Ionic Liquid Hydrogel Research Articles

Fabrication of Poly(ionic liquid) Hydrogels Incorporating Liquid Metal Microgels for Enhanced Synergistic Antifouling Applications.

Hydrogels are ideal for antifouling materials due to their high hydrophilicity and low adhesion properties. Herein, poly(ionic liquid) hydrogels integrated with zwitterionic copolymer-functionalized gallium-based liquid metal (PMPC-GLM) microgels were successfully prepared by a one-pot reaction. Poly(ionic liquid) hydrogels (IL-Gel) were obtained by chemical cross-linking the copolymer of ionic liquid, acrylic acid, and acrylamide, and the introduction of ionic liquid (IL) significantly increased the cross-linking density; this approach consequently enhanced the mechanical and antiswelling properties of the hydrogels. The swelling ratio of IL-Gel decreased eight times compared to the original hydrogels. PMPC-GLM microgels were prepared through grafting the zwitterionic polymer PMPC onto the GLM nanodroplet surface, which exhibited efficient antifouling performance attributed to the bactericidal effect of Ga3+ and the antibacterial effect of the zwitterionic polymer layer PMPC. Based on the synergistic effect of PMPC-GLM microgels and IL, the composite hydrogels PMPC-GLM@IL-Gel not only exhibited excellent mechanical and antiswelling properties but also showed outstanding antibacterial and antifouling properties. Consequently, PMPC-GLM@IL-Gel hydrogels achieved inhibition rates of over 90% against bacteria and more than 85% against microalgae.

Curcumin-Based Ionic Liquid Hydrogel for Topical Transdermal Delivery of Curcumin To Improve Its Therapeutic Effect on the Psoriasis Mouse Model.

Psoriasis is a systemic, recurrent, chronic autoimmune skin disease. However, psoriasis drugs have poor skin permeability and high toxicity, resulting in low bioavailability and affecting their clinical application. In this study, we propose a curcumin-based ionic liquid hydrogel loaded with ilomastat (Cur-Car-IL@Ilo hydrogel), which can effectively maintain the sustained release of drugs and improve the skin permeability of drugs. We used a model of imiquimod-induced psoriasis and demonstrated that local application of Cur-Car-IL@Ilo hydrogel can improve skin lesions in mice with significantly reduced expression levels of inflammatory factors, matrix metalloproteinase 8, and collagen-I. The expressions of iron death-related proteins SLC7A11 and ASL4 were significantly decreased after treatment with Cur-Car-IL@Ilo hydrogel. Flora analysis showed that the content of anaerotruncus, proteus, and UCG-009 bacteria in the gut of psoriatic mice increased. The levels of paludicola, parabacteroides, prevotellaceae_UCG-001, escherichia-shigella, and aerococcus decreased, and the levels of some of the above bacteria tended to be normal after treatment. Therefore, the curcumin-based ionic liquid hydrogel can be used as a multifunctional, nonirritating, noninvasive, and highly effective percutaneous treatment of psoriasis.

Enhanced Stability and Catalytic Activity of a Nanocatalyst with Reusable Ionic Liquid Hydrogels for the Reduction of Organic Pollutants.

Nitroaromatic compounds have a wide range of applications. However, they pose a significant threat to both the environment and human health. Ionic liquid hydrogels (ILs-gels) have emerged as a cost-effective and environmentally friendly option for various applications. However, conventional ILs-gels are known to possess mechanical flaws or defects. The procedure utilized a facile synthesis route that involved the polymerization of acrylamide (AM) and ionic liquids (ILs) to create a novel candidate for nanoparticle absorption. This study resolved this issue by creating toughened hydrophobic combined hydrogels synthesized through the addition of SiO2@poly(butyl acrylate) core-shell inorganic-organic hybrid latex particles (SiO2@PBA) to the AM-ILs mixture. The SiO2@PBA particles were chosen to provide the hydrogels with exceptional stretchability (up to 4050% strain) and high mechanical properties (tensile strength of 126 kPa) by acting as both a nanotoughener and a cross-linking point for hydrophobic linkage. Additionally, the P(AM/ILs)-SiO2@PBA hydrogel served as a template for the in situ and stable formation of palladium (Pd) nanoparticles. By incorporation of these Pd nanoparticles as catalysts into P(AM/ILs)-SiO2@PBA hydrogel carriers, the resulting P(AM/ILs)-SiO2@PBA/Pd hydrogels exhibited the ability to catalyze the degradation of p-nitrophenol. Remarkably, even after 15 applications, the efficiency of the degradation process remained consistently above 90%. Thus, the innovative SiO2@PBA toughened ILs-hydrogel design strategy can be utilized to develop robust and stretchable hydrogel materials for catalytic use in the sewage disposal industry.

