Solvent Exchange Research Articles

Bispidine-Based Copper(II) Coordination Polymers with Remarkable Dynamic Properties, Selective Volatile Organic Compounds Adsorption and Exchange Capabilities.

This study presents novel Cu(II)-based bispidine coordination polymers (CPs) with remarkable dynamic properties, volatile organic compounds (VOCs) exchange and selective adsorption capabilities. The coordination requirements of Cu(II) enable, as demonstrated by SC-XRD and P-XRD, the formation of either 1D ribbon-like (1-TCMSC and 1-H2OSC) and 2D (1-MeCNSC) extended frameworks depending on the ability oftrapped solvents to interact as hydrogen bond (HB) donor with the metalcounterion. Hirshfeld Surface analysis and in situ VT SC- and P-XRD experiments reveal different interchain interactions in 1D vs. 2D CPs. Solvent exchange experiments on both single crystals and microcrystalline samples, set up to evaluate differences in the CPsdynamic nature, confirm the drastic effect of CP dimensionality. Additionally, amorphous desolvated phase 1-AmorphPwd was tested for VOC adsorption displaying affinity for acetonitrile and nitromethane, with high selectivity for the latter, but also having the ability to trap aromatic VOCs, capturing up to ca. 2 mmol/g of solvent. The adsorption experiments, conducted at r.t., 1 atm and no prior activation, underscore the potential of these materials for environmental and industrial applications. This work emphasizes the unique dynamic and selective behavior of bispidine-based CPs and provides foundation for their scalability and practical implementation in VOC capture technologies.

Regenerated Cellulose Aerogel Fibers with Lightweight and Exceptional Mechanical Performance for Thermal Insulation.

Recycling cellulose-based waste textiles (CBWT) into high-performance functional materials is a key challenge in sustainable green development strategies. Herein, a combination of water bath wet spinning and gradient solvent exchange methods is employed to develop a regenerated cellulose aerogel fiber (CAF) with excellent mechanical and thermal insulation properties. CAF fibers, with a core-shell structure, exhibited an excellent mechanical property, with a tensile strength of 16.56 ± 1.48MPa, a strain at break of 67.9% ± 10.37%, and toughness of 6.65MJm-3 in the absence of draft process. Furthermore, the CAF fabrics demonstrated outstanding thermal insulation performance (39.31mW/m/K), with a temperature difference of 45°C at 100°C, significantly reducing heat transfer compared to conventional materials, exhibiting a great promise for use in heat-resistant and cold-weather clothing. Most importantly, the process of CBWT dissolution is significantly accelerated by preheating the ionic liquid (IL)/DMSO solution system, which will significantly improve the recycling efficiency and economic benefits of CBWT. This study provides a simple and effective method for fabricating a high-performance regenerated cellulose aerogel fiber, aiming to promote the development of the textile recycling industry and the innovation of sustainable functional materials.

Architecting Three-Dimensional Porous Energy Harvesters with Bamboo-Like Filaments for Enhanced Piezoelectric Performance.

Three-dimensional (3D) poly(vinylidene fluoride) (PVDF)-based piezoelectric energy harvesters (PEHs) offer exceptional electromechanical conversion capabilities due to their flexible structures and customizable designs. However, how to design and construct such structures with enhanced strain for a higher piezoelectric output remains a complex challenge. This study presents a novel approach by combining the versatility of 3D printing with solvent exchange to create a unique 3D porous bamboo-structured PVDF/MXene PEH, allowing for a tailored hollow structure by adjusting the temperature and solvent concentration. This flexible design and construction of the macro- and micro-3D structures enables a synergistic amplification of stress-strain, hence a significant enhancement of the overall electromechanical conversion efficiency of the PEH. Additionally, the incorporation of MXene, with its abundant functional groups, achieves a high β-crystal content (92.6%) in the PVDF-based PEH. This coupling effect contributes to a piezoelectric output of 47 V and maximum sensitivity of 0.727 V/kPa, surpassing most PVDF-based sensors reported to date. Notably, the 3D PEH demonstrates its potential as a self-powered pressure sensor for monitoring human motions across varying amplitudes. This work unveils a universal strategy for harnessing 3D PEHs with high electromechanical conversion efficiency, paving the way for various applications in the fields of smart sensing and energy harvesting.

