Organic Gel Research Articles

Self-repairing thermal energy storage gels demonstrating superior thermophysical properties and wearability towards personal thermal management in static and dynamic modes

It is still a big challenge to develop state-of-art thermal energy storage materials based on phase-change materials (PCMs) with superior thermophysical properties and wearability for efficient advanced personal thermal management (PTM). A novel strategy for synthesizing thermal energy storage gel with sandwich structure by confining the inorganic PCM gel in the organic PCM gel was proposed to maximize the advantages of inorganic PCMs, organic PCMs and gel materials. Octadecane and sodium sulfate decahydrate were selected as the organic PCM and inorganic PCM, respectively to satisfy the requirements of the working temperature of PTM. The thermal energy storage gels with sandwich structure demonstrate superior thermophysical properties, such as the absence of supercooling (0 °C), high latent heat (158.65 J g−1), high form-stability (no leakage), high cyclic stability (200 cycles) and high economic benefits (4.85 × 10−3 ¥ J−1). Besides, they also have excellent wearability, such as high flexibility, self-healing feature and high biocompatibility. Due to the synergistic enhancement effect and various merits, the novel thermal energy storage gels are successfully utilized in the wearable PTM for human body thermal comfort. The inorganic–organic combination methodology is promising for the highly efficient applications of PCMs in the next-generation PTM.

Inorganic Subnanometer Nanowire-Based Organogels: Trends, Challenges, and Opportunities.

Organogels exhibit many excellent properties and multiple functions. Conventionally, polymers and low-molecular-mass organic gelators (LMOGs) are used for preparing organogels, showing potential applications. Recently, a subnanometer nanowire (SNW) gelator applicable for various organic liquids emerged, which has potential for semi-solidification, safe storage, and transportation of organic liquids and oil spill recovery. This perspective summarizes and compares these three kinds of organogels. Through this perspective, the challenges and opportunities for SNW-based organogels are made clearer. Regulating functions of gels by controlling the structure and composition of SNWs and developing other subnanometer material gelators may be further research directions.

Aluminum(III)-Based Organic Nanofibrous Gels as an Aggregation-Induced Electrochemiluminescence Emitter Combined with a Rigid Triplex DNA Walker as a Signal Magnifier for Ultrasensitive DNA Assay.

Due to effective tackling of the problems of aggregation-caused quenching of traditional ECL emitters, aggregation-induced electrochemiluminescence (AIECL) has emerged as a research hotspot in aqueous detection and sensing. However, the existing AIECL emitters still encounter the bottlenecks of low ECL efficiency, poor biocompatibility, and high cost. Herein, aluminum(III)-based organic nanofibrous gels (AOGs) are used as a novel AIECL emitter to construct a rapid and ultrasensitive sensing platform for the detection of Flu A virus biomarker DNA (fDNA) with the assistance of a high-speed and hyper-efficient signal magnifier, a rigid triplex DNA walker (T-DNA walker). The proposed AOGs with three-dimensional (3D) nanofiber morphology are assembled in one step within about 15 s by the ligand 2,2':6',2″-terpyridine-4'-carboxylic acid (TPY-COOH) and cheap metal ion Al3+, which demonstrates an efficient ECL response and outstanding biocompatibility. Impressively, on the basis of loop-mediated isothermal amplification-generated hydrogen ions (LAMP-H+), the target-induced pH-responsive rigid T-DNA walker overcomes the limitations of conventional single or duplex DNA walkers in walking trajectory and efficiency due to the entanglement and lodging of leg DNA, exhibiting high stability, controllability, and walking efficiency. Therefore, AOGs with excellent AIECL performance were combined with a CG-C+ T-DNA nanomachine with high walking efficiency and stability, and the proposed "on-off" ECL biosensor displayed a low detection limit down to 23 ag·μL-1 for target fDNA. Also, the strategy provided a useful platform for rapid and sensitive monitoring of biomolecules, considerably broadening its potential applications in luminescent molecular devices, clinical diagnosis, and sensing analysis.

A fluorescent test paper fabricated by in situ growth of a functional Zn-MOG for fast and effective detection of Cr(VI) and Fe(III)

Heavy metals, like iron and chromium(Cr), have been proved to be a serious pollutant to environmental and biological systems. Long-term exposure to Cr(VI) ions through drinking water is harmful to human and will cause some serious diseases. Therefore, exploring new method for selective and rapid detection of such specific pollutants in water is crucial for environmental protection and human health. Herein, a novel functional metal organic gel(MOG) was successfully fabricated. Its detection limit of Cr(VI) was 2.4 × 10−8 mol·L−1 in aqueous solution, and 1.2 × 10−6 mol·L−1 for Fe(III) Based on the excellent deformability of MOG materials, a fluorescent test paper which could realize visible detection of Cr(VI) was fabricated by the in situ growth of Zn-MOGs onto the filter paper. To the best of our knowledge, it is the first sample of Zn-MOGs Based Test Paper (Zn-MOGs-FP) fabricated by in situ growth.

