Amount Of Solvent Research Articles

An integrated life cycle assessment and techno-economic analysis: Evaluation on the production of polymers of intrinsic microporosity (PIM-1) and UiO-66-NH2 as membrane materials

Material synthesis requires an enormous amount of organic solvents which leads to huge environmental burdens. Being so, the necessity to utilize non-toxic chemicals is of growing interest in the global market. Harnessing a green fabrication strategy could be a sustainable remedy. Herein, life cycle assessment (LCA) and techno-economic assessment (TEA) using a cradle-to-gate approach to select the green synthesis route for the production of main components in mixed matrix membranes such as polymer and fillers were studied. Five representative synthesis routes of polymers of intrinsic microporosity (PIM-1) and fillers such as UiO-66-NH2 (UiO: University of Oslo) were conducted. Our findings revealed that the tetrachloroterephthalonitrile (TCTPN) synthesized PIM-1 using a novel approach (e.g., P5-Novel synthesis) and solvent-free synthesized UiO-66-NH2 (e.g., U5-Solvent-free) demonstrated the least environmental impact and are most economically feasible. The environmental burden and cost of PIM-1 synthesized by P5-Novel synthesis route decreased by 50 % and 15 %, respectively, while that of UiO-66-NH2 produced via U5-Solvent-free route reduced by 89 % and 52 %, respectively. Additionally, solvent reduction was found to have an apparent effect on cost-saving, whereby the production cost declined 13 % with a 30 % solvent reduction. Alleviation of environmental burdens could also be found through recovering solvents or substituting with a greener alternative (e.g., water). The fundamentals gained on the environmental impacts and economic feasibility of PIM-1 and UiO-66-NH2 production from this LCA-TEA study may provide a preliminary evaluation for the development of green and sustainable materials.

Progress in preparation of hollow nanomaterials and their application to sample pretreatment

Sample pretreatment technology plays a vital role in the analysis of complex samples and is key to the entire analytical process. Its main purpose is to separate the substance to be measured from the sample matrix or interfering substances in the sample and to achieve a state in which the instrument can be analyzed and detected. Traditional sample pretreatment techniques include liquid-liquid extraction, liquid-solid extraction, precipitation separation, solvent volatilization-rotary evaporation, filtration, and centrifugation. However, the applications of these methods are limited by their low extraction efficiency, complicated operation, long time consumption, unstable recovery, use of large amounts of organic solvents, and large error rates. Several new sample pretreatment techniques, including solid-phase extraction, magnetic solid-phase extraction, solid-phase microextraction, and dispersive solid-phase extraction, have been developed and rapidly applied to various fields to overcome the shortcomings of traditional sample pretreatment methods. However, the development of adsorbent materials with high selectivity and enrichment capability remains a challenge in sample pretreatment technology, in which adsorbents with excellent adsorption performance are crucial. In recent years, various nanomaterials with remarkable properties have been introduced and applied to sample pretreatment, and numerous nano-extraction materials with diverse functions and high selectivity and enrichment capability have been developed. Hollow nanomaterials are nanoparticles with large voids in their solid shells. Owing to their advantageous properties, which include a large effective surface area, abundant internal space, low density, variety of preparation methods, structural and functional tailorability, short mass transmission path, and high carrying capacity, hollow nanomaterials show great application potential in sample pretreatment. The extraction mechanism of these materials is based on the synergistic effects of π-π stacking, electrostatic, hydrogen-bonding, and hydrophobic interactions to achieve the efficient separation and enrichment of the target analytes. Given their noteworthy physicochemical properties, hollow nanomaterials have gained wide attention in various research fields and are considered a research frontier in the field of materials science. Changing the structure or surface properties of the core and shell can lead to various hollow nanomaterials with unique properties. Such changes can create synergy between the physicochemical properties and structural function of the original core-shell material, leading to novel materials with superior performance compared with the starting materials and broad application prospects in sample pretreatment. Nevertheless, only a few hollow nanomaterials with diverse structures and functions are currently used for sample pretreatment, and their adsorption capacity for target analytes is often unsatisfactory. Consequently, enhancing the adsorption selectivity of these materials toward various analytes is the most important step in sample pretreatment. First, hollow nanomaterials with a large specific surface area and suitable pore size can be designed to achieve the specific adsorption of target analytes of varying sizes. The combination of hollow nanomaterials with other materials presenting desirable adsorption properties could also lead to synergistic effects and enhance the performance of composite hollow nanomaterials. In addition, more green methods to prepare hollow nanomaterials with outstanding selectivity can be explored to achieve the superior adsorption of a specific target analyte. Efforts to synthesize hollow nanomaterials have been met with great success, but the available synthesis methods still suffer from complicated steps, high costs, relatively harsh conditions, and the use of highly toxic substances. This paper summarizes the main types of hollow nanomaterials, their synthesis methods, and research progress on sample pretreatment technologies (solid-phase extraction, solid-phase microextraction, magnetic solid-phase extraction, and dispersive solid-phase extraction) and describes the challenges encountered in the synthesis of hollow nanomaterials. The applications and developments of hollow nanomaterials in sample pretreatment are also discussed.

