| 1. |
- Adatia, Karishma K., et al.
(author)
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Structure–property relations of amphiphilic poly(furfuryl glycidyl ether)-block-poly(ethylene glycol) macromonomers at the air–water interface
- 2020
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 11:35, s. 5659-5668
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Journal article (peer-reviewed)abstract
- To deepen our knowledge of the film formation and the structure–property relations of poly(furfuryl glycidyl ether)-block-poly(ethylene glycol) (PFGEp-b-PEGq) macromonomers at the air–water interface, we synthesized PFGEp-b-PEGq in six different block lengths. The molar mass of the PFGEp-b-PEGq macromonomers varied from ∼2000 g mol−1 to ∼7000 g mol−1 and included a wide range of hydrophilic–lipophilic balance (HLB) values between 3.6 and 13.9. Surface pressure–area (π–A) isotherms of these amphiphilic macromonomers revealed that the block lengths and the molar mass influence the isotherm shape and onset. Smaller, more hydrophobic macromonomers (HLB < 8) showed a steeper surface pressure increase in the liquid condensed phase compared to larger, more hydrophilic macromonomers with HLB > 8. The molecular area for isotherm onsets increased almost linearly with growing molar mass of the macromonomers. Static and dynamic film stability measurements demonstrated limited stability of all macromonomer monolayers at the air–water interface. The more hydrophilic macromonomers PFGE8-b-PEG79, PFGE18-b-PEG66 and PFGE13-b-PEG111 (HLB > 8) showed higher film stability compared to the more hydrophobic macromonomers (HLB < 8). Hysteresis experiments displayed an almost linear increase of the film degradation with rising HLB values of the macromonomers. Due to partial film recovery of our macromonomers, we propose an interplay between a reversible folding and an irreversible submersion mechanism for the macromonomer monolayers at the air–water interface. The molecular structure and the film forming ability of the macromonomers at the air–water interface indicate that they are promising surface functionalization reagents for materials formed from aqueous solutions, such as hydrogels. In this regard, PFGE10-b-PEG9 is the most promising hydrogel surface functionalization reagent, because it can introduce the highest number of functional groups per surface area.
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| 2. |
- Ai, Chenxiang, et al.
(author)
-
One-pot construction of nitrogen-rich polymeric ionic porous networks for effective CO2 capture and fixation
- 2022
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 13:1, s. 121-129
-
Journal article (peer-reviewed)abstract
- Facile preparation of ionic porous networks (IPNs) with large and permanent porosity is highly desirable for CO2 capture and transformation but remains a challenge. Here we report a one-pot base-mediated construction of nitrogen-rich IPNs through a combination of nucleophilic substitution and quaternisation chemistry from H-imidazole. This strategy, as proven by the model reactions of 1H-imidazole or 1-methyl-1H-imidazole with cyanuric chloride, allows for fine regulation of porosity and physicochemical properties, leading to nitrogen-rich IPNs featuring abundant ionic units and radicals. The as-prepared networks, termed IPN-CSUs, efficiently capture CO2 (80.1 cc g−1 at 273 K/1 bar) with an ideal CO2/N2 selectivity of 139.7. They can also effectively catalyse the cycloaddition reaction between CO2 and epoxides with high yields of up to 99% under mild conditions (0.1 MPa, 298 K), suggesting their possible applications in the fields of both selective molecular separation and conversion. Unlike the previously known strategies generally involving single coupling chemistry, our strategy combining two coupling routes in one pot appears to be unique and potentially applicable to other building blocks.
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| 3. |
- Alexakis, Alexandros Efraim, et al.
(author)
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Bimodal nanolatexes prepared via polymerization-induced self-assembly : losing control in a controlled manner
- 2023
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 14:19, s. 2308-2316
-
Journal article (peer-reviewed)abstract
- The combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization with polymerization-induced self-assembly (PISA) is known to yield monodisperse nanolatexes. Interestingly, based on the results of the current study, reproducible bimodal nanolatexes were shown to be the result of chain extension of protonated poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) with methyl methacrylate (MMA) in water when aiming for a longer hydrophobic block, for which we provide the first imaging data to our knowledge. The bimodality was found to be induced by the hydrophilic Z-group of the RAFT agent, which has been reported in the literature to be the cause of bimodal molecular weight distributions in RAFT-mediated PISA in emulsion polymerization. Moreover, the advantages of such reproducible bimodal size distribution nanolatexes in coating applications were investigated briefly, underlining the possibilities of their one-pot synthesis. It was found that when bimodal nanolatexes are adsorbed onto cellulose filter paper, the contact angle against water is higher compared to chemically similar monomodal nanolatexes. Also, the morphological arrangement was found to be dependent on the drying protocol. This study aims to expand our understanding on bimodality and the identification of parameters that could promote it on demand to target high-end applications.
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| 4. |
- Andrén, Oliver, et al.
(author)
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Facile thiolation of hydroxyl functional polymers
- 2017
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 8:34, s. 4996-5001
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Journal article (peer-reviewed)abstract
- Sulfur is an important component in many biological systems. In the hands of an organic chemist it can provide an ample handle for a myriad of robust reactions including thiol-ene click chemistry. However, in polymer chemistry the thiol functionality is rarely attributed to the macromolecule due to unatainable synthetic protocols. Herein, we provide a simple and robust strategy to produce thiol-functional polymers. The chemistry capitalizes on an unsymmetrical disulfide that straightforwardly converts hydroxyl functional polymers to their thiolated counterpart. Finally, PEG hydrogels, using both thiol-ene and Michael addition, is used to showcase the possibilities presented by thiol functional polymers.
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| 5. |
- Arias, Veluska, et al.
(author)
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Selective degradation in aliphatic block copolyesters by controlling the heterogeneity of the amorphous phase
- 2015
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In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 6:17, s. 3271-3282
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Journal article (peer-reviewed)abstract
- Controlling the course of the degradation of aliphatic polyesters is a key question when designing new degradable materials. It is shown herein that it is possible to predetermine the degradation path of aliphatic block copolyesters by controlling the heterogeneity of the amorphous phase, which in turn regulates the availability of the hydrolyzable groups in the polyester backbone. To demonstrate these processes, we synthesized a set of degradable materials based on poly(l-lactide) (PLLA), poly(ε-decalactone) (PεDL) and poly(ε-caprolactone) (PCL) with varying compositions. The materials were subjected to hydrolysis for a six months period. The materials composed of PLLA and PεDL exhibited a heterogeneous amorphous phase, whereas the materials composed of PCL and PεDL presented a more homogeneous phase. The kinetics of the degradation indicated that the slowest degradation rate was observed for the more homogeneous compositions. The degradation path of the heterogeneous amorphous phase materials was driven by a random chain scission process, whereas the more homogeneous composition presented a degradation path driven by a more selective chain scission. The confinement of the amorphous phase by the more hydrolytically stable PεDL permitted a selective degradation of the available hydrolyzable groups. The random and more selective chain scission processes were further verified by using previously determined molecular modeling based on Monte Carlo procedures. Topographical images and thermal analyses of the materials under different degradation periods correlated with the proposed degradation paths. Detailed insights and the ability to predetermine the degradation pathways of aliphatic polyesters will continue to expand the great potential of renewable materials and their use in specific applications for a future sustainable society.
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| 6. |
- Asplund, Maria, et al.
(author)
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Electroactive polymers for neural interfaces
- 2010
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In: Polymer chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 1:9, s. 1374-1391
-
Research review (peer-reviewed)abstract
- Development of electroactive conjugated polymers, for the purpose of recording and eliciting signals in the neural systems in humans, can be used to fashion the interfaces between the two signalling systems of electronics and neural systems. The design of desirable chemical, mechanical and electrical properties in the electroactive polymer electrodes, and the means of integration of these into biological systems, are here reviewed.
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| 7. |
- Auty, Sam E. R., et al.
