Generation of transgene-free canker-resistant Citrus sinensis cv. Hamlin in the T0 generation through Cas12a/CBE co-editing.

Citrus canker disease affects citrus production. This disease is caused by Xanthomonas citri subsp. citri (Xcc). Previous studies confirmed that during Xcc infection, PthA4, a transcriptional activator like effector (TALE), is translocated from the pathogen to host plant cells. PthA4 binds to the effector binding elements (EBEs) in the promoter region of canker susceptibility gene LOB1 (EBEPthA4-LOBP) to activate its expression and subsequently cause canker symptoms. Previously, the Cas12a/CBE co-editing method was employed to disrupt EBEPthA4-LOBP of pummelo, which is highly homozygous. However, most commercial citrus cultivars are heterozygous hybrids and more difficult to generate homozygous/biallelic mutants. Here, we employed Cas12a/CBE co-editing method to edit EBEPthA4-LOBP of Hamlin (Citrus sinensis), a commercial heterozygous hybrid citrus cultivar grown worldwide. Binary vector GFP-p1380N-ttLbCas12a:LOBP1-mPBE:ALS2:ALS1 was constructed and shown to be functional via Xcc-facilitated agroinfiltration in Hamlin leaves. This construct allows the selection of transgene-free regenerants via GFP, edits ALS to generate chlorsulfuron-resistant regenerants as a selection marker for genome editing resulting from transient expression of the T-DNA via nCas9-mPBE:ALS2:ALS1, and edits gene(s) of interest (i.e., EBEPthA4-LOBP in this study) through ttLbCas12a, thus creating transgene-free citrus. Totally, 77 plantlets were produced. Among them, 8 plantlets were transgenic plants (#HamGFP1 - #HamGFP8), 4 plantlets were transgene-free (#HamNoGFP1 - #HamNoGFP4), and the rest were wild type. Among 4 transgene-free plantlets, three lines (#HamNoGFP1, #HamNoGFP2 and #HamNoGFP3) contained biallelic mutations in EBEpthA4, and one line (#HamNoGFP4) had homozygous mutations in EBEpthA4. We achieved 5.2% transgene-free homozygous/biallelic mutation efficiency for EBEPthA4-LOBP in C. sinensis cv. Hamlin, compared to 1.9% mutation efficiency for pummelo in a previous study. Importantly, the four transgene-free plantlets and 3 transgenic plantlets that survived were resistant against citrus canker. Taken together, Cas12a/CBE co-editing method has been successfully used to generate transgene-free canker-resistant C. sinensis cv. Hamlin in the T0 generation via biallelic/homozygous editing of EBEpthA4 of the canker susceptibility gene LOB1.

Advanced biomass-based Janus materials: Classification, preparation and application: A review.

In contrast to conventional particles characterized by isotropic surfaces, Janus particles possess anisotropic surfaces, resulting in unique physicochemical properties and functional attributes. In recent times, there has been a surge in interest regarding the synthesis of Janus particles using biological macromolecules. Various synthesis techniques have been developed for the fabrication of Janus materials derived from biomass. These methods include electrospinning, freeze-drying, secondary casting film formation, self-assembly technology, and other approaches. In the realm of Janus composite materials, those derived from biomass have found extensive applications in diverse domains including oil-water separation, sensors, photocatalysis, and medical materials. This article provides a systematic introduction to the classification of Janus materials, with a specific focus on various types of biomass-based Janus materials (mainly cellulose-based Janus materials, lignin-based Janus materials and protein-based Janus materials) and the methods used for their preparation. This work will not only deepen the understanding of biomass-based Janus materials, but also contribute to the development of new methods for designing biomass-based Janus structures to optimize biomass utilization.

Preparation of Polyimide/Ionic Liquid Hybrid Membrane for CO2/CH4 Separation.

