Polymer Chemistry Author of the Month: Sandra Schlögl

Dr Sandra SchloglSandra Schlögl studied Technical Chemistry at Graz University of Technology (Austria), where she obtained her Master degree in 2006. In 2006, she joined the Polymer Competence Center Leoben (PCCL), which is the leading ‘Center of Excellence’ for cooperative research in the area of polymer engineering and sciences in Austria. Two years later, she received her Ph.D. degree in Polymer Chemistry from Graz University of Technology. She was a visiting scientist at Politecnico di Torino (Italy) in the group of Prof. Marco Sangermano in 2016, and finished her habilitation (post-doctoral lecturing qualification) in Macromolecular Chemistry in 2017. Currently, she heads the ‘Chemistry of Functional Polymers’ division at PCCL. In addition, she is a lecturer at Montanuniversitaet Leoben (Austria) teaching courses at an MSc level in polymer photochemistry and in stimuli-responsive polymer materials. Her research centers on stimuli-responsive polymers, dynamic networks, elastomer chemistry and photochemistry in polymers. She is author of more than 50 peer-reviewed publications (Scopus H-index of 10), inventor of 11 patents (national and international) and has received several awards for her research (e.g. Paul Dufour Award in 2015, EARTO Innovation Award in 2016).

 

What was your inspiration in becoming a polymer chemist?

My career as a polymer chemist was not planned. In school, I always had a talent for natural-science subjects and back then, as today, I was intrigued by biological and biochemical processes of the human body. Obviously, my first plan was to study medicine and I even took Latin courses at school. However, during my voluntary work in the health care sector, I recognized that medicine is interesting in theory but hard to carry out in practice. I started to rethink my career plans, which led to my decision to study chemistry. The curriculum of the technical chemistry studies sounded promising since it also contained biochemistry, which was not so far away from medicine. However, during my studies I developed a favorite research activity: creating functional polymers. I took inspiring lectures and lab courses in polymer photochemistry, where I learned versatile and creative routes to change material properties on demand. Since then, the chemistry of polymers has me hooked.

What was the motivation behind your recent Polymer Chemistry article?

A strong focus of my working group is the synthesis of stimuli-responsive polymers, by introducing photocleavable chromophores and photoreversible binding motifs into polymer structures. These polymers change their material characteristics in response to external stimuli (such as light and temperature), which is used for numerous applications such as self-healable materials, reversible adhesives or switchable micropatterns.

Since several years, I have successfully cooperated with Marco Sangermano and Ignazio Roppolo from Politecnico di Torino on several research topics, joining the expertise of our working groups. Ignazio is not only a dedicated soccer player but also watches documentaries in his spare time. He was fascinated by the ability of desert beetles to collect humidity and transport water droplets across their skin. We discussed the topic and the idea was born to transfer the concept to photopolymer materials. Mimicking nature with synthetic materials for controlled water transport is not new, but the majority of the reported concepts rely on inorganic materials requiring time consuming and elaborate sample preparation techniques. With our recent Polymer Chemistry article, we succeeded to generate multi-gradients on polymer surfaces simply by light exposure. We introduced both a wettability gradient and a Laplace pressure gradient by a localized light-induced switching of the polarity, which is required to drive a water droplet across the photopolymer surface in a controlled way. This opens the path towards a precise movement of individual or multiple droplets on surfaces with complex topology and tailored surface polarity.

Which polymer scientist are you most inspired by?

In my field of research I am most inspired by the pioneering work of two scientists: Christopher N. Bowman (University of Colorado Boulder) and Christopher Barner-Kowollik (Queensland University of Technology). They are at the forefront of research in polymer photochemistry and their research is an important driving force for the development of new photopolymers with fascinating properties.

Can you name some up and coming polymer chemists who you think will have big impact on the field?

In my opinion, the research work of Miriam M. Unterlass (Vienna University of Technology) on hydrothermal polymerization has the potential to greatly influence future synthesis routes in polymer chemistry. Her research focuses on geomimetics, which takes inspiration from nature for generating novel synthetic materials under high pressure and with water as solvent. In one-pot reactions with low energy consumption, she is able to synthesis a great variety of materials involving polymers, dyes or inorganic-organic hybrids. I think that Miriam’s research has a great potential for the ‘green’ synthesis of new and traditional high-performance polymers; not only on a lab but also on an industrial scale.