(author)
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One-pot' sequential deprotection/functionalisation of linear-dendritic hybrid polymers using a xanthate mediated thiol/Michael addition
- 2015
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 6:4, s. 573-582
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Journal article (peer-reviewed)abstract
- Thiol-Michael addition chemistry is a powerful tool for the preparation of functional materials. In this first report of xanthate-functional linear-dendritic polymer hybrids, the preparation of four generations of xanthate-functionalised dendron atom transfer radical polymerisation macroinitiators is described using an orthogonal chemical strategy. The controlled polymerisation of tertiary butyl methacrylate is demonstrated to high conversion and without interference from the xanthate surface groups. Modification of the peripheral xanthate groups of dendrons at the hybrid polymer chain-end has been studied using a one-pot deprotection/functionalisation strategy and a range of commercially available and bespoke acrylate monomers to form complex polymer architectures from feedstock polymers, differing in the number of modified end groups and the surface chemistry of the dendron chain end.
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| 8. |
- Bini, Kim, 1987, et al.
(author)
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Broad spectrum absorption and low-voltage electrochromic operation from indacenodithieno[3,2-: B] thiophene-based copolymers
- 2019
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 10:16, s. 2004-2014
-
Journal article (peer-reviewed)abstract
- Electrochromic performance of conjugated polymers has quickly become an important design factor in a variety of applications. There is still significant need to develop highly stable materials with high optical contrast, desired colour switching and fast kinetics. Here, poly[indacenodithieno[3,2-b]thiophene-2,8-diyl] (PIDTT) is introduced as a new type of electrochromic polymer exhibiting a narrow absorption band, excellent electrochemical stability and fast colour switching kinetics between vibrant red (peak maximum at ∼550 nm) and transparent (peak maximum at ∼920 nm) within a low potential range of 0-0.8 V. To widen the spectral coverage of the well-functioning PIDTT over the entire visible range, a modified donor-acceptor approach is used by incorporating three different donor-acceptor-donor (DAD) segments into an indacenodithieno[3,2-b]thiophene (IDTT) based polymer backbone, so as to obtain three different alternating copolymers. This design motif is further rationalized by the maintained electrochemical stability of the new copolymers, and their full colour switching between black and transparent down to an ultra-low potential range of 0-0.6 V.
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| 9. |
- Carlsson, Linn, et al.
(author)
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Modification of cellulose model surfaces by cationic polymer latexes prepared by RAFT-mediated surfactant-free emulsion polymerization
- 2014
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 5:20, s. 6076-6086
-
Journal article (peer-reviewed)abstract
- This paper presents the successful surface modification of a model cellulose substrate by the preparation and subsequent physical adsorption of cationic polymer latexes. The first part of the work introduces novel charged polymer nanoparticles constituted of amphiphilic block copolymers based on cationic poly(N,N-dimethylaminoethyl methacrylate-co-methacrylic acid) (P(DMAEMA-co-MAA)) as the hydrophilic segment, and poly(methyl methacrylate) (PMMA) as the hydrophobic segment. First, RAFT polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) in water was performed at pH 7, below its pKa. The simultaneous hydrolysis of DMAEMA led to the formation of a statistical copolymer incorporating mainly protonated DMAEMA units and some deprotonated methacrylic acid units at pH 7. The following step was the RAFT-mediated surfactant-free emulsion polymerization of methyl methacrylate (MMA) using P(DMAEMA-co-MAA) as a hydrophilic macromolecular RAFT agent. During the synthesis, the formed amphiphilic block copolymers self-assembled into cationic latex nanoparticles by polymerization-induced self-assembly (PISA). The nanoparticles were found to increase in size with increasing molar mass of the hydrophobic block. The cationic latexes were subsequently adsorbed to cellulose model surfaces in a quartz crystal microbalance equipment with dissipation (QCM-D). The adsorbed amount, in mg m-2, increased with increasing size of the nanoparticles. This approach allows for physical surface modification of cellulose, utilizing a water suspension of particles for which both the surface chemistry and the surface structure can be altered in a well-defined way.
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| 10. |
- Carlsson, Linn, et al.
(author)
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Surface-initiated ring-opening metathesis polymerisation from cellulose fibres
- 2012
-
In: POLYM CHEM-UK. - : Royal Society of Chemistry. - 1759-9954. ; 3:3, s. 727-733
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Journal article (peer-reviewed)abstract
- In this study, cellulose fibres have been grafted utilizing surface-initiated ring-opening metathesis polymerisation (SI-ROMP). Initially, a Grubbs' type catalyst was immobilized onto filter paper whereafter SI-ROMP of norbornene was performed from the surface of the fibres at three different reaction temperatures, room temperature (RT), 0 degrees C and -18 degrees C, and for different reaction times. The evaluation of the grafted cellulose was performed by contact angle measurements, FT-Raman spectroscopy, FE-SEM and TGA. After the grafting, all samples were clearly hydrophobic with weight increases up to over 100%. The FT-Raman spectroscopy analysis showed significant structural changes after polymerization for cellulose substrates polymerized at 0 degrees C and RT, confirming that a polymer was grafted from the surface. FE-SEM images verified that these samples are covered by polynorbornene and that the fibrillar structure of the native cellulose disappeared. For the samples grafted at -18 degrees C, no significant changes were seen with these analysis methods. However, SI-ROMP appears to be a versatile method to modify cellulose fibres.
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| 11. |
- Cederholm, Linnea, et al.
(author)
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Chemical recycling to monomer: thermodynamic and kinetic control of the ring-closing depolymerization of aliphatic polyesters and polycarbonates
- 2023
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 14:28, s. 3270-3276
-
Journal article (peer-reviewed)abstract
- The thermodynamic equilibrium between ring-opening polymerization and ring-closing depolymerization is influenced by monomer-solvent-polymer interactions, an effect that can be utilized to promote chemical recycling to monomer. Here, the influence of monomer structure on this solvent effect has been investigated, showing that the chemical structure of the monomer influences the power of the solvent to supress the ceiling temperature. The study also demonstrates how catalyst selectivity can be utilized to obtain selective ring-closing depolymerization of one component of a polymer blend, even when the thermodynamics dictate otherwise.
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| 12. |
- Cederholm, Linnea, et al.
(author)
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Turning natural delta-lactones to thermodynamically stable polymers with triggered recyclability
- 2020
-
In: Polymer Chemistry. - : ROYAL SOC CHEMISTRY. - 1759-9954 .- 1759-9962. ; 11:30, s. 4883-4894
-
Journal article (peer-reviewed)abstract
- To extend the use of naturally occurring substituted delta-lactones within the polymer field, their commonly low ceiling temperature and thereby challenging equilibrium behavior needs to be addressed. A synthetic strategy to control the polymerization thermodynamics was therefore developed. This was achieved by copolymerizing delta-decalactone (delta DL) with either epsilon-decalactone (epsilon DL) or epsilon-caprolactone (epsilon CL) at room temperature (RT), with diphenyl phosphate (DPP) as catalyst. The thermodynamic stability of P delta DL-co-epsilon DL and P delta DL-co-epsilon CL increased with increased comonomer ratio in the feed, to 10% and 30% monomeric epsilon DL, respectively, at 110 degrees C. This is in contrast to the P delta DL homopolymer, which under the same conditions depolymerized to 70% monomeric delta DL at equilibrium. The copolymers' macromolecular structure, originating from the copolymerization kinetics, was found to be the crucial factor to mitigate delta DLs equilibrium behavior. To close the loop, designing materials for a circular economy, the recycling of P delta DL-co-epsilon DL was demonstrated, by reaction with benzyl alcohol (BnOH) as an external nucleophile, leading to cyclic monomers or dimers with BnOH at high yield.
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| 13. |
- Claudino, Mauro, et al.
