Stability In Organic Solvents Research Articles

Carbon molecular sieve membranes with integrally skinned asymmetric structure for organic solvent nanofiltration (OSN) and organic solvent reverse osmosis (OSRO)

Organic solvent nanofiltration is an energy-efficient separation process for solutes and solvents. Robust membranes that show stability in harsh environments are highly desirable. In this study, we developed free-standing integrally skinned asymmetric carbon molecular sieve membranes that synergize the advantages of stable carbon materials and porous polymer membranes. The membranes were prepared using a polyimide of intrinsic microporosity (PIM), known as 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)-3,3′-dimethylnaphthidine (DMN), via a phase inversion technique. Carbonization preserved the surface porosity and finger-like porous morphology of the membranes after structural rearrangement. The effects of pyrolysis temperature, membrane thickness, dope solution concentration, and polymer porosity on separation performance were investigated. The molecular sieving performance of the membranes was investigated using five solvents with different polarities. The membranes showed no swelling and high stability in strong acids, bases, and organic solvents, as well as an excellent rejection profile and reasonable permeance. The membrane pore size, molecular-weight cutoff, and performance were fine-tuned by controlling the pyrolysis temperature, dope solution concentration, and polymer porosity. The polymer porosity and the asymmetric structure of the membrane strongly affected the molecular sieving performance. Carbonizing porous 6FDA-DMN afforded a 10-fold higher permeance than that obtained by carbonizing nonporous 6FDA-m-phenylenediamine (mPDA). To the best of our knowledge, the developed membrane fabrication platform yielded one of the tightest, most robust, and highly solvent-resistant nanofiltration membranes reported thus far.

Bioinspired Ultrastable MXene/PEDOT:PSS Layered Membrane for Effective Salinity Gradient Energy Harvesting from Organic Solvents.

The waste organic solvents containing inorganic salts have been considered sustainable resources, which can effectively capture salinity gradient energy using ion-selective membranes. However, it still remains a great challenge to fabricate the ion-selective membranes with high conversion efficiency and stability in an organic system. Here, the bioinspired nacre-like layered MXene/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) (MP) composite membranes for capturing salinity gradient energy from an organic solvent are fabricated via filtration method, in which PEDOT:PSS molecules are introduced into MXene interlayers. Accordingly, the MP membrane exhibits high mechanical property and wonderful stability in common organic solvents. As expected, the power generation of the MP membrane reaches up to 3216 ± 603 nW in a 2/0.001 M methanol (Met)-LiCl solution and a record high power generation of 6926 ± 959 nW after adding NaOH into the Met-LiCl solution, which is superior to the previous report. Both experimental and theoretical studies confirm that the MP membrane has excellent cation selectivity and fast ion transport performance. The results are attributable to an increased interlayer spacing between MXene layers and an improved cation selectivity due to the insertion of PEDOT:PSS chains and the enhanced dissociation of negative charges by NaOH. The ultrastable two-dimensional (2D) nanochannel membrane provides practical application for harvesting energy from waste organic solvents.

Synthesis, characterization, ion-exchange, and catalytic properties of three isostructural copper(II) coordination polymers with a flexible bis(triazole) ligand

Ion-exchange processes are shown to occur in several coordination polymers (CPs) and their unique subclass of metal-organic frameworks (MOFs). The development of fast and economical routes to stable ion-exchange CP materials is important to broaden the range of applications for these materials. Herein, we report a greatly improved synthesis and coordinated anion exchange of three new copper(II) coordination polymers [Cu(Fbtx)2(NO3)2]n (1), [Cu(Fbtx)2(BF4)2]n (2) and [Cu(Fbtx)2(SO4)]n (3) (Fbtx ​= ​1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-tetrafluorobenzene) under the microwave-assisted hydrothermal conditions. The three Cu-CPs are crystallographically isostructural, exhibiting two-dimensional layered structures with the 44-sql topology. Complexes 1–3 display good thermal stability and excellent chemical stability in organic solvents and aqueous solutions with wide pH range of 1–13. The anion-exchange functions of the series of sql-type coordination networks were monitored by using powder X-ray diffraction, infrared spectroscopy and ion chromatography. The results revealed that these complexes can undergo anion-exchange under microwave irradiation, and the reversible exchange process depends on the size of the anions. These materials were demonstrated to be efficient heterogeneous catalysts for the direct carboxylation of 1-ethynylbenzene with CO2 under mild conditions, and various propiolic acids were synthesized in moderate to good yields under optimized reaction conditions. Moreover, the catalyst could be recycled up to five times with the retention of both catalytic activity and crystal structure.

