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1,3,4,5-Tetrasubstituted Poly(1,2,3-Triazolium) Obtained Through Metal-Free AA+BB Polyaddition of a Diazide and an Activated Internal Dialkyne
Abstract
A tetra(ethylene glycol)‐based 1,3,4,5‐tetrasubstituted poly(1,2,3‐triazolium) is synthesized in two steps including: i) the catalyst‐free polyaddition of a diazide and an activated internal dialkyne and ii) the N ‐alkylation of the resulting 1,2,3‐triazole groups. In order to provide detailed structure/properties correlations different analogs are also synthesized. First, parent poly(1,2,3‐triazole)s are obtained via AA+BB polyaddition using copper(I)‐catalyzed alkyne‐azide cycloaddition (CuAAC) or metal‐free thermal alkyne‐azide cycloaddition (TAAC). Poly(1,2,3‐triazole)s with higher molar masses are obtained in higher yields by TAAC polyaddition. A 1,3,4‐trisubstituted poly(1,2,3‐triazolium) structural analog obtained by TAAC polyaddition using a terminal activated dialkyne and subsequent N ‐alkylation of the 1,2,3‐triazole groups enables discussing the influence of the methyl group in the C ‐4 or C ‐5 position on thermal and ion conducting properties. Obtained polymers are characterized by ¹ H, ¹³ C, and ¹⁹ F NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, size exclusion chromatography and broadband dielectric spectroscopy. The targeted 1,3,4,5‐tetrasubstituted poly(1,2,3‐triazolium) exhibits a glass transition temperature of −23 °C and a direct current ionic conductivity of 2.0 × 10 ⁻⁶ S cm ⁻¹ at 30 °C under anhydrous conditions. The developed strategy offers opportunities to further tune the electron delocalization of the 1,2,3‐triazolium cation and the properties of poly(1,2,3‐triazolium)s using this additional substituent as structural handle.
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Triazoliums are a family of five-membered heterocyclic cations that contain three nitrogen and two carbon atoms. In contrast to the widely studied imidazolium cations, triazoliums are less explored. In terms of the chemical structure, triazolium replaces a carbon atom in the imidazolium cation ring with an electron-withdrawing nitrogen atom, which makes the triazolium more polarized. Among the many physical properties, the thermal responsiveness of triazoliums is of particular interest to us but has been rarely investigated. In this contribution, we prepared a series of 1,2,4-triazolium-based poly(ionic liquid)s (PILs) with varying alkyl substituents and counteranions and studied their thermal-responsive behavior. We found that 1,2,4-triazolim-based PILs with a polymeric backbone structure similar to that of polyimidazoliums exhibited opposite thermal phase transition processes in solvents. For example, methyl-substituted 1,2,4-triazolium-based PILs exhibited an upper-critical-solution-temperature (UCST)-type phase transition in methanol when the counterion was I– and a lower-critical-solution-temperature (LCST)-type phase transition in acetone when the counterion was PF6–. The thermal responsiveness was reversible and concentration-dependent. Interestingly, the thermal response of 1,2,4-triazolim-based PILs could be retained in the organogel form, which was applied in the pretreatment of anion-containing organic waste liquids and temperature-controlled “smart” switches.
Copper‐free synthesis of cationic glycidyl triazolyl polymers (GTPs) is achieved through a thermal azide‐alkyne cycloaddition reaction between glycidyl azide polymer and propiolic acid, followed by decarboxylation and quaternization of the triazole unit. For synthesizing non‐functionalized GTP (GTP‐H), a microwave‐assisted method enhances the decarboxylation reaction of carboxy‐functionalized GTP (GTP‐COOH). Three variants of cationic GTPs with different N ‐substituents [ N ‐ethyl, N ‐butyl, and N ‐tri(ethylene glycol) monomethyl ether (EG3)] are synthesized. The molecular weight of GTP‐H is determined via size exclusion chromatography (SEC). Thermal properties of all GTPs are characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The ionic conductivities of these cationic GTPs are assessed by impedance measurements. The conducting ion concentration and mobility are calculated based on the electrode polarization model. Among three cationic GTPs, the GTP with the N ‐EG3 substituent exhibits the highest ionic conductivity, reaching 6.8 × 10 ⁻⁶ S cm ⁻¹ at 25 °C under dry conditions. When compared to previously reported reference polymers, the reduction of steric crowding around the triazolium unit is considered to be a key factor in enhancing ionic conductivity.
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Charge transport, diffusion properties, and glassy dynamics of blends of imidazolium-based ionic liquid (IL) and the corresponding polymer (polyIL) were examined by Pulsed-Field-Gradient Nuclear Magnetic Resonance (PFG-NMR) and rheology coupled with broadband dielectric spectroscopy (rheo-BDS). We found that the mechanical storage modulus (G′) increases with an increasing amount of polyIL and G′ is a factor of 10,000 higher for the polyIL compared to the monomer (GIL′= 7.5 Pa at 100 rad s−1 and 298 K). Furthermore, the ionic conductivity (σ0) of the IL is a factor 1000 higher than its value for the polymerized monomer with 3.4×10−4 S cm−1 at 298 K. Additionally, we found the Haven Ratio (HR) obtained through PFG-NMR and BDS measurements to be constant around a value of 1.4 for the IL and blends with 30 wt% and 70 wt% polyIL. These results show that blending of the components does not have a strong impact on the charge transport compared to the charge transport in the pure IL at room temperature, but blending results in substantial modifications of the mechanical properties. Furthermore, it is highlighted that the increase in σ0 might be attributed to the addition of a more mobile phase, which also possibly reduces ion-ion correlations in the polyIL.