How do you spend your spare time?

I am fond of outdoor sports, which are a good balance to my professional life, which over the past years is less and less taking place in the chemical lab but more in the office. I am a hobby racing cyclist, who tries to avoid the mountain areas, which is not an easy task in Austria and I do some running in between. I also enjoy spending time with my family and friends and in case of bad weather I like reading novels from different genres.

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

I would choose again a profession in science since I can only agree with Madame Marie Curie that ‘science has great beauty’.

 

Read her Polymer Chemistry article for FREE until June 10th!


Directed motion of water droplets on multi-gradient photopolymer surfaces

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The present work highlights the controlled directional movement of water droplets across a photopolymer surface. The movement is propelled by multi-gradients including a wettability gradient and a Laplace pressure gradient. Both gradients are conveniently adjusted by light employing a photoresponsive thiol–yne photopolymer. o-Nitrobenzyl alcohol derivatives with terminal alkyne groups are synthetized and cured across di- and tri-functional thiols upon visible light exposure. The wettability gradient is generated in a subsequent step involving an asymmetrical irradiation of the polymer surface with light in the UV-A spectral region. Polar groups are formed in the exposed areas due to the photocleavage of the chromophore and photo-oxidation reactions (upon prolonged UV exposure in air). The wettability rises with increasing exposure dose and gradient surfaces are prepared with static water contact angles ranging from 97 to 19°. By simultaneously inscribing the wettability gradient in wedge-shaped patterns, a Laplace pressure gradient is realized on the photopolymer surface, which can be easily tailored by the size and the angle of the wedge. The combination of both gradients enables a rapid and directed movement of water droplets (2 μL droplet) over a reasonable distance (up to 10 mm). Due to the high adhesion of the photopolymer surface, the droplet can be driven in a controlled way, even if the surface is inclined (20°) or turned upside down.


 

About the Web writer

Simon HarrissonSimon Harrisson is a Chargé de Recherche at the Centre National de la Recherche Scientifique (CNRS), based in the Laboratoire des IMRCP in Toulouse. 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: Precise control of single unit monomer radical addition with a bulky tertiary methacrylate monomer toward sequence-defined oligo- or poly(methacrylate)s via the iterative process

Oh et al. improve iterative single unit monomer addition by introducing an activated ester pendant for the chloride initiator.

Being able to achieve perfect sequence of the repeating units/monomers has recently attracted significant attention within the polymer chemistry community and the ultimate aim is to achieve similar monomer precision with natural biomacromolecules, such as DNA or proteins. Ouchi and co-workers contributed to this direction by exploring in detail the iterative single unit monomer radical addition of a bulky tertiary, adamantyl and isopropyl methacrylic monomer (IPAMA) in order to yield sequence-defined oligo- or poly(methacrylates) in high yields. The authors focused on improving the efficiency of the single unit addition and eliminating all unfavourable products, which is a significant challenge of this technique. To achieve this, the introduction of an activated ester for the alkyl halide or the adduct was essential in improving the accuracy of the single unit addition of IPAMA. In particular, a 4 step cycle consisting of “radical addition”, “transformation”, “selective cleavage” and “active esterification” was elegantly developed. Although one more step was required to change the electron density of the halogen terminal, the efficiency of single unit addition was enhanced and high yields were obtained. Importantly, and despite the yields being close to 100%, the authors suggest that the additional introduction of some supporter such as solid resin would make the presented approach much more scalable and practical.

