MACROMOLECULAR RESEARCH
·
2021
·Vol. 29
·期 8
·543-550
·
IF 2.227
Sun Chong,Jiang Yehua,Zhang Zhifei,Zhao Shugao,Guo Laina
The preparation and properties of thermoreversible ethylene propylene diene rubber (EPDM) based on reversible Diels-Alder reaction were investigated. The reversible cross-linking ethylene propylene diene rubber was prepared by a two-step method. The EPDM which was grafted with maleic anhydride (MA) was firstly modified by furfurylamine to graft furan groups on rubber backbone, and then crosslinked with bismaleimide (BMI) via a Diels-Alder reaction. At room temperature, thermoreversible cross-linking EPDM exhibited excellent mechanical properties. The molar ratio between BMI and MA was studied, and it was found that too high and too low ratios were not conducive to the formation of high cross-linking density network. When the molar ratio between BMI and MA was 0.9, the cross-linking EPDM had the best mechanical property, with tensile strength of 2.3 MPa and the elongation at break of 312%. The dynamic mechanical analysis and dissolution experiments showed that the reversible Diels-Alder reaction at high temperatures led to the de-crosslinking of rubber networks. Despite the presence of a small number of side effects, the EPDM obtained by Diels-Alder reaction showed a better reshaping ability, and it could be recycled several times.
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CHINESE JOURNAL OF POLYMER SCIENCE
·
2013
·Vol. 31
·期 12
·1613-1622
·
IF 1.27
Zhang Fei-jun,Liu Xiao-hui
Initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) of acrylonitrile was first conducted at various ambient temperatures (30–45 °C). The key to success is ascribed to the usage of an appropriate low temperature radical initiator (2,2′-azobis(2,4-dimethylvaleronitrile)) and a high reactivity catalytic system (CuBr 2 /Me 6 TREN). The molar ratio of Cu catalyst to AN as low as 1:20000 was used to prepare well-defined polyacrylonitrile with controlled molecular weight and a narrow polydispersity index range of 1.08–1.30, while the monomer conversion was up to ca . 98%. The apparent activation energy of the polymerization was calculated to be 128.45 kJ/mol, suggesting that the polymerization strongly depended on reaction temperature. The very high chain-end functionality of the resultant polymer was confirmed by 1 H-NMR and GPC analyses as well as chain extension reaction.
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Science China-Materials
·
2019
·Vol. 63
·期 6
·959-964
·
IF 5.636
Chen Fang,Li Tianbo,Pan Xiaoli,Guo Yalin,Han Bing,Liu Fei,Qiao Botao,Wang Aiqin,Zhang Tao
Heterogenization of the homogeneous catalysis has been studied for almost 50 years. Single-atom catalysis has the advantages of both homo- and heterogeneous catalysis. It has been proposed, and subsequently experimentally verified that single-atom catalysis is able to bridge homo- and heterogeneous catalysis, thus providing a new avenue to realize the heterogenization of homogeneous catalysis. Alkoxycarbonylation of aryl halides is an effective method for the direct synthesis of carboxylic acid derivatives, and is commonly catalyzed by Pd-based homogeneous complexes with N/P-containing ligands and organic/inorganic base. Herein, we firstly reported that Pd 1 /CeO 2 single-atom catalyst showed good performance in the alkoxycarbonylation of aryl iodides reaction. Under base-free and ligand-free conditions, Pd 1 /CeO 2 single-atom catalyst can transfer different aryl iodides to corresponding products. The catalyst can be easily recovered and reused four times without significant loss of reactivity.
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MICROCHIMICA ACTA
·
2018
·Vol. 185
·期 10
·1-9
·
IF 5.705
Xu Shengnan,Chen Ligang,Ma Ling
The authors describe a fluorescent probe for sensitive and selective determination of quercetin, an indicator for the freshness of drinks. The probe consists of silica ball encapsulated graphitic carbon nitride (g-C 3 N 4 ) modified with a molecularly imprinted polymer (MIP). It was synthesized via reverse microemulsion. The resulting MIP@g-C 3 N 4 nanocomposite was characterized by fluorescence spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction. Quercetin quenches the fluorescence of the MIP@g-C 3 N 4 probe. The effect was used to quantify quercetin in grape juice, tea juice, black tea, and red wine by fluorometry (λ exc = 350 nm, λ em = 460 nm). Response is linear in the 10–1000 ng mL −1 quercetin concentration range. The detection limit is 2.5 ng mL −1 , recoveries range between 90.7 and 94.1%, and relative standard deviations are between 2.1 and 5.5%.
