Co-reporter:Yunxi Li, Mina Hoorfar, Kuizhi Shen, Jiyong Fang, Xigui Yue, Zhenhua Jiang
Electrochimica Acta 2017 Volume 232(Volume 232) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.electacta.2017.02.097
A poly (ether sulphone)-based pore-filling membrane was successfully fabricated and tested against a conventional Nafion-based membrane in direct methanol fuel cells. An amino-containing polymer with a low degree of sulphonation (DS) was synthesized and used as the supporting substrate. The porous substrate was prepared by introducing the porogenic agent (tetrafluoroborate) into the membrane casting solution. The effects of the content of the porogenic agent on the pore morphologies were evaluated using field emission scanning electron microscopy. Then, an epoxy resin was introduced into the porous electrolyte for the first time to minimize the swelling and methanol crossover that resulted from the high degree of sulphonation. In essence, solidification of the amino groups in the substrate results in 3D crosslinking of epoxy resins, which greatly suppresses the swelling and methanol crossover of the composite membranes with enhanced mechanical properties and enhances the thermal and oxidation stability compared to Nafion 117. The resulting composite membrane also shows high proton conductivity that is only slightly lower than that of Nafion 117. However, the selectivity between the proton conductivity and methanol permeability is higher for the composite membranes than that of Nafion 117. The composite membrane also shows a better performance in single cell tests with 10 M methanol.
Co-reporter:Jiyong Fang;Yingshuang Shang;Zheng Chen;Wei Wei;Ying Hu;Zhenhua Jiang
Journal of Materials Chemistry C 2017 vol. 5(Issue 19) pp:4695-4705
Publication Date(Web):2017/05/18
DOI:10.1039/C7TC00987A
A pre-modification method and a post-modification method have been developed to fabricate rice husk-based porous carbon and magnetic particles composite absorbers (RHPC/Fe and RHPC/Co). Magnetic Fe and Co particles were selected to incorporate into rice husk-based porous carbon to make full use of the synergistic effect between dielectric loss and magnetic loss. The structure, morphology, magnetic properties and electromagnetic (EM) wave absorption performance of the synthesized absorbers were investigated in detail. Inside the porous structure, the incident EM wave can be attenuated by means of Debye dipolar relaxation-derived dielectric loss and exchange resonance-derived magnetic loss through multiple scattering and absorption. For RHPC/Fe, at a thickness of 1.4 mm, a reflection loss (RL) value of −21.8 dB was achieved with the effective absorption bandwidth (RL ≤ −10 dB) of 5.6 GHz. For RHPC/Co, an RL value of −40.1 dB was obtained with the effective absorption bandwidth (RL ≤ −10 dB) of 2.7 GHz at a thickness of 1.8 mm. The excellent EM wave dissipation ability of RHPC/Fe and RHPC/Co can be attributed to the good EM impedance matching condition, quarter-wavelength cancellation and strong EM wave attenuation inside the absorber. Consequently, considering the EM wave absorption performance, the RHPC/Fe and RHPC/Co synthesized in this work are promising candidates in the field of EM wave attenuation.
Co-reporter:Jiyong Fang, Tao Liu, Zheng Chen, Yan Wang, Wei Wei, Xigui Yue and Zhenhua Jiang
Nanoscale 2016 vol. 8(Issue 16) pp:8899-8909
Publication Date(Web):31 Mar 2016
DOI:10.1039/C6NR01863G
A method combining liquid–liquid phase separation and the pyrolysis process has been developed to fabricate the wormhole-like porous carbon/magnetic nanoparticles composite with a pore size of about 80 nm (WPC/MNPs-80). In this work, the porous structure was designed to enhance interaction between the electromagnetic (EM) wave and the absorber, while the magnetic nanoparticles were used to bring about magnetic loss ability. The structure, morphology, porosity and magnetic properties of WPC/MNPs-80 were investigated in detail. To evaluate its EM wave attenuation performance, the EM parameters of the absorber and wax composite were measured at 2–18 GHz. WPC/MNPs-80 has an excellent EM wave absorbency with a wide absorption band at a relatively low loading and thin absorber thickness. At the absorber thickness of 1.5 and 2.0 mm, minimum RL values of −29.2 and −47.9 dB were achieved with the RL below −10 dB in 12.8–18 and 9.2–13.3 GHz, respectively. The Co and Fe nanoparticles derived from the chemical reduction of Co0.2Fe2.8O4 can enhance the graphitization process of carbon and thus improve dielectric loss ability. Polarizations in the nanocomposite absorber also play an important role in EM wave absorption. Thus, EM waves can be effectively attenuated by dielectric loss and magnetic loss through multiple reflections and absorption in the porous structure. WPC/MNPs-80 could be an excellent absorber for EM wave attenuation; and the design strategy could be extended as a general method to synthesize other high-performance absorbers.