Detection of Two Different Inner-Sphere Solvent Species in a Eu3+-Based ParaCEST Agent Dissolved in a Mixture of Methanol and Water: The Impact of Solvents on Exchange Dynamics.

Solvent binding and exchange kinetics are of fundamental importance for lanthanide-based MRI contrast agents, and these properties are critically affected by solvents. In the present work, a water and methanol mixture was used to investigate solvent exchange kinetics in a Eu3+-DOTA-tetraamide complex by high-resolution 1H NMR and CEST methods. Two distinct solvated complexes were observed by NMR, one complex capped by a single water molecule and the other by a single methanol molecule. CEST methods were used to measure exchange between all -OH species (free and bound water and methanol) and between exchanging methanol species via methyl proton resonances. The -CH3 CEST experiment offers the simplicity of monitoring exchange between two pools versus conventional -OH CEST, which must be described using a five-pool exchange model. The combined data showed that the two solvated species have similar solvent exchange kinetic constants (kex = 1.7 ± 0.3 × 103 and 1.1 ± 0.2 × 103 s-1 (methanol and water, respectively)). In water/methanol (1:4), solvent exchange became more rapid in both solvated species, 4-fold for (H2O)EuL and 2.6-fold for (MeOH)EuL. This suggests that the solvent shell around the EuL complex in a water/methanol mixture is less organized compared to a more highly organized solvent shell formed in a single solvent.

Starch hydrolysates, their impurities and the role of membrane-based technologies as a promising sustainable purification method at industrial scale.

Starch hydrolysates, their impurities and the role of membrane-based technologies as a promising sustainable purification method at industrial scale.

Supercooling suppression of microencapsulated capric acid-stearic acid eutectic via lignin-zein stabilized Pickering emulsion for highly efficient thermal energy storage.

Supercooling suppression of microencapsulated capric acid-stearic acid eutectic via lignin-zein stabilized Pickering emulsion for highly efficient thermal energy storage.

Diluted Alkaline Pretreatment in Hexafluoroisopropanol Facilitates Chemoenzymatic Depolymerization of Polyethylene Terephthalate.

Diluted Alkaline Pretreatment in Hexafluoroisopropanol Facilitates Chemoenzymatic Depolymerization of Polyethylene Terephthalate.

Anti-freezing, long-term-usability conductive organo-hydrogels containing lignin for the manufacture of high-performance flexible strain and temperature sensors.

Anti-freezing, long-term-usability conductive organo-hydrogels containing lignin for the manufacture of high-performance flexible strain and temperature sensors.

Biopolymer aerogels: Structural and functional tailoring of starch/sodium alginate networks.

Biopolymer aerogels: Structural and functional tailoring of starch/sodium alginate networks.

Efficient and stable copper tungstate catalyst for water treatment with peroxymonosulfate: Effect of synthetic pH, primary oxidant, and practical feasibility.

Efficient and stable copper tungstate catalyst for water treatment with peroxymonosulfate: Effect of synthetic pH, primary oxidant, and practical feasibility.

Degradable Alginate Hydrogel Intervention Catheters with Gradient Hardness in Length.

Interventional catheter, a medical device characterized by a gradient hardness from one end to the other, exhibits enhanced flexibility upon insertion into the human body. This unique configuration accommodates various anatomical structures and surgical requirements. This study reports, for the first time, a degradable hydrogel interventional catheter with gradient hardness. A novel aqueous reaction methodology is developed, enabling the direct transformation of a solid sodium alginate (SA) film strip into a hollow hydrogel interventional catheter. This process involves copper ions-induced asymmetry crosslinking in an aqueous solution, solvent exchange in ethanol, removal of copper ions by ethylenediaminetetraacetic acid, and subsequent bimetallic crosslinking in CaCl2 and FeCl3 aqueous solutions. This method results in gradient-hardness hydrogel interventional catheters without surface defects such as protrusions and pits. The hydrogel interventional catheter demonstrates gradient robustness with mechanical strength reaching 5.5MPa for the soft head and 28MPa for the hard tail. By incorporating a gradual stiffness variation, the hydrogel catheter with superior lubricity and flexibility more effectively adapts to the anatomical structures of the human body, potentially minimizing tissue damage and expediting surgical procedures. Consequently, it shows significant potential as a medical interventional catheter.

