Advances in ionic liquid-based antimicrobial wound healing platforms

Wound infections, marked by the proliferation of microorganisms at surgical sites, necessitate the development of innovative wound dressings with potent bactericidal properties to curb microbial growth and prevent bacterial infiltration. This study explores the recent strides in utilizing ionic liquid-based polymers as highly promising antimicrobial agents for advanced wound healing applications. Specifically, cationic polymers containing quaternary ammonium, imidazolium, guanidinium, pyridinium, triazolium, or phosphonium groups have emerged as exceptionally effective antimicrobial compounds. Their mechanism of action involves disrupting bacterial membranes, thereby preventing the development of resistance and minimizing toxicity to mammalian cells. This comprehensive review not only elucidates the intricate dynamics of the skin's immune response and the various stages of wound healing but also delves into the synthesis methodologies of ionic liquid-based polymers. By spotlighting the practical applications of antimicrobial wound dressings, particularly those incorporating ionic liquid-based materials, this review aims to lay the groundwork for future research endeavors in this burgeoning field. Through a nuanced examination of these advancements, this article seeks to contribute to the ongoing progress in developing cutting-edge wound healing platforms that can effectively address the challenges posed by microbial infections in surgical wounds.

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

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 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 1H, 13C, and 19F 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.

Application of quasi solid electrolytes in organic based electrochromic devices: A mini review

The interest in all solid organic based electrochromic devices (ECDs) is on the increase. This is because these devices offer the applicability of electrochromic materials in products such as smart sensors, smart windows, flexible wearables and energy storage devices. The use of quasi-solid electrolytes for the construction of these ECDs is attractive because of their ease of preparation, availability, low cost, improve electrochromic performance, good ionic conductivity and prevention of leakages in ECDs. Hence, in this review, a detailed discussion is presented on the progress in the development of semi-solid electrolytes for ECDs fabrication. The preparation of the most common electrolytes that have been applied for organic based ECDs are summarized. Particular attention is given to efforts and strategies that have been adopted to improve the efficiency of quasi-solid electrolytes. Importantly, knowledge gaps that warrant further research are clearly identified and recommendations for future works are suggested. This review will be very beneficial for both established and new researchers in the field of electrochromic devices and material science.

Rationally Designed Fluorinated Polycation Electrolytes for High-Rate, Dendrite-Free Lithium Metal Batteries

The investigation of high-performance polymer-based electrolytes holds significant importance for advancing the development of next-generation lithium metal batteries (LMBs). In this work, a quasi-solid-state electrolyte (EFA-G) comprising pyrrolidinium type polymeric ionic liquids and fluoropolymers was synthesized through a photoinitiated free radical copolymerization process in the presence of solvate ionic liquids. EFA-G not only exhibited high ionic conductivity (9.87 × 10-4 S cm-1) but also had a wide electrochemical stability window (0-5.0 V vs Li+/Li). The improvement in Li+ transport number (tLi+ = 0.33) of EFA-G was attributed to the enhancement of the Li+ migration ability and the hindrance of anion mobility. Due to the shielding effect of the polymeric ionic liquid on the lithium electrode and the formation of a LiF-rich solid electrolyte interphase (SEI), EFA-G supported stable long-term plating/stripping cycling (>1000 h) of lithium symmetric cells. Li/LFP cells assembled with EFA-G at 30 °C exhibited excellent battery performance with a discharge specific capacity of 78.1 mA h g-1 at 8 C and long cycling life (>600 cycles) with high discharge specific capacity (127.8 mA h g-1 after 600 cycles). EFA-G also enabled decent performance for high-voltage cathode batteries. This work provides insights into the design of high-performance polymer-based electrolytes for LMBs.

Intrinsically Stretchable Integrated Passive Matrix Electrochromic Display Using PEDOT:PSS Ionic Liquid Composite

The low power consumption of electrochromism makes it widely used in actively shaded windows and mirrors, while flexible versions are attractive for use in wearable devices. Initial demonstration of stretchable electrochromic elements promises good conformability to complex surfaces. Here, fully integrated intrinsically stretchable electrochromic devices are demonstrated as single elements and 3 × 3 displays. Conductive and electrochromic ionic liquid-doped poly(3,4-ethylenedioxythiophene) polystyrene sulfonate is combined with poly(vinyl alcohol)-based electrolyte to form complete cells. A transmission change of 15% is demonstrated, along with a reflectance change of 25% for opaque reflective devices, with <7 s switching time, even under 30% strain. Stability under both electrochemical and mechanical strain cycling is demonstrated. A passive matrix display exhibits addressability and low cross-talk under strain. Comparable optical performance to flexible electrochromics and higher deformability provide attractive qualities for use in wearable, biometric monitoring, and robotic skin devices.

