HIGH PERFORMANCE POLYMERS
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2018
·
IF 1.047
Li Zhang,Xian Wu,Shanyou Liu,Jinwu Peng,Baijun Liu
Some multi-ether linked polyimides (PIs) derived from two diamine monomers containing various amount of cyano groups are synthesized by a typical two-step polymerization. Meanwhile, the PIs with similar chemical structure but without cyano groups are prepared as counterparts for comparison purposes. The obtained PIs exhibit low glass transition temperature values of 211–258°C, which are associated with their multi-ether chemical structure. Furthermore, these PIs have high thermal stability, and the temperatures at 10% weight loss are in the range of 524–616°C under nitrogen atmosphere. It is found that the introduction of cyano groups would have a great influence on the properties of the PIs. The tensile strength and Young’s modulus of one cyano-containing PI reach 121 MPa and 1.4 GPa, respectively, which are much higher than those cyano-free ones. In addition, the cyano-containing PIs exhibit different behaviors of dielectricity and solubility in comparison with the corresponding cyano-free counterparts.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
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2021
·
IF 5.706
Huihuang Fang,Lijie Wu,Weikun Chen,Youzhu Yuan
Transition-metal carbides are attractive heterogeneous catalysts for the transformation of lignin-derived compounds. However, the effects of the surface carbon defect (C-defect) remain unclear due to coke deposition and exposed C terminations. Herein, we transform inert tungsten carbides (WC) into active catalysts via surficial C-etching using transition metals in the presence of H 2 . An optimized 1% Pt–WC catalyst with synergy of Pt and C-defects can perform a 78.6% conversion in the selective hydrogenolysis of guaiacol to phenol with 89.0% selectivity at 300 °C, while the intact WC only gives a 7.1% guaiacol conversion with 51.0% phenol selectivity under the same conditions. As a result, the 1% Pt–WC catalyst exhibits 19-fold higher reaction rate and 12.6-fold higher turnover frequency than those of WC. Moreover, no substantial loss of catalytic performance has been observed with 1% Pt–WC for 50 h on stream. A rational reaction pathway is accordingly proposed through in-depth characterizations.
研究领域:
化学工程
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催化材料
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DOI
高影响因子
RSC Advances
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2016
·Vol. 6
·期 87
·84284-84293
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IF 3.289
Wen-Qiang Zhang,Xiu-Li Wang,Gui-Cheng Liu,Li Chen,Yu-Zhong Wang
In order to make clear how the numbers of para-aryl ether linkages affect the solubility, thermal transition behavior and mechanical properties of para-(p-PEAs), meta-poly(ether-amide)s (m-PEAs), a series of para-substituted aryl ether diamine monomers with 2, 3, 4 or 5 ether linkages were synthesized, and then reacted with terephthalic acid and isophthalic acid via the Yamazaki–Higashi phosphorylation method to prepare wholly aromatic PEAs. The PEAs with intrinsic viscosity values in the range of 0.81–1.16 dL g−1 were obtained and characterized by FT-IR, NMR, and elemental analysis. Although the Tgs and Tms of PEAs decrease with the increasing numbers of aryl ether linkages, their Tgs and Tms still are above 180 °C and 320 °C, respectively. p-PEAs have a high crystallinity making it difficult to dissolve them in common organic solvents even when 5 aryl ether linkages are introduced. Conversely, except for m-PEA5 with a lower polarity, the other m-PEAs show good solubility due to their low crystallinity. Besides, the decomposition temperatures at 5% weight loss of all PEAs exceed 430 °C and their residual yields at 700 °C are above 50% in N2, illustrating that they have excellent thermal stability. It is found that by casting m-PEAs DMAc solution in a dish, the transparent films with high Young's modulus (2.6–3.5 GPa) can be successfully obtained.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
高影响因子
RSC Advances
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2016
·Vol. 6
·期 22
·17880-17887
·
IF 3.289
Guodian Zhu,Xinping Ouyang,Yun Yang,Tao Ruan,Xueqing Qiu
