Molecular Catalysis
·
2020
·
IF 3.687
Wei Peng,Jianmei Xie,Junying Zhang,Xia Yang,Aihua He
The isoprene polymerization kinetics by using TiCl 4 /MgCl 2 type Ziegler-Natta catalysts (TMC) with different titanium contents were studied for better understanding the possible active-specie structures of heterogeneous Ziegler-Natta (Z-N) catalysts for conjugated diene polymerizations. The catalytic features including the catalytic activity (CA), number of active centers ([C*]/[Ti]), rate constant for polymerization (k p ), stereoregularity of these TMC catalysts were studied. The low titanium content catalyst TMC-1 (Ti = 0.09 wt.%) with more isolated mononuclear titanium species showed higher CA and yielded cis-1,4-/trans-1,4- mixed microstructure polyisoprene with low molecular weight ( M w ) in the initial polymerization stage. The medium high titanium content catalyst TMC-2 (Ti = 2.38 wt.%) with more clustered mononuclear titanium species showed lower CA and yielded cis-1,4-/trans-1,4- mixed microstructure polyisoprene with high M w in the early stage of polymerization. The high titanium content catalyst TMC-3 (Ti = 3.76 wt.%) presented lowest CA and yielded high trans-1,4- polyisoprene with higher M w .
研究领域:
高分子化学
·
催化化学
·
聚合物合成
·
材料科学
·
配位聚合
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Mengyi Wang,Li Yin,Mingqi Li,Shaohua Luo,Chao Wang
To develop low-cost, high-capacity and long-life anode materials for lithium-ion batteries, glucose-C and F-doped C coated SiO composites with adjustable pore structure (p-SiO@gl-C@F-doped C) are synthesized by facile and scalable methods. The combination of the heterogeneous dual-carbon shells and porous structure significantly promotes the reaction kinetics of the electrode, effectively suppresses and buffers the volume expansion of SiO, and largely enhances the stability of solid electrolyte interface of the electrode. In a half cell, the optimized p-SiO@gl-C@F-doped C (7:3) composite shows a stable discharge capacity of 785 mAh g −1 at a current density of 200 mA g −1 . The discharge capacity is maintained at 772 mAh g −1 after 200 cycles. At a current density of 400 mA g −1 , the electrode shows a discharge capacity of 633 mAh g −1 after 500 cycles, with a capacity degradation of ∼0.0096% per cycle from the 2nd cycle to the 500th cycle. The full cell which is composed of the commercial LiFePO 4 as a cathode and the optimized composite as an anode, exhibits high capacity and good cycling stability.
研究领域:
材料科学
·
电化学
·
能源存储
·
纳米复合材料
·
电池技术
✓ 已验证
DOI
高影响因子
POLYMER
·
2018
·
IF 3.483
Dongxue Yang,Lingfeng Li,Binling Chen,Shuxian Shi,Jun Nie,Guiping Ma
In order to improve the removal ability of chitosan (CS) to heavy metal ions , in this study, rich amino-functionalized CS electrospun membranes have been prepared. During the efficient synthesis, poly (glycidyl methacrylate) (PGMA) and polyethylenimine (PEI) were sequentially grafted on the surface of CS electrospun membrane. The success of introduction of amino-group on the CS were confirmed by X-ray diffractometer (XRD), attenuated total reflection-fourier transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The ability of remove heavy metal ions (Cr(VI), Cu(II) and Co(II)) of the as-prepared membrane (CS-PGMA-PEI) was investigated. The adsorption equilibrium of the heavy metal ion solutions was rapidly established in 60 min. Adsorption kinetics analysis reveals that the adsorption process of CS-PGMA-PEI electrospun membrane was dominated by a Pseudo-second-order model. Its adsorption isotherm can be described by the Langmuir model. The maximum adsorption capacities calculated by Langmuir model were 138.96, 69.27 and 68.31 mg g −1 for Cr(VI), Cu(II) and Co(II), respectively. The adsorption ability of CS-PGMA-PEI electrospun membrane toward metal ions was found in an order of Cr(VI) > Cu(II) > Co(II). CS-PGMA-PEI membrane also exhibited a good reproducibility and stability. Our study may provide a way to synthesize membranes for water purification .