Cellulosic protic ionic liquid hydrogel confined Pd nanoparticles for selective hydrogenation of α-angelica lactone and alkenes

A cellulosic protic ILs hydrogel with confining ability to Pd NPs was synthesized through a cyclic anhydride cross-linking reaction in TMG/DMSO/CO2 solvent system, presenting good catalytic activity for the hydrogenation of α-AL and common alkenes.

Facile Preparation of a Photo-Cross-Linked Silk Fibroin-Poly Ionic Liquid Hydrogel with Antifreezing and Ion Conductive Properties.

The silk fibroin (SF)/ionic liquid (IL) based hydrogel is a kind of remarkable substrate for flexible devices because of its subzero-temperature elasticity, electrical conductivity, and water retention, although the procedure of the gelation is considered complex and time-consuming. In this work, we introduced an approximate method for the development of novel photo-cross-linked SF/IL hydrogel, that is, SF-IMA/PIL hydrogel via the modification of silk fibroin chain with 2-isocyanatoethyl methacrylate (SF-IMA) in a certain ionic liquid with an unsaturated double bond. The chemical cross-linking between methacrylated SF and IL was triggered by UV light, while the physical cross-linking of the hydrogel was attributed to the β-sheet formation of SF in SF-IMA/IL mixed solution. In addition to being a UV-induced three-dimensional (3D) printable one, the SF-IMA/PIL hydrogel performed significant ionic conductivity between room temperature and -50 °C and water retention within a wide range of relative humidity, which were the featured advantages as the ionic liquid involved. Moreover, the static and dynamic mechanical tests demonstrated that the hydrogel reserved its great elasticity at -50 °C and displayed its stiffness transition temperatures between -100 and -70 °C.

Tunable Hydrogel Electronics for Diagnosis of Peripheral Neuropathy.

Peripheral neuropathy characterized by rapidly increasing numbers of patients is commonly diagnosed via analyzing electromyography signals obtained from stimulation-recording devices. However, existing commercial electrodes have difficulty in implementing conformal contact with skin and gentle detachment, dramatically impairing stimulation/recording performances. Here, we develop on-skin patches with polyaspartic acid-modified dopamine/ethyl-based ionic liquid hydrogel (PDEH) as stimulation/recording devices to capture electromyography signals for the diagnosis of peripheral neuropathy. Triggered by a one-step electric field treatment, the hydrogel achieves rapid and wide-range regulation of adhesion and substantially strengthened mechanical performances. Moreover, hydrogel patches assembled with a silver-liquid metal (SLM) layer exhibit superior charge injection and low contact impedance, capable of capturing high-fidelity electromyography. We further verify the feasibility of hydrogel devices for accurate diagnoses of peripheral neuropathy in sensory, motor, and mixed nerves. For various body parts, such as fingers, the elderly's loose skin, hairy skin, and children's fragile skin, we regulate the adhesion of PDEH-SLM devices to establish intimate device/skin interfaces or ensure benign removal. Noticeably, hydrogel patches achieve precise diagnoses of nerve injuries in these clinical cases while providing extra advantages of more effective stimulation/recording performances. These patches offer a promising alternative for the diagnosis and rehabilitation of neuropathy in future. This article is protected by copyright. All rights reserved.

Ionic Liquid Hydrogels Based on Poly(2-acrylamido-2-methyl-1-propanesulfonic Acid -co-1-vinylimidazole): A Green and Efficient Catalyst Carrier for Ag Nanoparticles in Oxidation and Adsorption of Benzyl Alcohol in Water

Ionic Liquid Hydrogels Based on Poly(2-acrylamido-2-methyl-1-propanesulfonic Acid -co-1-vinylimidazole): A Green and Efficient Catalyst Carrier for Ag Nanoparticles in Oxidation and Adsorption of Benzyl Alcohol in Water

Next generation strategy for tuning the thermoresponsive properties of micellar and hydrogel drug delivery vehicles using ionic liquids

Thermoresponsive ionic liquid hydrogel delivery vehicles of reduced gelation temperature for injectable and controlled drug delivery applications.