Effects of repeat unit charge density on the physical and electrochemical properties of novel heterocationic poly(ionic liquid)s

The higher the charge density of PILs the higher their T_g and the lower their conductivity; the best conductivity (1.8 × 10⁻⁵ S cm⁻¹ at 25 °C): PILs with triazolium cations; the best cathodic stability (−0.4 V vs. Li⁺/Li at 70 °C): PILs with mixed type cations.

Ion Mobilities, Transference Numbers, and Inverse Haven Ratios of Polymeric Ionic Liquids

We probe the ion mobilities, transference numbers, and inverse Haven ratio of ionic liquids and polymerized ionic liquids as a function of their molecular weight using a combination of atomistic equilibrium and nonequilibrium molecular dynamics simulations. In contrast to expectations, we demonstrate that the inverse Haven ratio increases with increasing degree of polymerization (N) and then decreases at larger N. For a fixed center of mass reference frame, we demonstrate that such results arise as a consequence of the strong cation-cation correlated motions, which exceed (in magnitude) the self-diffusivity of cations. Together, our findings challenge the premise underlying the pursuit of pure polymeric ionic liquids as high transference number, single-ion conducting electrolytes.

Comparison of poly(ethylene glycol)-based networks obtained by cationic ring opening polymerization of neutral and 1,2,3-triazolium diepoxy monomers

The properties of two cross-linked epoxy networks obtained by ring opening polymerization of a synthetic diepoxy 1,2,3-triazolium and a commercial poly(ethylene glycol)diglycidyl ether using benzylamine trifluoroborate as cationic initiator are compared.

All-in-One Gel-Based Electrochromic Devices: Strengths and Recent Developments

Electrochromic devices (ECDs) have aroused great interest because of their potential applicability in displays and smart systems, including windows, rearview mirrors, and helmet visors. In the last decades, different device structures and materials have been proposed to meet the requirements of commercial applications to boost market entry. To this end, employing simple device architectures and achieving a competitive electrolyte are crucial to accomplish easily implementable, high-performance ECDs. The present review outlines devices comprising gel electrolytes as a single electroactive layer ("all-in-one") ECD architecture, highlighting some advantages and opportunities they offer over other electrochromic systems. In this context, gel electrolytes not only overcome the drawbacks of liquid and solid electrolytes, such as liquid's low chemical stability and risk of leaking and soil's slow switching and lack of transparency, but also exhibit further strengths. These include easier processability, suitability for flexible substrates, and improved stabilization of the chemical species involved in redox processes, leading to better cyclability and opening wide possibilities to extend the electrochromic color palette, as discussed herein. Finally, conclusions and outlook are provided.

Frontiers in poly(ionic liquid)s: syntheses and applications

We review recent works on the synthesis and application of poly(ionic liquid)s (PILs). Novel chemical structures, different synthetic strategies and controllable morphologies are introduced as a supplement to PIL systems already reported. The primary properties determining applications, such as ionic conductivity, aqueous solubility, thermodynamic stability and electrochemical/chemical durability, are discussed. Furthermore, the near-term applications of PILs in multiple fields, such as their use in electrochemical energy materials, stimuli-responsive materials, carbon materials, and antimicrobial materials, in catalysis, in sensors, in absorption and in separation materials, as well as several special-interest applications, are described in detail. We also discuss the limitations of PIL applications, efforts to improve PIL physics, and likely future developments.

Redox-Active Peptide-Functionalized Quinquethiophene-Based Electrochromic π-Gel

An electrochromic system based on a self-assembled dipeptide-appended redox-active quinquethiophene π-gel is reported. The designed peptide-quinquethiophene consists of a symmetric bolaamphiphile that has two segments: a redox-active π-conjugated quinquethiophene core for electrochromism, and peptide motif for the involvement of molecular self-assembly. Investigations reveal that self-assembly and electrochromic properties of the π-gel are strongly dependent on the relative orientation of peptidic and quinquethiophene scaffolds in the self-assembly system. The colors of the π-gel film are very stable with fast and controlled switching speed at room temperature.