Lignin is an abundant renewable feedstock with a complicated and ill-defined structure. As β-O-4 aryl ether bonds are dominant among all the linkages in lignin, it is important to explore lignin depolymerization targeting the cleavage of the β-O-4 aryl ether bond for efficiently utilizing this biomass. Selective cleavage of chemical bonds in β-O-4 lignin model compounds was investigated by using Fe2(SO4)3, HZSM-5 and Pd/C as catalysts under microwave irradiation. When Fe2(SO4)3 or HZSM-5 was used as a catalyst, the Cα–Cβ bond of the C3 side chain in the model compound was broken to form aldehyde, secondary alcohol or ketone compounds. When Pd/C and formate were used as the catalyst, the β-O-4 aryl bond of the non-phenolic model compound was selectively cleaved and hydrogenation of CC on the side chain occurred at the same time. However, the hydrogenation reaction of CC on the side chain was faster than that of cleavage of the ether bond. Increasing Pd content favored the selective cleavage of the β-O-4 bond, and microwave irradiation accelerated the cleavage of the β-O-4 bond dramatically. At a high dosage of formate or high temperature, the condensation reaction among phenolic products was promoted due to the presence of an active phenolic hydroxyl group. The β-O-4 bond of the phenolic model compound was also selectively cleaved with Pd/C as the catalyst, and the reaction temperatures of cleaving about one half β-O-4 bonds of the non-phenolic and phenolic model compounds were 120 and 100 °C, respectively.
研究领域:
生物化学
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可再生资源利用
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产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Guodian Zhu,Yuehua Wu,Yuebin Xi,Shaoqu Xie,Guoqiang Yin,Xiaojing Lv,Xuliang Lin
Lignin has immense potential for the production of monoaromatics that can be further prepared as target chemicals or alkyl biofuels. In this work, experiments and density functional theory (DFT) calculations were employed to investigate the effect of benzylic alcohol ( α -hydroxyl group, C α H─OH) dehydration to α , β -alkenyl group (C α = C β ) on the enhancement of the β -aryl ether ( β -O-4) bond cleavage reactivity of lignin model dimer over Pd/C by formic acid. This study demonstrated that the β -O-4 bond cleavage reactivity was significantly enhanced via the benzylic alcohol dehydration to C α = C β . The cleavage reactivity of the β -O-4 bond attached to C α functional groups was in the order of α -hydrogen atom (C α H─H) > C α H─OH > α -carbonyl group (C α = O). An easy formation of the C α H─H from the C α = C β hydrogenation led to the enhancement of the β -O-4 bond cleavage reactivity being achieved. The β -O-4 bond cleavage rate was increased by 6.2 times in the presence of the C α H─H compared to the C α = O. Due to few and lower required energy barriers after C α H─OH dehydration, the β -O-4 bond attached to the C α = C β was more thermodynamically favorable to be cleaved. The work highlights the prospect of efficient depolymerization of lignin into monoaromatics.
研究领域:
化学工程
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可再生资源
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICAL BIOCHEMISTRY
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2023
·
IF 2.9
Cheng-lu Zhang,Chang Liu,Yan-wei Ding,Hai-tao Wang,Shi-ru Nie,Yan-peng Zhang
In view of the superior chemical activity of selenoether bond (–Se–) and the excellent optical properties of naphthimide, a novel fluorescent probe ( NapSe ) with near-rectangular structure, which contains double naphthimide fluorophores linked by selenoether bond, is designed for specific fluorescence detection of hydrogen sulfide (H 2 S). NapSe has excellent optical properties: super large Stokes Shift (190 nm) and good stability in a wide pH range. The selectivity of NapSe fluorescence detection of H 2 S is high, and displays excellent "turn-on" phenomenon and strong anti-interference. And the fluorescence intensity increased obviously, reaching 42 times. The time response of probe NapSe is very rapid (3 min) compared with other fluorescence probes that respond to H 2 S. It shows high sensitivity by calculating the detection limit (LOD) as low as 5.4 μM. Notably, the identification of H 2 S by probe NapSe has been successfully applied to the detection of test paper and the detection of exogenous and endogenous fluorescence imaging of MCF-7 breast cancer cells.
