Focus on: Polymers and Rotaxanes

This month the focus is on Polymers and Rotaxanes, inspired by a recent lecture I attended, given by Sir J. Fraser Stoddart. He received the Nobel Prize in Chemistry in 2016, which was awarded jointly between himself, Jean-Pierre Sauvage and Bernard L. Feringa. His talk, which was part of the Krebs series of lectures at the University of Sheffield, featured his research in the field of mechanically interlocked molecules: rotaxanes and catenanes, which led to his pioneering work on “Molecular Machines”, for which the Nobel Prize was awarded.

Rotaxanes and catenanes are mechanically interlocked molecules; rotaxanes consist of a dumbbell shaped unit, with an encircled ring trapped by the dumbbell ends, whilst catenanes contain a number of interlocked macrocycles. The pioneering work of the Nobel laureates mentioned above has seen these systems developed, whereby through controlling the complexity and chemical functionality of the interlocked structures, work is possible, therefore leading to the term “Molecular Machines”.

Whilst rotaxane and catenane chemistry is well established, the same concept applied in polymer chemistry is currently a smaller area of research interest. However, this area of polymer chemistry research is emerging, with one article featured in Polymer Chemistry this month on the use of a non-polymeric rotaxane crosslinker to form toughened polymer networks. Looking back at previous Polymer Chemistry issues, two further articles utilising rotaxanes have been highlighted below.

1. A vinylic rotaxane cross-linker for toughened network polymers from the radical polymerization of vinyl monomers
J. Sawada, D. Aoki, M. Kuzume, K. Nakazono, H. Otsuka, T. Takata
Polym. Chem., 2017, 8, 1878-1881; DOI: 10.1039/c7py00193b

The authors describe the use a non-polymeric rotaxane crosslinker (RC), with two polymerisable vinyl groups, one on each constituent of the rotaxane unit, for the preparation of rotaxane crosslinked polymers (RCP). The RCPS were prepared via the free radical polymerisation of either butyl acrylate or ethylhexyl acrylate with the RC. The RCPs showed a higher toughness and fracture energy when compared with an equivalent polymer crosslinked with a standard divinyl monomer.

2. Mechanically linked poly[2]rotaxanes constructed from the benzo-21-crown-7/secondary ammonium salt recognition motif
Peng Wang, Zhao Gao, Ming Yuan, Junlong Zhua, Feng Wang
Polym. Chem., 2016, 7, 3664-3668; DOI: 10.1039/c6py00494f

Here, poly[2]rotaxanes were prepared through Cu(I) catalysed click polymerisation of the individual rotaxane units to give a linear polymer. The rotaxane monomer was prepared via a so-called “threading-followed-by-stoppering” strategy. The rheological properties of the poly[2]rotaxanes were investigated and exhibited shear-thinning behaviour not observed for the poly(caprolactone) precursors.

3. Phototriggered supramolecular polymerization of a [c2]daisy chain rotaxane
Xin Fu, Rui-Rui Gu, Qi Zhang, Si-Jia Rao, Xiu-Li Zheng, Da-Hui Qu, He Tian
Polym. Chem., 2016, 7, 2166-2170; DOI: 10.1039/c6py00309e

The formation of a polyrotaxane was achieved through the initial protection of two 2-ureido-4-pyrimidinone (Upy) end groups with photolabile coumarin groups. Exposure to UV light removed the coumarin protecting groups, which led to the self-assembly of the Upy groups and supramolecular polymerisation of the [c2] daisy chain rotaxane monomer. This work represents an interesting stimuli-responsive supramolecular polymers utilising rotaxanes.

Read these articles for free until May 21th


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: Novel alkoxyamines for the successful controlled polymerization of styrene and methacrylates

Simula et al. report the synthesis of poly(styrene) and poly(methacrylates) using novel alkoxyamines.

