Nano Research
·
2019
·Vol. 12
·期 4
·823-827
·
IF 8.515
Yang Peng,Yang Ai-Guo,Chen Lingxiu,Chen Jing,Zhang Youwei,Wang Haomin,Hu Laigui,Zhang Rong-Jun,Liu Ran,Qu Xin-Ping,Qiu Zhi-Jun,Cong Chunxiao
Chemical vapor deposition (CVD) is the most efficient method to grow large-area two dimensional (2D) transition metal dichiacogenides (TMDCs) in high quality. Monolayer molybdenum disulfide (MoS 2 ) and seed-assistant are the mostly selected 2D TMDC and growth strategy for such CVD processes, respectively. Though the advantages of seed catalysts in facilitating the nucleation, achieving higher yield and better repeatability, as well as their effects on the morphologies of as-grown MoS 2 have been studied, the influence of seeding promoters on both optical and electrical properties of as-grown monolayer MoS 2 is not known comprehensively, which is indeed critical for understanding fundamental physics and developing practical application of such emerging 2D semiconductors. In this report, we systematically investigated the effect of different seeding promoters on the properties of CVD-grown monolayer MoS 2 . It is found that different seed molecules lead to different impacts on the optical and electrical properties of as-grown monolayer MoS 2 . Among three different seed catalysts (perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS), copper phthalocyanine (CuPc), and crystal violet (CV)), PTAS performs better in obtaining large area monolayer MoS 2 with good optical quality and high electrical mobility than the other two. Our work gives a guide for modifying the properties of as-grown monolayer MoS 2 and other 2D transition metal dichalcogenides in seeding promoters-assisted synthesis process.
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高影响因子
Journal of the Iranian Chemical Society
·
2020
·Vol. 17
·期 9
·2379-2384
·
IF 1.552
Liang Zhengyong,Wei Tong,Xie Jun,Li Hua,Liu Hui
In this study, continuous ozonolysis of terminal alkenes in a rotating zigzag bed was developed. Rotating zigzag bed is a new type high gravity unit relative to the previous rotating packed bed and can intensify mass transfer remarkably. The rotating zigzag bed takes advantage of centrifugal force to mix liquid and gas phase effectively. The H 2 O in acetone acts as an in situ reducing agent for the carbonyl oxide intermediate, providing aldehydes directly from the reaction mixture. Critical factors were investigated and achieved optimum reaction conditions. Under these conditions, the yields of series aldehydes ranged from 72.3 to 95.8%. The discrepancy in product yields among different olefin substrates likely originates from the electronic stability of the carbonyl oxide intermediate, which is longer lived for aryl olefines with electron donor group and longer carbon chain alkene (C n H 2 n , n ≥ 10).
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 21
·18036-18044
·
IF 2.324
Hu Querui,Wang Yiping,Wu Lei,Yin Jiang,Chen Lang,Yuan Guoliang,Yang Ying
Piezoelectric ceramics x LiNbO 3 – y BiScO 3 –(1− x − y )PbTiO 3 (LN–BS–PT, 0.00 ≤ x ≤ 0.10, 0.30 ≤ y ≤ 0.36) were synthesized and their phase diagram and morphotropic phase boundary between rhombohedral and tetragonal phases have been confirmed. The optimal properties were found at the composition of 0.03LN–0.36BS–0.61PT with piezoelectric coefficient d 33 * value of 702 pm/V, d 33 of 551 pC/N, planar electromechanical coupling factor k p of 0.51, remnant polarization P r of 46.5 µC/cm 2 , Curie temperature T c of 337 °C, and a large strain of 0.351% at an electric field of 50 kV/cm and frequency of 2 Hz with a low strain hysteresis of 5.9%. The Curie temperature of the ternary system presents a linear relationship with LiNbO 3 and BiScO 3 contents. The optimization of these electric properties was probably ascribed to the enhancement in domain walls and the improving mobility of domain switching due to LiNbO 3 doping.