Load-Bearing Organogels: Hierarchical Anisotropic Composite Structure for High Mechanical Toughness and Antifatigue-Fracture Capability under Extreme Conditions.

Gels with excellent mechanical properties and antifatigue-fracture capability are attractive materials for load-bearing applications; however, at extreme temperatures, they still suffer from catastrophic failure caused by freezing- or dehydration-induced crack propagation. Here, we present a series of hierarchical anisotropic composite organogels that are strong yet tough and antifatigue-fracture over a wide temperature range (-30 to 60 °C) through the combination strategies of freezing-casting, annealing, and solvent exchange with polyols. Such a hybrid design endows the gels with anisotropic and hierarchical structures and excellent tolerance to extreme temperatures, thus guaranteeing efficient energy dissipation and crack propagation resistance under both ambient and harsh conditions. For instance, the organogel obtained via solvent exchange with glycerol exhibited high strength (22.6 MPa), toughness (198.0 MJ/m3), fatigue threshold (6.92 kJ/m2), and particularly, a superhigh fracture energy (665.7 kJ/m2), which is even higher than anhydrous elastomers, metals, and alloys. Importantly, these values were further boosted at extreme temperatures, such as fatigue thresholds of 8.01 and 9.77 kJ/m2 at -30 and 60 °C, respectively. This work offers an attractive strategy for fabricating gel materials that are reliable for load-bearing applications under extreme conditions.

Progress of Ionogels in Flexible Pressure Sensors: A Mini-Review.

This paper reviews the research progress on ionogels in flexible pressure sensors. Ionogels comprise solid carrier networks and ionic liquids (ILs) dispersed therein and have good non-volatility, high conductivity, thermal stability, a wide electrochemical window, and mechanical properties. These characteristics give ionogels broad application prospects in wearable electronic devices, intelligent robots, and healthcare. The article first introduces the classification of ionogels, including the classification based on ILs and solid carrier networks. Then, the preparation methods and processing technologies of ionogels, such as the direct mixing method, in situ polymerization/gel method, and solvent exchange method, are discussed. Subsequently, the article expounds in detail on the properties and modification methods of ionogels, including toughness, conductivity, hydrophobicity, self-healing, and adhesiveness. Finally, the article focuses on the application of ionogels in flexible pressure sensors and points out the challenges faced in future research. The language of this mini-review is academic but not overly technical, making it accessible to even researchers new to the field and establishing an overall impression of research. We believe this mini-review serves as a solid introductory resource for a niche topic, with large and clear references for further research.

Lignin micro/nanoparticles from alternative biomass sources for neutral-pH Pickering emulsions and quercetin encapsulation.

Lignin micro/nanoparticles from alternative biomass sources for neutral-pH Pickering emulsions and quercetin encapsulation.

Manipulation of Solvent Donor Effects to Overcome the Calcium Schlenk Equilibrium.