研究领域:
化学
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生物医学
✓ 已验证
DOI
PubMed
高影响因子
FUEL
·
2020
·
IF 5.578
Jing-Pei Cao,Tao Xie,Xiao-Yan Zhao,Chen Zhu,Wei Jiang,Ming Zhao,Yun-Peng Zhao,Xian-Yong Wei
Selective hydrogenolysis, the aromatic ether C-O bonds under mild conditions, is crucial for the valorization of lignin. In this context, the effects of H 2 and solvent on the hydrogenolysis of lignin model compounds over Ru catalysts were explored. With H 2 as hydrogen donor, the Ru/AC exhibited the highest activity for converting lignin model compounds into monomeric compounds, whereas H 2 led to low selectivity of aromatics. However, isopropanol was the good H-donor solvent, which could provide a large amount of active hydrogen to promote the cleavage of C-O bonds. Additionally, the yield of aromatics in isopropanol was higher than that under H 2 atmosphere. It could be ascribed to the fact that isopropanol is the protic solvent which displays Lewis basicity, and is a good H-bond donor and a good H-bond acceptor. The higher electron-releasing inductive effect of isopropanol made it easier to provide active hydrogen. Based on the experiments, the mechanism of benzyl phenyl ether hydrogenolysis in H 2 and isopropanol system was presented.
研究领域:
化学工程
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催化科学
✓ 已验证
DOI
高影响因子
GREEN CHEMISTRY
·
2017
·Vol. 19
·期 8
·1895-1903
·
IF 9.125
Yongxiang Zhai,Chuang Li,Guangyue Xu,Yanfu Ma,Xiaohao Liu,Ying Zhang
Lignin primarily composed of methoxylated phenylpropanoid subunits is an abundant biomass that can be used to produce aromatics. Herein, a series of non-precious bimetallic Ni–Fe/AC catalysts were prepared for efficiently depolymerizing lignin. When organosolv birch lignin was used to determine the efficiency of the catalysts in methanol solvent, the Ni1–Fe1/AC (the ratio of Ni and Fe was 1 : 1) achieved the highest total yield of monomers (23.2 wt%, mainly propylguaiacol and propylsyringol) at 225 °C under 2 MPa H2 for 6 h. From GPC analysis, it is also proved that lignin was efficiently depolymerized. The Ni–Fe alloy structure was formed according to XRD, HRTEM, H2-TPR and XPS characterization. Based on the model compounds’ tests, the Ni1–Fe1/AC catalyst showed high efficiency in ether bond cleavage without hydrogenation of aromatic rings which could be attributed to the synergistic effect of Ni and Fe on the alloy structure. The total yield of monomers by using the Ni1–Fe1/AC catalyst reached 39.5 wt% (88% selectivity to PG and PS) when birch wood sawdust was used as the substrate.
研究领域:
生物质化学
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催化化学
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DOI
高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2020
·Vol. 68
·期 4
·582-591
·
IF 1.554
Changzhou Chen,Peng Liu,Haihong Xia,Minghao Zhou,Jianchun Jiang
There is an urgent need to develop a selective hydrogenolysis of C aryl -O bonds in lignin to produce valued-added chemicals and fuels. Recently, hydrogen has been used in the hydrogenation reaction, which hides inevitable danger and is not economical. Therefore, isopropanol, as a hydrogen-donor solvent, is employed for aryl ether hydrogenolysis in lignin models over nickel supported on a carbon nanotube (CNT). Except for aromatic ether (4-O-5), the Ni/CNT catalyst is also found to be suitable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in control experiments. The physicochemical characterizations were carried out by means of H 2 -temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The catalyst can be magnetically recovered and efficiently reused for five consecutive recycling tests in the transfer hydrogenation of aromatic ethers. A mechanism study indicated that the hydrogenolysis cleavage of the ether bond is the first step in the reaction process, and hydrogenation of aromatic rings is only a successive step in which phenol and benzene are intermediate states and are then further hydrogenated. Furthermore, it has been demonstrated that aryl groups play an important role in the hydrogenation of phenol in the competitive catalytic hydrogenation reaction of phenol.