Metal-organic framework based on iron and terephthalic acid as a multiporous support for lipase Burkholderia lata LBBIO-BL02 and its potential for biocatalysis

Metal-organic frameworks (MOFs) are versatile materials because they have a large internal surface area and tuneable pores, making them suitable for enzyme immobilization. In this study, we prepared a typical microporous Fe-BDC MOF through a thermal treatment to produce additional meso and macropores interconnected to each other, capable of immobilizing the Burkholderia lata LBBIO-BL02 (BLL) lipase by entrapment and physical adsorption. The immobilization efficiency (E) was 90%, and the activity retention (R) was 400% (pNPP hydrolysis). The immobilized lipase (BLL@BDC) also showed excellent activity in the hydrolysis of vegetable oils in aqueous medium, achieving up to 3,200 U g−1 for olive oil, as well as high stability in organic solvents, especially for polar ones, such as iso-propanol (101.5 ± 2.6%), ethanol (103.0 ± 6.0%) and acetone (107.7 ± 8.3%). The results indicate that the multiporous Fe-BDC MOF is a promising support for lipase immobilization and further application in biocatalysis performed in organic media.

Stable Lanthanide Metal-Organic Frameworks with Ratiometric Fluorescence Sensing for Amino Acids and Tunable Proton Conduction and Magnetic Properties.

Four new isostructural lanthanide metal-organic frameworks (MOFs), namely {[Ln(DMTP-DC)1.5(H2O)3]·DMF}n [H2DMTP-DC = 2',5'-dimethoxytriphenyl-4,4″-dicarboxylic acid; LnIII = EuIII (1), GdIII (2), TbIII (3), and DyIII (4)], have been synthesized and characterized. Single-crystal structure analysis reveals that 1-4 are three-dimensional Ln-MOFs with rich H-bonding of coordinated H2O molecules in the network channels. The X-ray diffraction patterns indicate that Ln-MOF 1 displays good stabilities in organic solvents and aqueous solutions with distinct pH values. Both 1 and 3 show characteristic emission of LnIII ions. Ln-MOF 1 can be used as a ratiometric fluorescence sensor for arginine and lysine in aqueous solution, and the detection limits are 24.38 μM for arginine and 9.31 μM for lysine. All 1-4 show proton conductivity related to relative humidity (RH) and temperature, and the maximum conductivity values of 1-4 at 55 °C and 100% RH are 9.94 × 10-5, 1.62 × 10-4, 1.71 × 10-4, and 2.67 × 10-4 S·cm-1, respectively. The value of σ increases with the decrease in ionic radius, indicating that the radius of the LnIII ions can regulate the proton conductivity of these MOFs. Additionally, 2 exhibits a significant magnetocaloric effect (MCE) with a magnetic entropy change (-ΔSm) of 18.86 J kg-1 K-1 for ΔH = 7 T at 2 K, and 4 shows weak field-induced slow relaxation of magnetization. The coexistence of good fluorescence sensing capability, attractive proton conductivity, and relatively large MCE in Ln-MOFs is rare, and thus, 1-4 are potentially multifunctional MOF materials.