Multigram-Scale Synthesis of Luminescent Cesium Lead Halide Perovskite Nanobricks for Plastic Scintillators.

Cesium lead halide perovskite nanocrystals of general formula CsPbX3 are having tremendous impact on a vast array of technologies requiring strong and tunable luminescence across the visible range and solutions processing. The development of plastic scintillators is just one of the many relevant applications. The syntheses are relatively simple but generally unsuitable to produce a large amount of material of reproducible quality required when moving from proof-of-concept scale to industrial applications. Wastes, particularly large amounts of lead-contaminated toxic and flammable organic solvents, are also an open issue. We describe a simple and reproducible procedure enabling the synthesis of luminescent CsPbX3 nanobricks of constant quality on a scale going from 0.12 to 8 g in a single batch. We also show complete recycling of the reaction wastes, leading to dramatically improved efficiency and sustainability.

Nanocrystalline Flash Annealed Nickel Oxide for Large Area Perovskite Solar Cells.

The industrialization of perovskite solar cells requires adequate materials and processes to make them economically viable and environmentally sustainable. Despite promising results in terms of power conversion efficiency and operational stability, several hole-transport layers currently in use still need to prove their industrial feasibility. This work demonstrates the use of nanocrystalline nickel oxide produced through flash infrared annealing (FIRA), considerably reducing the materials cost, production time, energy, and the amount of solvents required for the hole transport layer. X-ray photoelectron spectroscopy reveals a better conversion to nickel oxide and a higher oxygen-to-nickel ratio for the FIRA films as compared to control annealing methods, resulting in higher device efficiency and operational stability. Planar inverted solar cells produced with triple cation perovskite absorber result in 16.7% power conversion efficiency for 1 cm2 devices, and 15.9% averaged over an area of 17 cm2 .

Mesoscale Simulations of Structure Formation in Polyacrylonitrile Nascent Fibers Induced by Binary Solvent Mixture.

Polyacrylonitrile (PAN) is widely used as a raw material for the production of high-modulus carbon fibers, the internal structure of which is directly affected by the spinning of the precursor. Although PAN fibers have been studied for a long time, the formation of their internal structure has not been sufficiently investigated theoretically. This is due to the large number of stages in the process and the parameters controlling them. In this study, we present a mesoscale model describing the evolution of nascent PAN fibers during the coagulation. It is constructed within the framework of a mesoscale dynamic density functional theory. We use the model to study the influence of a combined solvent of dimethyl sulfoxide (DMSO, a good solvent) and water (a non-solvent) on the microstructure of the fibers. A porous structure of PAN is formed as a result of the microphase separation of the polymer and the residual combined solvent at a high water content in the system. The model shows that one of the possible ways to obtain the homogeneous fiber structure is to slow down the coagulation by increasing the amount of good solvent in the system. This result is in agreement with the existing experimental data and confirms the efficiency of the presented model.