Reversible addition-fragmentation chain transfer polymerization (RAFT) and transition metal-mediated radical polymerization (TMM-RDRP) are two widely used techniques employed for the preparation of controlled polymeric architectures. However, both of them exhibit significant colouring and complete purification of the final materials is challenging. On the other hand, nitroxide mediated polymerization (NMP) requires no or minimal purification although designing alkoxyamines that can facilitate the controlled polymerization of both styrene and methacrylates is a challenge. In this contribution, Asua and co-workers employed three different alkoxyamines to study the homopolymerization of styrene and its chain extension with methacrylates. Upon careful evaluation of the reaction kinetics as well as variation of the polymerization temperature, high monomer conversions with uncompromised end group fidelity could be achieved. A wide range of molecular weights were targeted in order to identify the limitations of the system. It was found that for targeted degrees of polymerization beyond 333, there was an increased difference between theoretical and experimental molecular weights, due to the thermal initiation of styrene. In addition, the nature of the substituents in the nitroxide adduct was also found to be crucial for the controlled polymerization of styrene with bulkier adducts providing more extensive control. The retention of the reactive alkoxyamine chain end was further confirmed via nuclear magnetic resonance (NMR) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-ToF-MS). Well-defined PS-b-PBMA and PMMA-b-PS block copolymers were also successfully prepared highlighting these classes of alkoxyamines as a versatile mediator for the controlled polymerization of both methacrylates and styrene.

 

 

Tips/comments directly from the authors:

  1. It is important to monitor the temperature throughout the polymerisation in order to ensure optimum kinetics.

 

  1. The appropriate temperature should be employed for methacylates (< 100 °C) and styrene (> 110 °C). For instance, this can influence the final molar mass distributions of a block copolymer. The preparation of a poly(methyl methacrylate) macro-alkoxyamine first, followed by the chain extension with styrene provides a PMMA-b-PS block copolymer with moderate MMD. However, the preparation of the PS block first would yield a block copolymer with high dispersity value due, in part, to the high temperatures employed.

 

  1. Several matrix/salt combinations should be tested when conducting MALDI-ToF MS analysis. The reactive chain ends might not be observed with some matrixes, such as trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB).

 

 

Read this exciting research for free until 16/05/2017 through a registered RSC account:

 

Novel alkoxyamines for the successful controlled polymerization of styrene and methacrylates
Polym. Chem., 2017,8, 1728-1736, DOI: 10.1039/c6py02190e

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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 information.

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Chemical weapons trapped the swell way

Hypercrosslinked polymers absorb deadly agents

UK researchers have shown that polymers can absorb chemical warfare agents. When dried, the densely crosslinked polystyrene networks can swell to accommodate organic molecules. They can therefore act not just as universal sorbents for soaking up a wide range of chemicals, but also as a new way to decontaminate stockpiles of chemical weapons.

 

Source: © Royal Society of Chemistry
Reaction used to prepare the hypercrosslinked polymer networks



Read the full story by Hugh Cowley in Chemistry World.


This article is free to access until 26 April 2017.

C Wilson et al, Polym. Chem., 2017, DOI: 10.1039/c7py00040e

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Global Conference on Polymer and Composite Materials 2017

23-25 May 2017, Guangzhou, China

 

Polymer and Composite Materials 2017, which takes place at the South China University of Technologyis dedicated to cover all theoretical and experimental aspects of polymers and composite materials. Building on the hugely successful preceding conferences (PCM 2014 in Ningbo, PCM 2015 in Beijing, and PCM 2016 in Hangzhou), PCM 2017 will provide an ideal academic platform for researchers to present their latest findings, and to facilitate networking and in-depth discussion with peers from Asia, Europe and USA.

The scientific program will focus not only on current advances in the research, but also in the production and use of polymers and composite materials in different fields. The conference setting has a highly focused technical program through plenary, invited, contributed, and poster presentations, supported by Polymer Chemistry and Molecular Systems Design & Engineering.

In addition, the conference will also offer the possibility to publish your research either in the conference proceedings (Indexed by Ei, Scopus, Inspec, CPCI, etc) or in well-known journals with ISI impact factors. You can find out more about how to submit your paper via the publication guide.

Keynote speakers:

Register for the event here.

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Focus on: Carbon Dioxide and Polymers

Carbon dioxide constitutes a small amount of our atmosphere (currently around 0.04%) however it is vital for the survival of life on our planet. CO2 has been found to be a useful trigger for stimuli-responsive materials as it is benign, abundant, “green” and inexpensive. The reversible self-assembly of polymers and their response to the presence of CO2 has been of particular interest, for example in biomedical applications.