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Tips/comments directly from the authors:

  1. The adamantyl and isopropyl methacrylic monomer (IPAMA) shows no homopolymerization ability due to the bulkiness.  The double bond of IPAMA is active enough for radical species like general methacrylic monomers and thus single unit addition is anticipated under the condition of reversible deactivation radical polymerization or controlled radical polymerization.
  2. The tertiary and bulky ester pendant can be transformed into less bulky alkyl substituent.  Such transformation allows iterative  single unit addition to give sequence-defined methacrylic oligomers and polymers.
  3. The introduction of an activated ester in an alkyl halide dormant species for ATRP allows quantitative single unit radical addition of IPAMA, in contrast to general alkyl halide resulting in bimolecular coupling and/or less quantitative reaction.
  4. The activated ester pendant on the penultimate unit for the adduct is transformed into alkyl ester (transformation), followed by selective cleavage of the terminal IPAMA unit under acidic condition.  The relative high molecular weight of N-hydroxy-5-norbornene-2,3-dicarboxyimide ester as activated ester was useful for study in single unit addition by SEC.
  5. The excess amount of IPAMA (10 eq for the halide) is required to complete the radical addition at a suitable rate.  The unreacted monomer can be removed by preparative SEC or silica column chromatography.
  6. The Cp*-based ruthenium complex with bisphosphine monoxide was useful as the catalyst for single unit radical addition.  The copper catalyst with dNbpy was also available.  Other copper catalysts were not studied.  The high efficiency in the radical addition is desirable for synthesis of sequence-defined methacrylic oligomers and polymers in high yields.
  7. Temperature is important to balance the quantitative reaction with the speed.
  8. COMU was best among condensing agents for the esterification studied in this work.

 

Read the full article for FREE until 3rd June!

Precise control of single unit monomer radical addition with a bulky tertiary methacrylate monomer toward sequence-defined oligo- or poly(methacrylate)s via the iterative process, Polym. Chem., 2019, 10, 1998-2003, DOI: 10.1039/C9PY00096H

 

About the webwriter

Professor Athina Anastasaki

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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Paper of the month: Microscale synthesis of multiblock copolymers using ultrafast RAFT polymerisation

Tanaka et al. explore the low volume synthesis of multiblock copolymers using thermal RAFT polymerisation

Oxygen is considered detrimental for radical polymerizations and as such traditional deoxygenation strategies (e.g. freeze pump thaw, nitrogen sparging, etc.) are typically required for the complete removal of oxygen. However, such methods may also possess drawbacks (e.g. lack of reproducibility) and as such alternative polymerization strategies that do not require external deoxygenation have been developed. To this end, Wilson, Perrier, Tanaka and co-workers reported the ultrafast polymerization of a range of acrylamide monomers in water exploiting reversible addition-fragmentation chain-transfer (RAFT) polymerization in the presence of air. The authors used microvolume insert vials as the reaction vessels and found that good control over the molecular weight and the dispersity could be maintained at very low volumes (down to 2 μl scale). Importantly, the resulting materials were successfully chain extended multiple times by sequential monomer additions allowing the facile synthesis of pentablock copolymers with a final volume of the reaction mixture not exceeding 10 μl. Nuclear magnetic resonance and gel permeation chromatography have been used to characterize the materials which were found to reach very high monomer conversions accompanied with low molecular weight distributions. These results demonstrate that RAFT polymerization can be used as a high-throughput screening method for the preparation of complex sequence-controlled multiblock copolymers. The authors are currently looking at expanding the scope of their investigation to include the synthesis of more complex structures and investigate their applicability to biological sciences.

 

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Tips/comments directly from the authors:

  1. In general, the aqueous ultrafast RAFT conditions (Polym. Chem., 2015, 6, 1502-1511) used in our work can also be scaled up (> 50 ml), however, depending on the set up, it may take longer time to permit sufficient heat transfer.
  2. The protocol is limited to acrylamidic monomer family in solvent mixture that constitutes mostly water to permit ultrafast polymerisation open to air without prior deoxygenation with quantitative monomer conversion. In addition, changing RAFT agent with a more stabilizing R group requires some modification to the protocol due to a longer induction period.
  3. Scaling down works very well in microvolume inserts, using centrifuge to spin down the reaction mixture to the bottom. Caution has to be taken when spinning inserts/vials inside a centrifuge, as leaving it spinning for too long may break the vials.
  4. For sequential chain extensions, the reactions vessels were cooled with liquid nitrogen, which was admittedly an overkill. Instead, it can also be cooled with ice-water bath. Cooling between blocks is essential at microscale for premixing the sequential monomer solution and subsequent centrifuge is advised to spin down the mixture again before reheating.
  5. For multiple reactions, a piece of cardboard was punctured and used as a platform for multiple inserts to be conveniently placed in an oil bath at the same time.
  6. The master mix containing PATBC (the RAFT agent) to target DP25, may appear somewhat cloudy with only 20% dioxane (of the total solvent volume added) especially when cooled or stored in refrigerator, however it will turn clear upon heating.
  7. When targeting high DP (>100), although some dioxane was used in our paper, the monomer (DMA, NAM) can sufficiently solubilise the PABTC without any co-organic solvents.