Pressurized Liquid Extraction for the Recovery of Carotenoids and Functional Compounds from Green and Orange Dunaliella salina Biomasses

In recent years, intensive research has been conducted on natural carotenoids extraction using several processes. Conventional extraction methods require high amounts of solvents and a long extraction time. However, pressurized liquid extraction demonstrated to be an interesting method. The extraction efficiencies of pressurized liquid for the recovery of carotenoids, from the green and the orange biomasses of the microalga Dunaliella salina DunaDZ1, are described. Organic solvents were tested including ethanol, n-hexane, ethyl acetate and a mixture of n-hexane:ethanol (3:4). Moreover, three extraction temperatures were used (90, 120 and 150 °C) at constant pressure. Extraction efficiency and extracts characterization were conducted. Results have shown that temperature has a positive effect on extraction yield. HPLC characterization showed that β-carotene is the main carotenoid in the orange biomass, and lutein in the green biomass, with the presence of other minor carotenoids in both biomasses. The highest carotenoid amounts were found in the n-hexane orange biomass extract, with β-carotene isomers as the main carotenoid (138.54 and 357.10 mg/g of dry extract, for cis and trans isomers, respectively). Otherwise, extracts obtained at the lowest tested temperature provided the best carotenoid yields. The best results for the antioxidant activity were obtained at 120 °C for orange biomass ethyl acetate extract.

Water Separation Performance in Bitumen Recovery from Athabasca Oil Sands: Implementation of Separation Efficiency Index

The oil (diluted bitumen)–water separation efficiency at steam-assisted gravity drainage (SAGD) process conditions has been evaluated in a laboratory environment by using a custom-built batch gravity setup, using SAGD field fluids and commercial gas condensate as a diluent. The key parameters and conditions investigated are solvent amount, shear conditions, water-to-oil ratio, and the presence and wettability of fine solids. The results demonstrate the complexity of the oil–water separation process, affected by the dependence of the investigated parameters from one another. A new quantification approach is introduced to facilitate the oil–water separation efficiency evaluation, based on the proposed descriptor, referred to as a separation efficiency index (SEI). Defined as the average of the residual water-in-oil and oil-in-water indices, SEI ranges from 0 to 1, where 1 represents a “perfect” (complete) separation and 0 corresponds to a complete emulsification. The SEI allows one to describe the separation efficiency throughout the entire separation vessel volume, using discrete vertical water distribution profiles, and represents the separation efficiency with a single number, regardless of the experimental approach taken. The findings show that in the range of solvent concentrations of 30 vol % or lower, the mixing speed affects the separation performance and becomes predominant at the relatively low solvent concentrations of 10 and 20 vol %. The amount of solvent added becomes predominant in the oil–water separation process and overcomes all other effects in the highest solvent addition (40 and 50 vol %) range. The presence of water-wet solids improves the separation performance, while the presence of oil-wet solids impedes the oil–water separation. The results presented in this study, in particular the proposed SEI, are important for improving the oil–water separation efficiency and can be used to develop operational envelopes and new solvent injection strategies, in terms of location, amount, and stages, further improving the quality of the oil product obtained in SAGD.

High-enthalpy biphasic phase change organogels with shape memory function based on hydrophobic association and H-bonding interaction

Low-temperature solid–liquid organic phase change materials (OPCMs) offer tremendous opportunities in thermal management techniques but suffer from leakage problems above the melting temperature. Here, inspired with the universal hydro/organogels using three-dimensional polymer networks capable of holding large amounts of liquid solvents, a kind of form-stable high-enthalpy biphasic phase change organogels (BPCOGs) were developed by the integration of hydrophobic association for synthesizing intrinsic phase change matrices and H-bonding interaction for binding OPCM liquids. The porous phase separated poly(acrylamide-octadecyl acrylate) (P(AM-co-OA)) matrices with uniformly dispersed thermal conductive carbon nanotubes were fabricated from the hydrophobically associating hydrogels (HAHs), in which POA segments provide the phase change energy storage microdomains and the PAM network is capable of binding a series of melted OPCMs by hydrogen bond engineering. The fabricated BPCOGs possess form-stability, high phase change enthalpy (high up to 215.5 J g−1) and high energy storage efficiency (>90%), and show excellent electrical/optical-thermal energy conversion as well as shape memory performances. This study provides a universal strategy to prepare flexible biphasic OPCMs suitable for a variety of solid–liquid OPCMs including fatty alcohols, fatty acids and polyethylene glycol, and demonstrates the great potentials of these BPCOGs in solar energy utilization and functional flexible devices.