Flexible supercapacitor based on MXene cross-linked organic gel electrolyte with wide working temperature

Recently, hydrogel materials have been widely used in flexible energy storage devices due to their excellent electrical conductivity and nearly solid mechanical properties. But, due to the plenty of water in the traditional hydrogel electrolyte, the disadvantages of high temperature water loss and low temperature icing are inevitable. In order to solve this problem, we have fabricated an organic gel electrolyte (OGE) and assembled it with activated carbon electrode into flexible organic gel electrolyte supercapacitors (OGESCs). In terms of gel design, the MXene crosslinked polyacrylic acid-N-hydroxyethyl acrylamide (PAA-NHEA-MXene) hydrogel network is replaced by a mixture of lithium chloride and ethylene glycol solvent, showing excellent electrical conductivity (3 and 19.8 mS/cm at −20 and 25 °C, respectively) and good mechanical properties. Due to the replacement of the solvent, the operating temperature of OGESCs is extended (-20-80 °C) and meets the needs of flexible wearable devices. In addition, OGESCs exhibit cyclic stability at both low and high temperatures (capacitance decreases by 3.2% after 10,000 cycles), laying a solid foundation for its application in complex and varied environments.

Stabilizing Wide Bandgap Triple‐Halide Perovskite Alloy through Organic Gelators

Engineering the chemical composition of metal‐halide perovskites via halide mixing allows a facile bandgap modulation but renders perovskite materials prone to photoinduced halide segregation. Triple‐halide alloys containing Cl, I, and Br were recently reported as a means to stabilize CsyFA1–yPb(BrxI1–x)3 perovskite under illumination. Herein, these triple‐halide alloys are found to be intrinsically less stable with respect to the reference I‐Br in ambient conditions. By exploiting the influence of low‐molecular‐weight organic gelators on the crystallization of the perovskite material, a triple‐halide alloy with improved moisture tolerance and thermal stability at temperatures as high as 120 °C is demonstrated. The hydroxyl‐terminated organic gelators are found to aggregate into nanoscale fibers and promote the gelation of the solvent inducing the formation of a 3D network, positively interfering with perovskite solidification. The addition of a tiny amount of organic gelators imparts a more compact morphology, higher crystallinity, and compositional stability to the resulting triple‐halide polycrystalline films, making them more robust over time without compromising the photovoltaic performance. Overall, this approach offers a solution toward fabrication of active perovskite materials with higher energy gap and improved stability, making these triple‐halide alloys truly exploitable in solar cells.

Phosphate ions functionalized spinel iron cobaltite derived from metal organic framework gel for high-performance asymmetric supercapacitors

Spinel iron cobaltite (FeCo2O4) with high theoretical capacity is a promising positive electrode material for building high-performance supercapacitors. However, its inherent poor conductivity and deficient electrochemical active sites hinder the improvement of its electrochemical kinetics behavior. Herein, phosphate ions modified FeCo2O4 is obtained in the presence of oxygen vacancies (P-FeCo2O4-x) by a simple metal organic framework gel-derived strategy. Phosphate ions added on the surface of P-FeCo2O4-x greatly enhances its surface activity, thus prompting the faster charge storage kinetics of the electrode material. Due to its ample electrochemical active sites and rapid ion diffusion and electron mobility, the optimized P-FeCo2O4-x electrode delivers a superior specific capacity of 1568.8 F g−1 (784.4 C g−1) at a current density of 1 A/g and has an excellent cycling stability with 93.3 % initial capacity retention ratio after 5000 cycles. More impressively, the assembled asymmetric supercapacitor consisting of P-FeCo2O4-x and activated carbon which act as positive and negative electrode materials, respectively displays a favorable energy density of 60.2 Wh kg−1 at a power density of 800 W kg−1 and has a long cycling lifespan. These results demonstrate the potential importance of modifying the surface of spinel cobaltite with phosphate ions and incorporating oxygen defects in it as a facile strategy for enhancing the electrochemical kinetics of electrode materials.

