NEW JOURNAL OF CHEMISTRY
·
2021
·Vol. 45
·期 35
·15892-15900
·
IF 3.591
Shengjie Guan,Fan Wu,Qian Wu,Zhichao He,Jing Jiang,Yudong Huang,Li Liu
A series of new types of modified hydrosilanes were synthesized, using hydrosilanes and nitrogen heterocycles (triethoxysilane, 2-aminopyrimidine, 1,2,4-triazin-3-amine, benzylamine and 2-aminobenzothiazole), by Si–N cross-dehydrocoupling catalyzed by Ru3CO12. The results of the synthesis were then demonstrated by 1H nuclear magnetic resonance and GPC testing. Furthermore, modified silicone resins were obtained by a hydrolytic condensation reaction catalyzed by tetramethylammonium hydroxide and characterized by TGA, DSC and FT-IR. Next, excellent thermal stabilities were determined (best initial decomposition temperature was approximately 400 °C, T95% was 595 °C, the mass residue rate at 800 °C was 87.2%). Carbon fiber reinforced silicone matrix composites were manufactured according to the technical process developed using DSC and rotary viscometer test results, and the mechanical property (ILSS) showed great improvement from 34.8 to 45.8 MPa because of the modification of Si–N cross-dehydrocoupling. After pyrolysis up to 1000 °C, the composites still showed a superior ILSS value (19.6 MPa) and the modified silicone resins had a more regular and rounded microstructure and appeared to have ceramic-like particles of Si3N4. This work indicated that the silicone resin (Si–N) modified by cross-dehydrocoupling had greater competitiveness in the field of resin matrix composites.
研究领域:
材料科学
·
化学工程
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DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2017
·Vol. 35
·期 10
·1268-1275
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IF 1.692
Peng Xin,Liu Tian-qi,Shang Cong,Jiao Chen,Wang Hui-liang
Simple preparation of stimuli-responsive hydrogels with good mechanical properties and mild stimuliresponsiveness is essential for their applications as smart soft robots. Mechanically strong Janus poly( N -isopropylacrylamide)/graphene oxide (PNIPAM/GO) nanocomposite hydrogels with stimuli-responsive bending behaviors are prepared through a simple one-step method by using molds made of a Teflon plate and a glass plate. Residual oxygen in the air bubbles on the Teflon plate surface affects the polymerization and hence the cross-linking density, leading to the different swelling/deswelling rates of the two sides of the gels. Therefore, the hydrogels exhibit bending/unbending behaviors upon heating/cooling in water. The incorporation of GO nanosheets dramatically enhances the mechanical properties of Janus hydrogels. Meanwhile, the photo-responsive property of the GO nanosheets also imparts the hydrogels with remotecontrollable deformation under IR irradiation. The application of the Janus PNIPAM/GO hydrogels as thermo-responsive grippers is demonstrated.
研究领域:
材料科学
·
智能材料
·
生物医学工程
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DOI
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2019
·Vol. 166
·期 15
·B1491
·
IF 3.12
Xiaoying Liu,Wenbin Li,Tianqin Zeng,Silu Zhang,Bijing Zhou,Muyi Li,Peng Zhao,Chang Peng
Heteroatom doped carbon materials have attracted intense attention in constructing electrochemical sensors because of their outstanding electrocatalytic performance. Up to now, most of the researches were focused on the electrochemical application of single heteroatom doped carbon microspheres. In this work, N, P-co-doped carbon microspheres (NP-CMs) modified electrode was developed as highly sensitive electrochemical sensor for acetaminophen. NP-CMs were acquired by the calcination of products from the one-pot reaction of dopamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Experimental results revealed that NP-CMs showed better electrocatalytic performance compared with N-doped carbon microspheres. Under the optimal conditions, the response of NP-CMs/GCE showed a linear relationship with acetaminophen concentration from 0.07 μM to 30 μM, the linear equation was Y = 0.01356X+0.7417 and the detection limit was 40 nM (S/N = 3). The recoveries of the NP-CMs modified GCE for the assay of acetaminophen in human serum samples were from 94.0% to 106.0%. It was believed that N, P-co-doped carbon microspheres have a great potential in the design of novel pharmaceutical analysis methods.