The Effect of NCO Content in Polyurethane Foam for Automotive Instrument Panel

A thermoplastic polyurethane (TPU) series for automotive panels with high durability have been newly synthesized using the reacting process based on polyester polyol (BTG), polycaprolactone triol (PCL), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and 1,4-butanediol chain extender as a function of NCO/OH ratio (NCO index). The dependence of varying NCO index of synthesized TPUs on tensile strength and hardness have evaluated. To form PU foams with suitable rigidity and uniform skin-pores, the optimal synthetic process was controlled precisely by the amount of solvent, foaming agent, silicone surfactant, and catalysts content. A considerable NCO index dependence was observed in the range of 0.96 ≤ NCO index ≤ 0.99 at almost same molecular weight. When NCO index of TPU was 0.98, mechanical properties achieved maximum value due to the uniform open cell structure of molding PU foam. With the ratio of NCO/OH increasing, the hardness of PU foam also increased until 0.98 NCO index while the hardness of 0.99 NCO index decreased. The designed TPU with 0.98 NCO could be a promising formulation for molding foams of automotive skin panels and seating.

Enhanced stability, formulations, and rheological properties of nanoemulsions produced with microfludization for eco-friendly process

HypothesisEco-friendly processes that are emerging around the world require mass production of low-energy, low-cost nanoemulsions. The process involving the high-concentrated nanoemulsions and diluting them with a large amount of solvent can certainly save the cost; however, not much detailed research has been conducted on the stability mechanism and rheological characteristics of high-concentrated nanoemulsions. ExperimentsIn this study, we produced nanoemulsions via the microfluidization (MF) process, comparing their dispersion stability and rheological characteristics with macroemulsions across various oil and surfactant concentrations. Droplet mobility and dispersion stability depended on these concentrations, with Asakura-Osawa-type attractive depletion considering interparticle interaction's role in stability changes. We investigated nanoemulsions' long-term stability based on turbidity and droplet size changes over four weeks, proposing a stability diagram showing four different states depending on emulsification conditions. FindingsWe explored the microstructure of emulsions under varying mixing conditions, observing their effects on droplet mobility and rheological properties. We monitored changes in rheology, turbidity, and droplet size over 4 weeks, establishing stability diagrams for macro- and nanoemulsions. The stability diagrams revealed that the stability of emulsions are sensitively dependent on the droplet size, concentrations, surfactant cocentrations and the strcture of coexistent phases in case of macroscopic segregation are significantly different depending on the droplet sizes. We identified their respective stability mechanisms and discovered the relationship between stability and rheological properties for highly concentrated nanoemulsion.

Pervaporation dehydration of ethylene glycol/water mixture via hydrophilic polymer of intrinsic microporosity (PIM) derivatives

The chemical process for manufacturing raw materials requires a substantial amount of organic solvent, and it is important to recover the solvent overused during the reaction. This work uses membrane pervaporation to recover ethylene glycol by dehydrating water from a mixture of ethylene glycol (EG) and water. As a feasible membrane material suitable for the dehydration of lean-EG/water (with a water content of 70–95 wt%), we suggest two hydrophilic derivatives from the polymer of intrinsic microporosity (PIM-1). Two PIM-derivatives, amidoxime-functionalized PIM (AO-PIM) and 2,4-diamino-1,3,5-triazine-functionalized PIM (DAT-PIM), were effectively produced through hydrophilic functional group modification and retained their intrinsic microporosity based on a rigid and highly twisted polymer backbone. The PIM-derivatives showed increased water sorption capacity, resulting in tenfold greater water permeability of both PIM-derivative membranes than pure PIM-1. In addition, the modified membranes retained a water content of 99.9% in the permeate. This study demonstrated a simple method for modifying suitable dehydration materials while maintaining the original polymer's structural quality.