Imidazole ionic liquids (ILs) have good affinity and good solubility for carbon dioxide (CO2). Such ionic liquids, combined with polyimide membrane materials, can solve the problem that, today, CO2 is difficult to separate and recover. In this study, the ionic liquid (IL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (IL1), 1-pentyl-3-methylimidazolium tetrafluoroborate (IL2), 1-octyl-3-methylimidazolium tetrafluoroborate (IL3), and 1-dodecylimidazolium tetrafluoroborate (IL4) with different contents were added to a polyimide matrix, and a series of polyimide membranes blended with ionic liquid were prepared using a high-speed mixer. The mechanical properties and gas separation permeability of the membranes were investigated. Among them, the selectivity of the PI/IL3 membrane for CO2/CH4 was 180.55, which was 2.5 times higher than the PI membrane, and its CO2 permeability was 16.25 Barrer, which exceeded the Robeson curve in 2008; the separation performance of the membrane was the best in this work.

Transgene-free genome editing of vegetatively propagated and perennial plant species in the T0 generation via a co-editing strategy.

Transgene-free plant genome editing in the T0 generation is highly desirable but challenging1,2. Here we achieved such a goal using a co-editing strategy via Agrobacterium-mediated transient expression of cytosine base editor to edit ALS encoding acetolactate synthase to confer herbicide chlorsulfuron resistance as a selection marker, Cas12a/CRISPR RNA for editing gene(s) of interest, and green fluorescent protein for selecting transgene-free transformants. The biallelic/homozygous transgene-free mutation rates for target genes among herbicide-resistant transformants ranged from 1.9% to 42.1% in tomato, tobacco, potato and citrus. This co-editing strategy is particularly useful for transgene-free genome editing of vegetatively propagated and perennial plant species in the T0 generation.

B-Doped g-C3N4/Black TiO2 Z-Scheme Nanocomposites for Enhanced Visible-Light-Driven Photocatalytic Performance.

Black TiO2 with abundant oxygen vacancies (OVs)/B-doped graphitic carbon nitride (g-C3N4) Z-scheme heterojunction nanocomposites are successfully prepared by the one-pot strategy. The OVs can improve not only photogenerated carrier separation, but also the sorption and activation of antibiotic compounds (tetracycline hydrochloride, TC). The prepared heterojunction photocatalysts with a narrow bandgap of ∼2.13 eV exhibit excellent photocatalytic activity for the degradation of tetracycline hydrochloride (65%) under visible light irradiation within 30 min, which is several times higher than that of the pristine one. The outstanding photocatalytic property can be ascribed to abundant OVs and B element-dope reducing the bandgap and extending the photo-response to the visible light region, the Z-scheme formation of heterojunctions preventing the recombination of photogenerated electrons and holes, and promoting their effective separation.

Synthesis and Characterization of a Novel DOPO-Based Flame Retardant Intermediate and Its Flame Retardancy as a Polystyrene Intrinsic Flame Retardant.

The research on intrinsic flame retardant has become a hot topic in the field of flame retardant. The synthesis of reactive flame-retardant monomer is one of the effective methods to obtain an intrinsic flame retardant. In addition, in view of the small molecular flame retardant easily migrates from the polymer during the use process, which leads to the gradual reduction of the flame retardant effect and even the gradual loss of flame retardant performance, and the advantages of atom transfer radical polymerization (ATRP) technology in polymer structure design and function customization, we first synthesized reactive flame retardant monomer 6-(hydroxymethyl)dibenzo[c,e][1,2]oxaphosphinine 6-oxide (FAA-DOPO), then synthesized polystyrene bromine (PS148-Br) macromolecular initiator by ATRP technology, and finally obtained block copolymer polystyrene-b-poly{6-(hydroxymethyl)dibenzo[c,e][1,2]oxaphosphinine 6-oxide} (PS-b-PFAA-DOPO) by the polymerization of FAA-DOPO initiated by macromolecular initiator PS148-Br by ATRP technology. The chemical structure of FAA-DOPO was characterized by 1D and 2D NMR (1H, 13C, DEPT 135, HSQC, COSY, NOE, and HMBC) spectra, Fourier transform infrared spectroscopy (FTIR), liquid chromatography-tandem mass spectrometry (LC-MS) and X-ray photoelectron spectroscopy (XPS). The chemical structure and molecular weight of PS-b-PFAA-DOPO were characterized by FTIR and gel permeation chromatography (GPC). The thermal and flame-retardant properties of PS-b-PFAA-DOPO were characterized by thermogravimetry analysis (TG), UL-94, limiting oxygen index (LOI), and microscale combustion calorimetry (MCC). It was found that FAA-DOPO could be used as a monomer for polymerization, although FAA-DOPO had a large steric hindrance from the chemical structure of FAA-DOPO, the UL-94 grade of PS-b-PFAA-DOPO reached the V-0 grade, and the LOI increased by 59.12% compared with PS148-Br.