研究领域:
分析化学
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材料科学
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药学
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DOI
高影响因子
Catalysts
·
2019
·Vol. 10
·期 1
·10
·
IF 3.444
Wan-Qiang Wang,Hua Cheng,Ye Yuan,Yu-Qing He,Hua-Jing Wang,Zhi-Qin Wang,Wei Sang,Cheng Chen,Francis Verpoort
The transition-metal-catalyzed alcohol dehydrogenation to carboxylic acids has been identified as an atom-economical and attractive process. Among various catalytic systems, Ru-based systems have been the most accessed and investigated ones. With our growing interest in the discovery of new Ru catalysts comprisingN-heterocyclic carbene (NHC) ligands for the dehydrogenative reactions of alcohols, we designed and prepared five NHC/Ru complexes ([Ru]-1–[Ru]-5) bearing different ancillary NHC ligands. Moreover, the effects of ancillary and additional ligands on the alcohol dehydrogenation with KOH were thoroughly explored, followed by the screening of other parameters. Accordingly, a highly active catalytic system, which is composed of[Ru]-5combined with an additional NHC precursorL5, was discovered, affording a variety of acid products in a highly efficient manner. Gratifyingly, an extremely low Ru loading (125 ppm) and the maximum TOF value until now (4800) were obtained.Keywords:ruthenium (Ru);N-heterocyclic carbenes (NHCs);carboxylic acids;ancillary ligands;additional ligands
研究领域:
化学
·
催化反应
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DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 84
·68972-68980
·
IF 3.84
Quanqing Zhang,Qinghe Zhang,Zhichao Xiong,Hao Wan,Xiaoting Chen,Hanfa Zou
Highly selective and efficient enrichment of glycans from complex biological samples is of great significance for the discovery and diagnosis of disease via identifying the related biomarkers. Mesoporous carbon materials were widely employed for the selective enrichment of glycans due to the strong interactions between carbon and glycans. In this study, novel carbon-functionalized ordered magnetic mesoporous silica composites (denoted as Fe3O4@3SiO2@mSiO2–C) with a core–shell structure, high carbon content, excellent hydrophilic property and unique magnetic character were designed and synthesized. A strategy involving CTAB as the mesoporous structure-directing agent and the carbon precursor during in situ carbonization was proposed. Besides, a compact silica layer with adequate thickness was essential to protect the magnetic core during the sulphonation process in further high-temperature calcination. As a result, the obtained Fe3O4@3SiO2@mSiO2–C composites exhibited a high carbon content (25%) with graphite structure, rapid magnetic separation (within 10 s), large pore volume (0.257 m3 g−1), high BET surface area (269.14 m2 g−1) and a well-ordered mesostructure (3.39 nm). In addition, a strong magnetic response with a saturation magnetization value (59.8 emu g−1) has been confirmed. By taking the advantage of the special interaction between the carbon and glycans, the size-exclusion ability and highly hydrophilic as well as unique magnetic properties, the Fe3O4@3SiO2@mSiO2–C composites exhibit satisfying enrichment ability in glycomic analysis. Better selectivity and efficiency than active carbon have been confirmed. Furthermore, 42 N-linked glycans with sufficient peak intensities were obtained from human serum after treatment with the Fe3O4@3SiO2@mSiO2–C composites, showing great potential as a tool for the enrichment and detection of glycans in biological samples.
研究领域:
分析化学
·
生物医学
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DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2020
·
IF 7.489
Hui Xue,Ziqing Zhao,Rui Chen,John L. Brash,Hong Chen
Hypothesis : Poly( N -isopropylacrylamide) microgels are used extensively in the design of drug carriers, surfaces for control of cell adhesion, and optical devices . Particle size is a key factor and has a significant influence in many areas. Experiments : In this work, precise control of the particle size of poly( N -isopropylacrylamide) microgels was achieved by controlling the separation distance of the poly( N -isopropylacrylamide) chains. Dibromoalkanes of different size were used as an adjustable “molecular ruler” to measure molecular dimensions in poly( N -isopropylacrylamide) nanoaggregates at the critical crosslinking temperature. Findings : We find that the chain separation distance decreases as the temperature increases with a sharp decrease over the 55-to-65 °C interval. Based on the observed relationships between chain separation and crosslinker, the particle size of poly( N -isopropylacrylamide) microgels can be regulated by changing the length of the “molecular ruler” (crosslinker) at the same temperature. Furthermore, for partly crosslinked poly( N -isopropylacrylamide) microgels that contain free crosslinkable sites, the particle size can be reduced still more by further crosslinking (“re-crosslinking”) with crosslinkers of different size. It is shown that the particle size can be regulated by adjusting the length of “molecular ruler” and the degree of crosslinking. This work provides a “molecular level” method for precise control of poly( N -isopropylacrylamide) microgel particle size.