Reversible crosslinking of polybenzimidazole-based organic solvent nanofiltration membranes using difunctional organic acids: Toward sustainable crosslinking approaches

Solvent resistance is a crucial property for achieving organic solvent nanofiltration (OSN) membranes with good separation performance and long lifespan. Polybenzimidazole (PBI) has been widely used for OSN membrane fabrication owing to its excellent mechanical properties, thermal stability, and resistance in various organic solvents. However, pristine PBI membranes show unsatisfactory stability in polar aprotic solvents. To circumvent this issue, extensive research has been conducted on the covalent crosslinking of PBI membranes. Herein, to develop a more sustainable crosslinking strategy, difunctional organic acids — oxalic and squaric acids — were used for the reversible crosslinking of PBI membranes in water at room temperature, affording robust membranes with long-term stability in polar aprotic solvents. An analysis at the molecular level of the difunctional acid crosslinking system based on p K a values and binding energies was presented. The molecular weight cutoff and solvent flux of the PBI membranes crosslinked with oxalic and squaric acids were 779 and 844 g mol −1 and 153.9 and 139.7 L m −2 h −1 bar −1 in N , N -dimethylacetamide at 30 bar, respectively. The crosslinking was successfully reversed under basic conditions, allowing the recovery of the pristine PBI polymer. A sustainability assessment revealed the advantages of the proposed crosslinking system over conventional covalent crosslinking approaches. The solvent-resistant properties of polybenzimidazole membranes are enhanced using a crosslinking approach by employing oxalic and squaric acids as mild organic acid crosslinkers in water under ambient conditions. • OSN membranes formed via mild organic acid crosslinking at ambient conditions in aqueous solutions. • Difunctional organic acids with p K a lower than 5.23 can crosslink polybenzimidazole (PBI) membrane. • Improved membrane stability in NMP, DMSO, DMAc, DMF polar aprotic solvents up to two weeks. • Less hazardous and more sustainable crosslinking approach for OSN membrane fabrication. • Membranes crosslinked with oxalic and squaric acids were recovered as pristine PBI.

ZIF-8 channeled and coordination-bridging two-dimensional WS2 membrane for efficient organic solvent nanofiltration

Zeolitic imidazolate framework-8 (ZIF-8)/WS2 composite 2D membranes were constructed by in-situ growth of ZIF-8 in the interlayer of WS2 laminar membrane. The growth of ZIF-8 nanoparticles in WS2 membrane expanded the interlayer spacing, and endowed WS2 membrane with fixed interlayer spacing by coordination-bridges between WS2 and ZIF-8, which made ZIF-8/WS2 membrane possess not only high solvent permeance but also excellent stability in organic solvents. Isopropanol (IPA) permeance through ZIF-8/WS2 membrane reached 272 L/m2·h·bar, which was about 1.6 times higher than that through pristine WS2 membrane, and the rejection rates for Direct Black 38 (DB38), Congo Red (CR) and Rose Bengal (RosB) were 99%, 99% and 30% respectively. Furthermore, the IPA permeance through ZIF-8/WS2 membrane was almost unchanged after soaking in IPA for 192 h, and IPA permeance and rejection rate for DB 38 changed slightly during 100 h of cross-flow filtration, demonstrating remarkable stability of ZIF-8/WS2 membranes in organic solvents and a promising application potential in organic solvent nanofiltration.

Synthesis of Accordion‐like Ti3CN MXene and its Structural Stability in Aqueous Solutions and Organic Solvents