Cichoric acid aerosol for inhalation therapy in respiratory syncytial virus

Cichoric acid (CA) is a caffeic acid derivative, which has significant anti respiratory syncytial virus (RSV) effect and low toxicity. However, due to the low oral bioavailability and poor intestinal absorption of CA, it is not suitable to be made into oral preparations. In this study, CA was made into metered dose inhaler (MDI), allowing the drug to target the site of action, thus achieving more effective treatment. Through preliminary experiments, the drug content and prescription composition of the preparation were determined. Clarity and stability of solution were used as indexes to screen the composition of latent solvent. Single factor and orthogonal test were used to optimize the amount of latent solvent in CA-MDI, and the optimal prescription was verified. The aerosol prepared according to the optimal formula was characterized and preliminary stability was studied. The final formula of CA-MDI was: CA 15 mg, absolute ethanol 1 g, propylene glycol 0.4 g and 1,1,1,2-tetrafluoroethane 10 g. CA-MDI was prepared with the best prescription, with the specification of 150 actuation per bottle and 75 μg per actuation. After quality inspection, three batches of inhaled aerosols showed that the main drug content per bottle was 77.91 ± 1.63 μg (n = 3), and the total number of bottles was 185 ± 3 (n = 3), all of which met the standards of China Pharmacopoeia and the proposed specifications. The preliminary stability study showed that the quality of inhaled aerosols in CA was stable and reliable.

Selective aqueous-phase hydrogenation of furfural to cyclopentanol over Ni-based CNT catalysts

Cyclopentanol (CPL) was an eco-friendly solvent as well as important platform chemical which could be generated from biomass-derived furfural (FFA). In this paper, A series of Ni, Cu, Mo, Co bimetallic catalysts with different metals loadings supported on Carbon nanotubes (CNT) were synthesized by an impregnation method for aqueous-phase hydrogenation of FFA to obtain CPL. Various effects of reaction parameters such as, reaction solvent, reaction temperature, reaction time, and different loading amount of Ni over bimetallic Ni-based CNT catalysts were fully investigated. Among the catalysts studied, (15 + 5) wt% NiCu/CNT catalysts showed high conversion of FFA and 88% selectivity towards CPL in water and 96% selectivity towards acetal in methanol at mild condition of 160℃, 2 MPa hydrogen and 4 h reaction time. NiCu bimetallic synergistic effect was interpreted through H2-TPR and NH3-TPD measurement and a possible pathway was proposed. The features of the CNT supported catalysts were investigated via XRD, XPS, TEM, H2-TPR and NH3-TPD. The Ni and bimetallic NiCu catalysts synthesized in this work were inexpensive and simple, which made them a promising candidate for the conversion of biomass-derived FFA to CPL.

Evaluation of solvent releases from microfluidic devices made of cycloolefin polymer by temperature-desorption mass spectrometry

Microfluidic devices have been used in various biological experiments. The working temperature of the devices spans a wide range (approximately 23 °C–95 °C). Among thermoplastic materials, cyclo olefin polymers (COPs) are promising materials for microfluidic devices. This is because COP can overcome the well-known disadvantages of polydimethylsiloxane, a commonly used material, and have the advantage of better observability than polystyrene and polymethyl methacrylate. However, most COP-based devices are fabricated using solvents and adhesives during the bonding process. These solvents, which are known to affect biological experiments, may remain in the device and be released during the experiments. It is necessary to investigate whether solvents are actually released and, if so, how they are released. Here we introduce thermal desorption spectroscopy as a simple and quantitative method to observe solvent release from solvent-bonded and vacuum ultraviolet (VUV)-bonded products. Solvents are released from the solvent-bonded product at 31.5 °C, suggesting that it may have negative effects on various biological experiments. On the other hand, the VUV-bonded product releases solvents (cyclohexane and toluene), which are used during olefin polymerization in the synthesis process of COP, at temperatures above 84 °C. Therefore, the experiments conduct below 84 °C (e.g. in situ hybridization, reverse transcription (RT) and loop-mediated isothermal amplification) were not affected. In addition, the amount of solvent released above 84 °C is small (1/548–1/913 of the solvent-bound product), so it is expected that the extent of the effect on experiments conducted above 84 °C (RT and polymerase chain reaction) is small, if there is any. We conclude that solvent-bound devices can have undesirable effects in many biological applications, not just cell culture. We believe that evaluating solvent release from devices is important for the development of new devices in the future.