There is also a growing interest in carbon capture as environmental concerns increase, due to the rise in CO2 levels since the industrial age. Carbon capture has been proposed as a method to reduce the amount of CO2 in the atmosphere. Therefore several researchers have been interested in preparing materials which could be used absorb and store CO2 to remove it from the atmosphere.

This month we look at three articles published in Polymer Chemistry; two articles which describe CO2 responsive polymers, and one which investigates materials for CO2 absorption.

1. Oxygen and carbon dioxide dual gas-responsive homopolymers and diblock copolymers synthesized via RAFT polymerization
Xue Jiang, Feng Chun, Guolin Lu, Huang Xiaoyu
Polym. Chem., 2017, 8, 1163-1176; DOI: 10.1039/C6PY02004F

Firstly a monomer containing both O2 and CO2 responsive groups was prepared (containing a CF3 and tertiary amine group), and polymerised by reversible addition-fragmentation chain-transfer (RAFT) polymerisation. This polymer and a diblock copolymer containing PEG, showed responsivity when O2 and CO2 were bubbled through the solution compared with N2. The results suggest potential biomedical applications for the PEG containing polymer which formed micelles in solution.

2. CO2-Responsive graft copolymers: synthesis and characterization
Shaojian Lin, Anindita Das, Patrick Theato
Polym. Chem., 2017, 8, 1206-1216; DOI: 10.1039/C6PY01996J

Through a combination of controlled radical polymerisation and a grafting-to post-polymerisation modification, the authors describe the synthesis of CO2 responsive graft-copolymers, where the incorporation of a tertiary amine monomer imparts the CO2 responsive behaviour. The graft copolymers could be self-assembled to form vesicles in aqueous media, which swelled upon purging with CO2, for applications such as responsive drug delivery vehicles.

3. Microporous polyimide networks constructed through a two-step polymerization approach, and their carbon dioxide adsorption performance
Hongyan Yao, Na Zhang, Ningning Song, Kunzhi Shen, Pengfei Huo, Shiyang Zhu, Yunhe Zhang, Shaowei Guan
Polym. Chem., 2017, 8, 1298-1305; DOI: 10.1039/C6PY01814A

In contrast to the two previous articles, this paper reports the preparation of microporous polyimide networks, through polycondensation reaction and subsequent crosslinking. The formation of micropores was promoted due to the crosslinked structure, which restricted macromolecular conformational changes. The materials exhibited BET surface areas up to 497 m2g-1, with comparable CO2 uptake values to other microporous polyimides prepared from rigid tri-dimensional monomers.

Read these articles for free until April 16th


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: Vesicles of double hydrophilic pullulan and poly(acrylamide) block copolymers: a combination of synthetic- and bio-derived blocks

Willersinn et al. report the synthesis of double hydrophilic pullulan and poly(acrylamide) block copolymers.

Double hydrophilic block copolymers (DHBC) self-assemble to various structures in aqueous solutions due to a strong difference in hydrophilicity. This is in contrast to amphiphilic block copolymers that self-assemble due to the insolubility of the hydrophobic block in water. In their recent contribution, Schmidt and co-workers were able to extend the principle of double hydrophilic self-assembly to novel polysaccharide-polyacrylamide block copolymers namely pullulan-b-poly(N,N-dimethylacrylamide) (Pull-b-PDMA) and pullulan-b-poly(N-ethylacrylamide) (Pull-b-PEA). The bio-derived pullulan block was obtained via acid catalyzed depolymerisation, while the polyacrylamide homopolymer blocks were synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization. Subsequently the blocks were conjugated via copper catalyzed azide alkyne cycloaddition (CuAAC). The presence of formed vesicular structures was investigated via cryogenic electron microscopy (cryo SEM), static light scattering (SLS) and dynamic light scattering (DLS) measurements showing diameters in the range of 200 to 500 nm. Finally, laser confocal scanning microscopy (LSCM) was employed using Rhodamine B staining or Rhodamine B labelled block copolymers to image the formed particle structures. These novel vesicular structures may find use in a wide range of applications including drug delivery.