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Zilu Li,Kefei Zhao,Yue Wang,Zirui Zheng,Chenhui Zhang,Yuxia Gao,Fengpei Du
Impact and spread of droplet on superhydrophobic surface are ubiquitous in inkjet printing , pesticide spraying, paint coating, and other fields. However, due to the extremely water-repellent properties of superhydrophobic surface, droplets frequently splash or roll off, causing great waste and serious environmental problems. Thus, searching for an effective strategy to regulate the droplet splash and spread on superhydrophobic surfaces is of remarkable significance. To address the above issues, herein, we demonstrate the controllable regulation on superhydrophobic lotus leaf surface by tuning the double-chain length of surfactants . The outcomes indicate different regularities for droplet splash in a short time (~10 ms) and spread in a relatively long period (~100 s). It can be concluded that dynamic surface tension of surfactant, diffusion rate of surfactant from the bulk to the interface, and assembly disaggregation rate dominate the impact process, whereas the adsorption kinetic and effectiveness of surfactant along with the spreading driving force determine the wetting transition. Surfactant owning suitable hydrophilic and hydrophobic ratio, fast diffusion rate, and unstable assembly could inhibit droplet splash and improve spreading pronouncedly, thereby enhancing the droplet deposition on superhydrophobic surfaces. This study makes original contribution to screen suitable surfactants from the structural aspects, especially double-chain length, which has not been treated in much detail to date. Our work not only creates a big impetus in illuminating the mechanism of surfactant molecular structure on droplet deposition processes but also greatly expands the applications of surfactant in many fields.
研究领域:
胶体与界面化学
·
农业化学
·
材料科学
·
流体力学
·
环境科学
·
应用物理
·
纳米科技
✓ 已验证
DOI
高影响因子
Materials Today Communications
·
2021
·
IF 3.383
Daifeng Wu,Rui Li,Tai Sun,Renheng Tang,Fangming Xiao
Mg/MgH 2 as a thermochemical energy storage (TCES) material suffers from a slow hydrogenation-dehydrogenation kinetic and poor reversibility. Addition of metal oxide is an effective way to improve the kinetic properties of Mg/MgH 2 . However, there is little study on the effects of complex oxides . Thus, the catalytic effects of complex metal oxides and its catalytic mechanism were investigated in this paper. Results show that the dehydrogenation peak temperature and apparent activation energy of MgH 2 -Ta 2 O 5 are 320.8 °C and 128.54 kJ/mol. Combined with complex metal oxide, MgH 2 -Ta 2 O 5 -Nd 2 O 3 could further reduce the dehydrogenation peak temperature (307.2 °C) and apparent activation energy (95.33 kJ/mol). MgO and NdH 2.61 are found in the dehydrogenated MgH 2 -Ta 2 O 5 -Nd 2 O 3 , indicating that n-typed oxide Ta 2 O 5 and p-typed oxide Nd 2 O 3 are formed and improved the kinetics properties of MgH 2 . Furthermore, Nd 2 O 3 /Ta 2 O 5 interface is formed and acted as “p-n junction”. When heating, the “p-n junction” is exposed to thermal radiation and produce electrons and holes, and then the kinetics properties of MgH 2 are further enhanced.
研究领域:
材料科学
·
能源化学
·
物理化学
·
无机功能材料
·
热能存储
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2019
·
IF 4.561
Qi Liu,Xiaoxiao Chen,Yan Guo,Chuanhong Han,Jing Li,Lihan Jia,Jie Liu,Xilian Wei
A ternary phase diagram of the system of 1-butyl-3-methylimidazolium tetrafluoroborate ([ Bmim ]BF4), sodium dodecylbenzenesulfonate (SDBS) and water using ocular estimate and turbidity method was drawn based on experimental data at 298.2 K. We got a narrow aqueous two-phase region near the side of water-ionic liquid (IL). A series of samples with different compositions around the phase diagram were chosen. The enthalpy change of these systems after injecting triply distilled water into these samples has been studied by using isothermal titration microcalorimetry (ITC). It is found that with increasing the water content there are weak endothermic and exothermic processes appearing, separately, which matches perfectly with the location of the formation and disappearance of the aqueous two-phase in the ternary phase diagram. This suggests the ITC is a feasible and effective method for the thermodynamic study of aqueous two-phase systems (ATPS) and was first reported. The experimental results show that the formation of the ATPS is endothermic (Δ H > 0), but the process of disappearing is exothermic (Δ H < 0). Due to the formation of aqueous two-phase is a thermodynamic spontaneous process under the isothermal constant pressure, we can judge that the formation of this ATPS is an entropy driven course and the vanishing is a synergy driven process by entropy and enthalpy.