Synthetic access toward well-defined, monomeric s-block metal complexes is mired with chemical challenges, primarily attributed to the formation of homoleptic complexes promoted by the Schlenk equilibrium. Ligand redistribution is significantly pronounced for the heavier s-block metals, such as calcium, which form bischelate complexes readily through traditional synthetic routes such as transmetalation, amination, and ligand exchange. Mechanistic investigation of each of these routes with phenoxyimine (ONN) ligands was explored to ascertain the fundamental parameters promote bischelate formation. Donor effects from coordinated solvent proved to be deleterious, and in an effort to circumvent bischelation, a new calcium bisamide, {Ca[N(SiMe3)2]2(diox)2}∞, was synthesized and characterized as a coordination polymer with a unique square planar geometry, rarely seen for group 2 complexes. Amination with {Ca[N(SiMe3)2]2(diox)2}∞ was found to significantly shift the Schlenk equilibrium to favor heteroleptic species, allowing for the characterization of new phenoxyimine calcium-amido complexes: [ONN1Ca-N(SiMe3)2]2(diox) and [ONN3Ca-N(SiMe3)2(diox)]∞. Subsequent studies showed that solvent exchange from the isolated dioxane complexes with THF notably shortened the stability of the complex in solution. Although steric parameters have previously been regarded as the key to the stabilization of heteroleptic calcium complexes, it is equally important to consider the donor ability of coordinated solvent ligands to achieve longer-lived heavy s-block complexes.

Fabrication of Elastic Color-Changing Films-Elastomer Films Incorporating Mechanochromic Fluorenylidene-Acridane.

A pressure-sensitive elastomer film incorporating fluorenylidene-acridane (FA) in its folded conformation was successfully developed for use in pressure-sensitive applications. The elastomer network was swollen with acetone, creating space to accommodate FA molecules. Although FA dissolved in acetone and adopted a twisted conformer, a solvent exchange process with methanol facilitated the reprecipitation of FA in its yellow folded conformation within the elastomer matrix. Confocal and scanning electron microscopy confirmed the incorporation of FA in its folded form within the matrix, while film stretching testing and water resistance analyses highlighted the film's durability. The film exhibited a reversible color change upon mechanical pressure, reverting back to yellow when treated with methanol. This approach presents a promising method for the integration of FA into elastomer films, with potential applications in flexible mechanical sensors and other responsive materials.

Topological Design of Pyrene‐Based Metal‐Organic Framework Nanosheets as a Luminescent Thermometer for Live Bioimaging

AbstractMetal−organic frameworks (MOFs) represent an attractive family of materials for diverse biomedical applications due to their porosity, chemical versatility, and stimuli‐responsive properties. Next to their drug delivery and bioimaging applications, MOFs have been recently considered as efficient luminescent thermal probes. However, the relatively low thermal sensitivity together with the biocompatibility of most MOF thermometers limits their practical applications. Here, a series of new MOFs based on Zn ions and a rectangular tetratopic ligand H4TBAPy (1,3,6,8‐tetrakis(p‐benzoic acid)pyrene) is reported, demonstrating a temperature‐dependent photoluminescence (PL) with up to 2.12% K−1 relative thermal sensitivities over the 7 – 300 K temperature range. Using a topological design approach, the structure of the obtained MOFs is tuned from two‐ to three‐dimensions via solvent exchange in order to build the optimal structure of the PL thermometer. Then, the resulting MOFs have been exfoliated to obtain MOF nanosheets (NSs) to be easily injected into living organisms. As a result, MOF NSs, intracardiac injected or introduced into the digestive system of the Casper fish, reveal a 100% survival rate together with an efficient in vivo PL thermometry of organs, thereby, paving the way to a rational design of highly sensitive and biocompatible MOF‐based thermometers.

A bio-based alginate hydrogel with considerable thermoelectric performance, mechanical strength and flame retardancy for ultra-fast and sustained early fire-alarm system.

A bio-based alginate hydrogel with considerable thermoelectric performance, mechanical strength and flame retardancy for ultra-fast and sustained early fire-alarm system.

Ambient drying fabrication of mechanically robust, flame-retardant, thermal-insulating cellulose/aramid nanofiber composite foam via freeze-casting combined ion cross-linking.

Ambient drying fabrication of mechanically robust, flame-retardant, thermal-insulating cellulose/aramid nanofiber composite foam via freeze-casting combined ion cross-linking.

Understanding drug release mechanisms of risperidone in situ forming implant depots in rabbits.

Understanding drug release mechanisms of risperidone in situ forming implant depots in rabbits.