Platinum group metal-free Fe−N−C catalysts for PEM fuel cells derived from nitrogen and sulfur doped synthetic polymers

• PGM-free Fe−N−C catalysts are produced from N or N/S co-doped porous organic gels. • S-doping alters fundamental properties of carbon materials vs S-free counterparts. • S co-doping induces extensive ultramicroporosity (pores of ∼0.6 nm) • Ultramicropores could enhance ORR via their strong adsorption potential. • S co-doped Fe−N−C catalysts achieve ∼0.15 W cm −2 peak power density in a H 2 –air FC. • Morphology dominates other Fe−N−C characteristics and determines FC performance. Fe−N−C electrocatalysts were obtained via pyrolysis of N- or N/S co-doped synthetic polymers impregnated with FeCl 3 . The influence of the presence/absence of sulfur co-doping, the initial FeCl 3 content and phenanthroline addition on the Fe−N−C–based cathode catalyst layers (CCLs) performance in H 2 -air PEM fuel cells was studied. To this end the Fe−N−C materials were first characterized concerning their chemical composition, surface chemistry, porosity and morphology. Sulfur and phenanthroline additions strongly affect these characteristics of Fe−N−C materials. This in turn determines (to various extents) the electrochemical properties as measured with a rotating ring-disk electrode and upon infusion in the cathode catalyst layer in H 2 -air PEM fuel cells. While simultaneous sulfur and phenanthroline addition yields Fe−N−C catalysts with high N-content and specific surface area, this does not translate into good electrochemical performance. We discuss the multitude of factors determining the catalysts’ and the final CCLs’ performances and conclude that the specific micro-colloidal morphology of the carbon gel-based materials dominates other Fe−N−C characteristics and determines overall FC performance. The best performing CCL provided peak power density of ∼0.15 W⋅cm −2 in a H 2 -air PEMFC.

Novel ferrocene chalcone organic gels for oil spill treatment and recovery

Herein, we developed three novel ferrocene-based chalcone gelators Y1-3. The three gelators were synthesized by introducing long alkyl chains of different lengths into the chalcone structure. The gelation behavior of the gelators in the solvent, especially in the oil phase, was studied, and the synthesized gelators were proved to have good gelation properties in the oil phase. Through the self-assembly behavior of gelators Y1-3 in the oil phase and the study of thermal stability, the effects of different alkyl long chains on the gelation ability of gelators in the oil phase were investigated, indicating that alkyl groups the longer the chain, the more stable the gel formed. The gelation mechanism of gelators Y1-3 was deduced by Gaussian calculation. Finally, the application research on oil identification and oil spill recovery was done on the gelators, and it was found that the gel factors can identify the adulteration of fuel oil and effectively recover the oil spill. This intelligent oil spill recovery material may stimulate more related research in the future.

Antibiofouling Performance of a Metal‐Organic Gel Based on 2‐Amino‐5‐Mercapto‐1,3,4‐Thiadiazole and CuI

AbstractMetal–organic gels or metallogels (MOGs), which usually made up with metal ions and organic ligands, are promising in the area of medicine, environment, and biology. Herein, a new metal–organic gel containing Cu+ (Cu‐MOG‐5) is prepared at room temperature using 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole (AMT) and CuI. Considering the excellent low surface energy characteristics of polydimethylsiloxane (PDMS), the as‐prepared Cu‐MOG‐5 is infused into porous PDMS to obtain Cu‐MOG‐5/PDMS coating, which combines the bactericidal properties of Cu+ containing hydrogels and the low surface energy of PDMS. The morphology of the Cu‐MOG‐5 and Cu‐MOG‐5/PDMS coating is investigated by FE‐SEM, and the structure of the new Cu‐MOG‐5 is verified by FT‐IR, 1H NMR, XPS, EDS, and elemental analysis. The antibiofouling properties are assessed using Escherichia coli (E. coli) and mussel. The results show that the newly prepared Cu‐MOG‐5/PDMS coating exhibits superior antibiofouling performance because of the synchronous action of hydrogel including Cu+ and PDMS.

Synthesis of polyacrolein organic gel and its adsorption properties on acid fuchsin

Synthesis of polyacrolein organic gel and its adsorption properties on acid fuchsin

A Library of Rare Earth Oxide Ultrathin Nanowires with Polymer-Like Behaviors.

Ultrathin nanowires (NWs) have always attracted the attention of researchers due to their unique properties, but their facile synthesis is still a great challenge. Herein we developed a general method for the synthesis of rare earth (RE) oxide ultrathin NWs at atmospheric pressure and low temperature (50 °C). The formation mechanism of ultrathin NWs lies in two aspects: thermodynamic advantage of one dimensional (1D) growth at low temperature, and supplement of effective monomers. As an extension, fifteen kinds of RE oxide ultrathin NWs were synthesized through this strategy, and they all exhibited polymer-like behaviors. Meanwhile, the high viscosity, organic gel, wet- and electro-spinning of Ce-Mo-O NWs were studied in detail, demonstrating the similarity of ultrathin inorganic NWs to polymers. In addition, the Ce-Mo-O ultrathin NWs were used as photocatalysts for toluene oxidation and showed excellent performance with toluene conversion ratio of 83.8 %, suggesting their potential application in organic photocatalysis.