Tips/comments directly from the authors:

1. The synthesis of block copolymers via CuAAc can be significantly simplified via the utilization of azide functionalized resins. As described in the paper the alkyne functionalized building block is utilized in excess. The resin is added after sufficient reaction time directly to the reaction mixture to react with residual alkyne end functionalized polymer and finally the resin is easily removed via filtration after the reaction. Therefore, no optimization of equivalents or absolute molecular weight data is needed to obtain a pure product without homopolymer contamination.
2. The choice of blocks is crucial for DHBC self-assembly in water. The blocks have to feature a significant difference in hydrophilicity. Moreover, high polymer concentrations are needed to obtain self-assembled structures.
3. For a pure DHBC self-assembly the utilized blocks should not feature LCST or other stimulus responsive behaviour that alters the solubility of the individual blocks. Otherwise the self-assembly might be driven via hydrophobic interactions as with an amphiphilic block copolymer.

Read this exciting research for free until 16/04/2017 through a registered RSC account:

Vesicles of double hydrophilic pullulan and poly(acrylamide) block copolymers: a combination of synthetic- and bio-derived blocks
Polym. Chem., 2017,8, 1244-1254, DOI: 10.1039/c6py02212j

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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 information.

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Outstanding Reviewers for Polymer Chemistry in 2016

Following the success of Peer Review Week in September 2016 (dedicated to reviewer recognition) during which we published a list of our top reviewers, we are delighted to announce that we will continue to recognise the contribution that our reviewers make to the journal by announcing our Outstanding Reviewers each year.

We would like to highlight the Outstanding Reviewers for Polymer Chemistry in 2016, 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.

Dr Athina Anastasaki, University of California Santa Barbara
Dr Brigitte Bibal, Universite Bordeaux
Dr Cyrille Boyer, University of New South Wales
Dr Gaojian Chen, Soochow University
Dr Priyadarsi De, IISER Kolkata
Dr Sophie Guillaume, Institut des Sciences Chimiques de Rennes
Dr Xiaoyu Huang, Shanghai Institute of Organic Chemistry
Dr Elango Kumarasamy, Colombia University
Dr F.J. Xu, Beijing University of Chemical Technology
Professor Youliang Zhao, Soochow University

We would also like to thank the Polymer Chemistry board and the journal 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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Focus on: Polymers in Emulsions

This month we look at three articles that feature in Polymer Chemistry that report the use of polymers in emulsions.  Both in emulsion polymerisation and high internal phase emulsions.

Emulsion polymerisation can be utilised to prepare polymers as polymeric particles with high solids content, and is commonly used in industry and academia alike. Seeded emulsion polymerisation is a technique where a seed particle is utilised in an emulsion polymerisation, to overcome any variability in the nucleation step.

High internal phase emulsions (HIPE) are those that have a droplet (internal) phase that constitutes 74.05% or more of the total emulsion volume. PolyHIPEs have gained a great deal of interest, where the polymerisation occurs in the continuous phase forming voids around the dispersed droplets, leading to highly porous materials.

1. Impressed pressure-facilitated seeded emulsion polymerization: design of fast swelling strategies for massive fabrication of patchy microparticles
Lei Tian, Xue Li, Panpan Zhao, Zafar Ali, Qiuyu Zhang
Polym. Chem., 2016, 7, 7078-7085; DOI: 10.1039/C6PY01778A

The authors present a pressure-facilitated seeded emulsion polymerisation of poly(glycidyl methacrylate)/poly(styrene), whereby the utilisation of high pressure and temperature allowed for an accelerated seed swelling process, overcoming typical disadvantages of seeded emulsion polymerisation.  The resulting particles could be designed to be patchy and anisotropic in shape, through tuning the polymerisation time and dibutyl phthalate/styrene ratios.

2. Rational design of functionalized polyacrylate-based high internal phase emulsion materials for analytical and biomedical uses
Gloria Brusotti, Enrica Calleri, Chiara Milanese, Laura Catenacci, Giorgio Marrubini, Milena Sorrenti, Alessandro Girella, Gabriella Massolini, Giuseppe Tripodo
Polym. Chem., 2016, 7, 7436-7445; DOI: 10.1039/C6PY01992G

PolyHIPEs (with water contents of 80-90%) were designed through the polymerisation of (meth)acrylate monomers: butyl acrylate, glycidyl methacrylate and trimethylolpropane triacrylate as the oil phase. Various parameters were optimised, such as the monomer, cross-linker and surfactant concentrations, to give structural porous polyHIPEs with interesting morphology, thermal stability and porosity. The materials have potential for the immoblization of biomolecules for various applications.