研究领域:
材料科学
·
生物医学工程
·
纳米技术
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DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2013
·
IF 5.787
Lin Guo,Yu Fan,Xiaojun Bao,Gang Shi,Haiyan Liu
Silicoaluminophosphate (SAPO-11) samples with enhanced acidity were synthesized by two-stage crystallization in the presence of dodecyltrimethylammonium bromide (DoTAB), in which the Si source was added after the aluminophosphate framework was formed. The structure, elemental composition, acidity, Si environment, and n-octane di-branched isomerization of the as-synthesized SAPO-11 with small crystallites were investigated. The results showed that compared with the conventional one-stage crystallization, the two-stage crystallization produced more Si borders in the resulting SAPO-11. Among the SAPO-11 samples synthesized by two-stage crystallization, the SAPO-11 with the optimal DoTAB content (mol(DoTAB)/mol(SiO 2 ) = 0.015) had the most Si( n Al) (0 < n < 4) species with moderate and strong Brønsted acidity. The catalyst based on the small crystallite SAPO-11 containing a greater number of moderate and strong Brønsted acid sites exhibited superior performance for n-octane di-branched isomerization. This two-stage DoTAB-assisted crystallization opens a new route to enhancing the SAPO-11 acidity and can be extended to the other SAPO molecular sieves.
研究领域:
化学工程
·
催化科学
·
材料科学
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DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2015
·
IF 2.587
Mengshuai Liu,Bo Liu,Shifa Zhong,Lei Shi,Lin Liang,Jianmin Sun
In this contribution, a series of N-heterocyclic compounds cooperated with ZnBr2 catalyst for chemical fixation of CO2 to cyclic carbonates was developed without utilization of additional organic solvents. It was found that the catalytic activity of N-heterocyclic compounds could be obviously enhanced in the presence of ZnBr2, and the N-methylimidazole (Mim)/ZnBr2 catalytic system was the most efficient among the catalysts employed. Under the optimum reaction conditions, 99% yield of propylene carbonate was achieved with TOF of 474 h–1, and the catalysts were also versatile for CO2 cycloaddition with less active epoxides such as styrene oxide and cyclohexene oxide. Furthermore, a possible synergistic catalytic mechanism was proposed. Moreover, the rate constants were determined as a function of reaction temperature in the range of 130–160 °C, the activation energy was determined to be 41.1 kJ·mol–1, and the kinetic equation on the synthesis of propylene carbonate catalyzed by Mim/ZnBr2 was also obtained.
研究领域:
化学工程
·
催化化学
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DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 73
·59286-59291
·
IF 3.84
Shifeng Li,Min Xing,Haiyan Wang,Li Zhang,Yiman Zhong,Lei Chen
In this work, water-soluble ZnS quantum dots (QDs) modified with 3-mercaptopropionic acid (MPA), L-cysteine (L-Cys) and thioglycolic acid (TGA) were synthesized. The nanostructure and optical properties were characterized by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), UV-Vis absorption spectrum and fluorescence spectrum. Through the study of the ZnS QDs effects on the chemiluminescence (CL) system of luminol, we found that ZnS QDs could obviously enhance the CL of the luminol–N-bromosuccinimide (NBS) system in an alkaline medium. At the optimal experimental conditions, we researched the impact of 17 kinds of amino acids on this system. It was found that L-tryptophan (Trp) and L-tyrosine (Tyr) had significantly inhibitory effects on luminol–NBS–ZnS QDs CL. Based on the inhibitory effects, a novel CL method with a wider linear range and lower detection limit for determination of Trp and Tyr was developed. The detection limits were 1.5 × 10−11 g mL−1 and 2.0 × 10−10 g mL−1, respectively. The possible CL reaction mechanism was also discussed briefly.