A series of clickable α-azide-ω-alkyne ionic liquid (IL) monomers with an ethylene oxide spacer were developed and applied to the synthesis of 1,2,3-triazolium-based poly(ionic liquid)s (TPILs) with high ionic conductivities via one-step thermal azide–alkyne cycloaddition click chemistry. Subsequently, the number of IL moieties in the resultant TPILs was further increased by N-alkylation of the 1,2,3-triazole-based backbones of the TPILs with a quarternizing reagent. This strategy affords the preparation of TPILs having either one or two 1,2,3-triazolium cations with bis(trifluoromethylsulfonyl)imide anions in a monomer unit. Synthesis of the TPILs was confirmed by ¹H and ¹³C NMR spectroscopy and gel permeation chromatography. The effects of the length of the ethylene oxide spacer and the number of IL moieties in the IL monomer unit on the physicochemical properties of the TPILs were characterized by differential scanning calorimetry, thermogravimetric analysis, and impedance spectroscopy. The introduction of a longer ethylene oxide spacer or an increase in the number of IL moieties in the monomer unit resulted in TPILs with lower glass-transition temperatures and higher ionic conductivities. The highest ionic conductivity achieved in this study was 2.0 × 10–5 S cm–1 at 30 °C. These results suggest that the design of the IL monomer provides the resultant polymer with high chain flexibility and a high IL density, and so it is effective for preparing TPILs with high ionic conductivities.
We report the synthesis and structure/property correlations of a series of eight poly(ionic liquid)s (PILs) obtained from sequential AA + BB polyaddition by copper(I)-catalyzed azide–alkyne cycloaddition and the subsequent N-alkylation reaction. The different repeat units contain one to four ion pairs, with one to four bis(trifluorosulfonyl)imide (TFSI) anions and one or two types of ammonium, imidazolium or 1,2,3-triazolium counter-cations. Their physical, ion conducting and electrochemical properties are discussed based on the repeat unit charge density and structure of the cationic moieties. The
comparison of several pairs of polyelectrolytes revealed that ionic conductivity is dependent on (1) the ratio between the number of charge carriers per monomer unit and the number of surrounding atoms/groups that can solvate the ions and (2) the nature of the cation. The highest conductivity (1.8 x 10-5 S cm-1 at 25 °C) was reached when PILs contain two 1,2,3-triazolium cations that are separated by an oxyethylene spacer. The incorporation of an additional type of cation (either imidazolium or ammonium with 1,2,3-triazolium) in one PIL allows its cathodic limit to be increased up to -0.4 V vs. Li+/Li (70 °C) and the oxidation instability of 1,2,3-triazolium cations to be overcome.
A series of aromatic poly(1,2,3‐triazolium iodide)s were synthesized by step growth polymerization of dipropargyl bisphenol A with aliphatic and aromatic diazides followed by quantitative or partial N‐alkylation of the main‐chain 1,2,3‐triazole groups using iodomethane. After characterization by ¹H NMR spectroscopy, SEC and DSC the corresponding self‐standing membranes were obtained by hot pressing. Poly(1,2,3‐triazolium iodide) membranes were converted to the corresponding hydroxide‐containing membranes by anion exchange. Structure–property correlations are discussed based on the evolution of water uptake and ionic conductivity with respect to the ionic exchange capacities of the different materials having distinct chemical structure, quaternization degree and counter‐anion structure. Poly(1,2,3‐triazolium hydroxide) anion exchange membranes exhibit water uptakes below 150% and ionic conductivity in the hydrated state up to 4 mS cm⁻¹ for ionic exchange capacities up to 3.2 meq g⁻¹. © 2019 Society of Chemical Industry
Capture and conversion of CO2 are of great importance for environment-friendly and sustainable development of human society. Poly(ionic liquid)s (PILs) combine some unique properties of ILs with that of polymers and are versatile materials for CO2 utilization. In this contribution, we briefly outline innovative poly(ionic liquid)s emerged over the past few years, such as polytriazoliums, deep eutectic monomer (DEM) based PILs, and polyurethane PILs. Additionally, we discuss their advantages and challenges as materials for Carbon Capture and Storage (CCS), and the fixation of CO2 into useful materials.
This contribution reviews the applications of click chemistry reactions in design and synthesis of various macromolecular architectures that hold key aspects in polymer science. By considering the emerging concepts that shape how synthetic polymer chemistry and macromolecular engineering utilize ‘reactions’ in ‘fabrication’, in the last decade, the click chemistry methodologies have been pioneered the chemical approaches that allow to access diverse complex macromolecules. The common and leading features of click chemistry reactions rely on efficient, fast, selective and easy to implement chemical transformations giving very high to quantitative coupling efficiencies. These are essential virtues that provide triumphing in macromolecular engineering, since the building blocks are usually large polymer chains. For the efficient building of complex macromolecules via click reactions, properly functionalized polymers are key components in which special design is required to successful installation of ‘clickable’ reactive groups on polymer end groups or side chains. In this report, the synthetic methods encompassing various click chemistry reactions in fabrication and applications of a range of complex macromolecular architectures have been reviewed.
Novolac-based poly(1,2,3-triazolium)s with 1,2,3-triazolium side groups spaced by oligo(ethylene glycol), a new kind of poly(ionic liquid) membrane, was prepared via the well-known Click chemistry (1,3-dipolar cycloaddition reaction). The thermal properties, ionic conductivity and gas permeation performance of these self-standing membranes were investigated. The obtained membranes exhibit glass transition temperatures ranging from −1 °C to −7.5 °C, and a temperature at 10% weight loss above 330 °C. These membranes have good ionic conductivity (σDC up to 5.1 × 10⁻⁷ S cm⁻¹ at 30 °C under anhydrous conditions) as compared with the reported 1,2,3-triazolium-based crosslinked polymers. And they could be potentially used for CO2 separation as they exhibit enhanced CO2 permeability up to 434.5 barrer at 4 atm pressure.
A 1,2,3-triazolium-based poly(siloxane ionic liquid) (PSIL) is synthesized by UV-triggered thiol-ene ligation between a poly[(mercaptopropyl)methylsiloxane] and a tailor-made vinyl-functionalized triethylene glycol-based 1,2,3-triazolium ionic liquid. The quantitative nature of the thiol-ene coupling is demonstrated by ¹H and ¹³C NMR, whereas properties of this new PSIL are discussed based on solubility, size exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy measurements. Besides exhibiting low glass transition temperature (Tg = -62 °C) and high thermal stability (Td10 = 284 °C), this new class of poly(1,2,3-triazolium) demonstrates the highest value of bulk anhydrous ionic conductivity reported to date for PILs (σDC = 7 × 10⁻⁵ S cm⁻¹ at 30 °C).