Synthesis and Characterization of a Self-Polycondensation Diazaphthalanone Monomer and Its Polymers from Polycondensation Reactions.

Polyether ketone (PEK) plastics are linear thermoplastic polymers connected by at least one ether bond and at least one ketone bond on the aryl group. The reason for their excellent heat resistance, rigidity, and mechanical strength is that their main molecular chain contains plenty of aromatic rings and polar carbonyl groups, and their molecular chain presents a large rigidity and strong intermolecular force. In addition, the main chain contains a considerable number of ether bonds, resulting in a certain toughness. However, polyether ketone materials have the disadvantage of poor solubility because of their excellent rigidity. To improve the solubility of polyether ketone, the preparation method of a novel nitrogenous heterocyclic polyaromatic ether monomer, 2-(4-chlorophenyl)-2,3-dihydrophthalazine-1,4-dione (CDD), was proposed, and its activity of polymerization was studied. The average molecular weight of the poly(aryl ether ketone) containing a nitrogenous heterocyclic polyaromatic ether group obtained by self-polycondensation of CDD was 4.181 × 103 kg/mol, and the yield was 90.5%. In order to further explore the activity of monomers, novel copolymerized poly(aryl ether ketone) (PBCD) containing a nitrogenous heterocyclic polyaromatic ether structure was prepared by ternary copolymerization with 4,4-difluorobenzophenone (DFBP) and bisphenol fluorene (BHPF) with high activity. The average molecular weight of PBCD was 72.793 × 103 kg/mol, the molecular weight distribution was 2.344, and the yield was 88.1%. Fourier transform infrared spectroscopy (FT-IR) and 1H NMR were used to confirm the structure of the obtained polymer. Through thermogravimetric analysis (TGA), the determined weight loss temperature of 5% under nitrogen was higher than 500 °C, indicating excellent thermal stability. Compared with the solubility of the binary copolymer containing fluorenyl poly(aryl ether ketone) (PBD), the polymer showed reasonable solubility in selective solvents such as chloroform and N,N-dimethylacetamide.

Activation of TLR4 induces inflammatory muscle injury via mTOR and NF-κB pathways in experimental autoimmune myositis mice.