Sustainable Solvent-Free Selective Oxidation of Benzyl Alcohol Using Ru(0) Supported on Alumina

The selective oxidation of primary alcohols into their corresponding carbonyl compounds is challenging because of the easy over oxidization to acids and esters. The traditional reaction requires large amounts of solvent and oxidant, causing serious environmental issues. Recently, several efforts have been made to transform the reaction into a more sustainable process. Here, we investigated the solvent-free oxidation of benzyl alcohol using air as a green oxidant in the presence of ruthenium supported on alumina and zirconia, thereby meeting atom economy and environmental requirements. The materials were extensively characterized and, in addition to their activity, selectivity, and reusability, the environmental sustainability of the process was assessed according to green chemistry metrics. XRD, TEM, and XPS analyses suggest that the formation of metallic Ru on the support plays a key role in the catalytic activity. Ru supported on alumina, after a reduction treatment, achieves good activity (62% conversion) and a complete selectivity in a very sustainable process (without a solvent and with air as oxidant), as indicated by the very low E-factor value. The formulation is very stable and maintains high activity after recycling.

First-Principles Simulations of Salt-Concentrated Electrolytes for Li-Based Batteries: How Solvents Tune Solvation Structures and Li-Ion Conductivity

Salt-concentrated nonaqueous electrolytes, due to their special properties in increasing the stability of batteries by the formation of anion-derived solid electrolyte interphases (SEIs), have attracted considerable attention in recent years. Despite extensive efforts to explore the microscopic solvation structures of electrolyte solutions, a clear relationship between the microstructures and electrolyte performance, especially the Li-ion conductivity, is still in demand. In this work, we performed ab initio molecular dynamics (AIMD) simulations as well as density function theory (DFT) calculations for three as-designed electrolytes, namely lithium bis(fluorosulfonyl)imide (LiFSI) with acetonitrile (AN), 1,2-dimethoxyethane (DME), and 2,2-dimethyl-3,6,9-trioxa-2-siladecane (siloxane). We observed that for the above electrolytes at high concentrations, Li-ion conduction proceeds when the solvation structure changes from one form to another in a few tens of fs, involving the binding/debinding of both the solvent and FSI anion with the Li-center. The dynamics of binding between the solvents and Li decrease with the increase in the strength of the solvation sheath, which is influenced by the polarity of the solvent. The steric shielding effect was clearly detected in the siloxane-LiFSI system which became almost nonconductive at a concentration of 3 mol L–1. It should be noted that despite the high concentration of each electrolyte (≥5 mol L–1), there is still a certain amount of free solvents according to the simulation results. Our results deepen the understanding of the Li-ion conduction process in salt-concentrated electrolytes and provide guidelines for designing high-performance electrolytes.

Recent Developments in Green Chromatography

In recent decades, green analytical chemistry has received more attention due to the growing concern over environmental conservation and the use of non-renewable resources. Among the analytical techniques, liquid chromatography is the most widely used in quality control analysis of food, drugs, and clinical analysis among others, but it is also the technique that uses the largest amount of hazardous organic solvents and generates large volumes of waste. Therefore, strategies such as the miniaturization of chromatographic systems, the use of online sample preparation systems, and the replacement of hazardous organic solvents by green solvents have been applied to develop greener chromatographic methods. In this paper, strategies for greening methods and recent developments in green chromatography are presented. In addition, metrics for the proper evaluation of these methods are discussed.