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高影响因子
CELLULOSE
·
2021
·Vol. 28
·期 11
·7213-7225
·
IF 5.044
Zhang Jing,Bao Yan,Guo Mingyuan,Peng Zhenghua
Poor water solubility of cellulose acetate is a key factor limiting its application in leather finishing field. Herein, a self-emulsifying aqueous emulsion was synthesized by using cellulose diacetate (CDA) as the substrate, dimethylolbutyric acid (DMBA) as the hydrophilic agent, and hexamethylene diisocyanate (HDI) as the bridging agent. Because the flexible carbon chain of HDI has the advantages of easy bending and deformation, the problem of large steric hindrance and low reactivity of -OH during water-based CDA can be solved by using the method of converting reactive functional groups and transferring reactive sites. At the same time, the flexible molecule 1,4-butanediol (BDO) and propylene glycol polyether (N210) are used as chain extenders to increase the molecular stretch and curl ability by adjusting the ratio of molecular soft and hard segments, and improve emulsion stability and coating flexibility. And through the reaction of -NH 2 and -NCO on the surface of nano SiO 2 modified by KH550, the nano SiO 2 is evenly distributed in the CDA water-based polymer to improve the comprehensive performance of the emulsion coating. Thus the nano-SiO 2 modified cellulose acetate water-based polymer emulsion (SiO 2 /WCDA) is obtained for leather finishing. The emulsion particles show an oil-in-water (O/W) core–shell structure, and the average particle size and dispersion coefficient (PDI) of the particles are 88.79 nm and 0.150, respectively. The surface of the coating film is compact, flat, and hydrophobic, with the contact angle is 104.3 °. In addition, the coating film has good adhesion, water resistance, heat resistance, yellowing resistance, chemical resistance, flexibility and mechanical properties.
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高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
·
2019
·Vol. 50
·期 10
·4827-4838
·
IF 1.985
Liu Jun-Kai,Zhang Guo-Hua,Sun Guo-Dong
We propose a process to produce ultrafine W-10 wt pct Cu composite powders by reducing the mixtures of copper tungstate (CuWO 4 ) and tungsten trioxide (WO 3 ) (from the calcination of a mixture of ammonium paratungstate and copper nitrate trihydrate) with carbon black and hydrogen. First, ultrafine pre-reduced tungsten-copper (W-Cu) powders containing a small amount of WO 2 were produced by reducing mixtures of CuWO 4 and WO 3 with insufficient carbon black; then the obtained products were further reduced by hydrogen to remove the residual oxygen. This method provides a simple and low-cost route to prepare ultrafine W-10 wt pct Cu composite powders. The composite powders were sintered at different temperatures [1323 K (1050 °C), 1373 K (1100 °C), 1423 K (1150 °C), 1473 K (1200 °C), and 1523 K (1250 °C)] for 3 hours. A maximum densification of the obtained compact was achieved at a sintering temperature of 1523 K (1250 °C), with a relative density, Vickers hardness and thermal conductivity of the W-10 wt pct Cu composites of 97.8 pct, 365 HV and 165 W/m K, respectively.
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OPTICAL AND QUANTUM ELECTRONICS
·
2021
·Vol. 53
·期 10
·1-8
·
IF 2.084
Li Chunfang,Zhang Hongyan,Xue Qihao,Li Dongxiang
Azobenzene compounds have been widely used in many fields and through their response to light they can be used to regulate the properties of ordered structures. In this paper, sub-micrometer colloidal SiO 2 spheres were prepared and azobenzene groups were grafted on the surface of SiO 2 microspheres. The SiO 2 microspheres grafted with azobenzene groups could self-assemble to form photosensitive photonic crystals, whose photonic bandgaps red-shifted as irradiated by UV light due to the structure change of the azobenzene groups.