Schematic of the synthesis of the MIP@g-C 3 N 4 by a reverse microemulsion method. The probe was applied for the selective recognition and fluorometric determination of quercetin.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2019
·Vol. 30
·期 14
·13636-13646
·
IF 2.195
Liang Honghuo,Sun Tao,Xu Lang,Sun Chaoying,Wang Dewei
Porous carbons with ultrahigh specific surface area (> 3000 m 2 /g) prepared at low KOH/char ratio (e.g. less than 0.5) is of great importance for their future applications, yet this remains a significant challenge due to the uneven dispersion of the activating agent within carbon source. Herein, a universal combination strategy (solid-state reaction at room temperature followed by chemical activation) to prepare ultrahigh surface area porous carbons has been developed. The specific surface area can reach to 3775 m 2 /g even at a very low KOH/char ratio (0.19), and the morphologies, specific surface and pore size distributions of the products can be simply tuned by the KOH/char ratios. We found the solid-state reaction at room temperature prior to chemical activation is an efficient way to achieve the even dispersion of the activating agent and thus improve the utilization of KOH greatly. As a typical example, the as-obtained EDTA-3 K not only have an ultrahigh specific surface area up to 3614 m 2 /g, but also deliver a large total pore volume of 2.09 m 3 /g. Benefited from the ultrahigh specific surface area, hierarchically porous structure and unique morphology, the EDTA-3 K based supercapacitor exhibits excellent capacitive performance in both KOH and Li 2 SO 4 electrolyte. Hence, this study not only exploits a new approach for the synthesis of hierarchically porous carbon materials with ultrahigh specific surface area for electrochemical energy storage applications, but also provides a universal combination strategy to improve the utilization ratio of activating reagent for the producing of porous carbons.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2016
·Vol. 80
·期 3
·675-682
·
IF 1.473
Wang Ting,Song S.-H.,Xu Ting,Wang Meng
Multiferroic BiFeO 3 nanopowders are synthesized through a sol–gel route using the environment-friendly and non-toxic maltose as the complexing and reducing agent. A high content of hydroxyl groups is found to be critical in the preparation of phase-pure BiFeO 3 materials. Fourier transform infrared spectroscopy, thermogravimetric analysis and differential scanning calorimetry reveal that the optimal calcination temperature of BiFeO 3 precursor is about 450 °C in the synthesis, leading to the formation of phase-pure and well-crystallized BiFeO 3 nanopowders with sizes being about 40 nm. Magnetic measurements illustrate the ferromagnetic behavior of BiFeO 3 nanopowders at room temperature. The maximum and remanent magnetizations of the nanopowders are about 0.657 and 0.048 emu/g, respectively, under the magnetic field of 50 kOe. Moreover, the energy band gap of the nanopowders is approximately 2.27 eV, confirming their strong absorbance of the visible light. Graphical
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2014
·Vol. 18
·期 8
·2077-2085
·
IF 2.234
Liu Xiaoyan,Zhu Kunlei,Tian Jianhua,Tang Qiwei,Shan Zhongqiang
A yolk-shell sulfur/carbon (S/C) composite for the cathode of lithium–sulfur batteries was successfully prepared by an accessible method with tetrahydrofuran as solvent. The as-prepared composites are characterized by thermal gravimetric, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption and desorption. In this composite, sulfur particle is encapsulated in the carbon shell even entering into the micropores of carbon Bp2000. The electrochemical performance of the S/C composites is evaluated. The results indicate that the S/C composite with 50 wt% sulfur content shows good reversibility, excellent rate capability, and slow degradation. It delivers an initial capacity of 784.4 mAh g −1 (based on sulfur weight) and preserves at 598.3 mAh g −1 after 195 cycles at 1C. It achieves a high-capacity retention of 76.27 % from the 5th to 200th cycle, and as high as 91.19 % during the latter 150 cycles. The improvement is mainly attributed to the favorable structure of the S/C composite, in which the carbon cannot only facilitate transport of electrons and Li + ions but also trap polysulfides and retard the shuttle effect during charge/discharge process.
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International Journal of Machine Learning and Cybernetics
·
2024
·Vol. 15
·期 12
·5981-6010
·
IF 3.1
Zhang Jinlu,Wei Lixin,Guo Zeyin,Hu Ziyu,Che Haijun
Industrial applications and optimization problems in reality often involve multiple objectives. Due to the high dimensionality of objective space in many-objective optimization problems (MaOPs), the ability of traditional evolution operators to search the optimal region and generate promising offspring sharply decreases. Besides, as the number of objectives increases, it becomes difficult to balance the convergence and diversity of the population. Considering all these facts, this paper proposes a mutation individual position detection strategy. It estimates both individual fitness and diversity contributions, and assigns appropriate positions to individuals in the mutation operator through individual ranking. Then, by introducing an external population to adjust the weight vectors, its maintenance process takes into account the matching information between the population and the weight vectors. By comparing five representative algorithms, numerical experiments have shown that the algorithm can obtain a well distributed final solution set on optimization problems of various objective scales. Moreover, it also demonstrates advantages in generating excellent offspring individuals and balancing the overall performance of the population. In summary, the algorithm has competitiveness in solving MaOPs.
