Đ = 1.9) with a very high degree of branching (DB) value of 0.8 and more than twenty highly reactive Py–Ds groups present at the terminal or linear unit of a polymer on an average. The reactive Py–Ds groups can be completely replaced by post-polymerization functionalization using a hydrophilic thiol resulting in bio-reducible amphiphilic HBPDS. It produces micellar aggregates in water with a hydrodynamic diameter of ∼80 nm, a low critical aggregation concentration (7.0 μM) and a high dye (Nile red) loading content. The exchange dynamics of these micellar aggregates, studied by fluorescence resonance energy transfer (FRET), reveals practically no inter-micellar exchange after 6 h indicating very high non-covalent encapsulation stability. On the other hand, in the presence of glutathione, the PDS backbone can be degraded resulting in an efficient triggered release of the encapsulated dye. Dye release kinetics strongly depends on the GSH concentration and interestingly with a fixed concentration of glutathione the release kinetics appears to be much faster for the hyperbranched PDS micelle compared to its linear analogue. MTT assay with two representative cell lines indicates that the amphiphilic HBPDS is biocompatible up to 500 μg mL−1 which is further supported by hemolysis assay showing merely 6.0% hemolysis up to a polymer concentration of 500 μg mL−1.


About the Webwriter

Simon HarrissonSimon Harrisson is a Chargé de Recherche at the Centre National de la Recherche Scientifique (CNRS), based at the Laboratoire de la Chimie des Polymères Organiques (LCPO) in Bordeaux, France. His research seeks to apply a fundamental understanding of polymerization kinetics and mechanisms to the development of new materials. He is an Advisory Board member for Polymer Chemistry. Follow him on Twitter @polyharrisson

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Outstanding Reviewers for Polymer Chemistry in 2019

We would like to highlight the Outstanding Reviewers for Polymer Chemistry in 2019, as selected by the editorial team, for their significant contribution to the journal. The reviewers have been chosen based on the number, timeliness and quality of the reports completed over the last 12 months.

We would like to say a big thank you to those individuals listed here as well as to all of the reviewers that have supported the journal. Each Outstanding Reviewer will receive a certificate to give recognition for their significant contribution.

Prof. Dagmar D’hooge, Ghent University, ORCID: 0000-0001-9663-9893

Dr Ming Jin, Tongji University, ORCID: 0000-0002-8014-2812

Prof. Dominik Konkolewicz, Miami University, ORCID: 0000-0002-3828-5481

Dr Hua Lu, Peking University, ORCID: 0000-0003-2180-3091

Dr Stefan Naumann, University of Stuttgart, ORCID: 0000-0003-2014-4434

Dr Bernhard Schmidt, University of Glasgow, ORCID: 0000-0002-3580-7053

Dr Yan Xia, Stanford University, ORCID: 0000-0002-5298-748X

Dr Pu Xiao, Australian National University, ORCID: 0000-0001-5393-7225

Prof. Youliang Zhao, Soochow University, ORCID: 0000-0002-4362-6244

Prof. Junpeng Zhao, South China University of Technology, ORCID: 0000-0002-2590-0027

We would also like to thank the Polymer Chemistry board and the polymers community for their continued support of the journal, as authors, reviewers and readers.

 

If you would like to become a reviewer for our journal, just email us with details of your research interests and an up-to-date CV or résumé.  You can find more details in our author and reviewer resource centre.

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Paper of the month: Synthesis of lipase–polymer conjugates by Cu(0)-mediated reversible deactivation radical polymerization: polymerization vs. degradation

Graphic imageZhang and co-workers report aqueous polymerization-induced self-assembly by atom transfer radical polymerization to generate protein-based nanoassemblies.

Polymerization-induced self-assembly (PISA) has opened the way for the in-situ formation of a wide range of nanoparticles with applications ranging from the material to the biomedical field. However, the vast majority of reports focus on utilizing reversible addition-fragmentation chain transfer polymerization as the main methodology while atom transfer radical polymerization (ATRP) is very rarely combined with PISA, mostly due to the limitations of ATRP in water. Zhang and co-workers utilized Cu(0) reversible deactivation radical polymerization by exploiting the disproportionation of CuBr/ligand in aqueous media generating both Cu(0) particles and Cu(II) deactivator. Upon modifying Candida Antarctica lipase B (CALB), it was used as a macroinitiator for both hydrophilic and hydrophobic monomers generating well-defined protein-based nanoassemblies. A range of acrylamide and acrylate based monomers were successfully polymerized under mild reaction conditions (e.g. room temperature) via he “grafting from” strategy. When hydrophilic monomers were selected, water-soluble conjugates could be obtained in a facile manner while by polymerizing more hydrophobic monomers yields spherical nanoparticles, consistent to a traditional PISA formulation. Importantly, it was also found that they hydrolysis of the ester bonds can be very significant in the presence of lipase-based macroinitiators, which will catalyze the hydrolysis of poly(acrylate) to poly(acrylic acid). The versatility of the reported methodology combined with the use of mild reaction conditions may find applications in enzyme immobilization and nanoreactors.