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高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-12
·
IF 14.7
Cui Zhuangzhuang,Jia Zhuangzhuang,Ruan Digen,Nian Qingshun,Fan Jiajia,Chen Shunqiang,He Zixu,Wang Dazhuang,Jiang Jinyu,Ma Jun,Ou Xing,Jiao Shuhong,Wang Qingsong,Ren Xiaodi
Constraining the electrochemical reactivity of free solvent molecules is pivotal for developing high-voltage lithium metal batteries, especially for ether solvents with high Li metal compatibility but low oxidation stability ( <4.0 V vs Li + /Li). The typical high concentration electrolyte approach relies on nearly saturated Li + coordination to ether molecules, which is confronted with severe side reactions under high voltages ( >4.4 V) and extensive exothermic reactions between Li metal and reactive anions. Herein, we propose a molecular anchoring approach to restrict the interfacial reactivity of free ether solvents in diluted electrolytes. The hydrogen-bonding interactions from the anchoring solvent effectively suppress excessive ether side reactions and enhances the stability of nickel rich cathodes at 4.7 V, despite the extremely low Li + /ether molar ratio (1:9) and the absence of typical anion-derived interphase. Furthermore, the exothermic processes under thermal abuse conditions are mitigated due to the reduced reactivity of anions, which effectively postpones the battery thermal runaway.
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高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2014
·Vol. 32
·期 5
·531-539
·
IF 1.42
Xing Xin-ming,Liu Guang-ming,Ding Yan-wei,Zhang Guang-zhao
The lower critical solution temperature (LCST) behavior of poly(acrylamide- co -diacetone acrylamide) (poly(AM- co -DAM)) copolymer in aqueous solutions was studied. The results demonstrate the LCST linearly decreases as the molar fraction of DAM ( f
DAM ) increases. In the range of f
DAM < 0.36, the transmittance increases as f
DAM decreases because the more hydrophilic copolymer chains can form looser aggregates with a lower refractive index. The transmittance exhibits a minimum when f
DAM is less than 0.28 as the chains form micelle-like structure with a size smaller than the wavelength. The LCST decreases with the initial polymer concentration, but it levels off when the polymer concentration is high enough. Moreover, no hysteresis can be observed in the change of transmittance during the heating-cooling process because no additional hydrogen bonds are formed in the collapsed state due to the steric hindrance of the large side groups in DAM units.
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高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2021
·Vol. 39
·期 9
·1211-1216
·
IF 3.603
Xiang Ming-Yue,Lyu Dong,Liu Ling-Zhi,Men Yong-Feng
Crystallinity of bottlebrush polymers due to side chain crystallization has been considered to be related to the length of the side chains only under the assumption of complete participation of crystallization by all side chains. Recent experimental results revealed that in poly( n -alkyl methacrylate)s a fraction of side chains could not crystallize due to constraints imposed by the trapped main chain entanglements and required expansion of main chain-main chain distance. This result renders the original simplified consideration of the origin of crystallinity in bottlebrush polymers questionable. In this work, we introduce a new parameter f c , the fraction of crystallizable side chains, to better describe the crystallinity of bottlebrush polymers. A linear relationship between the melting enthalpy and the number of alkyl groups in side chains for bottlebrush polymers reported repeatedly indicates that f c remains essentially unchanged when bottlebrush polymers had the same main chain structure and grafting degree but different side chain lengths. The slope of the above-mentioned linear relationship is thus \(\Delta H_{\text{CH}_2}\times f_{c}\) , where \(\Delta H_{\text{CH}_2}\) stands for the melting enthalpy of one mole alkyl group packed into the crystal. With a known value of f c , it is possible to estimate the value of \(\Delta H_{\text{CH}_2}\) . In case of poly( n -alkyl methacrylate)s, we estimated \(\Delta H_{\text{CH}_2}\) of hexagonal crystal being at most 5.74 kJ/mol with the knowledge of possibly smallest f c of 0.67 obtained from small angle X-ray scattering data. Therefore, the crystallinity of bottlebrush polymer would be calculated based on the equation \(X_{\rm{c}}=f_{\rm{c}}\times\frac{N_{\rm{c}}}{N}\) with N and N c being the number of alkyl groups in a side chain and those packed in the crystalline structure, respectively. Both chemical structure and grafting degree of bottlebrush polymers affect f c .
