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991.
992.
Li Song Jiaxiang Lin Yang He Jingqing Li Jing Sheng Shichun Jiang Dinghai Huang 《Journal of Polymer Science.Polymer Physics》2019,57(3):142-151
Time‐dependent demixing enthalpy recovery behavior of aqueous poly(vinyl methyl ether) (PVME) solutions exhibits distinct recovery characteristics in three concentration regions. The absence of recovery behavior below a water concentration of 38.3 wt % indicates that the PVME coil is in a globular state. The typically sigmoidal recovery behavior of demixing enthalpy above 38.3 wt % is ascribed to the reswelling of the collapsed polymer coils induced by the entropic effect. The increase in difference between the upper and lower limits indicates the continued swelling of the PVME coils. Above 65 wt %, a dominant diluting effect can be observed, and a much longer phase separation time is needed to reach the expected lower limit. In contrast, the recovery of demixing enthalpy in a wide range of water concentration (from 38.3 to 90 wt %) exhibits the same feature. The infrared spectroscopy results are in agreement with the above macroscopic differential scanning calorimetry results. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 142–151 相似文献
993.
Dr. Hongming He Qian-Qian Zhu Jia-Nan Zhao Dr. Hongming Sun Jing Chen Dr. Cheng-Peng Li Prof. Miao Du 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11474-11480
CO2 is considered as the primary greenhouse gas, resulting in a series of serious environmental problems that affect people's life and health. Carbon capture and sequestration has been implemented as one of the most appealing pathways to control and use CO2. Here, we rationally integrate various functional sites within the confined nanospace of a microporous metal–organic framework (MOF) material, which is constructed by mixed-ligand strategy based on metal-adeninate vertices. It not only exhibits excellent stability but also can efficiently transform CO2 and epoxides to cyclic carbonates under mild and cocatalyst-free conditions. Additionally, this catalyst shows extraordinary recyclability for the CO2 cycloaddition reaction. 相似文献
994.
Tao He Bin Li Li-Chuan Liu Jing Wang Wen-Peng Ma Guang-Yu Li Prof. Dr. Qing-Wei Zhang Prof. Dr. Wei He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(4):966-970
A copper-catalyzed trifunctionalization of alkynes that provides rapid access to oxindoles bearing a geminal diboronate side chain, highlighted by the simultaneous formation of one C−C bond and two C−B bonds, is reported. This new reaction features simple reaction conditions (ligand-free catalysis), a general substrate scope, and excellent chemoselectivity. Mechanistic study revealed a reaction sequence constituted by, in the order, borylation, intramolecular cross-coupling, hydroboration, which has been rarely documented. 相似文献
995.
Jing Zhou Shihua Song Feng Jiang Chunling Fu Prof. Shengming Ma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(42):9948-9958
Herein, we report the total synthesis of traumatic lactone and rhizobialide by utilizing allenoic acid to construct the lactone ring. The key starting materials, allenoic acids, could be prepared by the ATA (allenation of terminal alkynes) of a terminal alkyne with an aldehyde that contained a protected hydroxyl group followed by hydrolysis. Importantly, the asymmetric synthesis could be realized just by replacing racemic diphenylprinol with (R)- or (S)-diphenylprinol to deliver the optically active allenoate. 相似文献
996.
Jing Zhao Jihai Zhang Mengfan Jing Guopeng Sui Dingyao Liu Ke Wang Qiang Fu 《Journal of Polymer Science.Polymer Physics》2019,57(7):368-377
Herein, we reported the formation mechanism of hybrid crystalline (cylindrite) in isotactic polypropylene (iPP)/carbon fiber (CF) via pulling a CF within the iPP melt. The α‐row nuclei layer closely attached to the surface of CF acts as a self‐nucleation site, rather than a heterogeneous nucleation one, to grow cylindrites. As a result, the polymorphic feature of iPP/CF cylindrite is significantly influenced by the microstructure of α‐row nuclei. With decreasing crystallization temperature (Tc), the polymorphic cylindrite changes from pure α‐form to mixed α‐/β‐form and to β‐rich form. The main characteristics of this change include: (a) the outlines of α‐row nuclei layer correspond to wave‐like, saw‐like, and straight lines; (b) the orientation level of iPP molecules in the α‐row nuclei layer become higher; (c) the α‐lamellae rearrange from loose to compact; and (d) the distance between the growth sites of β‐sectors and the surface of CF is evidently longer than in the case of α‐sectors. Moreover, this study provides a guideline for developing the interfacial enhanced iPP/CF composites through manipulation of polymorphic structure in cylindrites. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 368–377 相似文献
997.
Dr. Fabian O. von Rohr Alice Ryser Dr. Huiwen Ji Dr. Karoline Stolze Dr. Jing Tao Jessica J. Frick Prof. Greta R. Patzke Prof. Robert J. Cava 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(8):2082-2088
We describe the previously unreported oxygen excess hexagonal antimony tungsten bronze with composition Sb0.5W3O10, in the following denoted as h-SbxWO3+2x with x=0.167, to demonstrate its analogy to classical AxWO3 tungsten bronzes. This compound forms in a relatively narrow temperature range between 580 °C<T<620 °C. It was obtained as a dark-blue polycrystalline powder, and as thin, needle-shaped, blue single crystals. h-SbxWO3+2x crystallizes in the hexagonal space group P6/mmm with the cell parameters a=7.4369(4) Å and c=3.7800(2) Å. The antimony and excess oxygen occupy the hexagonal channels within the network of corner-sharing WO6 octahedra. h-SbxWO3+2x has a resistivity of ρ300 K≈1.28 mΩ cm at room temperature, with little if any temperature-dependence on cooling. DFT calculations on a simplified model for this compound find a metallic-like electronic structure with the Fermi level falling within rather flat bands, especially around the Γ point. 相似文献
998.
999.
蜂窝状有序多孔膜是一种典型的具有微、纳米尺寸的图案化高分子薄膜材料,在超疏水表面、光电材料、组织工程、生物医学、传感器等领域都具有良好的应用前景。表面形貌或性质具有可逆刺激响应特性的智能型多孔膜不仅拥有常规多孔膜的性能,而且还拥有独特的开-关功能,因此受到广泛关注。本文回顾了智能有序多孔膜近年的研究进展,重点对其体系构建、响应方式、机理、性能和相关应用进行了归纳与分析,评述了不同刺激响应多孔膜的特点及优劣势,探讨了智能多孔膜的优化设计及提高响应性能等问题,指出了目前面临的挑战,并展望了未来的发展方向。 相似文献
1000.