The increasing level of carbon dioxide (CO2) in the atmosphere is a big threat to the environment and plays a key role towards global warming and climate change. In this context to combat such issues, polymeric ionic liquids (PILs) serve as potential substitutes that offer extremely versatile and tunable platform to fabricate a wide variety of sorbents for CO2 capture; in particular for flue gas separation (CO2/N2) and natural gas purification (CO2/CH4). Formerly, there have been several reports on exploitation of ionic liquids for CO2 sorption with promising results. However, just a few have focused on polymeric ionic liquids which significantly over-performed the sorption efficiency of the molecular ionic liquids. This review is first ever of its kind in showcasing the potential of PILs as a new member of CO2 adsorbent family. The most dynamic aspect of PILs research at present is the curiosity to explore their potential as solid sorbents for CO2 capture and separation. This review not only highlights the recent advances in the area of PILs as sorbents for CO2 uptake but also portray the forthcoming challenges in improving their efficiency. The effect of various cations, anions, polymer backbone, alkyl substituents, porosity, cross-linking, molecular weight and moisture on the CO2 sorption capacity and separating efficiency is scrutinized in detail. Moreover, future strategies to increase the CO2 capture performance of PILs are also discussed.
A series of cationic poly(acrylate ionic liquid)s having a triethylene glycol (TEG) spacer and a pendant 1,2,3-triazolium group is synthesized by post-polymerization sequential chemical modifications. A chloride -functionalized polyacrylate common precursor is first obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of a TEG-based chloride-functionalized acrylate. Sequential azida-tion, copper-catalyzed azide–alkyne cycloaddition with 1-pentyne and alkylation of the resulting 1,2,3-triazole by methyl iodide affords a poly(acrylate ionic liquid) having pendant 3-methyl-4-propyl-1,2,3-tri-azolium iodide groups. Further anion metathesis with three different fluorinated salts yields a series of 1,2,3-triazolium-based PILs with distinct counter anions. The polymer precursors and resulting poly(1,2,3-triazolium ionic liquid)s (PTILs) are characterized by 1 H NMR spectroscopy, size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and broadband dielectric spectroscopy (BDS). Well-defined PTIL derivative with bis(trifluoromethane)sulfonimide anion (M n = 113,600 g mol −1 and Đ = 1.23) exhibits the lowest glass transition temperature (T g = −36 °C), the highest thermal stability (T d10 = 321 °C) and the highest anhydrous ionic conductivity (σ DC = 1.1 × 10 −5 S cm −1 at 30 °C) of the series.
Accessing 1,2,3-triazole compounds through the copper-catalysed azide–alkyne ‘‘click’’ cycloaddition
reaction is now a routine synthetic tool which has resulted in a huge amount of novel molecules of varied
complexity bearing such heterocycles. 3-N-Alkyl-1,2,3-triazolium salts constitute an example of ‘‘post-click’’
chemistry arising from the ‘‘click’’ pool. This Focus review outlines emerging fields of application for
triazolium cations, including their use as functional ionic liquids, as precursors of mesoionic carbenes, or
as components of supramolecular assemblies and molecular machines.
The demand for environmental friendly methodologies had shifted the the approach of scientific community for using easy and green reaction conditions instead of using hazardous and harsh reaction conditions. One of the suggested approaches, use of catalyst remained prime choice for harsh free green reaction. The difficulty in the separation of homogeneous catalyst from reaction product increased the attention of chemists for heterogeneous catalysts. The present review summarizes some recent important developments in heterogeneous catalysis using “click reaction” for obtaining 1,2,3-triazoles via Cu-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC). A vast collection of papers is efficiently grouped into two significant classes to increase readability in easy language. Firstly, the CuAAC reactions, and secondly, other metal-catalyzed azide-alkyne cycloaddition (MAAC) reactions are discussed. The CuAAC reactions are further grouped into two sub-classes of Cu(I)-nanoparticle catalyzed azide-alkyne cycloaddition (Cu-NPs-AAC) and simple Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. In most cases, the formation of 1,4-disubstituted 1,2,3-triazoles, as reported, was conveniently presented with the help of colored schemes.
The exploration of activated alkyne-based polymerizations recently has attracted considerable attention for their huge potentials in a diverse range of real-life applications from polymer chemistry to materials science, supramolecular science, and biomedicine and pharmaceutical chemistry. In this review, we summarized the recent achievements in activated alkyne-related polymerizations and the properties and applications of the prepared polymers. Through representative examples, we elucidated the essential construction principle, developing strategy and optimization approach of each polymerization and illustrated the diverse and appealing properties and applications of the resulting polymers to offer guidance for the development of new polymerization and promote the development of polymeric materials with more superior and innovative properties and applications.
In this work, two fluorinated poly(1,2,3-triazolium ionic liquid)s (PTILs) are accessed in two steps by copper(I)-catalyzed azide–alkyne cycloaddition AA + BB polyaddition between an α,ω-dialkyne-perfluoroether and either 1,12-dodecyl-diazide or α,ω-diazido-tetra(ethylene glycol), followed by N-alkylation of the resulting poly(1,2,3-triazole)s (PTs) by N-methyl bis(trifluoromethylsulfonyl)imide. The structure/properties correlations of PTILs and their PT intermediates are discussed based on solubility, 1H, 13C and 19F NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy. Dodecyl- and tetra(ethylene glycol)-based PTILs exhibit glass transition temperatures of − 38 and − 29 °C, temperatures at 10% weight loss of ca. 340 °C and anhydrous ionic conductivities at 30 °C of 1.2 × 10−5 and 8.4 × 10−6 S cm−1, respectively. The impact of different lithium salts (i.e. LiSO3CF3, LiTFSI, and LiClO4,) on ionic conductivity of the tetra(ethylene glycol)-based PTIL was also investigated. A ca. twofold increase in ionic conductivity could be obtained by the addition of 5 wt% of LiClO4.