AbstractMXene materials have shown promising applications in selective separation membranes and many other fields. However, their structural stability which is critically important to applications in the presence of aqueous solutions and organic solvents remains largely unexplored. In this work, we have conducted a systematic study on the synthesis of accordion‐like Ti3CN MXene and its stability in aqueous solutions, ethanol and N,N‐dimethylformamide (DMF). Based on the XRD, SEM and TEM results, 20 % HF acid and an etching time of 24 h is regarded as the optimal parameter to synthesize accordion‐like Ti3CN MXene. Ti3CN MXene exhibits limited stability in the aqueous solutions. Ti3CN MXene partially transforms to anatase TiO2 nanoparticles in pH=1 and 7 aqueous solutions, and amorphous TiO2 nanowires in pH=14 aqueous solution after a 7‐day test at 25 °C. When the testing temperature is increased to 80 °C, this structure transformation rate is increased remarkably. Meanwhile, Ti3CN MXene shows excellent stability in C2H5OH and DMF up to 7‐day at 25 and 80 °C, respectively. It is believed that these findings are helpful for guiding the controllable synthesis of Ti3CN MXene and seeking the potential applications in the presence of aqueous solutions, ethanol and DMF.

An Esterase with Increased Acetone Tolerance from Bacillus subtilis E9 over Expressed in E. coli BL21 Using pTac Bs-est Vector.

Bacillus subtilis E9 was identified as a potential strain producing esterase. The gene coding esterase from B. subtilis E9 was amplified using esterase-specific primers and the sequence was translated in silico. The presence of conserved catalytic triad amino acid residues (His-Ser-Asp/Glu) confirmed the functional nature of the esterase enzyme. Docking studies conducted with modeled protein and the ligand p-nitrophenyl acetate showed that the amino acid residues interacting with the ligand were Ser77, His76, and Gly103. The gene coding for esterase from B. subtilis E9 was cloned into an assembled vector having Tac promoter (pTac), pUC origin of replication, Ni-Histidine residues, ampicillin cassette, and T7 terminator using Golden gate DNA assembly method. The generated pTac Bs-est (4598bp) recombinant plasmid was transformed and heterologously expressed in Escherichia coli BL21 (DE3) strain. The tagged recombinant protein was purified to yield 43.4% pure protein with specific activity of 772 U/mg. The purified recombinant protein was subjected to peptide sequencing and the identity was confirmed as esterase by peptide tandem mass fragmentation method using the LC-MS/MS analysis. The purified recombinant esterase was found to be organic solvent stable and tolerant up to 5days retaining around 95% residual activity in 30-90% v/v Acetone. The recombinant esterase expressed in our study was found to exhibit better organic solvent stability and tolerance than compared to the original bacterial esterase from B. subtilis E9, a property which could be explored in the biocatalytic and synthetic transformation reactions for industrial applications.

Polycrystalline Iron(III) metal-organic framework membranes for organic solvent nanofiltration with high permeance

There is an urgent demand for separation membranes based on metal-organic frameworks (MOFs) with high efficiency, low waste generation, and low energy consumption. Herein, we report the fabrication of high-quality, continuous iron (III)-based PCN-250 polycrystalline MOF membranes for organic solvent nanofiltration. Due to the usage of rub seeding, the PCN-250 membrane has a small thickness of 3.7 μm and exhibits pure solvent permeance as high as 337.9 L m −2 h −1 bar −1 for methanol, 69.2 L m −2 h −1 bar −1 for ethanol, and 17.2 L m −2 h −1 bar −1 for N-methyl-2-pyrrolidone (NMP). The membrane has pore sizes ranging from 0.6 to 1.0 nm, with a molecular weight cut-off of ca. 1300 g/mol. In addition, it exhibits excellent molecular separation performance (methyl blue rejection of 93.7%) alongside a high NMP permeance of 2.6 L m −2 h −1 bar −1 . Moreover, our study confirms that the PCN-250 MOF membrane has good water, acid, and organic solvent resistance. This remarkable separation performance, combined with the outstanding stability in water, acid, and organic solvents, makes the PCN-250 membrane a promising candidate for organic solvent nanofiltration. • Fe(III)-based PCN-250 membranes were fabricated for organic solvent nanofiltration. • The thickness of PCN-250 membrane was controlled by rub seeding with secondary growth. • PCN-250 membrane has pore sizes ranging from 0.6 to 1.0 nm, with a molecular weight cut-off of ca. 1300 g/mol. • PCN-250 membrane has high solvent permeance with good solvent and acid stability. • PCN-250 membrane has methyl blue rejection of 93.7% with high NMP permeance of 2.6 L m −2 h −1 bar −1 .