(author)
-
Bringing D-limonene to the scene of bio-based thermoset coatings via free-radical thiol-ene chemistry : macromonomer synthesis, UV-curing and thermo-mechanical characterization
- 2014
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954. ; 5:9, s. 3245-3260
-
Journal article (peer-reviewed)abstract
- The increasing pursuit for bio-based plastic materials led us to investigate the potential use of the monoterpene limonene in thermoset synthesis using the free-radical mediated thiol-ene reaction. The high efficiency of this reaction to prepare multifunctional ene-terminated resins, as intermediary macromolecular precursors, for thermosets synthesis was demonstrated under thermal and photoinitiated conditions. Although an excess of terpene favors formation of well-defined macromonomers in organic solution, the characteristic low-vapor pressure of limonene hinders its simple removal (or recycling) via evaporation after synthesis. Alteration to an initial thiol-ene stoichiometry of 1 : 0.5 enables production of high molecular weight resins in the form of 'hyperbranched oligomeric-like' structures having moderate polydispersity. UV-curing of these polyfunctional resins combined with equal mole compositions of multifunctional alkyl ester 3-mercapto propionates yields highly sticky, amorphous and flexible elastomers with different thermo-mechanical properties. These can be further modulated by varying the amount of unreacted thiol occluded within the networks working as a plasticizer. Introduction of a renewable cycloaliphatic structure into the materials offers a convenient way to enhance the glass-transition temperature and stiffness of traditional thiol-ene networks. The materials synthesized may be considered potentially useful as sealants and adhesives in a wide variety of applications including organic coatings. The versatility of UV-irradiation over thermal initiation makes this method particularly suitable for green industrial synthesis processes via thiol-ene chemistry using limonene and multifunctional thiols. The thiol-ene system evaluated herein serves as a model example for the sustainable incorporation of natural diolefinic monomers into semisynthetic thiol-ene networks exhibiting a range of thermo-mechanical properties.
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| 14. |
- Congrave, Daniel G., et al.
(author)
-
Suppressing aggregation induced quenching in anthracene based conjugated polymers
- 2021
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 12:12, s. 1830-1836
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Journal article (peer-reviewed)abstract
- Anthracene is a highly valuable building block for luminescent conjugated polymers, particularly when a large singlet-triplet energy gap (Delta E-ST) is desired. Unfortunately, the extended pi system of anthracene imparts a strong tendency for polymer aggregation, resulting in detrimental effects on its solid state photophysics. A large decrease in photoluminescence quantum yield (PLQY, phi(F)) on going from solution to the solid state is especially common, represented in terms of a low phi(R) (phi(R) = phi(F film)/phi(F sol.)). Significant and undesirable red-shifting of fluorescence in the solid state is also typical due to processes such as excimer formation. In this work a series of alkylene-encapsulated conjugated anthracene polymers is developed to overcome these challenging problems. We demonstrate a promising material which displays a good solid state PLQY that is effectively unchanged compared to solution measurements (phi(R) similar to 1, phi(F film) similar to 40%), alongside an identical PL 0-0 transition wavelength in solution and thin film. Such a direct transfer of luminescence properties from solution to the solid state is remarkable for a conjugated polymer and completely unprecedented for one based on anthracene.
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| 15. |
- Edlund, Ulrica, et al.
(author)
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Self-assembling zwitterionic carboxybetaine copolymers via aqueous SET-LRP from hemicellulose multi-site initiators
- 2012
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 3:10, s. 2920-2927
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Journal article (peer-reviewed)abstract
- The zwitterionic carboxybetaines, (3-methacryloylamino-propyl)-(2-carboxy-ethyl)-dimethyl-ammonium (CBMAA-3) and (3-acryloylamino-propyl)-(2-carboxy-ethyl)-dimethyl-ammonium (CBAA-3), were successfully grafted from a galactoglucomannan macroinitiator. The macroinitiator was prepared from the hemicellulose acetylated galactoglucomannan functionalised with alpha-bromoisobutyric acid. The polymerisation of the betaines was efficiently carried out by a Cu(0) wire catalysed single electron-transfer living radical polymerisation (SET-LRP) in aqueous solution yielding water-soluble graft copolymers and nearly pseudo-first order kinetics suggesting a good degree of control over the polymerisation process. The graft copolymers spontaneously self-assembled in aqueous solution into well-defined nanoparticles highly stable in aqueous media.
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| 16. |
- Engström, Joakim, et al.
(author)
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Investigating the adsorption of anisotropic diblock copolymer worms onto planar silica and nanocellulose surfaces using a quartz crystal microbalance
- 2021
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 12:42, s. 6088-6100
-
Journal article (peer-reviewed)abstract
- Electrostatic adsorption of cationic polyelectrolytes onto anionic cellulosic substrates is an attractive route for facile surface modification of biorenewable materials. Recently, attention has focused on adsorbing cationic spherical diblock copolymer nanoparticles onto model cellulose and/or nanocellulosic substrates. Herein, we investigate physical adsorption of highly anisotropic copolymer worms bearing either anionic or cationic charge onto planar silica, cellulose nanocrystal (CNC) or cellulose nanofibril (CNF) surfaces using quartz crystal microbalance with dissipation monitoring. Electrostatic interactions dominate in the case of anionic silica and CNC surfaces because the adsorbed mass of cationic worms was greater than that of anionic worms. However, either anionic or cationic worms could be adsorbed onto in situ generated CNF substrates, suggesting that additional interactions were involved: hydrogen bonding, van der Waals forces, and possibly covalent bond formation. Scanning electron and atomic force microscopy studies of the dried planar substrates after adsorption experiments confirmed the presence of adsorbed copolymer worms. Finally, composite worm/CNF films exhibited restricted swelling behavior when immersed in water compared to reference CNF films, suggesting that the worms reinforce CNF films by acting as a physical crosslinker. This study is the first investigation of the physical adsorption of highly anisotropic diblock copolymer worms onto cellulosic surfaces.
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| 17. |
- Engström, Joakim, et al.
(author)
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Soft and rigid core latex nanoparticles prepared by RAFT-mediated surfactant-free emulsion polymerization for cellulose modification-a comparative study
- 2017
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 8:6, s. 1061-1073
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Journal article (peer-reviewed)abstract
- Latex nanoparticles comprising cationically charged coronas and hydrophobic cores with different glass transition temperatures (Tg) have been prepared by surfactant-free, RAFT-mediated emulsion polymerization, where the particles form through a polymerization-induced self-assembly (PISA) type mechanism. Poly(2-dimethylaminoethyl methacrylate-co-methacrylic acid) (P(DMAEMA-co-MAA)) was utilized as a hydrophilic macroRAFT agent for the polymerization of methyl methacrylate (MMA) or n-butyl methacrylate (nBMA), respectively, resulting in two different latexes, with either a core of high (PMMA) or low (PnBMA) Tg polymer. By varying the molar mass of the hydrophobic block, latexes of different sizes were obtained (DHca. 40-120 nm). The adsorption of the latexes to cellulose model surfaces and cellulose nanofibrils (CNF) was studied using quartz crystal microbalance with dissipation monitoring (QCM-D). The surfaces with adsorbed PnBMA latexes yielded hydrophobic surfaces both before and after annealing, whereas surfaces with adsorbed PMMA latex became hydrophobic only after annealing, clearly showing the influence of the Tg of the core. The latexes were also used to modify macroscopic cellulose in the form of filter papers. Similar to the CNF surfaces, no annealing was required to achieve hydrophobic surfaces with PnBMA latexes. Finally, nanocomposites of CNF and the polymer nanoparticles were prepared through a one-pot mixing procedure. It was found that the largest synthesized PMMA latex (120 nm) facilitated a more strainable CNF network at 50% relative humidity, with a nearly 200% increase in strain at break compared to the neat CNF reference film as well as to the composite films with PnBMA latexes or to the smaller sized PMMA latexes. This difference was attributed to the spherical shape and rigidity of the large PMMA latex nanoparticles during composite formation. This highly interesting result should indeed be considered in the future design of novel biocomposites.