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高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2015
·Vol. 26
·期 11
·8413-8420
·
IF 1.569
Tian Jiao,Ma Qianli,Dong Xiangting,Yang Ming,Yang Ying,Wang Jinxian,Yu Wensheng,Liu Guixia
The flexible color-tunable [Eu(BA) 3 phen + Tb(BA) 3 phen]/PMMA composite nanobelts have been fabricated by single axial electrospinning. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and fluorescence spectroscopy were used to characterize the final products. As-prepared nanobelts are almost uniform and the thickness and width of them are respectively ca. 890 nm and 16.6 ± 0.09 μm. The fluorescence intensity of Eu 3+ is increased with adding more Eu(BA) 3 phen into the composite nanobelts, and the fluorescence intensity of Tb 3+ is found to increase monotonically with introducing more Tb(BA) 3 phen into the composite nanobelts. By adjusting the ratio of Eu(BA) 3 phen to Tb(BA) 3 phen complexes, the fluorescence color of composite nanobelts can be tuned from red to yellow, yellow green, and green under the excitation of 290-nm single-wavelength ultraviolet light. Besides, the emission color could also be tuned easily from red to yellow, yellow to green via variation of excitation wavelengths. The novel color-tunable composite nanobelts have potential applications in the fields of color displays and sensor systems.
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高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2021
·Vol. 36
·期 9
·1835-1845
·
IF 3.089
Chen Changsong,Wu Yihua,Zhu Zhi-Gang,Shih Wan Y.,Shih Wei-Heng
Abstract All-inorganic perovskite materials have many advantages such as adjustable emission range, narrow emission peaks, and good crystallinity, which have attracted widespread interest. They can be used as solar cells, LEDs, photodetectors, displays, and other optoelectronic devices. However, poor environmental stability is the major factor limiting its applications. We introduced a Poly(styrene-ethylene-butylene-styrene) SEBS polymer to create perovskite/SEBS composite films which have excellent stability even in the water environment. Besides, due to the elastic nature of SEBS, the composite films exhibited good mechanical deformability and could maintain most of its fluorescence intensity after being stretched hundreds of times. A WLED device was constructed by stacking CsPbBr 3 /SEBS films and CsPbI 3 /SEBS films over a blue LED. The WLED performed well with color rendering index of 82.6 with chromaticity coordination (0.35, 0.36) and color temperature 4784 K. Graphic Abstract
In order to create a stable and flexible photoluminescent material, we combined a
poly(styrene-ethylene-butylene-styrene) (SEBS) polymer and cesium lead-halide
nanocrystals forming a flexible photoluminescent composite. The composite films
show both good environment stability and excellent flexibility.
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CELLULOSE
·
2018
·Vol. 25
·期 2
·1499-1511
·
IF 3.809
Chen Yong,Zhang Qiang,Ma Yijia,Han Qiuxia
Most research efforts focus on synthesis of new biocides. This study shows that orientating biocidal groups on top surface with the help of a low-surface-tension constituent also imparts enhanced antibacterial ability. A CO 2 -philic biocidal silicone with pyridinium pendants was synthesized by hydrosilylation reaction of (45% methylhydrosiloxane)–dimethylsiloxane random copolymer (P(MHS–DMS)) and 4-vinylpyridine and subsequent quaternization of pyridine groups with 6-perfluorooctyl-1-bromohexane. The fluorinated pyridinium silicone was impregnated into cotton yarns in supercritical CO 2 to form a 50 nm thickness biocidal layer at 24 MPa and 50 °C. Pyridinium groups preferentially segregated to the top surface with the aid of low-surface-tension perfluorooctyl segments and provided higher biocidal efficacy against Staphylococcus aureus and Escherichia coli compared to their counterparts that were quaternized with 1-bromohexane at similar total pyridinium content of about 4.65 × 10 16 /cm 2 . The synthesis and coating results were characterized by FTIR, SEM, and XPS. The stabilities of fluorinated pyridinium silicone layer toward washing cycles, UV irradiation, and storage were good. The presented strategy uses environmentally benign CO 2 as solvent and affords a general method to functionalize polymers for improved biocidal capability due to the surface orientation of pyridinium groups.
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高影响因子
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