Poly(ionic liquid)-based polyurethanes having imidazolium, ammonium, morpholinium or pyrrolidinium cations

The synthesis of cationic polyelectrolytes based on condensation-derived backbone is rarely performed due to the difficulty obtaining of the respective ionic monomers in high purity. Despite such an approach is favorable as it results in ionic polymers with well-defined chemical structure and ionic group distribution. In this work two efficient methods are presented for the synthesis of ionic diols in high purity, namely the technique with pyranyl protection of OH-groups and the direct quaternization of tertiary amine alcohols. Applying these methods five novel ionic diols bearing various cations, namely, 1,1-bis(2-hydroxyethyl)pyrrolidin-1-ium bromide, 4,4-bis(2-hydroxyethyl)morpholin-4-ium bromide, N, N-bis(2-hydroxyethyl)-N-methylethanammonium, 1,1′-(pentane-1,5-diyl)bis(1-(2-hydroxyethyl)pyrrolidin-1-ium) dibromide, and 3-(2-hydroxyethyl)-1-(5-(3-(3-hydroxypropyl)-1H-imidazol-3-ium-1-yl)pentyl)-1H-imidazol-3-ium dibromide, were synthesized in high purity and high yields. The tin(II) mediated solution polycondensation of ionic diols with commercial hexamethylene diisocyanate or 4,4′-methylenebis(cyclohexyl isocyanate) resulted in a series of ionic, high molecular weight ( Mw = 2.3 × 104 −8.0 × 104) polyurethanes (PUs). The influence of various reaction parameters including reaction temperature and time, catalyst concentration and solvent nature upon PUs molecular weight was investigated. After the exchange of bromide to (CF3SO2)2N- anion the obtained poly(ionic liquid)s exhibit high thermal stability with onset mass loss above 225°C and demonstrate glass transition temperatures in the wide range from −22°C to 76°C depending on the nature of ionic diol used. Ionic PUs present excellent solubility in most organic solvents and are capable to form tough, flexible films with tensile strength up to 29.7 MPa.

Achieving Low-Energy Driven Viologens-Based Electrochromic Devices Utilizing Polymeric Ionic Liquids

Herein, three kinds of viologens-based electrochromic devices (ECDs) (heptyl viologen (HV(BF₄)₂), octyl viologen (OV(BF₄)₂), and nonyl viologen (NV(BF₄)₂)) were fabricated utilizing ferrocene (Fc) as a redox mediator. Among them, the NV(BF₄)₂-based ECD exhibits the highest coloration efficiency (36.2 cm²/C) owing to the lowest driving energy. Besides, switching between 0 and 1.2 V, the NV(BF₄)₂-based ECD shows a desirable initial transmittance change (ΔT = 56.7% at 605 nm), and long-term stability (ΔT = 45.4% after 4000 cycles). Furthermore, a UV-cured polymer electrolyte containing polymeric ionic liquid (PIL, 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and ethoxylated trimethylolpropane triacrylate (ETPTA) was introduced to the NV(BF₄)₂-based ECD. By controlling the weight percentage of the PIL, different curing degrees of the polymer electrolytes were obtained and led to an improved stability of the NV(BF₄)₂-based ECD because of the immobilization of NV(BF₄)₂. This observation was explained by calculating the apparent diffusivity (D_app) of the redox species in the NV(BF₄)₂-based ECD under various curing degrees. In addition, increasing the amount of PIL leads to a lower driven energy needed for the NV(BF₄)₂-based ECD, following the same trend as the value of D_app. Among all NV(BF₄)₂-based ECDs, 20 wt % of PIL addition (20-PIL ECD) exhibits large transmittance change (ΔT = 55.2% at 605 nm), short switching times (2.13 s in coloring and 2.10 s in bleaching), high coloration efficiency (60.4 and 273.5 cm²/C at 605 nm, after excluding the current density at the steady state), and exceptional cycling stability (ΔT = 53.8% after 10,000 cycles, or retained 97.5% of its initial ΔT).

Poly(1,2,3-triazolium)s: a new class of functional polymer electrolytes

Poly(1,2,3-triazolium)s are tunable and highly functional ion conducting materials that stretch out the actual boundaries of PILs macromolecular design.

