YanWu Zhang

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Name: 张延武; YanWu Zhang
Organization: Zhengzhou University
Department: School of Chemical Engineering and Energy
Title: Associate Professor

TOPICS

Co-reporter:Yongqin Wang;Hongjun Hou
Journal of Applied Electrochemistry 2017 Volume 47( Issue 2) pp:
Publication Date(Web):
DOI:10.1007/s10800-016-1029-y
Co-reporter:Yongqin Wang;Hongjun Hou
Journal of Applied Electrochemistry 2017 Volume 47( Issue 2) pp:
Publication Date(Web):
DOI:10.1007/s10800-016-1029-y
Co-reporter:Yongqin Wang;Hongjun Hou
Journal of Applied Electrochemistry 2017 Volume 47( Issue 2) pp:237-248
Publication Date(Web):19 December 2016
DOI:10.1007/s10800-016-1029-y
A macromolecular electrolyte is designed with different chemical moieties to perform different functions, and it is extremely suitable to be applied in solid high-temperature lithium ion batteries. The preparation of the electrolyte involves synthesis of a comb-like macromolecule and immobilization of lithium ions. The comb-like macromolecule is synthesized via a ring-opening metathesis copolymerization of norbornene derivatives anchored with phosphate and polyethylene glycol monomethyl ether (–O(CH2CH2O)nCH3) and is partially cross-linked through polyethylene glycol (–(CH2CH2O)n–) bridge. The immobilization of lithium ions is carried out by lithium bis(trifluoromethyl-sulfonyl)imide. The as-prepared electrolyte membrane has a bicontinuous morphology consisting of a cross-linked mechanical scaffold intertwined with continuous Li+ ions conducting channels. Apart from lithium ion transference number close to unity and remarkable ionic conductivity, the electrolyte also displays strong strength, high flexibility, good thermal stability and outstanding flame retardancy. At 80 °C, LiFePO4/macromolecular electrolyte/Li coin cells, with the discharge capacity of 134.1 mAh g−1 at a current density of 0.2 C, are able to maintain a value of 120.7 mAh g−1 after 100 cycles of charge and discharge.
Co-reporter:Yongqin Wang;Hongjun Hou
Journal of Applied Electrochemistry 2017 Volume 47( Issue 2) pp:237-248
Publication Date(Web):19 December 2016
DOI:10.1007/s10800-016-1029-y
A macromolecular electrolyte is designed with different chemical moieties to perform different functions, and it is extremely suitable to be applied in solid high-temperature lithium ion batteries. The preparation of the electrolyte involves synthesis of a comb-like macromolecule and immobilization of lithium ions. The comb-like macromolecule is synthesized via a ring-opening metathesis copolymerization of norbornene derivatives anchored with phosphate and polyethylene glycol monomethyl ether (–O(CH2CH2O)nCH3) and is partially cross-linked through polyethylene glycol (–(CH2CH2O)n–) bridge. The immobilization of lithium ions is carried out by lithium bis(trifluoromethyl-sulfonyl)imide. The as-prepared electrolyte membrane has a bicontinuous morphology consisting of a cross-linked mechanical scaffold intertwined with continuous Li+ ions conducting channels. Apart from lithium ion transference number close to unity and remarkable ionic conductivity, the electrolyte also displays strong strength, high flexibility, good thermal stability and outstanding flame retardancy. At 80 °C, LiFePO4/macromolecular electrolyte/Li coin cells, with the discharge capacity of 134.1 mAh g−1 at a current density of 0.2 C, are able to maintain a value of 120.7 mAh g−1 after 100 cycles of charge and discharge.
Co-reporter:Mingjie Jin;Mingce Long;Hanrui Su;Yue Pan
Environmental Science and Pollution Research 2017 Volume 24( Issue 2) pp:1926-1937
Publication Date(Web):31 October 2016
DOI:10.1007/s11356-016-7866-8
To develop highly efficient and conveniently separable iron containing catalysts is crucial to remove recalcitrant organic pollutants in wastewater through a heterogeneous Fenton-like reaction. A maghemite/montmorillonite composite was synthesized by a coprecipitation and calcination method. The physiochemical properties of catalysts were characterized by XRD, TEM, nitrogen physisorption, thermogravimetric analysis/differential scanning calorimetry (TG/DSC), zeta potential, and magnetite susceptibility measurements. The influence of calcination temperatures and reaction parameters was investigated. The calcined composites retain magnetism because the presence of montmorillonite inhibited the growth of γ-Fe2O3 nanoparticles, as well as their phase transition. The catalytic activities for phenol degradation were significantly enhanced by calcinations, which strengthen the interaction between iron oxides and aluminosilicate framework and result in more negatively charged surface. The composite (73 m2/g) calcined at 350 °C had the highest catalytic activities, with more than 99 % phenol reduction after only 35 min reaction at pH 3.6. Simultaneously, this catalyst exhibited high stability, low iron leaching, and magnetically separable ability for consecutive usage, making it promising for the removal of recalcitrant organic pollutants in wastewater.
Co-reporter:Xiaolei Zhang;Junqing Jiang
Journal of Applied Polymer Science 2016 Volume 133( Issue 41) pp:
Publication Date(Web):
DOI:10.1002/app.43992