研究领域:
物理化学
·
热力学
·
胶体与界面化学
·
分离科学
·
分析化学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·Vol. 47
·期 7
·9083-9089
·
IF 3.83
Hongli Liu,Lantian Zhang,Jing Li,Hongyan Li,Guoqing An,Yajing Li,Zhong Chen
SiBCN ceramic aerogels have excellent properties such as ultra-high temperature stability, low density and high thermal insulation . The aerogels have better potential applications in aerospace and other fields. However, similar to inorganic aerogels , the low mechanical strength of SiBCN ceramic aerogels are the main limitation of its application. Based on the principle of inorganic double network enhancement, the first network was constructed by PVA and HNTs , and HNTs/SiBCN dual network aerogels were constructed by SiBCN ceramic aerogels as the second network. The structure and mechanical properties were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), specific surface area analyzer and pressure tester. Compared with SiBCN ceramic aerogels, 6 wt% HNTs-SiBCN ceramic hybrid aerogels have better microscopic properties (maintaining basic porous network structure and structural stability) and mechanical properties.The continuous HNTs first network can effectively transfer the stress load and enhance the strength of SiBCN ceramic aerogels.
研究领域:
材料科学
·
无机非金属材料
·
纳米复合材料
·
航空航天材料
·
高分子复合材料
✓ 已验证
DOI
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 86
·45930-45938
·
IF 3.708
Mengmeng Zhang,Hongxia Yan,Xiaowei Yang,Chao Liu
In this paper, graphene oxide (GO) was functionalized with a hyperbranched cyclotriphosphazene polymer, which was synthesized by the repeated reactions of hexachlorotriphosphazene with hexamethylenediamine. Subsequently, the resultant functionalized GO was incorporated into dicyclopentadiene bisphenol dicyanate ester (DCPDCE) to prepare composites. Fourier-transform infrared spectra, X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron spectroscopy were employed to examine the surface functionalization of GO. The effects of functionalized GO on the curing reactivity, mechanical, dielectric, thermal and water resistent properties of DCPDCE resin were investigated systematically. Results show that the addition of modified GO can facilitate the curing reaction of DCPDCE. Meanwhile, the appropriate content of modified GO can enhance the mechanical properties including impact and flexural strengths of DCPDCE resin. When modified GO content is 0.6 wt%, the corresponding composite exhibits slightly higher dielectric constant but lower dielectric loss than pure DCPDCE resin over the testing frequency from 10 to 60 MHz. In addition, the thermal stability and moisture resistance of modified GO/DCPDCE nanocomposties are also superior to that of pure DCPDCE resin.
研究领域:
高分子化学
·
复合材料科学
·
材料物理与化学
·
纳米材料
·
绝缘材料
✓ 已验证
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 79
·75855-75861
·
IF 3.289
Qixuan Song,Hui Wang,Baoshan Yang,Fei Wang,Xinrong Sun
A novel silver nanoparticle-modified magnetic multi-walled carbon nanotube composite (Ag-FMWCNTs) was synthesized by embedding Fe3O4 and assembling Ag nanoparticles in one-step. The properties of the Ag-FMWCNTs composites and magnetic multi-walled carbon nanotubes (FMWCNTs) were studied by scanning electron microscopy, vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy. The adsorption isotherms, adsorption kinetics and the effects of solution pH and ionic strength to adsorb emerging contaminant sulfamethoxazole (SMX) from aqueous solution on different multi-walled carbon nanotubes-based adsorbents were determined. The results showed that the adsorption kinetics could be explained well by means of the pseudo-second-order and intraparticle diffusion models. The pH experiments showed that maximum adsorption occurred at pH 4. Additionally, all adsorbents had a strong adsorption ability to SMX and the Langmuir maximum capacity followed the order: 5% Ag-FMWCNTs (118.58 mg g−1) > 3% Ag-FMWCNTs (86.41 mg g−1) > MWCNTs (73.69 mg g−1) > 1% Ag-FMWCNTs (70.26 mg g−1) > FMWCNTs (45.13 mg g−1). The spent adsorbents were regenerated in methanol. It was also found that after regenerating four times, multi-walled carbon composites retained up to 80% of their original adsorption performance. Therefore, the Ag-FMWCNTs composite could be used as a potential adsorbent for removing sulfamethoxazole from water.