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| 18. |
- Eriksson, Magnus G., et al.
(author)
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One-pot enzymatic polycondensation to telechelic methacrylate-functional oligoesters used for film formation
- 2011
-
In: POLYM CHEM. - Cambridge : ROYAL SOC CHEMISTRY. - 1759-9954 .- 1759-9962. ; 2:3, s. 714-719
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Journal article (peer-reviewed)abstract
- Based on largely renewable monomers, an enzymatic one-pot polycondensation route towards functional oligomers with targeted molecular weights and end-groups was developed. This one-pot synthesis was performed by combining Candida antarctica lipase B (CALB), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol, and divinyl adipate under reduced pressure (72 mbar) at 60 degrees C. The polymerization went to completion (>95% conversion for all monomers) within 24 h and the fraction of methacrylate end-groups was >90%. Three targeted dimethacrylate functional oligomers with molecular weights of 920, 1700 and 2500 g mol(-1) (degrees of polymerization 4, 8, and 13 respectively) were synthesized. The oligomer products were characterized by NMR, MALDI-TOF MS and SEC. The dimethacrylate functional oligomers were further UV homopolymerized or combined with a tetrathiol crosslinker to demonstrate the potential to produce novel networks with tunable thermal properties dependent on chain length of the telechelic building blocks. This research is the first to demonstrate methacrylate functionalization and condensation polymerization in a one step process, which expands the growing toolbox for polymer/material chemists towards an increased throughput in available macromonomers used in material design.
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| 19. |
- Gazzotti, Stefano, et al.
(author)
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Poly(alditol sebacate)-PLA copolymers : enhanced degradability and tunable surface properties
- 2024
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962.
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Journal article (peer-reviewed)abstract
- The synthesis of aliphatic, degradable polyesters based on biobased alditols was investigated. Mannitol and dulcitol were employed as biobased building blocks for the synthesis of aliphatic polyesters in combination with sebacoyl chloride. In order to achieve optimal control over the macromolecular architecture of the polymer, multifunctional monomers were converted to bifunctional species through a straightforward protection strategy. Bifunctional di-O-isopropylidene derivatives were synthesized starting from mannitol and dulcitol in a one-step procedure and exploited as monomers to yield linear poly(mannitol sebacate) (PMS) and poly(dulcitol sebacate) (PDS) derivatives. The use of a bifunctional monomer allowed an optimal control over the macromolecular architecture and the synthesis of PMS and PDS-based polyols. These polyols were then employed as initiators for the synthesis of PLA-based copolymers. Two different concentrations of PMS and PDS were tested and the related effects investigated, regarding the molecular weight and thermal properties of the resulting PLA-based copolymers. Deprotection of the isopropylidene moieties on the polyol backbone was then evaluated in order to determine the influence of liberation of free OH- groups on the wettability of the materials. Finally, degradation tests were performed in different aqueous environments, showing the influence of PMS and PDS on the degradation rate of PLA-based materials. The synthesis of aliphatic, degradable polyesters based on biobased alditols was investigated.
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| 20. |
- Gedefaw, Desta Antenehe, 1971, et al.
(author)
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Conjugated polymers based on benzodithiophene and fluorinated quinoxaline for bulk heterojunction solar cells: thiophene versus thieno[3,2-b]thiophene as π-conjugated spacers
- 2014
-
In: Polymer Chemistry. - 1759-9954 .- 1759-9962. ; 5:6, s. 2083-2093
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Journal article (peer-reviewed)abstract
- Two conjugated donor–acceptor copolymers based on a benzodithiophene donor unit and a fluorinated quinoxaline acceptor unit, spaced with either thiophene or thieno[3,2-b]thiophene π-bridges, were designed and synthesized. The effect of different π-bridges and of the processing conditions on the optical, electrical, morphological and photovoltaic properties of the polymer:fullerene blend films were investigated. The polymer containing the thieno[3,2-b]thiophene π-bridge (PBDTFQ-TT) showed a red-shifted absorption and enhanced charge carrier mobility, as compared to its analogue with the thiophene π-bridge (PBDTFQ-T), due to its narrower optical gap (by ~ 0.1 eV) and stronger inter-chain interactions, favored by the structural planarity and increased linearity of the polymer backbone, as also supported by DFT calculations. The blend of PBDTFQ-TT and PC61BM ([6,6]-phenyl-C61-butyric acid methyl ester), compared to the PBDTFQ-T:PC61BM one processed in the same conditions (by blade-coating technique), showed greatly enhanced photovoltaic performance, with more than doubled power conversion efficiency (PCE up to 5.60% for the best device) due to the increased short-circuit current density and fill factor. However, similar PCEs were also achieved for PBDTFQ-T:PC61BM-based devices by optimizing the processing conditions through the addition of 1,8-diiodooctane (DIO) as the solvent additive. Through morphological and electrical analysis of the films, produced with and without additive, it was observed that the addition of DIO greatly enhances the self-organization, and consequently the charge mobility, of the thiophene π-bridge-based polymer, while it was detrimental for the nanoscale morphology and photovoltaic performances of the thieno[3,2-b]thiophene π-bridge-based polymer in the corresponding blend.
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| 21. |
- Gårdebjer, Sofie, 1985, et al.
(author)
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Using Hansen solubility parameters to predict the dispersion of nano-particles in polymeric films
- 2016
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 7:9, s. 1756-1764
-
Journal article (peer-reviewed)abstract
- We suggest a rough and straightforward method to predict the dispersibility of modified cellulose nanocrystals (CNC) in nanocomposites using Hansen solubility parameters (HSP). The surface of CNC was modified using a novel approach where Y-shaped substituents with two different carbon chain lengths were attached to the surface. Approximate HSP values were calculated for the modified CNC, and dispersions of unmodified and modified CNC in solvents with varying HSPs were studied. The best dispersibility was observed in dichloromethane, when the CNC surface was modified with longer carbon chains. Dichloromethane has HSP similar to low-density polyethylene (LDPE). Nanocomposites with both unmodified and modified CNC were produced. The materials with modified CNC showed increased adhesion between the filler and the matrix, followed by a decreased water permeability compared to unmodified CNC, suggesting a better dispersibility of modified CNC in LDPE and confirming the usefulness of this approach.
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| 22. |
- Halhalli, Mahadeo, et al.
(author)
-
Insights into the formation, structural properties and performance of RAFT polymerized L-phenylalanine anilide molecularly imprinted polymers
- 2015
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 6:41, s. 7320-7332
-
Journal article (peer-reviewed)abstract
- Conventional molecularly imprinted polymers (MIPs) are amorphous materials with a nonuniform microenvironment and a broad distribution of binding sites. Controlled radical polymerization has been demonstrated to improve their properties in this regard. The RAFT method was employed in the present study with the aim of achieving more homogeneous MIP monolithic structures. RAFT control by α-cyanobenzyldithiobenzoate was employed during the synthesis of a poly(methacrylic acid-co-ethylene glycol dimethacrylate) conventional MIP for L-phenylalanine anilide. The influence of the amount of the added RAFT agent on the polymerization as well as on the polymer porous structure and properties was studied. The results demonstrate that the RAFT agent promoted retardation and a more gel-like polymer morphology as reflected in a decrease in pore diameter and an increased swelling factor with the added RAFT agent. This was accompanied by an enhanced thermal stability of up to 100 °C compared to a corresponding MIP prepared by FRP. The RAFT polymers were then tested in the chromatographic mode due to their ability to resolve the racemate D,L-PheNHPh. An optimum RAFT agent level during polymerization was found to result in a markedly enhanced selectivity, column efficiency and resolution accompanied by a considerably higher sample loading capacity when compared to polymers prepared in the absence of the RAFT agent.
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| 23. |
- Hansson, Susanne, et al.