A Library of Rare Earth Oxide Ultrathin Nanowires with Polymer‐Like Behaviors

AbstractUltrathin nanowires (NWs) have always attracted the attention of researchers due to their unique properties, but their facile synthesis is still a great challenge. Herein we developed a general method for the synthesis of rare earth (RE) oxide ultrathin NWs at atmospheric pressure and low temperature (50 °C). The formation mechanism of ultrathin NWs lies in two aspects: thermodynamic advantage of one dimensional (1D) growth at low temperature, and supplement of effective monomers. As an extension, fifteen kinds of RE oxide ultrathin NWs were synthesized through this strategy, and they all exhibited polymer‐like behaviors. Meanwhile, the high viscosity, organic gel, wet‐ and electro‐spinning of Ce‐Mo‐O NWs were studied in detail, demonstrating the similarity of ultrathin inorganic NWs to polymers. In addition, the Ce‐Mo‐O ultrathin NWs were used as photocatalysts for toluene oxidation and showed excellent performance with toluene conversion ratio of 83.8 %, suggesting their potential application in organic photocatalysis.

Dendritic organic molecular gel coating with molecular shape selectivity and its application in selective separation by liquid chromatography.

Dendritic organic molecular gels are a promising class of three-dimensional network compounds. Here, we have synthesized a new type of dendritic organic molecular gel stationary phase (SiO2-G3) by using benzyl alcohol as raw material and dimethyl 5-hydroxyisophthalate as growth unit to synthesize a third-generation organic molecular gel G3, which grafted onto the silica surface by cyanogen chloride (CC). The developed stationary phase not only exhibits high molecular shape selectivity but also has a RPLC/HILIC/IEC mixed-mode characteristic for HPLC due to the ordered structure, the multiple strong π-π stacking interactions and the introduction of a hydrophilic triazine fraction during the grafting process. Compared with a commercial C18 column, the developed column exhibited flexible selectivity, enhanced separation performance and excellent separation of monosubstituted benzene, polycyclic aromatic hydrocarbons (PAHs), positional isomers, nucleosides and nucleobases, benzoic acid and aniline compounds. In addition, the new column provided baseline separation of polycyclic aromatic hydrocarbon contaminants in Yellow River water, verifying its potential for application in the analysis of real samples.

Tuning the Circularly Polarized Luminescence of Supramolecules via Self-Assembly Morphology Control.

Tuning the circularly polarized luminescence (CPL) is a paramount yet challenging issue in the research field of chiral materials. Here, the chiral supramolecules were constructed with a chiral inducer LL-diphenylalanine (LPFF) and a triphenyl-1,3,5-triazine-derived achiral molecule (DMAC-TRZ) to generate differentiated aggregates, giving rise to tunable responses of CPL. Specifically, the well-defined supercrystallines had an exceptional superior CPL emission located at 485 nm with a large luminescence dissymmetry factor (glum) value as high as +0.16, whereas the formed organic gel possessed a relatively strong CPL emission peaked at 495 nm with a glum value of -0.04 in respect to the water fraction about 50%. The distinguished glum value was assigned to the choice of spatial arrangement of the π-chromophores of DMAC-TRZ responding to the volume water fraction in the H2O/DMSO system, resulting in a tunable glum value. This strategy provides an efficient way to regulate CPL signals by modulating the π-stacking way of organic materials responding to external stimuli.

Magnetic porphyrin-based metal organic gel for rapid RhB removal and enhanced antibacterial activity by heterogeneous Photo-Fenton reaction under visible light.

Nanomaterials with visible light-driven catalytic ability are beneficial in controlling environmental pollutants. Porphyrin-based metal organic gel (MOG) was herein synthesized in one step and magnetic metal organic gel (MMOG) was successfully prepared via in-situ reaction of MOG and Fe3O4. This MMOG was developed as a novel visible light assisted Fenton-like catalyst. The catalytic experiments showed the high photo-Fenton activity of MMOG in the degradation of Rhodamine B (RhB) in the presence of visible light and H2O2 with a RhB degradation efficiency of 94.2% within 40min. Notably, the obtained MMOG can kill E. coli and S. aureus with high killing rate (>99.999%) under visible light. Importantly, the MMOG can be recovered simply by an external magnetic field due to the unique magnetic property. This easily synthesized MMOG with photo-Fenton activity under visible light and magnetic property makes MOG based on the photo-Fenton reaction a prospective material for the environmental and biomedical applications.