 

Read the full Open Access article: Microscale synthesis of multiblock copolymers using ultrafast RAFT polymerisation, Polym. Chem., 2019, 10, 1186-1191, DOI: 10.1039/C8PY01437J

 

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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Outstanding Reviewers for Polymer Chemistry in 2018

Outstanding Reviewers for Polymer Chemistry in 2018

We would like to highlight the Outstanding Reviewers for Polymer Chemistry in 2018, 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.

Professor Cyrille Boyer, University of New South Wales ORCiD: 0000-0002-4564-4702

Dr Sophie Guillaume, Institut des Sciences Chimiques de Rennes ORCiD: 0000-0003-2917-8657

Dr Xiaoyu Huang, Shanghai Institute of Organic Chemistry ORCiD: 0000-0002-9781-972X

Professor Dominik Konkolewicz, Miami University ORCiD: 0000-0002-3828-5481

Dr Vincent Ladmiral, ICGM ORCiD: 0000-0002-7590-4800

Dr Zachariah Page, University of Texas at Austin ORCiD: 0000-0002-1013-5422

Professor Felix Schacher, Friedrich Schiller University Jena ORCiD: 0000-0003-4685-6608

Professor Takeshi Shinono, Hiroshima University ORCiD: 0000-0002-1118-9991

Professor Lin Yuan, Soochow University ORCiD: 0000-0001-6966-8584

Professor Youliang Zhao, Soochow University ORCiD: 0000-0002-4362-6244

We would also like to thank the Polymer Chemistry board and the research 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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2019 Polymer Chemistry Lectureship awarded to Frederik Wurm

It is with great pleasure that we announce Priv.-Doz. Dr. Frederik Wurm (Max Planck Institute for Polymer Research) as the recipient of the 2019 Polymer Chemistry Lectureship.

This award, now in its fifth 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.

Read on to find out more about Frederik…

Frederik Wurm Frederik received his PhD in 2009 from the Johannes Gutenberg-Universität Mainz (Germany) working on nonlinear block copolymers. From 2009 to 2011 he was a postdoctoral Humboldt fellow at the Ecole Polytechnique Fédérale de Lausanne (EPFL, Switzerland) focusing on novel bioconjugation strategies. In 2012 he joined the Max Planck Institute for Polymer Research (Germany) as a group leader in the department of Katharina Landfester. He is also junior faculty of the Max Planck Graduate Center (MPGC). He finished his habilitation in 2016 about “Polyphosphoresters and Smart Nanocarriers”.

Frederik has published over 150 research articles and received several awards such as the Georg Manecke Award and the Reimund Stadler Award of the Gesellschaft Deutscher Chemiker (GDCh), the European Young Chemist Award, and the Lecturer Award of the German Chemical Industry Fund.

Frederik leads the research group “Functional Polymers” and develops new degradable and molecularly adjustable polymers. He has been particularly interested in biodegradable polyesters based on phosphoric acid in recent years. He has developed new bioinspired materials to facilitate their interaction with biomaterials, e.g. in human blood. Furthermore, such polyphosphoesters are interesting as alternatives to conventional plastics, with the ecological advantage of their degradability.

Frederik will present his lecture and receive his award at the European Polymer Congress in Crete in June.