Idiopathic inflammatory myopathy (IIM) is an autoimmune disease that invades skeletal muscle; however, the etiology of IIM is still poorly understood. Toll-like receptor (TLR) 4 has been widely reported to take part in the autoimmune inflammation of IIMs. The mammalian target of rapamycin, mTOR, is a key central substance which mediates immune responses and metabolic changes, and also has been confirmed to be involved in the pathogenesis of IIMs. However, the interconnectedness between TLR4 and mTOR in IIM inflammation has not been fully elucidated. We hypothesized that TLR4 may play an important role in IIM inflammatory muscle injury by regulating mTOR. Mice were divided into four groups: a normal control group, IIM animal model (experimental autoimmune myositis, EAM) group, TAK242 intervention group and rapamycin (RAPA) intervention group. The results of EAM mice showed that TLR4, mTOR, nuclear factor-kappa B (NF-κB) and inflammatory factors interleukin-17A (IL-17A) and interferon γ (IFN-γ) mRNA levels were significantly upregulated. These factors were positively correlated with the degree of muscle inflammatory injury. When EAM mice were given the antagonist TAK242 to inhibit the TLR4 pathway, the results demonstrated that both mTOR and NF-κB were downregulated in the muscle of the mice. Muscle staining showed that the inflammatory injury was alleviated and the EAM mouse muscle strength was improved. Then, RAPA was used to inhibit the mTOR pathway, and the inflammatory factors IL-17A and IFN-γ were downregulated in EAM mouse muscle and serum. Consistently, muscle inflammatory injury was significantly reduced, and muscle strength was significantly improved. Our results suggest that TLR4 may regulate inflammatory muscle injury in EAM by activating the mTOR and NF-κB pathways, which provides both an experimental complement for the pathological mechanism of IIM and an encouraging target for the selection of effective treatments.

Preparation and Separation Properties of Electrospinning Modified Membrane with Ionic Liquid Terminating Polyimide/Polyvinylpyrrolidone@Polydopamine.

In this paper, superhydrophilic polyimide (PI) membranes were prepared using the electrostatic spinning method, capped with a hydrophilic ionic liquid (IL), and blended with polyvinylpyrrolidone (PVP). Using this preparation, the surface of the fiber membranes was coated in polydopamine (PDA) by means of an in-growth method. Scanning electron micrographs showed prepared blend films can form continuous fibers, for whom the distributions of diameter and pore were uniform. Post-modification (carried out by adding hydrophilic substances), the ability of the membrane surface to adhere to water was also significantly improved. The water contact angle was reduced from 128.97 ± 3.86° in unmodified PI to 30.26 ± 2.16°. In addition, they displayed a good separation effect on emulsified oil/water mixtures. The membrane flux reached a maximum value of 290 L·m-2·h-1, with a maximum separation efficiency reached of more than 99%. After being recycled 10 times, the separation efficiency maintained a level exceeding 95%. The purpose of this study is to demonstrate the simplicity and efficiency of this experiment, thereby providing new ideas for the future application of membrane separation technology in wastewater treatment.

Preparation of Butadiene-Bridged Polymethylsiloxane/Ethylcellulose/1-Carboxymethyl-3-methylimidazolium Chloride Ternary Composite Membranes for Gas Separation.

Excessive CO2 emissions have resulted in global warming and are a serious threat to the life of people, various strategies have been implemented to cut carbon emissions, and one of them is the use of a gas separation membrane to capture CO2 effectively. In this experiment, the butadiene-bridged polymethylsiloxane (BBPMS)/ethyl cellulose (EC)/ionic liquid (IL) ternary composite membranes were prepared by EC as a substrate, BBPMS, and IL as additives in tetrahydrofuran under high-speed stirring and coated on the membrane. The membrane structure was characterized by a Fourier transform infrared spectrometer and scanning electron microscope, and the membrane properties were tested by a membrane tensile strength tester, thermal weight loss analyzer, and gas permeability meter. The results show that the surface of the ternary composite membrane is dense and flat with a uniform distribution, and the membrane formation, heat resistance, and mechanical properties are good. The permeability coefficient of the ternary composite membrane for CO2 reached 1806.03 Barrer, which is 20.00 times higher than that of the EC/IL hybrid matrix membrane. The permeability coefficient of O2 reached 321.01 Barrer, which is 19.21 times higher than that of the EC/IL membrane. When the doping amount of BBPMS is 70-80%, the O2/N2 gas permeation separation of the BBPMS/EC/IL ternary composite membrane is close to the Robertson 2008 curve. It is always known that in the gas separation process the membrane material is the most crucial factor. The success of this experiment points to a new direction for the preparation of new membrane materials.

Sm0.5Sr0.5Co1-xNixO3-δ-A Novel Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions.