A stable and highly luminescent 3D Eu(III)-organic framework for the detection of colchicine in aqueous environment

The metal-organic framework materials have an important application as sensors. In this work, a microporous three-dimensional (3D) Eu(III)-organic framework (Eu-MOF), [Eu2(3,5-bct)(phen)2(ox)2(H2O)]·H2O, was constructed from 3,5-bis(3′-carboxyphenyl)-1,2,4-triazole (3,5-H2bct), oxalate (ox) and 1,10-phenanthroline (phen) as a luminescent sensor. The free volume was found to be 15.7% per unit volume ignoring the free water molecules. The Eu-MOF showed bright red light due to the emission at 622 nm (5D0 → 7F2 transition) of the Eu(III) with high quantum yield (QY, 52.51%). The Eu-MOF exerted high luminescence stability in common organic solvents as well as aqueous solutions within a wide pH range from 4 to 11. Based on the luminescent Eu-MOF, the sensing behavior for colchicine in the aqueous environment was studied. Highly selective and sensitive detection (LOD = 2.43 × 10−5 mol L−1) of colchicine was observed by the Eu-MOF even in the presence of potential interfering components. The sensing mechanism for colchicine was investigated by experimental and theoretical results. It is worth noting that a film (Film@Eu-MOF) prepared by loading Eu-MOF showed intense characteristic red light emission under UV light. The luminescence color changed immediately from red to colorless when the Film@Eu-MOF came in contact with colchicine. Highly sensitive and rapid detection of colchicine in wastewater was achieved using this Film@Eu-MOF, which could be identified by the naked eye. The experimental results suggest that the synthesized Eu-MOF has potential application as a luminescent sensing material for pollutants in the environmental system.

Multi-responsive luminescent probes for Fe3+, Cr2O72− and acetylacetone with Cd-MOF based on tris(3′-F-4′-carboxybiphenyl)amine and trans-1,2-bis(4-pyridyl)ethene

A novel luminescent metal-organic framework (MOF) with the formula of [Cd2(TFBA)(HCOO)(bpe)H2O]n (MOF-1) (H3TFBA ​= ​tris(3′-F-4′-carboxybiphenyl)amine, bpe ​= ​trans-1,2-bis(4-pyridyl)ethene) has been designed and synthesized through solvothermal reaction. The Cd-MOF crystallizes in the monoclinic space group P21/C, exhibiting non-interpenetrating 3D microporous structure. MOF-1 displays outstanding stability in water and other common small organic solvents. It's noteworthy that water suspension of MOF-1 exhibits good fluorescence performance, which was effectively quenched by Fe3+ and Cr2O72− with the Ksv values of 1.15 ​× ​106 ​M-1 and 1.22 ​× ​104 ​M-1, respectively. Moreover, MOF-1 is capable of sensing acetylacetone in DMF with obvious luminescence enhancement and the detection limit is 37.30 ​ppm. Combined with anti-interference capability and reusability, MOF-1 can be considered as a potential luminescent sensor for detection of Fe3+ and Cr2O72− in H2O solution and acetylacetone in DMF. Additionally, the possible luminescent quenching and enhancement mechanisms were also discussed.