Highly Stretchable, Adhesive Ionic Liquid-Containing Nanocomposite Hydrogel for Self-Powered Multifunctional Strain Sensors with Temperature Tolerance.

The demand for wearable sensors consisting of multifunctional conductive hydrogels with fatigue resistance and adhesion properties is rising. More importantly, it is necessary to improve the freezing tolerance and dehydration resistance of hydrogels to avoid performance degradation in harsh environments. Herein, a robust nanocomposite ionogel was fabricated in [EMIM][Cl] ionic liquid and clay nanosheets were used as physical cross-linkers through rapid UV polymerization. The excellent mechanical properties, repeated self-adhesion to various substrates, freezing tolerance, and anti-drying properties were integrated into the nanocomposite ionic liquid hydrogel. The addition of clay nanosheets Laponite XLG endowed the ionogel with a high stretchability of up to 1200% and a tensile strength of up to 0.14 MPa, and the ionogel could be recovered when the external force was released. Ascribing to ionic liquids, the nanocomposite ionogel displayed ionic conductivity and temperature tolerance. An ionogel battery with a 0.72 V output voltage was formed by assembling the ionogel with a layer of zinc and copper sheet on each side to realize the conversion from chemical energy to electrical energy. The maximum voltage could reach 2.8 V when the four units are combined, which could provide energy for an LED bulb and could be used as a self-powered strain sensor under harsh conditions. In this work, a multifunctional ionogel self-powered sensor is proposed, which has potential applications in the fields of electronic skin, human-machine interaction, and biosensors over a wide temperature range.

Self-healing polymeric ionic liquid hydrogels with high mechanical strength and ionic conductivity

The poor mechanical properties of self-healing hydrogels limited their applications in the fields of biomedicine and industry. Here, a series of self-healing polymeric ionic liquid (PIL) hydrogels with high mechanical strength and electrical conductivity were prepared through hydrophobic association. Hydrophilic monomer vinyl ionic liquids (VILs) based on choline and amino acids, acrylamide (AAm) and hydrophobic monomers stearyl methacrylate (C18) were copolymerized in a micellar solution of sodium dodecyl sulfate (SDS); meanwhile, bacterial cellulose was introduced to enhance the mechanical strength of hydrogels. The resultant hydrogels exhibited excellent mechanical strength (5.8 MPa), extensive elongation at break (4250%) and outstanding self-healing efficiency (85%) without any external intervention. Even after healing, the tensile strength of most hydrogels could reach 2.5–3.9 MPa. At the same time, the incorporation of ILs endowed hydrogels with good electrical conductivity (a maximum of 1.258 S/m). These excellent properties predicted the potential application of the obtained PIL hydrogels in the fields of biomedicine and industry.

BSA adsorption, anthelmintic activity and swelling behavior of poly (N-cyclohexyl acrylamide-co-AMPS IL)hydrogel

In this study, the ionic liquid based hydrogels were synthesized by free radical polymerization. About 0.1 g of dried hydrogel placed in 20 ml of solution containing 4.0 mg/ml of BSA in BR buffer (various pH level) and allowed to equilibrate the swelling at 30 °C. The maximum protein separation 76.1% was achieved at pH 5.0 in room temperature. The hydrogels with various feed compositions possess good antibacterial as well as antifungal activity. The anthelmintic activity of hydrogels suggested that it can be effective against parasitic infections of humans. The DPPH scavenging assay results showed 89.44% of ionic liquid hydrogel as an antioxidant agent.

Mechanical, adhesive and self-healing ionic liquid hydrogels for electrolytes and flexible strain sensors

The prepared ionic liquid hydrogel was employed as flexible sensor and electrolyte with great mechanical, self-healing, adhesive and conductive properties.