3. Closed-cell and open-cell porous polymers from ionomer-stabilized high internal phase emulsions
Tao Zhang, Zhiguang Xu, Qipeng Guo
Polym. Chem., 2016, 7, 7469-7476; DOI: 10.1039/C6PY01725H

PolyHIPEs were prepared, utilising an ionomer as a stabiliser and either styrene (Sty) or butyl acrylate (BA) as the continuous phase. Sty based polyHIPEs resulted in closed-cell pores, whereas BA gave open-cell structures. When increasing the internal phase, the average pore diameters in the Sty polyHIPES decreased, whilst the average pore diameters for the BA polyHIPEs increased. Also, the amphiphilicity of the polyHIPEs could be tuned by simply exposing them to different water of different pH values.

Read these articles for free until March 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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Paper of the month: Probing the causes of thermal hysteresis using tunable Nagg micelles with linear and brush-like thermoresponsive coronas

Blackman et al. report the synthesis of thermoresponsive polymers with tunable aggregation numbers in order to study the causes of thermal hysteresis.

 

Thermoresponsive polymers are materials that exhibit a change in their solubility over a temperature range. Thanks to this unique characteristic, these polymers can be used as smart and switchable materials for a wide range of biomedical applications. However, the cloud points upon cooling and heating a thermoresponsive polymer do not coincide because the process of equilibration takes time. The temperature interval between the cloud points upon cooling and heating is called hysteresis and the reversibility of these polymer’s thermal transitions can be influenced by many factors. In order to shine a light to these factors, O’Reilly, Gibson and Blackman synthesized well-defined, responsive amphiphilic block copolymers containing four different thermoresponsive corona blocks and assembled them in micellar structures in aqueous media. All micelles were designed to have tunable aggregation number enabling the study of the effects of altering the corona chemistry, chain confinement and core hydrophobicity on the thermoresponsive behavior, specifically the degree of hysteresis. It was found that higher core hydrophobicities were associated with a higher degree of hysteresis due to differences in core hydration. Linear corona chains capable of forming polymer-polymer hydrogen bonding interactions (e.g. pNIPAM) showed a greater hysteresis than those that could not (pDEAm). Importantly, the authors demonstrates that polymers with a brush-like architecture (pDEGMA and pOEGMA) exhibit irreversible phase transitions at a critical chain density, owing to irreversible nanoscale rearrangement in the precipitated bulk. These findings offer a deeper and more comprehensive understanding of stimuli-responsive self-assemblies and further highlight the complexity of hysteresis in thermoresponsive polymer systems.

 

Tips/comments directly from the authors:

1. It is important to use a Peltier system fitted with a reference cell with an internal temperature probe in order to accurately measure the hysteresis in the cooling curve. We have found that those without this feature typically over-estimate the hysteresis by a few degrees.
2. When synthesizing the pOEGMA-containing diblock copolymers, careful consideration of the RAFT CTA was necessary; the use of 2-Cyano-2-propyl dodecyl trithiocarbonate, as was employed for pDEGMA-containing diblock copolymers, resulted in a significant amount of high molecular weight polymers in the molecular weight distribution. Additionally, lower conversions had to be employed in order to reduce the presence of such species.
3. It was also important to employ multiple angle light scattering coupled with an algorithm such as REPES, which could enable us to investigate the molecular weights of the major fast mode and filter out scattering from spurious slow modes typically found in thermoresponsive polymer systems attributed to non-Brownian interactive behavior.

 

Read this paper for free until March 14th

Probing the causes of thermal hysteresis using tunable Nagg micelles with linear and brush-like thermoresponsive coronas
Polym. Chem., 2017, 8, 233-244.
DOI: 10.1039/C6PY01191H


About the Webwriter:Athina 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 her website for more information.

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Advisory Board Top Picks: Sophie Guillaume

Sophie Guillaume is a member of the Advisory Board for Polymer Chemistry and a CNRS Research Director at the Institut des Sciences Chimiques de Rennes (ISCR), France.