Superior transport behavior of gold nanoparticles/P3HT blends by tuning optical and structural properties

Organic materials and blends have received a great deal of interests for application in large area, flexible, and low-cost organic/hybrid electronics. In this work the optical, structural and the electrical behaviors of a new active layer system composed by functionalized gold nanoparticles (AuNPs) and conjugated polymers, were investigated. For this purpose, gold nanoparticles with diameter of about 5 nm were chosen, coated with the bifunctional π-conjugated ligand (9,9-didodecyl-2,7-bis(acetylthio)fluorene, FL) for their high stability and easy dispersibility in organic solvents. The blends based on AuNPs and regioregular poly-3-hexylthiophene (P3HT) were prepared by adding an increasing percentage by weight of nanoparticles, i.e. from 10% to 90 wt%, in the P3HT polymeric matrix. The presence of nanoparticles was confirmed by UV-Vis spectroscopy, electron microscopy and X-ray diffraction techniques. The optical characterization of the composites demonstrated the possibility to tune the optical behavior of the P3HT by adding increasing percentages of AuNPs into the polymer matrix. Their inclusion results in a loss of P3HT crystallinity and in a simultaneous increase of the π-π interaction between the polythiophene chain and fluorene ligand. To better investigate the films, Grazing Incident X-ray Diffraction (GIXD) measurements were carried out and the blend containing 30 wt% of AuNPs in P3HT reveals an optimal condition, combining good structural order and interconnectivity in the polymer matrix. The electrical characterization of the AuNPs/P3HT blends reveals an improvement of the electrical conductivity in all the prepared blends, that show higher conductivity values compared to the pristine AuNPs and P3HT materials. The best performance is achieved adding 30 wt% of AuNPs to P3HT resulting in an enhancement of conductivity by about 350% compared to that of the pure polymer. This result could be of great interest for the realization of new conductive film composites to use in opto-electronic devices.

Using Molecular Simulation to Guide Protein Engineering for Biocatalysis in Organic Solvents.

Biocatalysis in organic solvents (OSs) is very appealing for the industry in producing bulk and/or fine chemicals, such as pharmaceuticals, biodiesel, and fragrances. The poor performance of enzymes in OSs (e.g., reduced activity, insufficient stability, and deactivation) negates OSs' excellent solvent properties. Molecular dynamics (MD) simulations provide a complementary method to study the relationship between enzymes dynamics and the stability in OSs. Here we describe computational procedure for MD simulation of enzymes in OSs with an example of Bacillus subtilis lipase A (BSLA) in dimethyl sulfoxide (DMSO) cosolvent with software GROMACS. We discuss main essential practical issues considered (such as choice of force field, parameterization, simulation setup, and trajectory analysis). The core part of this protocol (enzyme-OS system setup, analysis of structural-based and solvation-based observables) is transferable to other enzymes and any OS systems. Combining with experimental studies, the obtained molecular knowledge is most likely to guide researchers to access rational protein engineering approaches to tailor OS resistant enzymes and expand the scope of biocatalysis in OS media. Finally, we discuss potential solutions to overcome the remaining challenges of computational biocatalysis in OSs and briefly draw future directions for further improvement in this field.

Solvent and pH Stability of Poly(styrene-alt-maleic acid) (PSaMA) Membranes Prepared by Aqueous Phase Separation (APS).

In the single-polyelectrolyte aqueous phase separation (APS) approach, membranes are prepared by precipitating a weak polyelectrolyte from a concentrated aqueous solution using a pH switch. This has proven to be a versatile and more sustainable method compared to conventional approaches as it significantly reduces the use of organic solvents. Poly(styrene-alt-maleic acid) (PSaMA) is a polymer that has been extensively investigated for APS and has been the basis for both open and dense membranes with good performances. These membranes are chemically crosslinked and, in this work, we further investigated ultrafiltration (UF) and nanofiltration (NF) membranes prepared with PSaMA for their stability in various organic solvents and under different pH conditions. It was shown that these membranes had stable performances in both isopropanol (IPA) and toluene, and a slightly reduced performance in N-methyl-2-pyrollidone (NMP). However, PSaMA did not perform well as a selective layer in these solvents, indicating that the real opportunity would be to use the UF-type PSaMA membranes as solvent-stable support membranes. Additionally, the membranes proved to be stable in an acidic-to-neutral pH regime (pH 2–7); and, due to the pH-responsive nature of PSaMA, for the NF membranes, a pH-dependent retention of Mg2+ and SO42− ions was observed and, for the UF membranes, a strong responsive behavior was observed, where the pH can be used to control the membrane permeability. However, long-term exposure to elevated pH conditions (pH 8–10) resulted in severe swelling of the NF membranes, resulting in defect formation, and compaction of the UF membranes. For the UF membranes, this compaction did prove to be reversible for some but not all of the membrane samples measured. These results showed that in aqueous systems, membranes prepared with PSaMA had interesting responsive behaviors but performed best at neutral and acidic pH values. Moreover, the membranes exhibited excellent stability in the organic solvents IPA and toluene