 

To learn more about Frederik’s research have a look at some of his publications in Polymer Chemistry

Temperature responsive poly(phosphonate) copolymers: from single chains to macroscopic coacervates
Thomas Wolf,  Johannes Hunold,  Johanna Simon,  Christine Rosenauer,  Dariush Hinderberger  and  Frederik R. Wurm
Polym. Chem., 2018,9, 490-498

Triazolinedione-“clicked” poly(phosphoester)s: systematic adjustment of thermal properties
Greta Becker,  Laetitia Vlaminck,  Maria M. Velencoso,  Filip E. Du Prez  and  Frederik R. Wurm
Polym. Chem., 2017,8, 4074-4078

Surface-attached poly(phosphoester)-hydrogels with benzophenone groups
Greta Becker,  Zhuoling Deng,  Maria Zober,  Manfred Wagner,  Karen Lienkamp  and  Frederik R. Wurm
Polym. Chem., 2018,9, 315-326

The living anionic polymerization of activated aziridines: a systematic study of reaction conditions and kinetics
Elisabeth Rieger,  Tassilo Gleede,  Katja Weber,  Angelika Manhart,  Manfred Wagner  and  Frederik R. Wurm
Polym. Chem., 2017,8, 2824-2832

N-Ferrocenylsulfonyl-2-methylaziridine: the first ferrocene monomer for the anionic (co)polymerization of aziridines
Tatjana Homann-Müller,  Elisabeth Rieger,  Arda Alkan  and  Frederik R. Wurm
Polym. Chem., 2016,7, 5501-5506

Side-chain poly(phosphoramidate)s via acyclic diene metathesis polycondensation
Alper Cankaya,  Mark Steinmann,  Yagmur Bülbül,  Ingo Lieberwirth  and  Frederik R. Wurm
Polym. Chem., 2016,7, 5004-5010

 

We would like to thank everybody who nominated a candidate for the 2019 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 Frederik on winning this award!

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Paper of the month: A Diels–Alder reaction between cyanates and cyclopentadienone-derivatives – a new class of crosslinkable oligomers

Grätz et al. investigate the combination of cyanate esters with polyphenylenes through a Diels-Alder reaction.

Hyperbranched polyphenylenes and cyanate esters are two unique classes of materials that possess complementary properties. On one side, polyphenylenes are good insulators with remarkable solubility owing to their dense packing and the strongly twisted structure hinder π-conjugation respectively. Cyanate esters are also well renowned for their thermal stability as thermosetting materials. To combine these properties, Voit and co-workers investigated the copolymerisation of the two monomers 3,3′-(1,4-phenylene)bis(2,4,5-triphenylcyclo-pentadienone) and 2,2-bis(4-cyanatophenyl) propane through a Diels-Alder cycloaddition where carbon monoxide is released as a side product. The polymerisation was followed by UV/Vis spectroscopy and the structure of the oligomers could be further investigated by in-depth NMR studies. Importantly, the catenation proved to be completely statistical and independent of the temperature of the polymerization while the obtained oligomers can be cured via a trimerisation reaction of the terminal OCN-groups. Finally, the polymerisation and crosslinking reaction kinetics were also studied and upon crosslinking the resins exhibit high thermal resistance and transparency as well as a high refractive index. Thus, the resulting materials simultaneously possess the strengths of polyphenylene polymers while retaining the curing potential of the cyanate esters but at only the tenth of the activation energy of pure cyanate monomers, lowering the risk factors during handling. As the authors elegantly conclude, materials with such unique characteristics may find application in integrated optics.

10.1039/C8PY01374H

Tips/comments directly from the authors:

  1. The Diels-Alder cycloaddition with these substrates requires high temperatures. However, under these conditions the trimerisation reaction of cyanate esters also takes place. To avoid the premature crosslinking of the system while maintaining the cyanate ester termination a special protocol was developed. During the Diels-Alder reaction the ratios where adjusted to obtain a oligomer terminated with cyclopentadienone groups and only 15 minutes prior to the end of the reaction one additional equiv. of cyanate ester was added.
  2. The cyclopentadienone possesses a deep purple color while the polymer is colorless. Therefore, UV/Vis spectroscopy can be a powerful tool to track the reaction, but a simple look inside the reaction vial already gives indications on the state of the reaction.
  3. While cyclopentadienone monomers are sometimes challenging to synthesize there is a wide variety of commercial cyanate ester monomers and prepolymers allowing for a high degree of tunability of the resulting resin without changing the cyclopentadienone unit.
  4. Different to fully phenylene-based systems which are difficult to analyze by 13C NMR spectroscopy, the reaction with cyanate results in pyridine and cyanurate structures that can be well identified thus improving the structural characterization of such oligomers.