The development of non-precious metal catalysts with excellent bifunctional activities is significant for air-metal batteries. ABO3-type perovskite oxides can improve their catalytic activity and electronic conductivity by doping transition metal elements at B sites. Here, we develop a novel Sm0.5Sr0.5Co1-xNixO3-δ (SSCN) nanofiber-structured electrocatalyst. In 0.1 M KOH electrolyte solution, Sm0.5Sr0.5Co0.8Ni0.2O3-δ (SSCN82) with the optimal Co: Ni molar ratio exhibits good electrocatalytic activity for OER/ORR, affording a low onset potential of 1.39 V, a slight Tafel slope of 123.8 mV dec-1, and a current density of 6.01 mA cm-2 at 1.8 V, and the ORR reaction process was four-electron reaction pathway. Combining the morphological characteristic of SSCN nanofibers with the synergistic effect of cobalt and nickel with a suitable molar ratio is beneficial to improving the catalytic activity of SSCN perovskite oxides. SSCN82 exhibits good bi-functional catalytic performance and electrochemical double-layer capacitance.

LbCas12a-D156R Efficiently Edits LOB1 Effector Binding Elements to Generate Canker-Resistant Citrus Plants.

Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is an economically important disease in most citrus production regions worldwide. Xcc secretes a transcriptional activator like effector (TALE) PthA4 to bind to the effector binding elements (EBEs) in the promoter region of canker susceptibility gene LOB1 to activate its expression, which in turn causes canker symptoms. Editing the EBE region with Cas9/gRNA has been used to generate canker resistant citrus plants. However, most of the EBE-edited lines generated contain indels of 1-2 bp, which has higher possibility to be overcome by PthA4 adaptation. The adaptation capacity of TALEs inversely correlates with the number of mismatches with the EBE. LbCas12a/crRNA is known to generate longer deletion than Cas9. In this study, we used a temperature-tolerant and more efficient LbCas12a variant (ttLbCas12a), harboring the single substitution D156R, to modify the EBE region of LOB1. We first constructed GFP-p1380N-ttLbCas12a:LOBP, which was shown to be functional via Xcc-facilitated agroinfiltration in Pummelo (Citrus maxima) leaves. Subsequently, we stably expressed ttLbCas12a:LOBP in Pummelo. Eight transgenic lines were generated, with seven lines showing 100% mutations of the EBE, among which one line is homozygous. The EBE-edited lines had the ttLbCas12a-mediated deletions of up to 10 bp. Importantly, the seven lines were canker resistant and no off-targets were detected. In summary, ttLbCas12a can be used to efficiently generate biallelic/homozygous citrus mutant lines with short deletions, thus providing a useful tool for the functional study and breeding of citrus.

A Rigid and Planar Aza-Based Ternary Anhydride for the Preparation of Cross-Linked Polyimide Membrane Displaying High CO2/CH4 Separation Performance.

In this study, based on the preparation of hexaazatriphenylene-ternary-anhydride (HAT-T), polyimide membranes were prepared by reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4'-diaminodiphenyl sulfide (SDA), 2,2'-bis (trifluoromethyl)diaminobiphenyl (TFDB) and 5-amino-2-(4-aminophenyl) benzimidazole (PABZ). Polyimide films with a hexazobenzo structure have good film-forming properties, high molecular weight (Mn = 0.79-11.79 × 106, Mw = 1.03-16.60 × 106) and narrow molecular weight distribution (polymer dispersity index = 1.17-1.54). With the introduction of rigid HAT-T, the tensile strength and elongation at break of polyimide films are 195.63-510.37 MPa and 4.00-9.70%, respectively, with excellent mechanical properties. The gas separation performance test shows that hexaazatriphenylene-containing polyimide films have good gas selectivity for CO2/CH4. In particular, the separation performance of PIc-t (6FDA/PABZ/HAT-T) surpasses the "2008 Robeson Upper Bound". The selectivity of 188.43 for CO2/CH4 gas reveals its potential value in the separation and purification of methane gas.