Breathing Parylene-Based Nanothin Artificial SEI for Highly-Stable Long Life Three-Dimensional Silicon Lithium-Ion Batteries

Here, we present on the application and characterization of parylene layers of nanometric thickness as a highly efficient artificial elastic SEI layer for three-dimensional nano-silicon anodes. The simple deposition process of the parylene layers creates an extremely conformal layer, even on the most complex three-dimensional substrate geometries and can be easily controlled down to thicknesses of below 30nm with excellent uniformity. The parylene nanothin layers are shown to be extremely stable chemically, electrochemically and mechanically, while notably allowing the free diffusion of Li-ions into the Si underlying active layer. The elasticity of the organic parylene layer plays a key role in the applicability of parylene to act as an efficient artificial SEI structure, as it was shown to be capable to withstand the dramatic natural "breathing" effect of the underlying silicon nanostructures, without interruption to the active material volumetric changes, while partially preventing and slowing the formation of a secondary SEI layer. Combined with our unique, novel substrate which demonstrates a simple catalyst-free growth of highly electrically conductive Si-stainless steel composite anodes with high loadings of silicon nanostructures and binder-free nature, remarkable electrochemical results can be achieved. Electrochemical characterization reveals that the Parylene-F VT-4 nanolayer is superior to other parylene types, exhibiting more than 450 cycles with 75% capacitiy retention vs Li metal anode. Importantly, the parylene layer does not allow delamination and cracking of active Si material, as evident from the 95.5% capacity retention after 400 cycles at low C-rate. The unique combination of the parylene artificial SEI layer and highly conductive substrates allow for high C-rates (>2C) to be achieved with significant capacity retention. The parylene layer is shown to dramatically improve the anode cycle life compared to bare silicon-based anodes, while not limiting the active material loading degree achievable. Most importantly, parylene is shown to fulfill all the required properties of artificial SEI, including impeccable chemical stability in organic solvents, elasticity and mechanical stability, high adhesion to the silicon under-layer, lowering the SEI formation, ionically conductive and electrically insulating and cost-effective, scalable and simple fabrication. The simplicity, applicability and control of parylene deposition, along with its vast improvement of stability of bare silicon anodes, make it an excellent candidate for future applications as an efficient artificial SEI layer for next-generation silicon anodes and other active materials of interest. Figure 1

Luminescent Zn (II) coordination polymers for highly selective detection of triethylamine, nitrobenzene and tetracycline in water systems

Two novel coordination polymers (CPs), formulated as {[Zn3(L)1.5(DMF)3]•C2H7N} n (1), and [Zn(L)0.5(bpb)0.5(H2O)2] n (2), (H4L = 1, 1′-ethylbiphenyl −3, 3′, 5, 5′- tetracarboxylic acid, bpb = 1, 4-di(pyridin-4-yl) benzene), have been acquired under hydrothermal conditions. Complexes 1 and 2 display excellent luminescence characteristics and stability in antibiotics and organic solvents. Complex 1 can detect triethylamine (TEA) and tetracycline (TET) in water by fluorescence quenching. The detection limits of 1 towards TEA and TET are 1.07 μM and 0.1 μM, respectively. Complex 2 can be used as a luminescence sensor to detect nitrobenzene (NB) and the detection limit towards NB is 0.2 μM. Moreover, complexes 1 and 2 perform excellent reproducibility, because the changes of fluorescence intensity are negligible after four cycles. The mechanism of the fluorescence quenching is discussed in detail.