Her research focuses on the development of green pathways for the synthesis and structure–property relationships of synthetic polymers (especially polyesters, polycarbonates, polyolefins, and polyurethanes). Areas of emphasis include biobased degradable polymers and functionalized and reactive (co)polymers for advanced industrial and biomedical applications.

You can find all Advisory Board’s Top Picks papers in our web collection.




Focus on polyurethanes

All articles are free to read until Sunday 5th March.

Polyurethanes (PUs) are one of the most important classes of polymeric materials most widely used as coatings, adhesives, sealants, foams, or elastomers. These multiblock copolymers are formed by the stepwise addition of diols (or polyols) with diisocyanates (or polyisocyanates). Efforts to reduce their environmental impact and to improve their sustainability, resulted in the development of biobased monomers, and of greener processes towards non-isocyanate polyurethanes (NIPUs). Original PU materials with properties at least matching or improving those of the current PU market are thus being sought. To this end, functionalization introduced via the amine segment, the polyol moiety, or the repeating units’ pending groups, is a key parameter to tune towards the desirable characteristics and targeted applications. The biomedical field provides further opportunities for biocompatible and biodegradable PU materials which are widely used as nerve tissue scaffolds, vascular prostheses or drug delivery systems. However, their physical properties (mechanical properties, degradation performances and blood compatibility) still require improvements. These present trends are illustrated with the following top-picks.


Room temperature synthesis of non-isocyanate polyurethanes (NIPUs) using highly reactive N-substituted 8-membered cyclic carbonates

Alexander Yuen, Amaury Bossion, Enrique Gómez-Bengoa, Fernando Ruipérez, Mehmet Isik, James L. Hedrick, David Mecerreyes, Yi Yan Yang and Haritz Sardon
Polym. Chem., 2016, 7, 2105-2111

Current efforts in the polyurethane (PU) community aim at developing green strategies exempt of the use of toxic and dangerous isocyanates. Nowadays, the most promising route towards such non-isocyanate polyurethanes (NIPUs) is the aminolysis of dicyclic carbonates. H. Sardon and co-workers at the University of the Basque Country (Spain), have synthesized, at room temperature without the need for any additional catalyst, high molar mass NIPUs (up to 47 kg.mol1) from a (bis) N-substituted eight-membered cyclic carbonate (N-8CC) derived from renewable resources using a variety of diamines. These experimental results highlight the unique reactivity of this N-8CC over the smaller five- and six-membered cyclic carbonates, as further supported by computational insights which revealed a kinetically and theoretically more favourable ring opening of the N-8CC by an amine system.


Synthesis and hydrolytic properties of water-soluble poly(carbonate–hydroxyurethane)s from trimethylolpropane

Hiroyuki Matsukizonoa and Takeshi Endo
Polym. Chem., 2016, 7, 958-969

Poly(hydroxyurethane)s (PHUs) derived from the polyaddition of six-membered ring cyclic carbonates with diamines are promising non-isocyanate polyurethanes (NIPUs) alternatives to polyurethanes (PUs), as evidenced by T. Endo and co-worker at Kinki University (Japan). Such PHUs advantageously contain two primary hydroxyl groups in their side chains of repeating units, which improve the hydrophilicity and which can be chemically modified to design functional PHU materials. Original well-defined water-soluble poly(carbonate–hydroxyurethane)s comprising hydroxyurethane–carbonate–hydroxyurethane alternate structures were synthesized from trimethylolpropane and conventional diamines. Investigations of their hydrolytic properties in aqueous media at different pH values revealed their complete decomposition to their basic structures in carbonate buffers at pH 10.6 within one week.


Bio-based difuranic polyol monomers and their derived linear and cross-linked polyurethanes

Zehuai Mou, Shuo (Kelvin) Feng and Eugene Y. X. Chen
Polym. Chem., 2016, 7, 1593–1602

A series of linear and cross-linked polyurethanes (PUs) is reported by E. Chen and co-workers at Colorado State University (USA), from the catalysed polyadditions of diol, triol or tetraol derived from the biomass platform chemical 5-hydroxymethylfurfural (HMF) – one of the most value-added biomass building blocks or platform chemicals – with various diisocyanates in the presence of a catalyst (organocatalyst or dibutyltin dilaurate), respectively. The PU materials derived from the new diol monomer, namely 5,5’-bihydroxymethyl furil, and aromatic diisocyanates such as diphenylmethane diisocyanate, revealed valuable characteristics (Mn,SEC = ca. 40 kg mol−1, onset decomposition temperature = 234 °C, and Tg = 140 °C). Solvent casting from these PUs affords thin films ranging from brittle to flexible with a high strain at break of 300%.