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Scientific Reports
·
2021
·Vol. 11
·期 1
·1-19
·
IF 4.38
Gul Taza,Kashifullah,Bilal M.,Alghamdi Wajdi,Asjad M. Imran,Abdeljawad Thabet
The thermal management of the flow of the hybrid nanofluid within the conical gap between a cone and a disk is analyzed. Four different cases of flow are examined, including (1) stationary cone rotating disk (2) rotating cone stationary disk (3) rotating cone and disk in the same direction and (4) rotating cone and disk in the opposite directions. The magnetic field of strength \(B_{0}\) is added to the modeled problem that is applied along the z-direction. This work actually explores the role of the heat transfer, which performs in a plate-cone viscometer. A special type of hybrid nanoliquid containing copper Cu and magnetic ferrite Fe 3 O 4 nanoparticles are considered. The similarity transformations have been used to alter the modeled from partial differential equations (PDEs) to the ordinary differential equations (ODEs). The modeled problem is analytically treated with the Homotopy analysis method HAM and the numerical ND-solve method has been used for the comparison. The numerical outputs for the temperature gradient are tabulated against physical pertinent variables. In particular, it is concluded that increment in volume fraction of both nanoparticles \(\left( {\phi_{{Fe_{3} O_{4} }} ,\phi_{Cu} } \right)\) effectively enhanced the thermal transmission rate and velocity of base fluid. The desired cooling of disk-cone instruments can be gained for a rotating disk with a fixed cone, while the surface temperature remains constant.
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Scientific Reports
·
2018
·Vol. 8
·期 1
·1-6
·
IF 4.122
Chen Yingying,Lu Hang,Xiu Fei,Sun Tao,Ding Yamei,Liu Juqing,Huang Wei
Building transient electronics are promising and emerging strategy to alleviate the pollution issues from electronic waste (e-waste). Although a variety of transient devices comprising organic and inorganic materials have been described, transient light emitting devices are still elusive but highly desirable because of the huge amount of lighting and display related consumer electronics. Here we report a simple and efficient fabrication of large-area flexible transient alternating current electroluminescent (ACEL) device through a full-solution processing method. Using transparent flexible AgNW-polymer as both electrodes, the devices exhibit high flexibility and both ends side light emission, with the features of controlled size and patterned structure. By modulating the mass ratio of blue and yellow phosphors, the emission color is changed from white to blue. Impressively, the fabricated ACEL device can be thoroughly dissolved in water within 30 min. Our strategy combining such advances in transient light emitting devices with simple structure, widely used materials, full solution process, and high solubility will demonstrate great potential in resolving the e-waste from abandoned light-emitting products and expand the opportunities for air-stable flexible light emitting devices.
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Journal of Coatings Technology and Research
·
2024
·Vol. 21
·期 4
·1333-1342
·
IF 2.3
Wei Haoran,Liu Henghui,Li Min,Fu Zhinan,Liu Liqun,Zhang Hanjie,Fan Chuanjie,Xu Jun,Wang Jie
Polydimethylsiloxane (PDMS) has been widely used to improve the antifouling properties of polyurethane (PU) coatings due to its low surface energy. Herein, a novel type of waterborne polyurethane (WPU) coating with good antifouling and self-healing abilities was synthesized by incorporating PDMS and disulfide bonds. The effects of PDMS and the disulfide content on the thermal, mechanical and surface properties of the coatings were investigated. Benefiting from a rational structural design, the obtained WPU coating manifested superior antifouling properties. In addition, the WPU coating exhibited good healing capabilities owing to the collaboration between dynamic disulfide bonds. Interestingly, the self-healing of an experimental crack occurred at a temperature above 60°C, and the coating recovered its mechanical properties to 95%. This finding has great significance for the design of multifunctional smart coatings for diverse applications.
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CHROMATOGRAPHIA
·
2023
·Vol. 86
·期 7
·541-551
·
IF 1.7
Guo Xinyuan,Shang Panpan,Wei Benben,Du Wenrong,Lan Yong,Bai Ligai,Qiao Xiaoqiang,Ma Zhengyue
This study presents the development of three new chiral stationary phases. Three new peptide chiral stationary phases with a main chain of l- proline, l- phenylalanine, l- valine and l- leucine and different terminals of l- citrulline, l- lysine and l- tryptophan immobilized on 3-aminopropyltrimethoxysilane modified silica gel were prepared; furthermore, successful analyses and characterizations were conducted using Fourier transform infrared spectra, elemental analysis, and thermogravimetric analysis. After this, the enantioselective performance of the three peptide stationary phases columns was evaluated. The evaluation used nine racemic compounds under normal-phase high-performance liquid chromatography mode. Optimized enantiomeric separation conditions were established. Under these conditions, the resolutions of flurbiprofen, naproxen, benzoin, 1 ,1ʹ-bi-2-naphthol and ketoprofen on the CSP-1 column were 1.61, 2.0, 0.62, 0.52 and 1.20, respectively. In addition, the reproducibility of the CSP-1 column was also investigated. The results of the investigation illustrated that the stationary phases have good reproducibility (RSD = 0.12%, n = 5).
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危险品化学品经营许可证（带存储）