Repairing of graphene oxide membranes based on SPEEK substrate for organic solvents nanofiltration through PEI needle thread method

Owing to the increasing need to mitigate excessive organic solvents waste, the efficient separation and purification of organic solvents have attracted more attention. Carbon nanomaterials have attracted great attention in separation and purification technology. However, fabrication of GO-based organic solvents nanofiltration (OSN) membranes with stable and high effective separation performance is still a challenge due to their tendency to swell and inevitable GO interlaminar defects. In this work, we presented stable and crosslinked GO membranes based on (sulfonated polyether ether ketone) SPEEK substrate via polyethyleneimine (PEI) repairing for the first time. Specifically, the hydrogen bonds between the SPEEK substrate and GO eliminated interface incompatibility. The mitigation of microporous defects via PEI endowed the membranes with good permselectivity. A facile glutaraldehyde (GA) crosslinking restricted the expansion of the GO layer to promise high selectivity and long-term stability in organic solvents. The elemental analysis and Nano IR were used to evaluate the appearance of PEI among the GO interlayer. The resulting membranes exhibited ultrahigh flux for pure solvents (30, 27.16, 13.88, 9.94, 7.42 L m−2h−1bar−1 for water, acetone, methanol, ethanol, and IPA) and good dyes molecular separation performance (over 99%). Meanwhile, the membranes could highly separate mixed dyes with different molecular weights. Most importantly, long-term filtration operation and ultrasonic processing further proved the stability of the membranes. Our technique opens opportunities for fabricating stable and high effective membranes with carbon nanomaterials in organic solvents.

Fabricating lignin-containing cellulose nanofibrils with unique properties from agricultural residues with assistance of deep eutectic solvents

Lignocellulosic biomass-derived nanocellulose has been attracting more and more attentions due to its distinguished advantages and various applications, but its development has been restricted by the preparation especially with environmental friendly approach. Herein, lignin-containing cellulose nanofibrils (LCNF) was prepared from corncob via the combined pretreatment of choline chloride-based DES (ChCl-DES) and enzymatic hydrolysis followed by high-pressure homogenization. The effects of different types of ChCl-DES on the properties of LCNF were investigated and compared. The results showed that LCNF can be successfully fabricated through the combined pretreatments; the LCNF had an average diameter of 60–90 nm, exhibited good fluorescence, high thermal stability (up to 353 °C of Tmax), hydrophobicity, stability, and redispersibility in organic solvent; AC-LCNF showed well oriented arrangement, the highest hydrophobicity and fluorescence, and distinguished redispersibility especially in DMSO. ChCl-DES as one green and sustainable approach would realize efficient separation and high value-added utilization of agricultural residues.

Molecular Interactions and Layer Stacking Dictate Covalent Organic Framework Effective Pore Size.

Interactions among ions, molecules, and confining solid surfaces are universally challenging and intriguing topics. Lacking a molecular-level understanding of such interactions in complex organic solvents perpetuates the intractable challenge of simultaneously achieving high permeance and selectivity in selectively permeable barriers. Two-dimensional covalent organic frameworks (COFs) have demonstrated ultrahigh permeance, high selectivity, and stability in organic solvents. Using reactive force field molecular dynamics modeling and direct experimental comparisons of an imine-linked carboxylated COF (C-COF), we demonstrate that unprecedented organic solvent nanofiltration separation performance can be accomplished by the well-aligned, highly crystalline pores. Furthermore, we show that the effective, as opposed to designed, pore size and solvated solute radii can change dramatically with the solvent environment, providing insights into complex molecular interactions and enabling future application-specific material design and synthesis.