ABSTRACT

Catalytic thermal cleavage of thiocarbonylthio end-groups for RAFT synthesized polymers is usually accompanied by other side reactions such as chain-scission and crosslinking. Occurrence of these side reactions depends on polymers, end-groups, and oxidation–reduction property of reaction media in a liquid phase. Herein, well-defined hydrophilic poly(4-vinylpridine) (P4VP) and hydrophobic polystyrene (PS) are synthesized via a controlled RAFT polymerization in the presence of S-1-Dodecyl-S′-(R,R′-dimethyl-R″-acetic acid) trithiocarbonates (DDMAT). Then their thiocarbonylthio end-groups are cleaved through catalytic thermolysis in a liquid phase. Under the catalysis of Cu(0), all S-containing groups can be removed at 165 °C in 3 h. To study the effect of solvent on thermolysis and microstructure of polymer, nitrobenzene of oxidation property and diethylene glycol of reduction property are chosen as solvents. Because of oxidizing property of nitrobenzene, Z groups of RAFT agent are eliminated at the same time that thiocarbonylthio end-groups are removed. Therefore crosslinking among multipolymer chains occurs. While diethylene glycol is used as a solvent, no crosslinking occurs. Diethylene glycol is superior to nitrobenzene for synthesis of well-defined polymer without S-containing groups. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43992.