(2 × 4)-Type tetra-PEG ion gels were prepared through a copper-free azide–alkyne cycloaddition reaction between azide-functionalized tetra-branched poly(ethylene glycol) and electron-deficient alkyne-functionalized tetra(ethylene glycol) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The thermal, mechanical, and electrochemical properties of the ion gels were characterized. The tensile tests showed that the reaction efficiency of the cross-linking was over 90%. The prepared ion gels exhibited high mechanical toughness and stretchability characteristic of tetra-PEG gels. The electrochemical window of the ion gels was the same as that of the ionic liquid inside the gel. The ionic conductivities of the ion gels with 30 and 50 wt% polymer concentrations were 8.9 and 1.4 × 10⁻⁴ S cm⁻¹, respectively (25 °C, anhydrous conditions).
Metathesis cyclopolymerization of branched 1,2,3-triazolium-substituted 1,6-heptadiyne ionic monomer and tris(4-N,N-dipropargylaniline)amine trifunctional comonomer was conducted to afford polyacetylene-based copolymer with branched structure and flexible solid state when using appropriate amount of comonomer, which was better than the viscous semi-solid ionic homopolymer in view of film-forming property. The branched copolymer exhibited high intrinsic ionic conductivity of 2.610-5 S cm-1 at 30 oC, which could reach up to 9.010-5 S cm-1 and 1.010-3 S cm-1 after doping with LiTFSI and mixed dopant of ionic liquid/LiTFSI, respectively. Furthermore, the polyelectrolyte composite of LiTFSI-doped copolymer displayed good electrochemical stability with a high decomposition voltage of 5.2 V and ionic transference number of 0.39 versus Li/Li+, indicating that the flexible and stretchable copolymer has potential application in electric devices.
Azide-alkyne click polymerization has become a powerful and popular technique for the preparation of polytriazoles with diverse topological structures and versatile properties. However, the synthesis of post-functionalizable 1,4,5-trisubstituted polytriazoles (1,4,5-PTAs) is still a challenge. In this work, a metal-free polycycloaddition of aldehyde-activated internal diynes and diazides is developed, and a series of soluble and thermally stable poly(formyl-1,2,3-triazole)s (formyl-PTAs) with high weight-average molecular weights (Mw, up to 54 550) are facilely produced in high yields (up to 93%). The tetraphenylethene moiety containing formyl-PTAs exhibit the unique aggregation-induced emission features. Moreover, the aldehyde groups at the C-5 position of triazole rings in the formyl-PTA enables it to be a highly selective chemosensor for hydrazine detection and to serve as a useful platform for further post-functionalization, enriching the properties of proto-polytriazole as desired. Thus, this work combines a metal-free approach toward 1,4,5-PTAs with a post-functionalization strategy to pave a way for the development of a multitude of functional polytriazole-based materials.
Poly(1,2,3–triazolium)s are a versatile class of poly(ionic liquid)s that take advantage of the functional tolerance, orthogonal robustness and efficiency of the copper(I)–catalyzed azide–alkyne cycloaddition (CuAAC). We use this reaction to...
Topochemical reactions are solid-state reactions that transpire under the strict control of molecular packing in the crystal lattice. Due to this lattice control, these reactions generate products in a regio-/stereospecific manner and in very high yields. In a broader sense, topochemical reactions mimic nature's way of carrying out reactions in a confined environment of enzymes giving specific products. Apart from their remarkable specificity, topochemical reactions have many other interesting features that make these reactions more attractive than solution-phase reactions. Solution-phase reactions necessitate the use of reactants, reagents, catalysts, and solvents and often give products along with varying amounts of byproducts, necessitating complex workup and chromatographic purification using various chemicals. These inevitable chemical wastes from solution-state reactions could be avoided by topochemical reactions, as they are solvent-free and catalyst-free and often do not require any chromatographic purification in view of their specificity and high yielding nature. Also the confinement offered by the crystal lattice gives products that are not possible by solution-phase reactions. Another interesting feature of topochemical reactions is the possibility of formation of products in an ordered (crystalline) form, which imparts interesting properties. Thus, topochemical reactions have control not only at the molecular level (regio-/stereospecificity) but also at the supramolecular level (packing). Many topochemical reactions happen in single-crystal-to-single-crystal (SCSC) fashion, and crystal structure analysis of such reactions often gives mechanistic insights and knowledge about the geometrical criteria required for the reaction. Despite all these attractive features, reactions that can be done topochemically are limited. There is tremendous interest in the development of new categories of topochemical reactions and strategies to achieve reactivity in crystals. In this Account, we will summarize our attempts to develop topochemical azide-alkyne cycloaddition (TAAC) reactions. We have used hydrogen-bonding as the main noncovalent interaction for aligning azide-and-alkyne-substituted derivatives of various biomolecules in orientations suitable for their proximity-driven cycloaddition reaction in crystals. Overall, three major classes of biomolecules; carbohydrates, nucleosides, and peptides were successfully exploited for their TAAC reactions using conventional O-H···O, N-H···O, and N-H···N hydrogen bonds as supramolecular glues for controlling their assembly in crystals. The crystals of these monomers underwent TAAC reaction either spontaneously at room temperature or under heating yielding triazole-linked biopolymer mimics. The ordered packing of product molecules imparted special properties to the products formed. The legendary "cream of the crop" azide-alkyne click reaction has diverse applications in the areas of bioconjugation, material science, polymer synthesis, and so forth. Belonging to the same genre, TAAC is a novel metal-free approach for making the triazole-linked products employing the ordered crystal/gel as a reaction medium. In brief, our studies suggest that TAAC reaction can be implemented in diverse molecular categories and has high potential to develop into a field with practical applications.