Molecularly imprinted photoelectrochemical sensor for carcinoembryonic antigen based on polymerized ionic liquid hydrogel and hollow gold nanoballs/MoSe2 nanosheets

Using carcinoembryonic antigen (CEA) imprinted polymerized ionic liquid hydrogel as a recognition element and hollow gold nanoballs/MoSe2 nanosheets as a photoactive element, a photoelectrochemical (PEC) sensing platform was successfully fabricated. To accomplish the imprinted process under room temperature to maintain the biological activity and the configuration of CEA, and thus to improve the sensing performances, 3-{[{4-N,N-Bis[(carbamoyl)ethylmethacrylate]butyl}((carbamoyl)amino)ethyl methacrylate] -propyl}-1-ethenyl-1H-imidazol-3-ium bromide (BCCPEimBr) ionic liquid was synthesized. By using BCCPEimBr ionic liquid as the functional monomer, CEA as the template, a molecularly imprinted hydrogel film was prepared on a hollow gold nanoballs/MoSe2 nanosheets modified glassy carbon electrode surface. After removing the template, a CEA imprinted photoelectrochemical sensor was successfully fabricated. The imprinted PEC sensor shows good selectivity, sensitivity and stability towards CEA, produces a linear response in the concentration range from 0.05 to 5.0 ng mL−1 and shows a detection limit of 11.2 pg mL−1 (S/N = 3) under the optimized conditions. The imprinted PEC sensor was used to determine CEA in clinical human serum samples accurately. The procedure for the imprinted PEC sensing platform can be used for other biomolecules just by substituting the template.

Protein Crystallization in Ionic-Liquid Hydrogel Composite Membranes

Protein crystallization is a powerful purification tool. It is the first step for crystallographic structural investigations, and can be preparatory for biotechnological applications. However, crystallizing proteins is challenging and methods to control the crystallization process are needed. Ionic-liquid hydrogel composite membranes (IL-HCMs) have been used here as material capable of supporting protein crystallization and hosting grown crystals. We found that IL-HCMs affect the selection mechanism of glucose isomerase (GI) polymorphs and make GI crystals grow completely immersed into the hydrogel layer. X-ray diffraction studies show that IL ions do not bind to the protein, likely because IL molecules are constrained in the polymeric framework. Our GI crystal structures have been compared with many existing GI crystal structures using multivariate analysis tools, allowing a comprehensive overview of factors determining structural similarities, i.e., temperature variations and external stresses exerted during or after crystal growth, such as dehydration or presence of hydrogel of a different nature. GI crystals grown on IL-HCM fit perfectly in this framework, showing typical features induced by external forces. Overall, protein crystallization by IL-HCMs show potential for biotechnological applications, as it could constitute a natural means for containing crystallized enzymes in working conditions.

Ionic Liquid Hydrogel Composite Membranes (IL-HCMs)

In this work, novel hydrogel composites membranes comprising [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide as monomer, N,N-methylene bisacrylamide as cross-linker, and 1-butyl-3-methylimidazolium hexafluorophosphate as ionic liquid additive, have been developed. Ionic liquid hydrogel composite membranes (IL-HCMs) were tested for membrane contactors applications, aiming to reduce surface hydrophobicity of the polypropylene support, to reduce wetting tendency due to interaction with hydrophobic foulants, while affecting salts rejection in desalination operation, because of the entrapment of ILs inside the porous mesh-like structure of the gel layer. Transmembrane flux comparable to the sole polypropylene support was observed for IL content > 1 wt.%. Furthermore, all IL membranes presented a larger rejection to sodium chloride than the PP support or the composites without ionic liquid inside. Although the overall transmembrane flux of IL-HCMs developed in this work is comparable with that of state of the art MD membranes, this study demonstrated that the strong hydrophilic hydrogel layer, with C.A. < 50° for IL content larger than 1 wt.%, serves as a stabilization coating, by providing the new media between the feed and the hydrophobic membrane surface, thus potentially controlling the diffusion of hydrophobic foulant molecules. This would result in a decrease in the membrane wetting and fouling aptitude.

Molecularly Imprinted Photo-electrochemical Sensor for Human Epididymis Protein 4 Based on Polymerized Ionic Liquid Hydrogel and Gold Nanoparticle/ZnCdHgSe Quantum Dots Composite Film.