Effect of processing temperature on nanolignin quality during ultrafine friction grinding

Nanoparticles are a new frontier to valorize underutilized and abundant lignin generated by biorefineries. Typical chemical processes to synthesize lignin micro- and nano-particles (LMNPs) use large quantity of organic solvents and therefore, could adversely impact the environment. Hence, we have employed an eco-friendly mechanical approach, i.e., ultrafine friction grinding (UFG), to produce “green” LMNPs with controlled size and micromorphology. Specifically, we investigated the effect of processing temperature, at 0, 25 and 70 °C, on lignin nanosizing. Our results showed that low temperature (0 °C) significantly favored the size reduction of lignin where we achieved a median particle size of ∼100 nm after 12 grinding passes. At 70 °C, LMNPs reached a size equilibrium of ∼160 nm within four passes but did not decrease in size upon subsequent grinding. Moreover, analysis of the LMNPs by SEM showed that samples produced at 0 °C mostly had irregular flat shapes with sharp angles, such as stars and polyhedrons, with a glabrous surface, whereas, samples produced at 25 and 70 °C featured spheres and rods with nanoscopic pores on the surface. Physico-chemical properties of LMNPs, such as molecular weight and thermal degradation, did not change significantly compared to the original lignin, however, samples generated at 0 °C exhibited significantly fewer inter-unit linkages than those generated at 70 °C. Our study thus shows that varying the grinding temperature facilitates the customization of LMNP micromorphology. Furthermore, the proposed method for LMNP manufacturing is simple and eco-friendly, and presents a viable approach for lignin valorization.

Tough PEGgels by In Situ Phase Separation for 4D Printing

AbstractPolymer gels, consisting of cross‐linked polymer network systems swollen by a solvent, show great potential in biomedicine, flexible electronics, and artificial muscles, due to their tissue‐like mechanical properties. Due to the presence of a large amount of solvent, the improvement of the mechanical properties of the polymer gel is a challenge. Moreover, combining high toughness with useful properties, such as 3D printability or shape‐memory, in one polymer gel system is even more challenging. In this study, a simple and efficient method is developed for the fabrication of tough polymer gels by polymerizing 2‐hydroxyethyl methacrylate (HEMA) in a mixture of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). The polymerized elastic networkpresents distinct compatibility with PEG (compatible) and PPG (poorly compatible), resulting in in‐situ phase separation at the microscale. The resulting phase‐separated gel demonstrates high strength (8.0 MPa), favorable fracture strain (430%), and large toughness (17.0 MJ m−3). The separated hard phasewith a high glass transition temperature (75 °C) endows the whole soft polymer gel with the property of shape memory at room temperature. Finally, the fabrication of tunable tough PEGgels is combined with 3D printing as well as with shape memory properties, demonstrating the use of PEGgels for 4D printing.

Free-Standing Metal–Organic Framework Membranes Made by Solvent-Free Space-Confined Conversion for Efficient H2/CO2 Separation

Metal-organic frameworks (MOFs) are promising candidates for the advanced membrane materials based on their diverse structures, modifiable pore environment, precise pore sizes, etc. Nevertheless, the use of supports and large amounts of solvents in traditional solvothermal synthesis of MOF membranes is considered inefficient, costly, and environmentally problematic, coupled with challenges in their scalable manufacturing. In this work, we report a solvent-free space-confined conversion (SFSC) approach for the fabrication of a series of free-standing MOF (ZIF-8, Zn(EtIm)2, and Zn2(BIm)4) membranes. This approach excludes the employment of solvents and supports that require tedious pretreatment and, thus, makes the process more environment-friendly and highly efficient. The free-standing membranes feature a robust and unique architecture, which comprise dense surface layers and highly porous interlayer with large amounts of irregular-shaped micron-scale pore cavities, inducing satisfactory H2/CO2 selectivities and exceptional H2 permeances. The ZIF-8 membrane affords a considerable H2 permeance of 2653.7 GPU with a competitive H2/CO2 selectivity of 17.1, and the Zn(EtIm)2 membrane exhibits a high H2/CO2 selectivity of 22.1 with an excellent H2 permeance (6268.7 GPU). The SFSC approach potentially provides a new pathway for preparing free-standing MOF membranes under solvent-free conditions, rendering it feasible for scale-up production of membrane materials for gas separation.