Read the full paper for FREE until 1st April 2019!

A Diels–Alder reaction between cyanates and cyclopentadienone-derivatives – a new class of crosslinkable oligomers, Polym. Chem., 2019, 10, 698-704

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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GPC 2019: The Polymer and Biomacromolecular Applications and Characterization Conference

GPC2019 will be held in New Orleans, Louisiana on Wednesday, July 10, 2019 – Thursday, July 11, 2019

GPC2019 is a two day conference that focuses on innovations in the synthesis of polymers and biopolymers, the application of gel permeation chromatography (GPC) and advanced detection for the characterization of these materials. The conference will emphasize industrial applications and novel developments of synthetic and biopolymers.

This  conference is comprised of invited and contributed lectures, poster sessions – including 3 poster prizes sponsored by Polymer Chemistry – discussions, and information exchange on the synthesis of polymers/biopolymers and characterization by GPC and high temperature GPC.

GPC2019 is a single session conference that brings together organic/synthetic polymer chemists, analytical chemists, chemical engineers and material scientists from a variety of sectors that are involved in using and developing methods for polymer characterization that utilize GPC. It is a great networking opportunity: renew old friendships, establish new contacts, and exchange ideas with your colleagues and peers!

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Paper of the month: Synthesis of star thermoresponsive amphiphilic block copolymer nano-assemblies and the effect of topology on their thermoresponse

Cao et al. report the synthesis of star thermoresponsive amphimphilic block copolymer assemblies.

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Thermoresponsive polymers can be used in a wide range of applications ranging from drug delivery to bioengineering owing to their unique capability of undergoing a soluble-to-insoluble transition in response to an external thermal stimulus. Amphiphilic block copolymers that contain a thermoresponsive block can self-assemble into core-corona nanoassemblies where the core consists of the hydrophobic block and the corona is formed by the thermoresponsive block. Zhang, Han and co-workers were interested in studying the dependence of a thermoresponsive phase transition on the topology structure. To achieve this, reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization was employed to synthesize well-defined multi-arm star block copolymer nanoassemblies via polymerization-induced self-assembly. The block copolymer was designed to have the first part consisting of the thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and the second block being the hydrophobic polystyrene (PS). By carefully modifying the number of arms (n=1, 2, 3 and 4), the degree of polymerization of the hydrophobic block and the polymerization conditions, (PNIPAM-b-PS) nanoassemblies with similar degree of polymerization and chain density, albeit different topology structure, were obtained. A range of characterization techniques were subsequently employed to comparatively study the responsiveness of these materials including turbidity analysis, dynamic light scattering, variable-temperature 1H NMR and rheological analysis. The authors found that the topology of the tethered PNIPAM chains had a significant influence on their thermoresponsive phase transition which decreased upon increasing the number of arms. This can be attributed to the inter-and intra-particle chain entanglement in the synthesized star nanoassemblies. It can thus be concluded that the topology of the thermoresponsive polymers can significantly affect their thermoresponsive and should be taken into account when designing the synthesis of such materials.

 

This paper is FREE to read and download until 27th February!

 

Synthesis of star thermoresponsive amphiphilic block copolymer nano-assemblies and the effect of topology on their thermoresponse, Polym. Chem., 2019, 10, 403-411, DOI: 10.1039/C8PY01617H

 

About the  Webwriter

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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European Biopolymer Summit 2019

The 6th Edition of ACI’s European Biopolymer Summit will be taking place on 13th – 14th February 2019 in Ghent, Belgium.

The two day event specially designed to bring together senior executives, key industry experts, researchers and bioplastic manufacturers, to exchange and share their experiences and research results on all aspects of bioenvironmental polymer engineering, most recent innovations, trends and concern as well as solutions adopted in the sector.