研究领域:
化学工程
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催化科学
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产品关联
DOI
高影响因子
BIOPOLYMERS
·
2018
·Vol. 110
·期 4
·e23243
·
IF 1.99
Xiaohui Fu,Jiliang Tian,Zheng Li,Jing Sun,Zhibo Li
A series of pegylated polypeptoids have been readily synthesized by a strategy combining ring-opening polymerization (ROP) and thiol-yne photoaddition. The polypeptoids simultaneously incorporated branched oligo(ethylene glycol) (OEG) units and thioether bonds in the side-chains. All the polypeptoids are readily soluble in aqueous solution and show reversible thermo-responsive properties. The cloud points (CPs) were demonstrated to be readily tunable in the range of ~25 °C-60 °C by varying the chemical composition, OEG chain length and the degree of polymerization. Attractively, the chemical compositions of the side chains are readily tunable via adjusting the molar ratios of a mixture of thiol terminated OEG molecules, which avoid synthesizing new monomers or copolymerization of different monomers. Further, the oxidation/reduction of thioether groups shows significant influence on the CPs, providing a second stimulus to tune the phase transition behaviors. Considering the biocompatibility and degradability, the dual-responsive polypeptoids are potential candidates for various biomedical or biotechnological applications. Graphical
研究领域:
生物材料学
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高分子化学
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生物医药工程
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产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2022
·
IF 24.319
Haichuan Zhang,Zede Yi,Shiyu Fu,Changzhi Li,Lucian A. Lucia,Qiying Liu
A rational design of the intrinsic lattice structure of catalysts is vitally important to address catalytic performance. Herein is reported a top-down synthesis for the fabrication of a bifunctional metallic catalyst. First, palladium nanocubes with (100) lattices planes were synthesized through a shape-control strategy; next, the as-synthesized Pd/Co-ZIF was used as a template for in - situ phase reconstruction by a spontaneous phase transformation process in the presence of H 4 SiW under solvothermal conditions. Ultimately, formation of 3D hierarchical flower-like bimetallic nitride nanosheets (SiW 12 @Pd/Co-ZIF-NS) were generated because of this process. The SiW 12 @Pd/Co-ZIF-NS catalyst not only displays excellent catalytic transfer hydrogenolysis for C-O bond cleavage of lignin dimeric substrates, but also maintains superior recycling durability due to an encapsulation phenomenon preventing aggregation. Finally, the resulting nanocomposites exhibit superior activity and good size selectivity toward catalytic transfer hydrogenolysis of the actual lignin substrates to produce a significant amount of low-molecular-weight aromatic compounds .
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2019
·
IF 12.221
Hongji Li,Anon Bunrit,Jianmin Lu,Zhuyan Gao,Nengchao Luo,Huifang Liu,Feng Wang
Depolymerization of lignin meets the difficulty in cleaving the robust aryl ether bond. Herein, through installing an internal nucleophile in the β-O-4′ linkage, the selective cleavage of aryl ether was realized by the intramolecular substitution on aryl rings affording non-phenolic arylamine products. In particular, nitrogen-modified lignin models and lignin samples were employed to generate the iminyl radical under photocatalytic reduction, which acted as the internal nucleophile inducing aryl migration from O to the N atom. The following hydrolysis released primary arylamines and α-hydroxy ketones. Mechanism studies including electron spin resonance (ESR), fluorescence quenching experiments, and density functional theory (DFT) calculations proved the aryl migration pathway. This method enables access to non-phenolic arylamine products from lignin conversion.
研究领域:
化学
·
能源
·
环境科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）