Biallelic Editing of the LOB1 Promoter via CRISPR/Cas9 Creates Canker-Resistant 'Duncan' Grapefruit.

Citrus canker caused by Xanthomonas citri subsp. citri is one of the most devastating citrus diseases worldwide. Generating disease-resistant citrus varieties is considered one of the most efficient and environmentally friendly measures for controlling canker. X. citri subsp. citri causes canker symptoms by inducing the expression of canker susceptibility gene LOB1 via PthA4, a transcription activator-like (TAL) effector, by binding to the effector binding element (EBE) in the promoter region. In previous studies, canker-resistant plants were generated by mutating the coding region or the EBE of LOB1. However, homozygous or biallelic canker-resistant plants have not been generated for commercial citrus varieties, such as grapefruit (Citrus paradisi), which usually contain two alleles of LOB1 and thus, have two types of LOB1 promoter sequences: TI LOBP and TII LOBP. Two different sgRNAs were used to target both EBE types. Both 35S promoter and Yao promoter were used to drive the expression of SpCas9p to modify EBEPthA4-LOBP in grapefruit. Using 'Duncan' grapefruit epicotyls as explants, 19 genome-edited grapefruit plants were generated with one biallelic mutant line (#DunYao7). X. citri subsp. citri caused canker symptoms on wild-type and nonbiallelic mutant plants but not on #DunYao7. XccPthA4 mutant containing the designer TAL effector dLOB1.5, which recognizes a conserved sequence in both wild-type and #DunYao7, caused canker symptoms on both wild-type and #DunYao7. No off-target mutations were detected in #DunYao7. This study represents the first time that CRISPR-mediated genome editing has been successfully used to generate disease-resistant plants for 'Duncan' grapefruit, paving the way for using disease-resistant varieties to control canker.

Macromolecular Design for Oxygen/Nitrogen Permselective Membranes-Top-Performing Polymers in 2020.

Oxygen/nitrogen permselective membranes play particularly important roles in fundamental scientific studies and in a number of applications in industrial chemistry, but have not yet fulfilled their full potential. Organic polymers are the main materials used for such membranes because of the possibility of using sophisticated techniques of precise molecular design and their ready processability for making thin and large self-supporting membranes. However, since the difference in the properties of oxygen and nitrogen gas molecules is quite small, for example, their kinetic diameters are 3.46 Å and 3.64 Å, respectively, the architectures of the membrane macromolecules should be designed precisely. It has been reported often that oxygen permeability (PO2) and oxygen permselectivity (α = PO2/PN2) have trade-off relationships for symmetric membranes made from pure polymers. Some empirical upper bound lines have been reported in (ln α - ln PO2) plots since Robeson reported an upper bound line in 1991 for the first time. The main purpose of this review is to discuss suitable macromolecular structures that produce excellent oxygen/nitrogen permselective membranes. For this purpose, we first searched extensively and intensively for papers which had reported α and PO2 values through symmetric dense membranes from pure polymers. Then, we examined the chemical structures of the polymers showing the top performances in (ln α - ln PO2) plots, using their aged performances. Furthermore, we also explored progress in the molecular design in this field by comparing the best polymers reported by 2013 and those subsequently found up to now (2020) because of the rapid outstanding growth in this period. Finally, we discussed how to improve α and PO2 simultaneously on the basis of reported results using not only symmetric membranes of pure organic polymers but also composite asymmetric membranes containing various additives.

A Novel Imide-Bridged Polysiloxane Membrane Was Prepared via One-Pot Hydrosilylation Reaction for O2/N2 Separation.

The synthesis of poly(methyhydrosiloxane) (PMHS) and N,N'-bis(3-allyl)pyromellitic diimide was optimized for O2/N2 separation. The membrane exhibits excellent mechanical and thermal properties and shows an O2/N2 selectivity of up to 4.44 with an O2 permeability of 31.0 Barrer; compared with polydimethylsiloxane (PDMS) and pure polyimide (PI) membranes, the separation selectivity shows a 107% increase for PDMS, and the permeation shows a 660% increase for pure PI. The obtained results were well above the ones reported on the literature for similar conditions opening the door for the preparation of a stable polysiloxane (PMHS-I) gas separation membrane with extraordinary O2/N2 separation performance.