Co-reporter:Jiyong Fang, Yan Wang, Wei Wei, Zheng Chen, Yunxi Li, Zhi Liu, Xigui Yue and Zhenhua Jiang
RSC Advances 2016 vol. 6(Issue 6) pp:4695-4704
Publication Date(Web):23 Dec 2015
DOI:10.1039/C5RA24693H
A nanocomposite consisting of nanoparticles decorated by multi-wall carbon nanotubes (MWCNTs/Ag/Co0.2Fe2.8O4) was designed and synthesized to meet requirements for a wider, thinner, and stronger electromagnetic (EM) wave absorber. The structure and morphology analysis revealed the structure of the nanocomposite absorber. The introduction of Ag nanoparticles can increase the interface by bringing stronger coupling into the heterogeneous nanocomposite, whereas Co0.2Fe2.8O4 can introduce dipoles and magnetic loss as well as additional interfaces into the absorber. The electromagnetic parameters of absorber and wax composite with different absorber contents were measured in the range of 2–18 GHz to evaluate its EM wave attenuation performance. With an absorber loading of 20%, at a low thickness of 1.8 mm, the highest attenuation effectiveness value of −52.4 dB can be achieved at 10.2 GHz. Moreover, with absorber thicknesses from 1.1 to 3.7 mm, RL values below −20 dB can be achieved over a wide frequency range from 4.0 to 18 GHz covering the C band, the X band and the Ku band. Consequently, the nanocomposite absorber has an excellent EM wave attenuation ability with the characteristics of a wide absorption band (4–18 GHz), strong absorption (−52.4 dB) and low absorber thicknesses (1.1–3.7 mm). The excellent EM wave absorbency can be attributed to strong interfacial and dipole polarization, dielectric loss caused by Debye dipolar relaxation and the combination of dielectric loss and magnetic loss. Such a nanocomposite could serve as an attractive candidate for EM wave attenuation applications in the future.
Co-reporter:Jiyong Fang, Zheng Chen, Wei Wei, Yunxi Li, Tao Liu, Zhi Liu, Xigui Yue and Zhenhua Jiang
RSC Advances 2015 vol. 5(Issue 62) pp:50024-50032
Publication Date(Web):29 May 2015
DOI:10.1039/C5RA07192E
A three-phase heterostructure composite CF/Co0.2Fe2.8O4/PANI with a layer by layer (LBL) structure was designed and synthesized for achieving improvement in electromagnetic (EM) wave attenuation of carbon fiber (CF). The structure and morphology analyses demonstrated the LBL structure of the absorber. The electromagnetic parameters of the absorber and wax composite were measured at 2–18 GHz to evaluate its EM wave attenuation performance. The three-phase heterostructures absorber CF/Co0.2Fe2.8O4/PANI demonstrated the highest attenuation effectiveness value of −38.2 dB (>99.9% attenuation) at 12.7 GHz with a thickness of 4.1 mm. Moreover, for CF/Co0.2Fe2.8O4/PANI, with an absorber thickness of 3.1–4.1 mm, the minimum RL values are all lower than −20 dB in Ku band. The excellent EM wave absorbency in the Ku band for CF/Co0.2Fe2.8O4/PANI results from the combined effect of magnetic loss and dielectric loss by introducing more phase onto CF. Considering the EM wave absorption performance and the effortless fabrication process, it is believable that by introducing more specially designed phases, the EM wave attenuation performance of CF can be significantly improved.
Co-reporter:Jiyong Fang;Haibo Zhang;Wei Wei;Yunxi Li;Zhenhua Jiang
Journal of Applied Polymer Science 2015 Volume 132( Issue 41) pp:
Publication Date(Web):
DOI:10.1002/app.42644
ABSTRACT
A high-performance polymer polyethersulfone (CN-Azo-PES), with a flexible ethoxyl linkage between the azobenzene chromophore side chain and the PES backbone, has been designed and successfully synthesized for an application in a WORM type memory device as an active polymer layer. CN-Azo-PES has excellent thermal properties with Tg of 151°C and the degradation temperature higher than 373°C, which can contribute to a better performance of the device. The device based on CN-Azo-PES exhibits a write-once read-many (WORM) type memory performance with an onset voltage as low as −1.0 V and an ON/OFF current ratio higher than 102 at a reading voltage of 0.4 V. Moreover, the data can be maintained for longer than 4 × 105 s once written and can be read for more than 400 cycles under a reading voltage of 0.4 V. Thus CN-Azo-PES can serve as an energy saving memory material in the data storage field of next generation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42644.