A copoly(ionic liquid) (coPIL) based on 1,2,3-triazolium bearing trioxyethylene and tetraoxyethylene spacers was successfully synthesized as electrolyte for all-solid state electrochromic devices (ECD). This polyelectrolyte was produced by reacting triethylene glycol (TEG3)-diazide and tetraethylene glycol (TEG4)-dialkyne monomers through a ‘click’ reaction, copper-catalyzed alkyne-azidecycloadditon (CuAAC), and subsequently underwent several alkylation and anion metathesis. The new coPIL bearing ethylene glycol fragments exhibited excellent thermal degradation temperature (T d10 = 230 °C) and ionic conductivity (σ = 8.8 × 10 ⁻⁵ S cm ⁻¹ ) which resulted to an efficient color switching (t c = 11.8 s and t b = 6.2 s), a high optical contrast (ΔT = 24%) and a remarkable stability (after 3000 cycles) of a symmetric all-solid-state smart glass window. The structural design of this new polyelectrolyte material and its corresponding properties make it an excellent electrolyte for many electrochemical devices that require zero electrolyte leakage. © 2019 The Korean Society of Industrial and Engineering Chemistry
The quest for reliable and high-performance batteries has incentivized the development of new battery chemistries/materials that can potentially improve the current lithium-ion battery technologies in terms of gravimetric/volumetric energy density and safety. Polymeric ionic liquids [also called polymerized ionic liquids or poly(ionic liquid)s] containing both ionic liquid-like moieties and polymer frameworks are emerging as alternative electrolytes/binders candidates for Li-based rechargeable batteries, owing to their various intrinsic features , such as superior mechanical and chemical stability, structural controllability over the IL species and macromolecuar backbone and leak-proof nature and thereby improved safety. In this perspective, recent progresses and advances on the use of PILs-based electrolytes and binders for Li-based rechargeable batteries are overviewed and discussed, with a particular attention on the structural-properties relationships. Future directions and improvements of the properties of PILs-based materials are given from the standpoint of chemistry of Li-based batteries.
The Cu(I)-mediated and metal-free click polymerizations of azides and terminal alkynes have been developed into powerful techniques for constructing linear and hyperbranched polytriazoles. However, the 1,3-dipolar cycloaddition of azides with internal alkynes is rarely employed as a synthetic tool to prepare functional polymers. In this work, metal-free phenylpropiolate-azide polycycloaddition was developed for efficient synthesis of poly(phenyltriazolylcarboxylate)s (PPTCs), a kind of polyester. The aromatic and aliphatic diphenylpropiolates could readily react with diazides under heating, affording soluble PPTCs with high molecular weights (Mw up to 28 500) in excellent yields (up to 98%). The polymerization is insensitive towards oxygen and moisture, and can proceed smoothly in an open atmosphere. The obtained PPTCs are thermally stable with 5% weight loss temperatures higher than 318 oC. Due to their contained ester groups, the polymers exhibited fast degradation under basic conditions. The PPTC containing tetraphenylethene moieties shows a unique phenomenon of aggregation-induced emission, and can be employed as fluorescent chemosensors to sensitively detect explosive. Its thin film can generate two-dimensional fluorescent photopatterns by UV irradiation.
Main-chain poly(ionic liquid)s based on 1,2,3-triazole with pentaoxyethylene spacer was developed via copper-catalyzed alkyne-azide cycloaddition (CuAAC) of a novel azide/alkyne-terminal monomer and subsequently quaternized by alkyl halides followed by anion exchanges with several fluorinated salts. Introduction of the extended ethylene oxide fragments [–(CH2CH2O)5–] has made this new PIL with methyl substituent and bis(trifluoromethane)sulfonimide counteranion exhibit ionic conductivity of 1.16 × 10⁻⁴ S cm⁻¹ at 30 °C. This new electrolyte efficiently switches an electrochromic device (ECD) with 18% optical contrast from its transparent state to a colored state in 4.75 s and while bleaching takes 11.8 s. The development of this polyelectrolyte with simple structure and excellent physical and thermal properties is promising for the design of new all-solid state energy efficient smart windows and devices and other electrochemical device applications.
This paper deals with the synthesis of two new families of cationic poly(ionic liquid)s (PILs). The first one is obtained by free radical copolymerization of 1-[2-(2-(2-(methacryloyloxy)ethoxy)ethoxy)ethyl]-3-methylimidazolium bis(trifluoromethylsul-fonyl)imide with poly(ethylene glycol) methyl ether methacrylate, while the second one by chemical modification of poly(epichlorohydrin-co-ethylene oxide) via quaternization with N-methylimidazole and subsequent ion exchange with lithium bis(trifluoromethylsulfonyl)imide. Both PILs demonstrated Tg below 0 °C, bulk ionic conductivities in anhydrous state in the range of 8.4 × 10⁻⁷-1.5 × 10⁻⁵ S/cm (25 °C) and electrochemical stability of 3.1–3.4 V (25 °C). These PILs were further applied in the construction of symmetric truly all-polymer pseudo-supercapacitors. The first PIL, possessing high ionic conductivity of 1.5 × 10⁻⁵ S/cm at 25 °C, was chosen to play the role of separator, while the second one, demonstrating an ability to form good coatings, was used for the preparation of the thin electrode films via vapor phase polymerization of 3,4-ethylenedioxythiophene (EDOT), pyrrole (Py) or 3-methylthiophene (3 MT) in its solution. The varying of the electroactive polymer's nature allowed for the optimization of the devices parameters resulting in the assembly of PPy+PIL2/PIL1/PPy+PIL2 pseudo-capacitor showing best characteristics in terms of specific capacitance (2.8 and 7.0 F/g at 30 mV/s scan rate and 25 and 70 °C, respectively), energy and power (Emax = 1.39 Wh/kg and Pmax = and 286 W/kg at 70 °C and 30 mV/s scan rate). Such flexible device was cycled for 1000 cycles with 96% of capacitance retention at a voltage up to 1.2 V at 25 °C. To be clear, this level of electrochemical performance is not as high as other systems that have been reported in the literature. However, we emphasize that the novelty of these proof-of-concept experiments is the fact that they demonstrate the possibility, for the first time and to the best of our knowledge, to create pseudo-supercapacitors based on polymeric materials alone, with no low molecular weight components. This is significant because it represents a path to highly efficient, lightweight and safe devices requiring no sealing and tolerant of a much broader range of application conditions (reduced pressures, high temperature, etc.).