Adsorption Kinetics at Silica Gel/Ionic Liquid Solution Interface

A series of imidazolium and pyridinium ionic liquids with different anions (Cl(-), Br(-), BF₄(-), PF₆(-)) has been evaluated for their adsorption activity on silica gel. Quantification of the ionic liquids has been performed by the use of RP-HPLC with organic-aqueous eluents containing an acidic buffer and a chaotropic salt. Pseudo-second order kinetic models were applied to the experimental data in order to investigate the kinetics of the adsorption process. The experimental data showed good fitting with this model, confirmed by considerably high correlation coefficients. The adsorption kinetic parameters were determined and analyzed. The relative error between the calculated and experimental amount of ionic liquid adsorbed at equilibrium was within 7%. The effect of various factors such as initial ionic liquid concentration, temperature, kind of solvent, kind of ionic liquid anion and cation on adsorption efficiency were all examined in a lab-scale study. Consequently, silica gel showed better adsorptive characteristics for imidazolium-based ionic liquids with chaotropic anions from aqueous solutions in comparison to pyridinium ionic liquids. The adsorption was found to decrease with the addition of organic solvents (methanol, acetonitrile) but it was not sensitive to the change of temperature in the range of 5-40 °C.

Significance of weak interactions in imidazolium picrate ionic liquids: spectroscopic and theoretical studies for molecular level understanding

The effects of interionic hydrogen bonding and π-π stacking interactions on the physical properties of a new series of picrate anion based ionic liquids (ILs) have been investigated experimentally and theoretically. The existence of aromatic (C2-HO) and aliphatic (C7-HO-N22 and C6-HO-N20) hydrogen bonding and π-π stacking interactions in these ILs has been observed using various spectroscopic techniques. The aromatic and aliphatic C-HO hydrogen bonding interactions are found to have a crucial role in binding the imidazolium cation and picrate anion together. However, the π-π stacking interactions between two successive layers are found to play a decisive role in tight packing in ILs leading to differences in physical properties. The drastic difference in the melting points of the methyl and propyl derivatives (mmimPic and pmimPic respectively) have been found to be primarily due to the difference in the strength and varieties of π-π stacking interactions. While in mmimPic, several different types of π-π stacking interactions between the aromatic rings (such as picrate-picrate, picrate-imidazole and imidazolium-imidazolium cation rings) are observed, only one type of π-π stacking interaction (picrate-picrate rings) is found to exist in the pmimPic IL. NMR spectroscopic studies reveal that the interaction of these ILs with solvent molecules is different and depends on the dielectric constant of the solvent. While an ion solvation model explains the solvation in high dielectric solvents, an ion-pair solvation model is found to be more appropriate for low dielectric constant solvents. The enhanced stability of these investigated picrate ILs compared with that of inorganic picrate salts under high doses of γ radiation clearly indicates the importance of weak interionic interactions in ILs, and also opens up the possibility of the application of picrate ILs as prospective diluents in nuclear separation for advanced fuel cycling process.

Poly(vinyl ester 1,2,3-triazolium)s: a new member of the poly(ionic liquid)s family

A vinyl ester monomer carrying a pendant 1,2,3-triazole group is synthesized in two steps and polymerized by cobalt-mediated radical polymerization. Subsequent alkylation with N-methyl bis[(trifluoromethyl)sulfonyl]imide affords the corresponding poly(vinyl ester 1,2,3-triazolium). This unprecedented example of poly(vinyl ester ionic liquid) exhibits an ionic conductivity of 9.2 × 10(-7) S cm(-1) at 30 °C.

Preparation of anion-exchangeable polymer vesicles through the self-assembly of hyperbranched polymeric ionic liquids

Anion-exchangeable polymer vesicles including pH-indicative and protein-coated vesicles were prepared through the self-assembly of a hyperbranched polymeric ionic liquid.

Ionic liquids and γ-butyrolactone mixtures as electrolytes for supercapacitors operating over extended temperature ranges

Ionic liquid/solvent as high conductive electrolyte (2 mS cm⁻¹ at −50 °C) with suppression of phase transition and large electrochemical window (8 V).

Triethylene glycol-based poly(1,2,3-triazolium acrylate)s with enhanced ionic conductivity

A well-defined triethylene glycol-based poly(1,2,3-triazolium acrylate) having a bis(trifluoromethane)sulfonimide anion and an anhydrous ionic conductivity of 10⁻⁵ S cm⁻¹ at 30 °C is reported.

UV-Patterning of Ion Conducting Negative Tone Photoresists Using Azide-Functionalized Poly(Ionic Liquid)s

The patterning of solid electrolytes that builds upon traditional fabrication of semiconductors is described. An azide-functionalized poly(1,2,3-triazolium ionic liquid) is used as an ion conducting negative tone photoresist. After UV-irradiation through an optical mask, micron-scaled, patterned, solid polyelectrolyte layers with controlled sizes and shapes are obtained. Furthermore, alkylation of poly(1,2,3-triazole)s can be generalized to the synthesis of poly(ionic liquid)s with a tunable amount of pendant functionalities.