Synthesis of high-performance conjugated microporous polymer/TiO2 photocatalytic antibacterial nanocomposites.

High-performance conjugated microporous polymer (CMP)/TiO2 photocatalytic antibacterial nanocomposites were successfully synthesized by in situ Sonogashira polymerization. TiO2 was uniformly dispersed onto the surface and within the CMP which show the microporous nature with narrow pore size distribution. The high crystallinity and thermal stability of the CMP/TiO2 nanocomposites are attractive for use as antibacterial materials. The composites we prepared showed excellent photocatalytic antibacterial properties for the inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under visible light irradiation. The photocatalytic antibacterial rates of nanocomposites against E. coli and S. aureus after 120 min of visible light irradiation were 98.14% and 100%, respectively. The superoxide anion (O2-) was confirmed to be an important substance in the antibacterial process above. The cytocompatibility of the antibacterial agents was studied in terms of cytotoxicity against NIH 3T3 fibroblasts. More than 95% of the cells were still alive in the presence of the nanocomposites, both without and with light irradiation, indicating the good cytocompatibility of the nanocomposites. Judging from the excellent photocatalytic antibacterial properties and ultralow toxicity of nanocomposites, these materials can be used in many fields such as medical treatment, transportation and construction.

Preparation and High Performance of Cellulose Acetate Films by Grafting with Imidazole Ionic Liquid.

Cellulose acetate (CA) grafted with imidazole ionic liquids (CA-ILs) was synthesized by reacting CA with imidazole ionic liquids ([HO2CMmim]Cl, [HO2CEtmim]Cl, and [HO2CMmim]Br) by using tetrahydrofuran (THF) as the solvent and pyridine as the catalyst. The CA and CA-IL films were fabricated by using the casting solution method. The CA-IL films exhibited good film forming ability and mechanical properties. The successful grafting of CA with imidazole ionic liquids was confirmed by Fourier transform infrared (FTIR), 1H NMR, scanning electron microscopy (SEM), and elemental analysis, and the grafting degrees were 2.24, 2.45, and 3.30%, respectively. The CO2 permeation properties of the CA-IL films were 65.5, 105.6, and 88.3 Barrer, increased up to 2.0, 3.2, and 2.7 times, respectively, as compared to pure CA (32.6 Barrer). The CO2/CH4 selectivities of the CA-IL films were 15.6, 12.6, and 19.2, increased up to 1.7, 1.4, and 2.1 times, respectively, as compared to pure CA (9.26). Therefore, it can be concluded that the imidazole ionic liquids are immensely useful for improving the gas separation performance of CA films.

Optimization of a MOF Blended with Modified Polyimide Membrane for High-Performance Gas Separation.

The preparation, characterization and gas separation properties of mixed matrix membranes (MMMs) were obtained from polyimide capped with ionic liquid and blended with metal-organic frameworks (MOFs). The synthesized MOF was amine functionalized to produce UiO-66-NH2, and its amino group has a higher affinity for CO2. Mixed matrix membranes exhibited good membrane forming ability, heat resistance and mechanical properties. The polyimide membrane exclusively capped by ionic liquid exhibited good permselectivity of 74.1 for CO2/CH4, which was 6.2 times that of the pure polyimide membrane. It is worth noting that MMM blended with UiO-66-NH2 demonstrated the highest ideal selectivity for CO2/CH4 (95.1) with a CO2 permeability of 7.61 Barrer, which is close to the 2008 Robeson upper bound. The addition of UiO-66-NH2 and ionic liquid enhanced the permselectivity of MMMs, which may be one of the promising technologies for high performance CO2/CH4 gas separation.