In the last few years, efforts to broaden PILs properties, structures, functionalities, and applications have grown rapidly. One of their interesting potential uses is as antimicrobial systems, due to their versatility and capacity to be adjusted in different morphologies, sizes, and surface charges. This review gathers the recent advances in antimicrobial materials based on PILs. Initially, the synthesis of PILs with antimicrobial activity, showing the influence of the chemical structure, whether is cationic or anionic and their corresponding counter-ions, is pointed out. Equally, most of these PILs present modest mechanical performance that turn researchers to overcome it by grafting them to different surfaces, crosslinked with other monomers or by simple blending with polymers. Moreover, the nature of PILs makes them regulators of size and shape of inorganic antimicrobial particles, enhancing their effectivity.
A fast-switching all-solid state symmetrical electrochromic device was successfully fabricated using poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as electrode and a poly(ionic liquid) based on 1,2,3-triazole with oxyethylene spacer as solid electrolyte. PEDOT:PSS solution was spincoated on ITO glass and annealed to obtain the electrode layers. Two different types of electrolyte were synthesized via copper-catalyzed alkyne-azide cycloaddition (CuAAC) using novel azide/alkyne-terminal monomers. These newly developed main-chain 1,2,3-triazole-based poly(ionic liquid)s having variable spacer length underwent quaternization using methyl iodide and subsequently allowed to make anion exchange with lithium bis(trifluoromethane)sulfonimide salt to obtain PILs with remarkable properties. The PIL bearing [–(CH2CH2O)6–] spacer showed a conductivity of 1.20 × 10⁻⁴ S cm⁻¹ which is at par with best side-chain PILs in literature and it efficiently switches an electrochromic device (ECD) with 22% optical contrast from its transparent state to a colored state in 2.5 s and 3.2 s to return to its bleached state. Likewise, it exhibits excellent thermal and mechanical stability that is ideal for practical applications.
Alkyne-functional polymers synthesized by ATRP exhibit bimodal molecular weight distributions indicating the occurrence of some undesirable side reaction. By modeling the molecular weight distributions obtained under various reaction condi-tions, we show that the side reaction is alkyne-alkyne (i.e., Glaser) coupling. Glaser coupling accounts for as much as 20 per cent of the polymer produced, significantly compromising the polymer functionality and undermining the success of subse-quent click reactions in which they are used. Glaser coupling does not occur during ATRP but during post-polymerization workup upon first exposure to air. Two strategies are reported that effectively eliminate these coupling reactions without the need for a protecting group for the alkyne-functional initiator: (1) maintaining low temperature post-ATRP upon exposure to air followed by immediate removal of copper catalyst; (2) adding excess reducing agents post-ATRP which prevent the oxidation of Cu(I) catalyst required by the Glaser coupling mechanism. Post-ATRP Glaser coupling was also influenced by the ATRP synthesis ligand used. The order of ligand activity for catalyzing Glaser coupling was: linear bidentate> tridentate > tetradentate. We find that Glaser coupling is not problematic in ARGET-ATRP of alkyne-terminated polymers because a reducing agent is present during polymerization, however the molecular weight distribution is broadened compared to ATRP due to the presence of oxygen. Glaser coupling can also occur for alkynes held under CuAAC reaction conditions but again can be eliminated by adding appropriate reducing agents.
Two soluble poly(phenyltriazolylcarboxylate)s (PPTCs) with high molecular weights (M w up to 26 800) are synthesized by the metal-free 1,3-dipolar polycycloadditions of 4,4'-isopropylidenediphenyl diphenylpropiolate (1) and tetraphenylethene-containing diazides (2) in dimethylformamide at 150 °C for 12 h in high yields (up to 93%). The resultant polymers are soluble in common organic solvents and are thermally stable with 5% weight loss temperatures higher than 375 °C. The PPTCs are nonemissive in solutions, but become highly luminescent upon aggregation, showing a phenomenon of aggregation-induced emission. Their aggregates can be used as fluorescent chemosensors for high-sensitivity detection of explosives.
The interest in poly(ionic liquid)s for sensing applications is derived from their strong interactions to a variety of analytes. By combining the desirable mechanical properties of polymers with the physical and chemical properties of ILs, new materials can be created. The tunable nature of both ionic liquids and polymers allows for incredible diversity, which is exemplified in their broad applicability. In this article we examine the new field of poly(ionic liquid) sensors by providing a detailed look at the current state-of-the-art sensing devices for solvents, gases, biomolecules, pH, and anions.
During the past decade, significant advances in ionic liquid-based materials for the development of CO2 separation membranes have been accomplished. This review presents a perspective on different strategies that use ionic liquid-based materials as a unique tuneable platform to design task-specific advanced materials for CO2 separation membranes. Based on compilation and analysis of the data hitherto reported, we provide a judicious assessment of the CO2 separation efficiency of different membranes, and highlight breakthroughs and key challenges in this field. In particular, configurations such as supported ionic liquid membranes, polymer/ionic liquid composite membranes, gelled ionic liquid membranes and poly(ionic liquid)-based membranes are detailed, discussed and evaluated in terms of their efficiency, which is attributed to their chemical and structural features. Finally, an integrated perspective on technology, economy and sustainability is provided.
Poly(ionic liquid)s (PILs) are a unique class of polyelectrolytes having properties suited for modern technological applications such as electrochemical devices (batteries, supercapacitors, light-emitting electrochemical cells), ion-gated field effect transistors, electrochromic devices, fuel cells, dye sensitized solar cells, catalysis, or soft robotics. Their structure and properties can be finely tuned by unlimited combinations issued from extended pools of cationic and anionic building blocks. In a constant quest for the development of solid polymer electrolytes with enhanced physical, mechanical and (electro)chemical properties, a new class of PILs based on 1,2,3-triazolium cations has been recently developed. Their preparation takes advantage of the beneficial features of the multiple combinations between the Click chemistry philosophy with macromolecular engineering techniques to afford tunable and highly functional ion conducting materials thus stretching out the actual boundaries of PILs macromolecular design. This feature article summarizes the different strategies developed so far for the synthesis of 1,2,3-triazolium-based PILs (TPILs) since their first introduction in 2013.
