7 results on '"Zhongwu Wang"'
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2. Surface-grafting polymers: from chemistry to organic electronics
- Author
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Zhongwu Wang, Wenping Hu, Shuguang Wang, Jie Li, and Liqiang Li
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Organic electronics ,chemistry.chemical_classification ,business.industry ,Chemistry ,Nanotechnology ,Polymer ,Grafting ,Semiconductor ,Covalent bond ,Materials Chemistry ,OLED ,Surface modification ,General Materials Science ,Electronics ,business - Abstract
Surface-grafting polymers, also known as polymer brushes, have become an important tool for surface modification or functionalization. The strong covalent bond between the polymer brushes and the surface endow polymer brushes with several unique characteristics: precise control of surface property by the grafting process, better stability, easier patterning and so on. Thus, during the past few decades, surface-grafting polymers have gradually played an important role in the development of organic electronic devices, such as OFETs, OLEDs, OPVs, and so on. In this article, we will comprehensively review the recent progress in surface-grafting polymers, including their formation process and the utilization of surface-grafting polymers as functional materials of insulators, conductors and semiconductors in versatile organic electronic devices. Then, we will provide an outlook on the promising future of surface-grafting polymers in organic electronics. more...
- Published
- 2020
- Full Text
- View/download PDF
Catalog
3. Novel crosslinkable high-k copolymer dielectrics for high-energy-density capacitors and organic field-effect transistor applications
- Author
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Pingkai Jiang, Yuxin Wang, Zhongwu Wang, Xingyi Huang, Xiaojun Guo, Liqiang Li, and Tao Li
- Subjects
chemistry.chemical_classification ,Materials science ,Ferroelectric polymers ,Organic field-effect transistor ,Renewable Energy, Sustainability and the Environment ,02 engineering and technology ,General Chemistry ,Polymer ,Dielectric ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Capacitor ,chemistry ,Chemical engineering ,law ,Polymer chemistry ,General Materials Science ,Dielectric loss ,0210 nano-technology ,Leakage (electronics) ,High-κ dielectric - Abstract
High-dielectric-constant (high-k) polymers are highly desirable for energy storage and dielectric applications in power systems and microelectronic devices because of their easy processing and flexibility. However, the enhancement of k is usually at the cost of other undesirable properties such as increase of dielectric loss and leakage currents and decrease of breakdown strength. Herein, using reversible-addition fragmentation chain transfer (RAFT) polymerization, we report a series of novel low-temperature crosslinkable high-k copolymers, poly(2-(methylsulfonyl)ethyl methacrylate-co-glycidyl methacrylate) (poly(MSEMA-co-GMA)), which exhibit k values about 9–12. The crosslinking significantly enhances the breakdown strength (Eb ≈ 500 MV m−1), suppresses the leakage currents and improves the solvent resistance. The excellent dielectric performance makes the copolymers have both high energy storage capability and high energy efficiency. The discharged energy density reached 12.5 J cm−3 at 500 MV m−1. Noticeably, an efficiency higher than 85% was maintained even at a high field of 400 MV m−1, which is much higher than those of poly(vinylidene fluoride) (PVDF) based ferroelectric polymers with comparable k. Furthermore, the poly(MSEMA-co-GMA) copolymers were successfully applied as dielectric layers for organic field-effect transistors (OFETs) to realize low-voltage operation. more...
- Published
- 2017
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4. Structural evolution and mechanical behaviour of Pt nanoparticle superlattices at high pressure
- Author
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Zewei Quan, Yusheng Zhao, Xiaodong Wen, Ying-Bing Jiang, Jiye Fang, Chenyu Wang, Zhongwu Wang, Hongwu Xu, and Jinlong Zhu
- Subjects
Materials science ,Small-angle X-ray scattering ,Scattering ,Superlattice ,Nanowire ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,0104 chemical sciences ,Stress (mechanics) ,Crystallography ,Transmission electron microscopy ,Chemical physics ,General Materials Science ,0210 nano-technology - Abstract
High pressure is an effective means for tuning the interparticle distances of nanoparticle (NP) superlattices and thus for modifying their physical properties and functionalities. In this work, we determined the evolution of inter-NP distances of a Pt NP superlattice with increasing pressure using an in situ synchrotron small-angle X-ray scattering (SAXS) technique in a diamond-anvil cell (DAC). Transmission electron microscopy (TEM) was used to characterize the microstructures of pre- and post-compression samples. Our results demonstrate that the evolution of Pt NP assemblies with increasing pressure consists of four stages: (1) ligand elastic response, (2) uniform compression, (3) ligand detachment from NP surfaces, and (4) deviatoric compression of ligands between neighboring NPs. By controlling the magnitudes of applied pressure and deviatoric stress, one can sinter NPs into novel architectures such as nanowires and nanoceramics. more...