(author)
-
Selective cleavage of polymer grafts from solid surfaces : assessment of initiator content and polymer characteristics
- 2011
-
In: POLYM CHEM. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 2:3, s. 556-558
-
Journal article (peer-reviewed)abstract
- A novel initiator for atom transfer radical polymerization, also allowing for selective cleavage of polymer grafts, was designed and immobilized on a solid substrate. After cleavage, the initiator content was determined by utilizing Ellman's reagent and the cleaved polymer grafts were isolated and characterized by size exclusion chromatography.
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| 24. |
- Hansson, Susanne, et al.
(author)
-
Visualization of poly(methyl methacrylate) (PMMA) grafts on cellulose via high-resolution FT-IR microscopy imaging
- 2012
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954. ; 3:2, s. 307-309
-
Journal article (peer-reviewed)abstract
- Cellulose surfaces grafted with PMMA of different graft lengths were characterized via high-resolution FT-IR microscopy imaging, visualizing the polymer distribution on the surface. The results from the FT-IR measurements can be compared with the molecular weights obtained from SEC and (1)H NMR of the macromolecules formed in solution.
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| 25. |
- Hellström, Stefan, 1978, et al.
(author)
-
Synthesis and characterization of three small band gap conjugated polymers for solar cell applications
- 2010
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 1:8, s. 1272-1280
-
Journal article (peer-reviewed)abstract
- We report on a new series of small band gap conjugated polymers utilizing donor-acceptor-donor substructures in the polymer backbone to broaden and extend the optical absorption to longer wavelengths. Three polymers were prepared by Suzuki polymerization, using the same donor-acceptor-donor segment but with different comonomers. The goal was to investigate how the optical and electronic properties of the polymers were influenced by the different comonomers. Electrochemical spectroscopy, using square-wave voltammetry, shows that increasing the electron-donating strength of the comonomer will raise the HOMO energy level of the polymer, resulting in a decreased band gap. This result is also manifested by comparing open-circuit voltages from the corresponding laboratory fabricated solar cells. The best performing photovoltaic cell, based on APFO-Green15/[60]PCBM (1 : 4 w/w), reached a J(sc) of 4.2 mA cm(-2), a V-oc of 0.73 V, and a FF of 0.54, giving a PCE of 1.7%.
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| 26. |
- Hern, Faye Y., et al.
(author)
-
Model studies of the sequential and simultaneous statistical modification of dendritic functional groups and their implications within complex polymer architecture synthesis
- 2017
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 8:10, s. 1644-1653
-
Journal article (peer-reviewed)abstract
- Post-synthesis modification of polymers is a synthetically appealing approach to generate a range of samples from a single, well-characterised starting material. When partial or mixed-functionalisation is sought, an inevitable statistical distribution of modification outcomes will lead to considerable variation of chemical structures within the final sample. Here we have comprehensively investigated the postsynthesis sequential/partial and simultaneous mixed modification of xanthate-functional ideal dendrons and used this data to consider the implications for the more complex linear-dendritic hybrids and hyper-branched- polydendron analogues. Although H-1 NMR confirmed the potential to direct the reactions, it was clear from MALDI-TOF studies that very little of the actual targeted structures were generated in the statistical reactions.
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| 27. |
- Hult, Daniel, 1986-, et al.
(author)
-
Degradable High Tg Sugar Derived Polycarbonates from Isosorbide and Dihydroxyacetone
- 2018
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 9:17, s. 2238-2246
-
Journal article (peer-reviewed)abstract
- Polycarbonates from isosorbide and dihydroxyacetone (DHA) have been synthesised using organocatalytic step-growth polymerization of their corresponding diols and bis-carbonylimidazolides monomers. By choice of feed ratio and monomer activation, either isosorbide or ketal protected DHA, random and alternating poly(Iso-co-DHA) carbonates have been formed. Thermal properties by DSC and TGA were herein strongly correlated to monomer composition. Dilution studies using 1H-NMR of a model compound DHA-diethyl carbonate in acetonitrile and deuterated water highlighted the influence of α-substituents on the keto/hydrate equilibrium of DHA. Further kinetics studies of in the pH* range of 4.7 to 9.6 serve to show the hydrolytic pH-profile of DHA-carbonates. The Hydrolytic degradation of deprotected polymer pellets show an increased degradation with increasing DHA content. Pellets with a random or alternating configuration show different characteristics in terms of mass loss and molecular weight loss profile over time.
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| 28. |
- Ingratta, Mark, et al.
(author)
-
Grafting poly(phenylene oxide) with poly(vinylphosphonic acid) for fuel cell membranes
- 2010
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 1:5, s. 739-746
-
Journal article (peer-reviewed)abstract
- Densely phosphonated electrolyte membranes were prepared from poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) grafted with poly(vinylphosphonic acid) (PVPA) side chains. In the first step, PPO was lithiated in solution at room temperature by adding n-butyllithium to form an anionic macroinitiatior. Next, diethyl vinylphosphonate (DEVP) was anionically polymerized from the lithiated sites at -78 °C. This protocol gave good control over the density of the grafting sites and the copolymer composition. Films of copolymers containing between 35 and 74 wt% poly(diethyl vinylphosphonate) were first cast from solution, and subsequently fully hydrolyzed to produce transparent flexible proton conducting membranes of PPO-graft-PVPA containing up to 6 mmol phosphonic acid groups per gram dry copolymer. Thermogravimetric analysis showed anhydride formation at increasing temperatures above 100 °C with no copolymer degradation occurring until nearly 400 °C under air. Fully hydrated membranes reached proton conductivities above 1 mS/cm at -20 °C and 80 mS/cm at 120 °C.
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| 29. |
- Kirsebom, Harald, et al.
(author)
-
Cryostructuration as a tool for preparing highly porous polymer materials
- 2011
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 2:5, s. 1059-1062
-
Research review (peer-reviewed)abstract
- Cryostructuration is a technique which can be used to produce highly porous polymer materials from either monomeric or polymeric starting material. The technique utilizes freezing of dilute solutions or suspensions for the formation of porous materials. The process has been used in both aqueous and organic media for the preparation of porous materials. This mini-review highlights some recent trends for cryostructuration where it is based on a freeze/thawing approach.
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| 30. |
- Kroon, Renee, 1982, et al.
(author)
-
Comparison of selenophene and thienothiophene incorporation into pentacyclic lactam-based conjugated polymers for organic solar cells
- 2015
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 6:42, s. 7402-7409
-
Journal article (peer-reviewed)abstract
- In this work, we compare the effect of incorporating selenophene versus thienothiophene spacers into pentacyclic lactam-based conjugated polymers for organic solar cells. The two cyclic lactam-based copolymers were obtained via a new synthetic method for the lactam moiety. Selenophene incorporation results in a broader and red-shifted optical absorption while retaining a deep highest occupied molecular orbital level, whereas thienothienophene incorporation results in a blue-shifted optical absorption. Additionally, grazing-incidence wide angle X-ray scattering data indicates edge- and face-on solid state order for the selenophene-based polymer as compared to the thienothiophene-based polymer, which orders predominantly edge-on with respect to the substrate. In polymer : PC71BM bulk heterojunction solar cells both materials show a similar open-circuit voltage of similar to 0.80-0.84 V, however the selenophene-based polymer displays a higher fill factor of similar to 0.70 vs. similar to 0.65. This is due to the partial face-on backbone orientation of the selenophene-based polymer, leading to a higher hole mobility, as confirmed by single-carrier diode measurements, and a concomitantly higher fill factor. Combined with improved spectral coverage of the selenophene-based polymer, as confirmed by quantum efficiency experiments, it offers a larger short-circuit current density of similar to 12 mA cm(-2). Despite the relatively low molecular weight of both materials, a very robust power conversion efficiency similar to 7% is achieved for the selenophene-based polymer, while the thienothiophene-based polymer demonstrates only a moderate maximum PCE of similar to 5.5%. Hence, the favorable effects of selenophene incorporation on the photovoltaic performance of pentacyclic lactam-based conjugated polymers are clearly demonstrated.