An epoxy thiolactone on stage: four component reactions, synthesis of poly(thioether urethane)s and the respective hydrogels

Stefan Mommer, Khai-Nghi Truong, Helmut Keul and Martin Möller
Polym. Chem., 2016, 7, 2291–2298

The synthesis of a new epoxy thiolactone is described by H. Keul and M. Möller and co-workers at RWTH Aachen University (Germany), along with its ability to act in several concepts as a versatile tool towards polymeric materials. The reactivity of this epoxy thiolactone with an amine and catalytic amounts of a base, results in the selective ring opening of the thiolactone to generate an AB-type epoxy thiol monomer, which in situ starts a thiol-epoxy polymerization to ultimately form poly(thioether urethane)s (PTEUs). Besides the introduction of a new functionality – the organic residue – by the amine used for ring opening of the thiolactone, the PTEU backbone further exhibits a hydroxyl functionality. The latter increases the hydrophilicity of the polymer backbone and also provides a site for an additional functionalization. Two strategies were elaborated for the generation of functional gels from this epoxy thiolactone bis cyclic monomer, using a diamine or a triacrylate. These one pot processes are feasible and provide an interesting platform for a variety of polymer architectures hosting functionalities.

A novel biodegradable polyurethane based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ethylene glycol) as promising biomaterials with the improvement of mechanical properties and hemocompatibility

Cai Wang, Yudong Zheng, Yi Sun, Jinsheng Fan, Qiujing Qina and Zhenjiang Zhao
Polym. Chem., 2016, 7, 6120-6132

A novel block polyurethane (PU) based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), 4,4’-diphenylmethanediisocyanate and poly(ethylene glycol) (PEG) was synthesized by Zheng and co-workers at the University of Science and Technology Beijing (China), from the polyaddition of PHBV diol with ,-diisocyanate telechelic PEG. The resulting PU films exhibited biodegradability at 37 °C in phosphate buffer solution (PBS) at pH 7.4, non-cytotoxicity towards the growth and proliferation of the bone marrow mesenchymal stem cells, and hemocompatibility. The degradation rate results indicate that PHBV-based PUs are more suitable for biomedical applications requiring a longer degradation period. Greater PHBV contents also favourably influenced the mechanical properties and the thermal stability of these PU films. These new PHBV based PU materials with better mechanical properties, biodegradability, hemocompatibility and biocompatibility, may find potential applications in blood vessel tissue engineering.

Thermo- and pH-sensitive shape memory polyurethane containing carboxyl groups

Qiuju Song, Hongmei Chen, Shaobing Zhou, Keqing Zhao, Biqing Wang and Ping Hu
Polym. Chem., 2016, 7, 1739-1746

A multi-functional polyurethane (PU) with both a thermo-induced triple shape memory effect and a pH-sensitive dual shape memory effect has been developed by Chen and Hu and co-workers at Sichuan Normal University (China). The two-step polyaddition of polyethylene glycol (PEG), and 4,4’-diphenylmethane diisocyanate, followed by polymerization of the resulting diisocyanate end-functionalized PEG with dimethylolpropionic acid afforded the desired PUs bearing pendant carboxyl groups. In PU with 30wt% of PEG, the glass transition of PEG chains and the association/disassociation of carboxylic dimers act as two switches to control the triple-shape memory effect, while the carboxylic dimer is affected by pH values to associate in acidic solutions (pH 2) and dissociate in alkaline solutions (pH 9) to induce the pH-sensitive shape memory. The carboxylic dimers play an important role in the construction of shape memory properties in these PUs. Indeed, PUs with too high or too low carboxylic content (e.g. with 20 or 40wt% of PEG) did not exhibit any shape memory properties.

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