Self-Healable Poly(vinyl alcohol)─Metal–Organic Hybrid Gel Electrolyte for Flexible Capacitor Sensors

Supramolecular gels based on noncovalent interaction are attractive self-healable polymeric electrolytes due to their repeatable spontaneous recovery of mechanical and electrochemical performance. Herein, we report such a hybrid supramolecular gel electrolyte system composed of a poly(vinyl alcohol) (PVA)–palladium-coordination metal–organic gel (MOG) by controlling ligand conformation transition from cis to trans. The reversible coordination and hydrogen bonding interactions endow the PVA/MOG hybrid gels with 17 consecutive self-healing in 10000S and ultrafast self-healable ability in both mechanical and electrochemical time scales of 180 and 60 s, respectively. The polyaniline (PANI)-based printed interdigital capacitor (IDC) sensor with the hybrid gel electrolyte exhibits a wide voltage window of 0–2.75 V, stable charge–discharge cycle at a high scan rate of 500 mV/s. When printed onto a glove, our sensor can recognize the hand fist and open with good sensitivity. This work provides a promising direction for designing flexible capacitor sensors with self-healable MOGs.

The future of poly(2-oxazoline)s

Poly(2-oxazoline)s have gained significant interest in the past decade, especially driven by their high potential for biomedical applications, amongst others to substitute poly(ethylene glycol). Within this perspective article the emerging trends in the area of poly(2-oxazoline)s are discussed with a focus on synthetic advances, including the development of high molar mass polymers, the broadening of the cyclic imino ether monomer range, and the development of degradable poly(2-oxazoline) derivatives. Furthermore, emerging trends in the use of poly(2-oxazoline)s will be highlighted, including their use to study basic fundamental polymer properties, specific biomedical applications, including drug delivery and 3D scaffolds, as well as other applications as interlayers in organic devices and polymer gel electrolytes. Finally, this perspective article provides a discussion on the future vision for the area of poly(2-oxazoline)s.

Rheological Properties of Organic Kerosene Gel Fuel.

Gel fuel potentially combines the advantages of solid fuel and liquid fuel due to its special rheological properties, which have essential impacts on the application of gel fuel in propulsion systems. In this paper, we study the rheological property of organic kerosene gel through a series of measurements on its viscosity as a function of the shear rate, temperature, and shear history. The measured datasets are then fitted with constitutive relationships between the viscosity and shear rate at three different levels: the power law shear-thinning model, the power law dependency on both the temperature and shear rate, and the thixotropic property. It is found that intense pre-shear could exhaust thixotropy and reduce viscosity of the kerosene gel. For the power law shear-thinning model, the consistency index increases with the gellant mass fraction, whereas the power law exponent remains constant. The dependence of viscosity on temperature could be well approximated by an empirical power law relationship. As for the thixotropic property of the kerosene gel, the fitted second-order kinetic model corresponds accurately to the viscosity at different shear rates and shear times. The constitutive models fitted in this work at different levels are consistent with each other and provide useful tools for further applications of organic kerosene gel fuel.

Carboxylate Group-Based Phase-Selective Organogelators with a pH-Triggered Recyclable Property.

Phase-selective organogelators (PSOGs) have recently attracted more attention because of their advantages in handling oil spills and leaked organic solvents. However, it is difficult to separate and recover the organic phase and PSOGs from organic gels due to the strong interaction between them. Aiming to enhance the separation and recovery performance of the organic phase and PSOGs, we synthesized a series of pH-responsive PSOGs by using itaconic anhydride and fatty amines with carbon chain lengths of C12-C18. Here, PSOGs have an excellent gelation ability in that amounts of organic solvents and fuel oil can be solidified at a low concentration (<3 wt %). It is worth noting that these gels are stronger, which is more convenient for removal by a salvage operation. More importantly, compared with traditional organogelators, pH-responsive PSOGs can easily recover the organic phase and fuel oil with an adjustment of the pH without extraction or distillation. Because of the transformation between the hydrophilicity and hydrophobicity of PSOGs by pH stimulation, 83.15% PSOGs are recovered in three-cycle experiments. In addition, the recycled PSOGs can be used to realize the removal of the organic phase again. Herein, we find that pH-responsive PSOGs could be used as promising and sustainable materials for separating and recovering organic solvents/oils and PSOGs.