A series of novel hyperbranched poly(triazolium)s with different terminal groups were synthesized by alkylation and anion exchange reactions of the corresponding hyperbranched poly(triazole)s, which were obtained from an AB2-type monomer via Cu(I)-catalyzed azide–alkyne cycloaddition polymerization. The hyperbranched poly(triazolium)s showed high thermal stability with decomposition temperatures of 328–361 °C, and good flexibility, with glass transition temperatures (Tg) ranging from −6.2 to −14.9 °C. Among them, an oligo(ethylene glycol)-terminated hyperbranched poly(triazolium) presented the lowest Tg of −14.9 °C, the highest ionic conductivity (7.70 × 10−6 S cm−1 at 30 °C and 1.02 × 10−3 S cm−1 at 110 °C) and a wide electrochemical stability window of 6.0 V. Therefore, these hyperbranched poly(triazolium)s could act as new electrolyte materials.
A series of six 1,2,3-triazolium-based poly(ionic liquid)s (TPILs) having random distributions of 1,3,4- and 1,3,5-trisubstituted 3-methyl-1,2,3-triazolium units are prepared by the solvent- and catalyst-free 1,3-dipolar Huisgen cycloaddition of two α-azide-ω-alkyne monomers and simultaneous N-alkylation of the resulting 1,4- and 1,5-disubstituted poly(1,2,3-triazole)s by N-methyl bis(trifluoromethylsulfonyl)imide (TFSI), trimethyl phosphate or methyl methanesulfonate quaternizing agents. The physical and ion conducting properties of this series of TPILs having TFSI, dimethyl phosphate (DMP) or methanesulfonate (MSF) anions are discussed based on solubility, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), size exclusion chromatography (SEC) and broadband dielectric spectroscopy (BDS) measurements.
We report the synthesis of two novel α-azide-ω-alkyne monomers with short n-hexyl and diethylene glycol spacers. Their polyaddition by both copper(I)-catalyzed and thermal Huisgen azide-alkyne 1,3-dipolar cycloaddition followed by alkylation using N-methyl bis(trifluoromethylsulfonyl)imide afford the corresponding 1,2,3-triazolium-based poly(ionic liquid)s. Their physical, ion conducting and electrochemical properties are discussed based on the chemical structure of the spacer and the regiochemistry of the 1,2,3-triazolium groups. The main advantageous feature of these novel polyelectrolytes is related to the unusual combination of motionless main chain 1,2,3-triazolium cations with low glass transition temperature (Tg = -38 °C), high ionic conductivity under anhydrous conditions (σDC = 1.0 × 10-5 S cm-1 at 25 °C) and high electrochemical stability (ESW = 5.9 V vs Ag+/Ag).
Aromatic alkynes and azides were successfully polymerized under metal-free conditions using tetramethylammonium hydroxide (NMe4OH) as an organocatalyst at room temperature and soluble 1,5-regioregular polytriazoles P3a–P3e with high molecular weights (Mw up to 56000) were readily produced in high yields (up to 96%).
A series of poly(aroxycarbonyltriazole)s (PACTs) with high molecular weights and regioregularities is prepared in excellent yields by the metal-free click polymerization (MFCP) of dipropiolate (1) and diazides (2) in dimethylformamide (DMF) at 100 degrees C for 6 h. The MFCPs can proceed smoothly in an open atmosphere, without protection from oxygen and moisture. The PACTs show good solubility and processability. They are thermally stable and the temperatures of their 5% weight-loss are higher than 363 degrees C. The polymers exhibit high optical transparency and refractive indices with low chromatic dispersions. Moreover, the polymer film containing benzophenone units can be cross-linked upon UV irradiation to generate negative photoresist patterns with high resolution.
A straightforward and expeditious monotopic approach for the preparation of 1,2,3-triazolium-based poly(ionic liquids) (TPILs) is reported. It is based on the solvent- and catalyst-free polyaddition of an α-azide-ω-alkyne monomer in the presence of methyl iodide or N-methyl bis[(trifluoromethyl)sulfonyl]imide alkylating agents. Poly(1,2,3-triazole)s generated in bulk or by thermal azide-alkyne cycloaddition (AAC) are quaternized in-situ to afford TPILs composed of 1,3,4- and 1,3,5-trisubstituted 1,2,3-triazolium units. The physical and ion-conducting properties of the prepared samples are compared with the TPILs composed solely of 1,3,4-trisubstituted 1,2,3-triazolium units obtained through a multistep approach involving copper(I)-catalyzed AAC polyaddition, quaternization of the 1,2,3-triazole groups, and anion metathesis. TPILs obtained through the monotopic approach display thermal stabilities and ionic conductivities comparable to their pure regioisomeric analogues.
Using polymeric ionic liquids and PEDOT as ion conducting separators and electrodes, respectively, an all-polymer-based organic electrochromic device (ECD) has been constructed. The advantages of such an ECD are: fast switching time (3 s), high coloration efficiency (390 cm(2) C(-1) at 620 nm), optical contrast up to ΔT = 22% and the possibility of working under vacuum.
A highly tunable class of 1,2,3-triazolium-based ionenes containing triethylene glycol (TEG) repeating units are synthesized from the polyaddition of an α-azide-ω-alkyne monomer by copper-catalyzed azide-alkyne cycloaddition (CuAAC), followed by quaternization reactions with alkyl halides and subsequent anion exchanges with different fluori-nated organic salts. A detailed structure/properties relationship of solubility, thermal stability and ionic conductivity is investigated by means of 1H NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and broadband dielectric spectroscopy (BDS). One of these poly(ionic liquid)s with methyl substituent and bis(trifluoromethylsulfonyl)imide anion exhibits ionic conductivity as high as 0.02 mS/cm which is in par with the best PILs with side chain charge carriers reported so far. The straight forward synthesis, together with the broad structural design and enhanced properties of this new class of poly(ionic liquid)s, offers both fundamental and applicative perspectives.
Step growth polymerization of an α-azide-ω-alkyne monomer by copper-catalyzed azide-alkyne cycloaddition affords a high molar mass linear poly(1,2,3-triazole) that is subsequently reacted with iodomethane to yield the corresponding poly(3-methyl-1,2,3-triazolium iodide) derivative. The formation of this new type of poly(ionic liquid) having main-chain 1,2,3-triazolium groups in the repeating unit is demonstrated by 1H NMR. The large variety of 1,2,3-triazole-based architectures accessible by anion exchange and macromolecular engineering through click chemistry open new perspectives in the field of poly(ionic liquid)s.