Tips/comments directly from the authors:

  1. It is necessary to purify the commercial CuBr as it could be partially oxidized during storage and routine use.
  2. Typical Cu(0)-RDRP in water is fast enough to reach full conversion in minutes; however, the polymerizations would be slower when grafting from proteins, possibly due to the low concentration of macroinitiators.
  3. Although copper ions were known to be able to denature proteins, CALB still maintained its function after polymerization. The mild reaction conditions such as aqueous system, low reaction temperature (0-25 ℃) and fast polymerization rate (minutes to hours) could be suitable for more sensitive proteins.
  4. The degradation of lipase-poly(acrylate) conjugates was fast and gradual disappearance of precipitates could even be visually observed during the dialysis in water. So it is better to quickly purify the conjugates via centrifugation. From another point of view, such conjugates could be potentially used for drug delivery and controlled release.

Citation to the paper: Synthesis of lipase–polymer conjugates by Cu(0)-mediated reversible deactivation radical polymerization: polymerization vs. degradation, Polym. Chem., 2020, 11, 1386-1392, DOI: 10.1039/c9py01462d

Link to the paper:

https://pubs.rsc.org/en/content/articlelanding/2020/py/c9py01462d#!divAbstract

This paper is free to read until 10th April 2020!

About the Web Writer

Dr. Athina Anastasaki is an Editorial Board Member and a Web Writer for Polymer Chemistry. Since January 2019, she joined the Materials Department of ETH Zurich as an Assistant Professor to establish her independent research group.

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2020 Polymer Chemistry Lectureship awarded to Rachel O’Reilly

It is with great pleasure that we announce Prof Rachel O’Reilly (University of Birmingham) as the recipient of the 2020 Polymer Chemistry Lectureship.

This award, now in its sixth year, honours an early-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.

Rachel O'ReillyRead on to find out more about Rachel

Rachel O’Reilly holds a Chair in Chemistry within the College of Engineering and Physical Sciences at the University of Birmingham. From 1st August 2018 she became the Head of the School of Chemistry. She graduated from the University of Cambridge in 1998 with a BA in Natural Sciences, and in 1999 with an MSc in Chemistry and completed her PhD in 2003 from Imperial College London. She has held a number of prestigious fellowships from the ESPRC, Royal Society and Royal Commission for the Exhibition of 1851.

She has published over 175 research papers in scientific journals as well as reviews and book chapters in the fields of polymer synthesis, self-assembly, catalysis and DNA nanotechnology. She has given over 170 invited lectures and was recognised as one of the Royal Society of Chemistry’s 175 faces of Chemistry. She has received major grants and research support from the ERC, BP and EPSRC. She leads a large interdisciplinary team working at the interface of chemistry, materials and biology. Since 2006 she has graduated close to 25 PhD students and mentored over 20 postdoctoral researchers.

Rachel was appointed on the EPSRC strategic advisory network (SAN) in 2009 and served for almost 7 years. During this time she most significantly contributed to white papers on developing more flexible support for early career researchers, managing diversity and delivering impact. She holds a position as a review editor for Science and is an associate editor for Macromolecules.

Rachel leads the Rachel O’Reilly Group. Her group’s work has received numerous national and international awards for her polymer and material efforts, including, uniquely, four from the Royal Society of Chemistry (RSC), and, young researcher medals from the American Chemical Society (ACS) and the International Union of Pure and Applied Chemistry (IUPAC), the world authority on chemical nomenclature and terminology.

To learn more about Rachel’s research have a look at a selection of her publications in Polymer Chemistry:

Self-catalysed folding of single chain nanoparticles (SCNPs) by NHC-mediated intramolecular benzoin condensation
Sofiem Garmendia, Andrew P. Dove, Daniel Taton and Rachel K. O’Reilly

Polym. Chem., 2019,10, 2282-2289

Reversible ionically-crosslinked single chain nanoparticles as bioinspired and recyclable nanoreactors for N-heterocyclic carbene organocatalysis
Sofiem Garmendia, Andrew P. Dove, Daniel Taton and Rachel K. O’Reilly

Polym. Chem., 2018,9, 5286-5294

The application of blocked isocyanate chemistry in the development of tunable thermoresponsive crosslinkers
Marianne S. Rolph, Maria Inam and Rachel K. O’Reilly
Polym. Chem., 2017,8, 7229-7239

Understanding the CDSA of poly(lactide) containing triblock copolymers
Wei Yu, Maria Inam, Joseph R. Jones, Andrew P. Dove and  Rachel K. O’Reilly

Polym. Chem., 2017,8, 5504-5512

We would like to thank everybody who nominated a candidate for the 2020 Polymer Chemistry Lectureship. The Editorial Board had a very difficult task in choosing a winner from the many excellent and worthy candidates.

Please join us in congratulating Rachel on winning this award!

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