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| 31. |
- Kunz, Susanna, V, et al.
(author)
-
A simplified approach to thermally activated delayed fluorescence (TADF) bipolar host polymers
- 2022
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 13:29, s. 4241-4248
-
Journal article (peer-reviewed)abstract
- Organic Light Emitting Diodes (OLEDs) are a critical part of current consumer electronics, from mobile device displays to solid-state lighting. Thus demand for the development of industrially compatible OLED materials continues to increase. Herein, we introduce a series of solution-processible polymers incorporating a Thermally Activated Delayed Fluorescence (TADF) emitter and a host species in the side chain to finely adjust the charge transport properties. For balanced charge transport, a bipolar host polymer based on carbazole and alpha-carboline was investigated in addition to the commonly employed unipolar host mCP and an electron transporting version thereof. We demonstrate that the combination of unipolar co-hosts on one polymer chain can generate, with less synthetic effort, the same optoelectronic properties as a polymer carrying the corresponding bipolar host molecule as a pendant.
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| 32. |
- Larsson, Emma, et al.
(author)
-
Cellulose grafting by photoinduced controlled radical polymerisation
- 2015
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 6:10, s. 1865-1874
-
Journal article (peer-reviewed)abstract
- The photoinduced controlled radical polymerisation (CRP) technique has been utilised to graft methyl acrylate (MA) and di(ethylene glycol) ethyl ether acrylate (DEGA) from filter paper. Grafting of MA was performed from alpha-bromoisobutyryl bromide functionalised papers. The amount of polymer grafted on the surface could be regulated by modifying the target DP of the reaction. SEC of cleaved linear polymer grafts showed that the grafting from filter papers proceeded with different kinetics compared to polymerisation from a free initiator added to the reaction mixture, resulting in higher dispersity. Furthermore, filter papers were polymerised with a-chloro-epsilon-caprolactone by surface-initiated ring opening polymerisation, yielding linear grafts containing initiating functions through-out the main chain. This functionality was subsequently utilised for the photoinduced CRP grafting of DEGA, yielding a graft-on-graft structure, which resulted in a thermoresponsive cellulose surface.
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| 33. |
- Lee, Jookyeong, et al.
(author)
-
Terpyridine-functionalized stimuli-responsive microgels and their assembly through metal-ligand interactions
- 2018
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 9:8, s. 1032-1039
-
Journal article (peer-reviewed)abstract
- We developed a terpyridine-functionalized microgel (tpy-mG) for its supramolecular assembly. Tpy-mG was synthesized by amidation between 3-(4-([2,2′:6′,2′′-terpyridin]-4′-yl)phenoxy)propan-1-amine and carboxylates of a thermo-responsive p(NIPAM-co-MAA) microgel (A-mG), which was synthesized by emulsion polymerization. After decorating terpyridine, its effects on the hydrodynamic radius, volume phase transition temperature (VPTT), and the colloidal stability of the microgel were investigated. Tpy-mG can be assembled reversibly with several metal ions (Ni2+, Fe2+, Co2+, or Zn2+), and interestingly the assembled tpy-mG-M2+ showed different rheological properties depending on the metal ion type; the weakly bound ions (Co2+, Zn2+) indicated fast dynamics for "inter-particular" exchange, resulting in much higher storage (G′) and loss (G′′) moduli. Photocatalysts such as Ru dyes can be easily introduced into tpy-mGvia metal-ligand interactions, and the photooxidation of benzylamine was tested. The free Ru dye showed almost the same conversions at 25 and 50 °C, whereas the assembled Ru-tpy-mG-Mg2+ displayed reduced conversion at 50 °C (>VPTT). This is suggested to be due to the collapsed or "locked" structure around the photocatalytic center (Ru). Tpy-mG can be utilized as a good platform for developing responsive functional materials via reversible metal-ligand complexation.
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| 34. |
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| 35. |
- Li, Xiaoya, et al.
(author)
-
Nonionic nontoxic antimicrobial polymers: indole-grafted poly(vinyl alcohol) with pendant alkyl or ether groups
- 2022
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 13:16, s. 2307-2319
-
Journal article (peer-reviewed)abstract
- A series of new nonionic antimicrobial polymers with a biodegradable polyvinyl alcohol (PVA) backbone grafted with indole units and different hydrophobic alkyl or ether groups were synthesized by facile esterification. The chemical structures and thermal properties of the obtained polymers were characterized by GPC, NMR, FTIR, WAXD, TGA and DSC analyses. All these nonionic polymers showed a significant antibacterial effect similar to gentamicin against 9 food and human pathogenic bacteria according to the disk diffusion assay. The presence of alkyl or ether groups in most cases did not significantly affect the antibacterial effect compared to the polymer with unsubstituted indole units (with N–H moieties). The impacts of the OH conversion and molecular weight of the obtained polymers on their antimicrobial and anti-quorum sensing effects were also preliminarily investigated. Finally, the obtained indole-grafted PVAs were subjected to MTT assay using a mammalian cell line and hemolysis investigations, and the results showed excellent biocompatibility, particularly for those with ether substituents.
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| 36. |
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| 37. |
- Malmström, Eva, et al.
(author)
-
Controlled grafting of cellulose fibres : an outlook beyond paper and cardboard
- 2012
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954. ; 3:7, s. 1702-1713
-
Research review (peer-reviewed)abstract
- Cellulose is highly interesting from a materials science perspective, very much fuelled by its abundance, renewability and low cost. In this review, the heterogeneous grafting of cellulose fibres through controlled radical polymerization methods is highlighted. Techniques such as atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain-transfer (RAFT) allow for fibres with tailorable properties and built-in functionality to be produced. Undoubtedly, cellulose is a material for the future and it is foreseen that in a few years, the use of cellulose will probably extend far beyond the traditional application areas, such as in paper and cardboard.
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| 38. |
- Mauri, Massimiliano, 1987
(author)
-
Copolymerization of ethylene with a-olefins and cyclic olefins catalyzed by a Ti(IV) diisopropoxy complex bearing a tridentate [O¯,S,O¯]-type bis(phenolato) ligand
- 2014
-
In: Polymer Chemistry. - 1759-9954 .- 1759-9962. ; :5, s. 3412-3423
-
Journal article (peer-reviewed)abstract
- Ethylene (E) was copolymerized with some α-olefins [1-pentene (PEN), 1-hexene (HEX), and 4-methyl-1-pentene (4M1P)] and cyclic olefins [cyclopentene (CPE), norbornene (NB), and dicyclopentadiene (DCPD)] using the Ti(IV) thiobis(phenolate) complex [2,2′-S(4-Me,6-tBuC6H2O)2]Ti(OiPr)2 in combination with methylaluminoxane (MAO). The catalyst exhibited excellent activities (up to 106 g molTi−1 h−1). Crystalline E/α-olefin copolymers with a strong tendency for comonomer alternation were obtained with good comonomer incorporation (about 15 mol% for [Y]/[E] = 8; Y = comonomer) decreasing in the order HEX > PEN > 4M1P. Random copolymers with NB and DCPD were obtained with efficient comonomer incorporation (from 10 to 40 mol%) even for the Y/E molar ratio = 1 to 2, while the catalyst gave poor CPE incorporation. In order to collect information on the comonomer distribution in the copolymers, boiling solvent extraction was carried out and all the fractions were characterized by DSC, XRD, SEC, and NMR.
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| 39. |
- Mauri, Massimiliano, 1987, et al.