The synthesis of α-azide-ω-alkyne 1,4:3,6-dianhydrohexitols with controlled stereochemistry from starch-derived isosorbide, isomannide, and isoidide as well as a detailed study of their polyaddition by CuAAC in solution or by catalyst and solvent-free 1,3-dipolar Huisgen cycloaddition, was reported. α-Azide-ω-alkyne dianhydrohexitol stereoisomers 9-12 (RR, RS, SR, SS) were obtained from isosorbide, isoidide, and isomannide using a three-step synthetic pathway. Alkylation of the remaining hydroxyl group by propargyl bromide was then performed at room temperature to avoid any undesirable step growth polymerization. Monomers 9-12 were stored at -20°C, a temperature below which no traces of coupling products could be observed by 1H NMR after several months of storage. The regioselectivity of the CuAAC step growth polymerization was clearly demonstrated by 1H NMR with the appearance of a single signal at 8.16 ppm characteristic of 1,4-disubstituted 1,2,3-triazoles.
Positron annihilation lifetime and conductivity measurements have been performed for the poly(ether urethane) PEU-LiClO4 complex as a function of temperature in the temperature range from 120 to 360 K and from 280 to 360 K, respectively. According to the variations of free volume and fractional free volume, the structural transition of PEU-LiClO4 has been determined. Based on a polymer lattice model, the formation energy of a free-volume hole has been calculated in terms of fractional free volume derived from positron annihilation parameters. The temperature dependence of ionic conductivity obeys the Vogel-Tammann-Fulcher and Williams-Landel-Ferry equations, implying a free-volume transport mechanism. A direct relationship between the ionic conductivity and the fractional free volume has been established based on the experimental measurements. A linear least-squares procedure was used to evaluate the apparent activation energy in the Vogel-Tammann-Fulcher equation and several important parameters in the Williams-Landel-Ferry and Vogel-Tammann-Fulcher equations. The correlation between the segmental motion and the conductivity could be explained by means of the free-volume theory.
Herein we describe the sequential synthesis of a variety of azide-alkyne click chemistry-compatible heterobifunctional oligo(ethylene glycol) (OEG) linkers for bioconjugation chemistry applications. Synthesis of these bioorthogonal linkers was accomplished through desymmetrization of OEGs by conversion of one of the hydroxyl groups to either an alkyne or azido functionality. The remaining distal hydroxyl group on the OEGs was activated by either a 4-nitrophenyl carbonate or a mesylate (-OMs) group. The -OMs functional group served as a useful precursor to form a variety of heterobifunctionalized OEG linkers containing different highly reactive end groups, e.g., iodo, -NH(2), -SH and maleimido, that were orthogonal to the alkyne or azido functional group. Also, the alkyne- and azide-terminated OEGs are useful for generating larger discrete poly(ethylene glycol) (PEG) linkers (e.g., PEG(16) and PEG(24)) by employing a Cu(i)-catalyzed 1,3-dipolar cycloaddition click reaction. The utility of these clickable heterobifunctional OEGs in bioconjugation chemistry was demonstrated by attachment of the integrin (α(v)β(3)) receptor targeting peptide, cyclo-(Arg-Gly-Asp-d-Phe-Lys) (cRGfKD) and to the fluorescent probe sulfo-rhodamine B. The synthetic methodology presented herein is suitable for the large scale production of several novel heterobifunctionalized OEGs from readily available and inexpensive starting materials.
Precision synthesis of advanced polymeric materials requires efficient, robust, and facile chemical reactions. Paradoxically, the synthesis of increasingly intricate macromolecular structures generally benefits from exploitation of the simplest reactions available. This idea, combined with requirements of high efficiency, orthogonality, and simplified purification procedures, has led to the rapid adoption of “click chemistry” strategies in the field of macromolecular engineering. This Perspective provides context as to why these newly developed or recently reinvigorated reactions have been so readily embraced for the preparation of polymers with advanced macromolecular topologies, increased functionality, and unique properties. By highlighting important examples that rely on click chemistry techniques, including copper(I)-catalyzed and strain-promoted azide−alkyne cycloadditions, Diels−Alder cycloadditions, and thiol−ene reactions, among others, we hope to provide a succinct overview of the current state of the art and future impact these strategies will have on polymer chemistry and macromolecular engineering.
Heating mixtures of bis(aroylacetylene)s (5/6/9) and diazides (7/8) in polar solvents such as DMF/toluene at a moderate temperature of 100 °C readily affects their 1,3-dipolar polycycloadditions, producing poly(aroyltriazole)s (PATAs; PI−PXII) with high molecular weights (Mw up to 26 700) and regioregularities (F1,4 up to 92%) in high yields (up to 98%). The metal-free click polymerizations propagate smoothly in an open atmosphere without protection from oxygen and moisture. Through model reaction study and semiempirical calculation, the polymerization mechanism is proposed and discussed. Molecular structures of the PATAs are characterized spectroscopically. All the polymers are soluble in common organic solvents and are thermally stable, losing little of their weights when heated to 380 °C. The PATAs containing triphenylamine units emit visible light and show unique solvatochromism. The PATAs are nonlinear optically active, exhibiting large two-photon absorption cross sections due to the intramolecular charge transfer between their electron-donating triphenylamine and electron-accepting aroyltriazole units.
Atom transfer radical polymerization (ATRP) was used in combination with Glaser type coupling, allowing the clean and efficient formation of symmetrically coupled polymers with a central diacetylene unit. The feasibility of the clean acetylene coupling was investigated with alkyne terminated poly(ethylene glycol) and poly(styrene) obtained by ATRP. The latter allowed subsequent ATRP to be carried out from the coupled products, offering opportunities for the formation of well defined functional materials with central diacetylene units. Glaser coupling was also observed as a side reaction in Huisgens-type “click” reactions of polymeric alkynes with hindered surface azide groups. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3795–3802, 2009