A novel ionic liquid, 3-{[{4-[((carbamoyl)amino)ethyl methacrylate]butyl} ((carbamoyl)amino)ethyl methacrylate]propyl}-1-ethenyl-1H-imidazol-3-ium bromide (CCPEimBr) functionalized with vinyl, amino, and methacrylate groups, was synthesized and characterized with 1H NMR, FTIR, and HPLC-MS techniques. CCPEimBr was adopted as the functional monomer to prepare a molecularly imprinted polymerized ionic liquid hydrogel film on a glassy carbon electrode surface for human epididymis protein 4 (HE4) sensing. Gold nanoparticles (AuNPs) and ZnCdHgSe QDs were incorporated into the imprinted film as photo-electric active materials. The photocurrent response was measured to investigate the sensing performance of the imprinted sensors toward HE4. The imprinted photo-electrochemical sensor shows excellent selectivity, sensitivity, stability, and accuracy for HE4 determination. Experimental conditions including incubation time and pH value for determining HE4 were optimized in this study. The photocurrent variation (ΔI) decreased with increasing HE4 concentration (cHE4), and it was linearly proportional to cHE4 varied from 25 pg mL-1 to 4.0 ng mL-1. The detection limit of the imprinted sensor for determining HE4 was estimated to be 15.4 pg mL-1 (S/N = 3). The imprinted photo-electrochemical sensor was used to determine HE4 in human serum samples accurately.

Ionic liquid hydrogel templates: Bulkgel, cryogel, and microgel to be used for metal nanoparticle preparation and catalysis

Here, we report the preparation of various crosslinked polymeric matrices from 3-acrylamidopropyl)-trimethylammonium chloride as p(APTMACl) ionic liquid hydrogels in the forms of bulk gel, cryogel, and microgel. Their utilization for in situ metal nanoparticle synthesis of Co and Ni, and then the comparison of catalytic performances of these materials in the reduction of 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), and 4-nitrobenzaldehyde (4-NBA) to the corresponding amine forms of 4-AP, 4-AA, and 4-ABA, respectively, are investigated. As the polymeric hydrogel matrices are inherently positively charged, the metal salts of CoCl2 and NiCl2 were loaded into hydrogel matrices from the corresponding metal salt solution in ethanol. It was found that morphology and sizes of p(APTMACl) ionic liquid hydrogel materials played a great role in catalytic performances for the nitro compounds. The effect of temperature and kinetic parameters of different polymeric matrices for the reduction of 4-NP to 4-AP was investigated. The activation energies for bulk gel, cryogel, and microgel were calculated as 44.74, 34.02, and 40.7kJmol−1, respectively.

Swelling and shrinking properties of thermo-responsive polymeric ionic liquid hydrogels with embedded linear pNIPAAM.

In this study, varying concentrations of linear pNIPAAM have been incorporated for the first time into a thermo-responsive polymeric ionic liquid (PIL) hydrogel, namely tributyl-hexyl phosphonium 3-sulfopropylacrylate (P-SPA), to produce semi-interpenetrating polymer networks. The thermal properties of the resulting hydrogels have been investigated along with their thermo-induced shrinking and reswelling capabilities. The semi-interpenetrating networks (IPN) hydrogels were found to have improved shrinking and reswelling properties compared with their PIL counterpart. At elevated temperatures (50–80 °C), it was found that the semi-IPN with the highest concentration of hydrophobic pNIPAAM exhibited the highest shrinking percentage of ~40% compared to the conventional P-SPA, (27%). This trend was also found to occur for the reswelling measurements, with semi-IPN hydrogels producing the highest reswelling percentage of ~67%, with respect to its contracted state. This was attributed to an increase in water affinity due to the presence of hydrophilic pNIPAAM. Moreover, the presence of linear pNIPAAM in the polymer matrix leads to improved shrinking and reswelling response compared to the equivalent PIL.

Metal‐ion‐containing ionic liquid hydrogels and their application to hydrogen production

AbstractA cationic hydrogel synthesized from (3‐acrylamidopropyl) trimethyl ammonium chloride as poly[(3‐acrylamidopropyl) trimethyl ammonium chloride] [p(APTMACl)] was put into contact with the chloride salts of metals such as CoCl2, NiCl2, and CuCl2 in ethanol. The metal‐loaded p(APTMACl) hydrogels were used as catalyst systems in hydrogen generation from the hydrolysis of sodium borohydride (NaBH4) and ammonia borane. The activation energy values for the hydrolysis reaction were calculated for all of the catalyst systems and were found to be 53.43 and 26.74 kJ/mol for p(APTMACl)–[CoCl4]2− and p(APTMACl)–[NiCl4]2−, respectively. These activation parameters were better than values reported in the literature for the ionic liquid metal complexes of smaller molecules used for the same purpose. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40183.