(author)
-
Orange is the new white: Rapid curing of an ethylene-glycidyl methacrylate copolymer with a Ti-bisphenolate type catalyst
- 2018
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 9:13, s. 1710-1718
-
Journal article (peer-reviewed)abstract
- Polyethylene must be crosslinked if the polymer is to be used at elevated temperatures. However, established crosslinking methods result in the release of volatile by-products that can compromise the cleanliness and purity required for many electrical and medical applications. Currently available alternative curing processes, free from by-product formation, are too slow to be of practical relevance. Here, we demonstrate that an epoxy-bearing polyethylene copolymer, which contains one glycidyl methacrylate comonomer per 64 ethylene monomers, can be rapidly crosslinked with a click-chemistry curing process. We show that a titanium-based Lewis acid together with a bisphenol crosslinking agent allows the formation of thermosets. Compounding of the Lewis acid catalyst, crosslinking agent and copolymer through extrusion at 140 °C can be carried out without onset of the curing reaction. Then, at more elevated temperatures of 180 °C and above rapid crosslinking occurs. The competitive curing rate of the here explored formulation is due to in situ generation of a new titanium-phenoxide catalyst, which efficiently promotes crosslinking of the epoxy-bearing polyethylene copolymer. Adjustment of the curing time and temperature results in a high network density of at least 3 crosslinks per 1000 carbons in only 2 minutes at 240 °C and at a curing agent stoichiometry of 3 wt%, which corresponds to merely 0.04 wt% elemental titanium. The here established crosslinking chemistry opens up a by-product free method for rapid curing of epoxy-functionalised polyethylenes.
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| 40. |
- Mindemark, Jonas, et al.
(author)
-
Hydroxyl-functionalized poly(trimethylene carbonate) electrolytes for 3D-electrode configurations
- 2015
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 6:26, s. 4766-4774
-
Journal article (peer-reviewed)abstract
- Polymer electrolytes were prepared from an aliphatic polycarbonate with 10 mol% of repeating units having a hydroxyl-functional side group, with the addition of LiTFSI salt. The hydrogen bond-interacting side groups were found to be beneficial for improving adhesion to 2D planar electrode material surfaces. These favorable surface properties proved to be valid also for 3D-structured systems since thin, conformal coatings could be cast on 3D-microstructured electrodes. In addition, the electrolytes were found to have reasonable ionic conductivity (up to 2.7 x 10(-8) S cm(-1) at 25 degrees C and 2.3 x 10(-6) S cm(-1) at 60 degrees C) that was almost independent of salt concentration. This demonstrates how a hydroxyl-functional polymer approach is suitable for the creation of 3D-structured electrode-electrolyte assemblies for microbattery applications.
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| 41. |
- Mongkhontreerat, Surinthra, et al.
(author)
-
Functional porous membranes from amorphous linear dendritic polyester hybrids
- 2015
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 6:13, s. 2390-2395
-
Journal article (peer-reviewed)abstract
- By combining ATRP, dendrimer chemistry and 'click' reactions, a library of novel linear dendritic block copolymers (hybrids) was successfully synthesized. The isolated polymers displayed hydrophilic alkyne groups and T-g's ranging from 14 degrees C to 67 degrees C. A T-g threshold of 39 degrees C was found necessary for straightforward porous membrane fabrication via the breath figure method. Exploiting the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, a robust and benign protocol was identified enabling surface functionalization under aqueous conditions. Such manipulations included the introduction of fluorescent rhodamine for thorough assessment by confocal fluorescence microscopy as well as polyethylene glycol chains or perfluorinated groups for tuning the membrane wettability. Finally, with the initial indication of being nontoxic to human dermal fibroblasts (hDF) and osteoblast-like MG63, the porous membranes can potentially find use in the field of controlled cell culture such as patterning of cell growth.
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| 42. |
- Mousa, Maryam, et al.
(author)
-
Branched polyesters from radical ring-opening polymerization of cyclic ketene acetals : synthesis, chemical hydrolysis and biodegradation
- 2023
-
In: Polymer Chemistry. - 1759-9954 .- 1759-9962. ; 14:47, s. 5154-5165
-
Journal article (peer-reviewed)abstract
- Herein, we report a new synthetic route to the cyclic ketene acetal, 2-methylene-4-methyl-1,3-dioxepane (Me-MDO) as a way to expand the tool box of synthesis procedures for cyclic ketene acetals and actualize them as realistic alternatives for synthesizing biodegradable polymers. In this work, 2-methylene-1,3-dioxepane (MDO) and Me-MDO were polymerized by radical ring-opening polymerization to synthesize degradable polyesters. NMR and SEC were used to monitor the polymerization while DSC was used to study the thermal properties. Poly(2-methylene-1,3-dioxepane) (PMDO) showed increased degree of branching with higher conversion, subsequently decreasing crystallinity. The effect of branching and the introduction of side-groups on the chemical hydrolysis rate and biodegradability of the polyesters was assessed using a chemical hydrolysis test and the OECD 301D ready biodegradability screening test, respectively. A significant reduction in the chemical hydrolysis rate and biodegradability was observed upon the introduction of a side group in the poly(2-methylene-4-methyl-1,3-dioxepane) (PMe-MDO) polyester. Less obvious effects on the hydrolysis rate and biodegradability were observed as a result of the polyester branching.
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| 43. |
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| 44. |
- Naserifar, Shirin, 1991, et al.
(author)
-
In situ monitoring of cellulose etherification in solution: probing the impact of solvent composition on the synthesis of 3-allyloxy-2-hydroxypropyl-cellulose in aqueous hydroxide systems
- 2022
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 13:28, s. 4111-4123
-
Journal article (peer-reviewed)abstract
- Etherification of cellulose using allyl glycidyl ether was carried out in aqueous alkaline solutions of benzyltrimethylammonium hydroxide, tetramethylammonium hydroxide, NaOH and different mixtures of these bases in order to study the effect of hydroxide base composition on the course of the reaction and the resulting product properties. In situ FTIR spectroscopy and time sweep shear measurements were carried out to monitor the reactions in real time. Infrared Attenuated Total Reflectance Spectroscopy and H-1 NMR confirmed the synthesis of 3-allyloxy-2-hydroxypropyl-cellulose and 2D HSQC NMR confirmed substitution on C2, C3 and C6 in all of the solvents. Quantitative C-13 NMR was used to estimate the molar substitution. Cellulose solutions in these quaternary ammonium hydroxides showed higher stability at 50 degrees C during the course of reaction, faster dissolution and hydrolysis of allyl glycidyl ether and lower molar substitution values compared to NaOH. Even though the highest molar substitution value was obtained in NaOH, the isolated product from this medium had lower solubility in DMSO-d(6) and its C-13 NMR did not differ significantly except for higher intensity of C1 and C6 compared to the other spectra. The obtained results indicated a more pronounced cascade reaction on the substitution itself in NaOH and lower temperature stability of cellulose solutions in this solvent.
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| 45. |
- Ndizeye, Natacha, et al.
(author)
-
Polymer synthesis in non-ionic deep eutectic solvents
- 2019
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 10:39, s. 5289-5295
-
Journal article (peer-reviewed)abstract
- Herein, we report the use of the use of non-ionic deep eutectic solvents (ni-DESs) as porogens in polymer synthesis. Three ni-DES systems, acetamide-N-methylacetamide (AA-NMA), N-methylacetamide-N-methylurea (NMA-NMU) and N-methylacetamide-N,N'-dimethylurea (NMA-NN'DMU), were deployed in the synthesis of a series of cross-linked copolymer monoliths comprised of a functional monomer, methacrylic acid (MAA) or hydroxyethylmethacrylate (HEMA), and a cross-linking monomer, ethylene glycol dimethylacrylate (EGDMA) or divinylbenzene (DVB) or 1,4-bis(acryloyl)piperazine (BAP). Polymers were synthesized under thermally initiated conditions with 2,2'-azobis(2-methylpropionitrile) (AIBN) or 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAH) as an initiator. The resulting polymer monoliths were ground and sieved to yield particles of 63-125 mu m. Corresponding polymers prepared in conventional porogens, acetonitrile, toluene and water were synthesized to serve as controls. The influence of the respective niDESs on polymer morphologies was examined by Brunauer-Emmett-Teller (BET) N2-adsorption, Fourier transform infrared spectroscopy (FT-IR), elemental analysis, scanning electron microscopy (SEM) and zeta potential measurements. The materials displayed surface areas, pore volumes and pore diameters of 115-532 m(2) g(-1), 0.1-1.4 cm(3) g(-1) and 5.2-12.5 nm, generally comparable with those of polymers obtained using conventional solvents, thus presenting these ni-DESs as viable alternatives to conventional organic solvents. The post-polymerization recovery of the ni-DESs (>80%) was demonstrated, highlighting the potential for using these novel liquids as alternatives to conventional, and often more expensive, toxic, flammable or volatile solvents in polymer synthesis.