研究领域:
分析化学
·
生物化学
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DOI
高影响因子
PHYSICS OF FLUIDS
·
2021
·Vol. 33
·期 2
·
IF 3.521
Zhao Wenjing,Ma Hongzhi,Ji Wenjie,Li Weibin,Wang Jin,Yuan Quanzi,Wang Yuren,Lan Ding
Flows of thin fluid layers spreading, which have a distinguished history, have been studied since the days of Reynolds, who was among the early researchers to examine flows. Different from surfactant-driven spreading, which is currently the most common subject of study, we observe the spreading process of n -hexadecane driven by volatile silicone oil at the surface of the aqueous substrates and explore the influence of Marangoni flow caused by surface tension gradient on liquid-driven spreading. We find that on different substrates, the initial state of n -hexadecane is different, and there are two instability patterns during the spreading, subsequently, which are analyzed theoretically. While the n -hexadecane drop stationed on the liquid surface is small, it is driven to form a rim and then breaks up into beads, which shows the Rayleigh–Plateau instability patterns. When we put the n -hexadecane drop on the surface of the saturated sodium chloride solution, which spreads out more, it is driven to form a circular belt first and fingering instability subsequently occurs at the inner edge of the circular belt.
研究领域:
流体力学
·
物理化学
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DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL PHYSICS
·
2018
·Vol. 31
·期 6
·789-798
·
IF 0.586
Wang Xiao-yan,Fan Hai-yan,Ye Xiao-dong,Liu Shi-lin,Zhang Guang-zhao
Two narrowly-distributed poly( N - isopropylacrylamide) (PNIPAM) samples were prepared via atom transfer radical polymerization (ATRP) with a novel dansyl functionalized initiator. The other end of the PNIPAM was functionalized by dabcyl group via click reaction. From the static fluorescence measurements, the fluorescence intensity of dansyl group and energy transfer efficiency between dansyl and dabcyl groups increased when the temperature increased from 36 °C to 45 °C, indicating that the microenvironment surrounding dansyl became hydrophobic and the distance between dansyl and dabcyl decreased. The kinetics of the conformational change of the dye-labeled PNIPAM was studied by a home-made laser-induced temperature jump device with fluorescent measurement. Our results revealed that the characteristic transition time was 3.8 and 5.8 ms for PNIPAM with degrees of polymerization of 85 and 142, respectively, indicating that the characteristic transition time was related to the chain length. Besides, characteristic transition time for the change of the energy transfer efficiency was 2.9 ms for PNIPAM with the degree of polymerization of 85, suggesting that the energy transfer efficiency change was faster than the fluorescence intensity change of dansyl group.
研究领域:
高分子化学
·
生物物理学
✓ 已验证
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2021
·
IF 6.901
He-Qiang Chang,Guo-Hua Zhang,Kuo-Chih Chou
Electrochemical water splitting is considered a sustainable route for the hydrogen industry. In this work, Mo 2 C/MoC heterostructure supported on N -doped carbon (Mo 2 C/MoC@NC) was prepared via a carbonization strategy. For the product (Mo 2 C/MoC@NC-1-2) fabricated with a g-C 3 N 4 / ammonium molybdate tetrahydrate molar ratio of 1:2 at 700 °C under 10%CH 4 /H 2 atmosphere, a high stability and good HER activity with a η 10 of 113 mV in 1M KOH were achieved. To further enhance the catalytic performance of the synthesized Mo 2 C/MoC@NC, the phosphating strategy was proposed for the preparation of Mo 2 C/MoC/MoP heterostructure supported on N-doped carbon (Mo 2 C/MoC/MoP@NC). When the precursor Mo 2 C/MoC@NC-1-2 was phosphated at 650 °C with a heating rate of 5 °C min −1 and kept for 0 min, the as-synthesized Mo 2 C/MoC/MoP@NC-650-0 exhibits good HER catalytic activity with a pretty low η 10 of 78 mV, a j 0 of 0.398 mA cm −2 , and a Tafel slope of 52 mV dec −1 in 1M KOH. This good activity of HER can be ascribed to the N-doped carbon as substrate and the construction of transition metal-based heterostructures.
研究领域:
材料科学
·
电化学
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DOI
高影响因子
危险品化学品经营许可证（带存储）