- Published
- 2016
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5. Optical properties of PbS nanocrystal quantum dots at ambient and elevated pressure
- Author
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Zhongwu Wang, William A. Bassett, Tobias Hanrath, Hanqing Yang, Frank W. Wise, Kaifu Bian, and Benjamin T. Richards
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Bulk modulus ,Phase transition ,Materials science ,Absorption spectroscopy ,General Physics and Astronomy ,Nanotechnology ,Pressure coefficient ,Molecular physics ,Condensed Matter::Materials Science ,Nanocrystal ,Quantum dot ,Phase (matter) ,Physical and Theoretical Chemistry ,Absorption (electromagnetic radiation) - Abstract
We investigated pressure-dependent changes in the optical properties of PbS nanocrystal quantum dots (NQD) by combining X-ray scattering and optical absorption spectroscopy in a diamond anvil cell. We discovered that the excitonic absorption peak vanishes as the NQD crystal structure reversibly undergoes the pressure-induced phase transition from rock-salt to orthorhombic structure. In the rock-salt phase, the pressure coefficient ∂E(g)/∂P of PbS NQD is negative and decreases in magnitude with decreasing NQD size. The basic theoretical model based on literature values of the PbS bulk modulus significantly overestimated the change in pressure coefficient with NQD size. We present a model that includes the size-dependence of both the pressure coefficient and bulk modulus to describe the experimentally observed optical and structural trends. more...
- Published
- 2014
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6. Photoconducting response on bending of individual ZnO nanowires
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Enge Wang, Xuedong Bai, Kaihui Liu, Zhongwu Wang, Z. Xu, Peng Gao, and Wenlong L. Wang
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Photocurrent ,Materials science ,business.industry ,Photoconductivity ,Nanowire ,General Chemistry ,Bending ,medicine.disease_cause ,Transmission electron microscopy ,Materials Chemistry ,medicine ,Optoelectronics ,Field-effect transistor ,business ,Ultraviolet ,Diode - Abstract
The bending effect of individual zinc oxide (ZnO) nanowires on photoconducting behavior has been investigated by an in situtransmission electron microscopy (TEM) method. By increasing the nanowire bending, the photocurrent of ZnO nanowire under ultraviolet illumination drops dramatically and the photoresponse time becomes much shorter. A possible mechanism has been proposed and discussed. The improved photo response performance by bending ZnO nanowires could be of significance for their optoelectronics and sensor applications. more...
- Published
- 2009
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7. Ammonia molecule rotation of pressure-induced phase transition in ammonia hemihydrates 2NH3·H2O
- Author
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Qiang Zhou, Fangfei Li, Zhongwu Wang, Mingzhe Zhang, Fengxian Huang, Qiliang Cui, Chunli Ma, and Jingshu Wang
- Subjects
Diffraction ,Phase transition ,Chemistry ,General Chemical Engineering ,Analytical chemistry ,General Chemistry ,Synchrotron ,law.invention ,symbols.namesake ,Crystallography ,law ,Phase (matter) ,symbols ,Molecule ,Orthorhombic crystal system ,Binary system ,Raman scattering - Abstract
High-pressure Raman scattering and synchrotron angle-dispersive X-ray diffraction studies have been performed on liquid ammonia hemihydrates (2NH3·H2O) at room temperature up to 41.0 GPa. The results demonstrate that liquid 2NH3·H2O transforms into a solid phase at 3.5 GPa. Upon increasing pressure, a solid-solid phase transition is observed at about 19.0 GPa. When pressure is increased up to 25.8 GPa, another solid-solid phase transition is obtained. The first solid-solid phase transition at about 19.0 GPa originates from the rotation of type II ammonia molecule via the O–H⋯N bond, and this phase transition is from orthorhombic to body-centered-cubic. High-pressure Raman scattering and X-ray diffraction results of 2NH3·H2O provide significant information for better understanding the physical properties of the ammonia–water binary system under extreme conditions, and further for the structure state of the outer planets and large satellites in the solar system. more...
- Published
- 2012
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