Key topics include:

  • Evaluating Current Environmental Projects And Regulations Within The Biopolymer Industry
  • Assessing The Feedstock’s Landscape For The Biopolymers’ Production
  • Focusing On Biopolymers in The Circular Economy
  • Elaborating On The Application Of Biopolymers From Peoples’ And Planet’s Perspective
  • Introducing New Technologies In Processing New Bio-Based Materials
  • Brand Owners Perspective On The Use And Application Of Biopolymers
  • Focusing On The Basic Understanding Of Biodegradability
  • Assessing The Biobased New Content
  • Analysing The Impact Of Biobased Plastics On The CO2 Reduction
  • Changing Consumer Preference Towards Eco-Friendly Packaging
  • Assessing The End-Of-Life Of Materials, Through The Life Cycle Assessment

A £255 discount is available for all participants until January 31st. Register now

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Paper of the month: Synthesis of sheet-coil-helix and coil-sheet-helix triblock copolymers by combining ROMP with palladium-mediated isocyanide polymerization

Pomarico et al. report the synthesis of sheet-coil-helix and coil-sheet-helix triblock copolymers.

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Natural proteins are comprised of distinct secondary structure elements such as sheets, helices and coils. It is the combination of these diverse topologies that allow proteins to fulfil their functions. Owing to the properties of these structures, synthetic analogues of these materials are also of great interest to the polymer chemistry community. However, a covalent system where sheet, helix, and coil blocks are combined in a linear system has not been yet realized. Towards this direction, Weck, Elacqua and co-workers developed a new methodology to covalently link three distinct structures together with high fidelity without compromising the control over sequence. This was achieved by combining sequential ring-opening metathesis polymerization (ROMP) of sheet- and coil-forming monomers with palladium-mediated isocyanide polymerization of covalent coil-sheet-helix (ABC) and sheetcoil helix (BAC) domains. After polymerizing the initial sheet of coil-forming monomer through ROMP, the second monomer is introduced and subsequently polymerized yielding to a diblock comprised of sheet and coil structures. ROMP is then terminated by a special transfer agent that contains an isocyanide polymerization initiator. The telechelic diblock copolymers containing both coil-sheet and sheet-coil blocks, can serve as macroinitiators for the polymerization of a P-helix forming monomer. As such, this combination of sequential copolymerization and macroinitiation enables three different polymer chains to be linked covalently. Importantly, throughout the triblock copolymer synthesis, all individual blocks retained their secondary structures as evidenced by circular dicroism and fluorescence spectroscopies. The authors are confident that this work can be extended to the formation of a diverse array of tri- and multiblock copolymers enabling a range of new applications.

Tips/comments directly from the authors:

1. When synthesizing a topologically-diverse block copolymer, oftentimes it is necessary to use different polymerization techniques. If so, prudent selection and design of polymer backbone is key. First, select the class(es) of monomers you intend to employ. This will inform the type of polymerization method required, and subsequently, the initiator to be designed.

2. Ring-opening metathesis polymerization (ROMP) is a widely-used controllable polymerization method that allows for one to not only control molecular weight, but also is amenable to an iterative or tandem ROMP, which is desirable for sequence-controlled block copolymers

3. Performing 31P NMR spectroscopy after each step of block copolymer synthesis, especially before the final step to create the helical block, is crucial. It ensures that only one palladium species is present throughout.

4. Isocyanide polymerization mediated by palladium(II) is a robust technique; there is high functional group tolerance when synthesizing the initiator, which allows for the engineering of multipurpose catalysts like the one featured in this manuscript.

5. Topologically-diverse polymer backbones, such as sheets, helices, and coils, garner much interest from a biomimetic standpoint in the synthetic community. Judicious choice of polymer backbones, as well as block lengths, can inform characterization techniques, such as circular dichroism, fluorescence, and X-ray scattering to gain insights into topology.

6. We are available for any questions and to troubleshoot any issues you may have – please contact mw125@nyu.edu or eze31@psu.edu.

 

Synthesis of sheet-coil-helix and coil-sheet-helix triblock copolymers by combining ROMP with palladium-mediated isocyanide polymerization, Polym. Chem., 2018, 9, 5655-5659, DOI: 10.1039/C8PY01361F

 

About the webwriter

Dr Athina AnastasakiDr. Athina Anastasaki is a Web Writer for Polymer Chemistry. She is currently an Assistant Professor at ETH Materials Department.

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