研究领域:
环境科学
·
纳米技术
·
水污染控制
·
吸附材料
·
药物残留治理
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·Vol. 12
·期 5
·114091
·
IF 7.4
Xiaolong Dai,Tiangui Qi,Xiaobin Li,Zhihong Peng,Guihua Liu,Qiusheng Zhou,Yilin Wang,Leiting Shen
In recent years, lithium iron phosphate (LFP) batteries have been widely used in the electric vehicle industry. The recycling of spent LFP will be propitious to conserving resources and alleviating the environmental risks it poses. In this study, a selective extraction method for lithium from spent LFP was proposed using nitric acid . Lithium leached into the liquid phase, while P and Fe remained in the leaching residue. Under the conditions of 120°C, HNO 3 /Li molar ratio of 2, and time of 2 h, the leaching efficiency of lithium reached 99.5 %, with a selectivity reaching 82.1 %. Initially, LFP was decomposed to liberate Li, Fe, and P in the liquid phase. Subsequently, ferrous ions were oxidized to trivalent, high-valent iron ions re-precipitated as FePO 4 ·2 H 2 O. Thermodynamic calculations indicate that the temperature and pH value of the extraction system have significant influence on both the oxidation and reprecipitation steps. An imbalance of Fe/P ratio (<1) in the raw material hinders the selectivity of lithium extraction , and supplementing this portion of Fe can enhance the selectivity to over 90 %. Additionally, LiCO 3 and anhydrous FePO 4 were effectively regenerated from the leachate and residue. This study provides a novel approach for the recycling of spent LFP and probably contributes to the sustainability of the lithium ion battery industry.
研究领域:
环境科学
·
冶金工程
·
材料回收
·
可持续能源
·
化学工程
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·Vol. 47
·期 83
·35352-35364
·
IF 7.139
Zhichao Yu,Wei Zhang,Yongxi Zhang,Yaokun Fu,Ying Cheng,Sanyang Guo,Yuan Li,Shumin Han
Magnesium hydroxide (MgH 2 ) has excellent reversibility and high capacity, and is one of the most promising materials for hydrogen storage in practical applications. However, it suffers from high dehydrogenation temperature and slow sorption kinetics. Rare earth hydrides and transition metals can both significantly improve the de/hydrogenation kinetics of MgH 2 . In this work, MgH 2 –Mg 2 NiH 4 –CeH 2.73 is in-situ synthesized by introducing Ni@CeO 2 into MgH 2 . The unique coating structure of Ni@CeO 2 facilitates homogeneous distribution of synergetic CeH 2.73 and Mg 2 NiH 4 catalytic sites in subsequent ball milling process. The as-fabricated composite MgH 2 -10 wt% Ni@CeO 2 powders possess superior hydrogenation/dehydrogenation characteristics, absorbing 4.1 wt% hydrogen within 60 min at 100 °C and releasing 5.44 wt% H 2 within 10 min at 350 °C. The apparent activation energy of MgH 2 -10 wt% Ni@CeO 2 is determined to be 84.8 kJ/mol and it has favorable hydrogen cycling stability with almost no decay in capacity after 10 cycles.
研究领域:
材料科学
·
无机化学
·
能源化学
·
纳米催化
·
氢能源存储
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2017
·Vol. 135
·期 11
·45974
·
IF 1.86
Wenqi Xian,Lina Song,Baohua Liu,Hulan Ding,Zhao Li,Mengping Cheng,Le Ma
CO 2 copolymer diol-based thermal polyurethane elastomers (PPC-TPU) were prepared by the reaction of CO 2 copolymer diol and methylene diphenyl diisocyanate and chain extender (ethylene glycol/1,4-butanediol/1,6-hexanediol) (EG/BDO/HG). The rheological and mechanical properties of PPC-TPU were analyzed. The effects of shear rate, shear temperature, hard segment content, and variety of chain extender on the properties of PPC-TPU were studied. The results showed that the apparent viscosity (η) of PPC-TPU decreased with the increasing shear rate ( τ ), and the non-Newtonian index ( n ) was less than 1. PPC-TPU exhibited a typical character of pseudoplastic non-Newtonian rheological behavior. The degradation during the processing was obviously inhibited by adding plasticizer and antioxidant. It was also discovered that the apparent viscosity varied with the content of hard segment and chain extender. Under the same temperature (185 °C) and shear rate (50 s −1 ), the apparent viscosity increased considerably with the raise of hard segment content, and the apparent viscosity and tensile strength of PPC-TPU with EG as chain extender was the maximum. It can be seen that with the apparent shear rate increasing, the variation tendency of apparent shear stress levels off, and the nonlinear relationship of τ – γ curve tended to be obvious. PPC-TPU exhibited a typical character of pseudoplastic non-Newtonian rheological behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 45974.
研究领域:
高分子材料科学
·
流变学
·
功能高分子
·
生物基聚合物
·
材料力学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）