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| 46. |
- Nieboer, Vincent, et al.
(author)
-
Linear not cyclic : unravelling an anionic initiation pathway for Lewis pair polymerization of lactones
- 2023
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 14:20, s. 2485-2493
-
Journal article (peer-reviewed)abstract
- Zwitterionic Lewis pair (LP) catalysis is potent towards the polymerization of lactone monomers to form cyclic polymers. In pursuit of faster polymerization kinetics, the use of weaker Lewis acids, such as diethylzinc (ZnEt2), has hitherto been suggested. However, the strong Brønsted base character of ZnEt2 brings the question of the actual initiation mechanism. Here, the ZnEt2-1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) LP was studied as catalyst for the initiation and polymerization reactions of ω-pentadecalactone (PDL), ϵ-caprolactone, δ-valerolactone, and γ-butyrolactone. Collective MALDI-ToF MS, NMR, FT-IR, and Ubbelhode viscometry studies revealed a polymerization mechanism proceeding through deprotonation of the α-protons on the lactone and not zwitterionic ring-opening, yielding an anionic propagation mechanism and linear polymers. The polymerization kinetics display an initiation period that correlates to ethyl decomposition on ZnEt2 and the initiation period is shortened by increasing the reaction temperature, Lewis base equivalents, and the lactones, e.g. ϵ-caprolactone, δ-valerolactone, and γ-butyrolactone in the system.
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| 47. |
- Olsén, Peter, et al.
(author)
-
Establishing α-bromo-γ-butyrolactone as a platform for synthesis of functional aliphatic polyesters-bridging the gap between ROP and SET-LRP
- 2014
-
In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 5:12, s. 3847-3854
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Journal article (peer-reviewed)abstract
- Utilizing a-bromo-g-butyrolactone (aBrgBL) as a comonomer with 3-caprolactone (3CL) or L-lactide (LLA)produces copolymers with active and available grafting sites, e.g., for SET-LRP, where the choice of thegrafting monomers is limited only by one's imagination. This was deduced by utilizing a wide range ofdifferent acrylates of varying polarities and was realized with the aid of a fluorinated alcohol, 2,2,2-trifluoroethanol, which acts as a universal solvent for both the hydrophobic macroinitiators and thegrafting monomers. Using aBrgBL successfully provides a simple route to merge the two polymerizationmethodologies, ROP and SET-LRP. aBrgBL inherently meets all of the prerequisites to act as a platformmonomer for the synthesis of functional aliphatic polyesters, i.e., it is inexpensive, available, and able toform isolated grafting sites along the polymer chain. The copolymerization of aBrgBL together with twoof the most commonly used cyclic ester monomers, 3-CL and LLA, proceeds with a high degree ofcontrol and a linear relationship between the feed ratio of aBrgBL and its composition in the copolymer.The formation of isolated units of aBrgBL in the copolymer is visualized by the reactivity ratios of thecopolymerization reactions and confirmed by 13C-NMR spectroscopy. The incorporation of isolatedaBrgBL is the feature that makes this class of copolymers unique, and it can be considered to provide aroute to the “perfect graft copolymer” with a degradable backbone.
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| 48. |
- Olsson, Johan V., et al.
(author)
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Reactive imidazole intermediates : simplified synthetic approach to functional aliphatic cyclic carbonates
- 2014
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In: Polymer Chemistry. - : Royal Society of Chemistry. - 1759-9954 .- 1759-9962. ; 5:23, s. 6651-6655
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Journal article (peer-reviewed)abstract
- Reactive imidazole intermediates based on AB(2) and A(3) monomers, i.e. bis(methylol) propionic acid (bis-MPA) and trimethylolpropane (TMP) have successfully been synthesized and isolated on a 100 gram scale via a facile synthetic protocol using 1,1' -carbonyldiimidazole (CDI) as a key reagent. The robustness of the imidazole intermediates as bench stable precursors enabled the synthesis of a library of functional cyclic carbonates bearing relevant functionalities including hydrophilic PEGs, bioactive cholesterol and clickable groups. A number of functional polycarbonates were obtained by ring-opening polymerization, and their relevance in biomedical applications was highlighted by their low cytotoxicity on human dermal fibroblasts (hDF).
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| 49. |
- Porsch, Christian, et al.
(author)
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Thermo-responsive cellulose-based architectures : tailoring LCST using poly(ethylene glycol) methacrylates
- 2011
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In: POLYMER CHEMISTRY. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 2:5, s. 1114-1123
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Journal article (peer-reviewed)abstract
- There is a growing interest in designing advanced macromolecular architectures applicable for instance in drug delivery systems. Employing cellulose in these systems is particularly favorable due to attractive properties such as biocompatibility and low price. Additionally, thermo-responsive polymers of poly(ethylene glycol) methacrylates are promising in this field owing to their biocompatibility and non-toxicity. In the present study, amphiphilic thermo-responsive homo- and copolymers of oligo(ethylene glycol) methyl ether methacrylate (OEGMA(300)) and di(ethylene glycol) methyl ether methacrylate (DEGMA) were synthesized via ARGET ATRP. Both linear copolymers of DEGMA/OEGMA(300) as well as comb architectures with copolymers of DEGMA/OEGMA(300) grafted from hydroxypropyl cellulose were produced. The lower critical solution temperature of the linear copolymers was readily tailored by altering the monomer feed ratio. The grafting of the thermo-responsive polymers from hydroxypropyl cellulose resulted in a consistent decrease of the lower critical solution temperature compared to the linear analogues; however, interestingly the ability to tune the transition temperature remained. Moreover, the amphiphilic comb architectures formed polymeric micelles with low critical micelle concentrations. Consequently, these advanced architectures combine the favorable properties of hydroxypropyl cellulose with the interesting thermo-responsive and stealth properties of poly(ethylene glycol) methacrylates, and may, therefore, find potential applications in biomedicine.
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| 50. |
- Pronoitis, Charalampos, et al.
(author)
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Long-chain polyamide covalent adaptable networks based on renewable ethylene brassylate and disulfide exchange
- 2021
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In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 12:39, s. 5668-5678
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Journal article (peer-reviewed)abstract
- Conventional thermosets cannot be recycled once they reach their end-of-life creating unavoidable waste. Covalent adaptable networks (CANs) are a promising circular solution as they can be reprocessed by conventional techniques employed for processing thermoplastics. In this work, strong and chemically resistant, long-chain polyamide (PA) CANs were developed by introducing intrinsically reactive disulfides in PA networks. Following a solvent-free strategy and utilizing ethylene brassylate, a renewable cyclic diester, our approach brings together the high strength and chemical resistance of long-chain, crosslinked PAs with the reprocessability of dynamic networks in a sustainable fashion. The structure of the PA CANs was elucidated by X-ray diffraction analysis, and the effect of the disulfides on the thermal, mechanical, viscoelastic and dynamic properties was evaluated. The PA CANs had high gel content (86-98%) and they were reprocessable over three grinding-compression molding cycles, retaining their strength (15-20 MPa), crosslink density and gel content. They exhibited rapid stress relaxation with relaxation times as low as 1.06 s and were healable within 5 min. The long-chain PA CANs are easy to prepare and feature several elements of sustainable materials design, highly valued in plastics' circular economy.
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