Co-reporter:Xiaoming Zhou;Baijun Liu;Zhenhua Jiang
Journal of Applied Polymer Science 2014 Volume 131( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/app.40149
Abstract
Random, block, and alternative polyethersulfone/polyetherethersulfone copolymers (phenyl: ether: sulfone =7 : 4 : 3) with similar molecular weights and polydispersity were synthesized using different synthetic strategies. DSC and DMA analyses indicated that all copolymers are amorphous and possess extremely close glass transition temperature. The random copolymer displayed higher modulus and complex viscosity. It is interesting to find that the alternative copolymer exhibited a melt viscosity of 281 Pa s, which is much lower than that of the block copolymer (646 Pa s) and the random copolymer (1641 Pa s) at 4 s−1. Moreover, the alternative copolymer showed obviously higher elongation at break of 101.9%. These behaviors were highly related to their different sequence distribution. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40149.
Co-reporter:Wei Wei, Haibo Zhang, Shaowei Guan, Zhenhua Jiang, Xigui Yue
Polymer 2012 Volume 53(Issue 22) pp:5002-5009
Publication Date(Web):12 October 2012
DOI:10.1016/j.polymer.2012.08.059
From the molecular designing point of view, (p-amino)phenylhydroquinone (APH) and (3, 5-dimethoxy)phenylhydroquinone (DMPH) were prepared in a two-step synthesis. Polyetheretherketone with a large number of amino groups (APEEK) and polyethersulfone with quantities of hydroxyl side groups (HPES) were successfully synthesized from these bisphenol monomers. The functionalized polyarylethers were then grafted by isocyanatopropyltriethoxysilane (IPTS) through in-situ O-acylation reaction to obtained triethoxysilyl groups. Subsequently, these hydrolyzed triethoxysilyl groups formed network and produced covalent bonds between organic and inorganic phases via a sol–gel process under acid condition. Transparent polyarylether-silica (PAE-silica) hybrid films were fabricated through this in-situ sol–gel process. Furthermore, tetraethylorthosilicate (TEOS) and SiO2 nanoparticles were introduced as silica sources to improve the content of silica. The in-situ generated SiO2 by hydrolysis of the silica sources with triethoxysilyl groups on IPTS modified polyarylethers was covalently connected with the substrates. The present method achieved transparent hybrid films at high silica content of 40 wt%, which was resulted from inorganic and organic phases closely combination and homogenous distribution of silica particles in the polymer matrix.Graphical abstract
Co-reporter:Jiyong Fang, Yingshuang Shang, Zheng Chen, Wei Wei, Ying Hu, Xigui Yue and Zhenhua Jiang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 19) pp:NaN4705-4705
Publication Date(Web):2017/03/30
DOI:10.1039/C7TC00987A
A pre-modification method and a post-modification method have been developed to fabricate rice husk-based porous carbon and magnetic particles composite absorbers (RHPC/Fe and RHPC/Co). Magnetic Fe and Co particles were selected to incorporate into rice husk-based porous carbon to make full use of the synergistic effect between dielectric loss and magnetic loss. The structure, morphology, magnetic properties and electromagnetic (EM) wave absorption performance of the synthesized absorbers were investigated in detail. Inside the porous structure, the incident EM wave can be attenuated by means of Debye dipolar relaxation-derived dielectric loss and exchange resonance-derived magnetic loss through multiple scattering and absorption. For RHPC/Fe, at a thickness of 1.4 mm, a reflection loss (RL) value of −21.8 dB was achieved with the effective absorption bandwidth (RL ≤ −10 dB) of 5.6 GHz. For RHPC/Co, an RL value of −40.1 dB was obtained with the effective absorption bandwidth (RL ≤ −10 dB) of 2.7 GHz at a thickness of 1.8 mm. The excellent EM wave dissipation ability of RHPC/Fe and RHPC/Co can be attributed to the good EM impedance matching condition, quarter-wavelength cancellation and strong EM wave attenuation inside the absorber. Consequently, considering the EM wave absorption performance, the RHPC/Fe and RHPC/Co synthesized in this work are promising candidates in the field of EM wave attenuation.
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