Co-reporter:Guo Yang, Junqing Jiang, Yanwu Zhang
Progress in Organic Coatings 2015 Volume 78() pp:55-58
Publication Date(Web):January 2015
DOI:10.1016/j.porgcoat.2014.09.020
•Mg–Al hydrotalcite is rehydrated to improve its basicity through a liquid method.•Rehydrated Mg–Al hydrotalcite is used to catalyze aldol condensations in preparation of cyclohexanone-formaldehyde resin.•The phase transfer catalyst CTAB is introduced to enhance the mass transfer among liquid–liquid–solid tri-phases.•The reutilization and regeneration of rehydrated Mg–Al hydrotalcite is investigated.Cyclohexanone-formaldehyde resin (CFR) was synthesized over rehydrated Mg–Al hydrotalcite (HT). Therein, Mg–Al HT was rehydrated from Mg–Al HT of good crystallinity using a liquid method. Rehydrated Mg–Al HT (HT-r) shows certain catalytic activity for aldol condensation and catalytic activity is dramatically improved in the presence of hexadecyl trimethyl ammonium bromide (CTAB) because CTAB as a phase transfer catalyst is helpful to enhance the mass transfer among three phases. Both higher temperature and longer reaction time are preferable to increase the molecular weight of CFR. Though the catalytic activity of HT-r decreases as the reutilization cycle increases, the deactivated HT-r can be easily regenerated upon calcining and rehydrating.
Co-reporter:Yifan Hou, Junqing Jiang, Kai Li, Yanwu Zhang, and Jindun Liu
The Journal of Physical Chemistry B 2014 Volume 118(Issue 7) pp:1962-1967
Publication Date(Web):February 4, 2014
DOI:10.1021/jp411610a
Amphiphilic brushes of poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) are grafted onto halloysite nanotubes (HNTs) via a surface reversible addition–fragmentation chain transfer (RAFT) living polymerization through anchoring R group in RAFT agent S-1-dodecyl-S′-(R,R′-dimethyl-R″-acetic acid) trithiocarbonates (DDMAT). The characterization of TGA, TEM, and GPC show that amphiphilic brushes are successfully grafted onto HNTs in a living manner. To verify the amphiphilicity of HNTs grafted with block copolymers, their Pickering emulsification behavior in water/soybean oil diphase mixture is studied. The results show that modified HNTs can emulsify water/soybean oil diphase mixture and the emulsification performance is dependent on microstructure of amphiphilic brushes such as hydrophilic/hydrophobic segment size and sequence.
Co-reporter:Wencui Chai, Yanwu Zhang and Yifan Hou  
Polymer Chemistry 2013 vol. 4(Issue 4) pp:1006-1013
Publication Date(Web):18 Oct 2012
DOI:10.1039/C2PY20808C
Polyacrylamides and their derivatives are widely used as polyelectrolytes or polyampholytes. The morphology of polymer chains in solution plays an important role in their application. To illustrate the relationship between microstructure and properties, intrinsic viscosity as an apparent indication of the polymer chain hydraulic volume was focused on. A series of well-defined cationic polyacrylamides (C-PAMs) with dot-charges have been prepared via an aqueous living reversible addition fragmentation chain transfer (RAFT) polymerization, in which “dot-charges” means that any two cationic monomer units in the copolymer are not immediately connected each other. Water-soluble 4,4′-azobis (4-cyanovaleric acid) (V-501) and 2-(2-carboxyethyl-sulfanylthiocarbonylsulfanyl) propionic acid (CTA) were employed as the initiator and the chain transfer agent respectively and acryloyloxyethyltrimethylammonium chloride (DAC) acted as the cationic unit. The number of dot-charges and segment size between dot-charges were varied by adjusting the feed ratio and the polymerization time. The polymerization followed first order kinetics as indicated by gel permeation chromatography (GPC) characterization and the quantitative 1H-NMR analysis showed that DAC was incorporated into PAM chains as single dot-charges. The intrinsic viscosity of the well-defined C-PAMs solution was determined in an electrolyte solution and the result showed that end-groups with opposite charges in C-PAMs had serious effects on the expansion of polymer coil in aqueous solution. According to modified Rushing–Hester theory, a semi-empirical model based on molecular weight, chain length, cationic degree and charge distribution was established to explain the dependence of a dimensionless viscosity upon a dimensionless length and a dimensionless mass by regression analysis. The model will give theoretical suggestions for designing polyelectrolytes with desired viscosity.
Co-reporter:Jian-Hua Qiu, Yan-Wu Zhang, Ya-Tao Zhang, Hao-Qin Zhang, Jin-Dun Liu
Journal of Colloid and Interface Science 2011 Volume 354(Issue 1) pp:152-159
Publication Date(Web):1 February 2011
DOI:10.1016/j.jcis.2010.09.090
Poly(4-vinylpyridine) (P4VP) brushes were grafted onto microporous polysulfone (PSF) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and then immobilized copper (II) ions on the modified membrane. Copper-loaded membranes exhibited excellent antibacterial properties with the added advantage of repeated use. The chemical composition and surface morphology of the functionalized membrane was characterized by ATR-FTIR, XPS, SEM, and AFM. The results showed that P4VP brushes clustered to rod-shaped covering and the sub-layer of membrane maintained sponge-like structures at the same time. Additionally, the kinetic study of SI-ATRP reaction revealed that the chain length of P4VP brushes increased linearly as the polymerization time increased. The antibacterial effects of copper-loaded CMPSF-g-P4VP membrane against Escherichiacoli were examined and the antibacterial efficiency reached 100% when 2.49 wt.% of copper (II) ions was immobilized on membrane. The presented results could serve as a good starting point for the fabrication of antibacterial CMPSF membranes for waste-water treatment applications.Graphical abstractThe modification of chloromethylated polysulfone (CMPSF) membranes with poly(4-vinylpyridine) (P4VP) polymer brush was achieved by surface-initiated atom transfer radical polymerization (SI-ATRP). .Research highlights► Preparation of chloromethylated polysulfone membrane. ► Surface-initiated atom transfer radical polymerization of poly(4-vinylpyridine). ► Immobilized copper (II) ions on modified membranes. ► Copper-loaded membrane leads to improve the antibacterial property.
Co-reporter:Jianhua Qiu, Yanwu Zhang, Yongbo Shen, Yatao Zhang, Haoqin Zhang, Jindun Liu
Applied Surface Science 2010 Volume 256(Issue 10) pp:3274-3280
Publication Date(Web):1 March 2010
DOI:10.1016/j.apsusc.2009.12.018

Abstract

Polyacrylamide (PAM) brushes were grafted from chloromethylated polysulfone (CMPSF) membrane surface by surface-initiated atom transfer radical polymerization (SI-ATRP) to improve the membrane's hydrophilic property. In order to anchor the initiator onto polysulfone (PSF) membrane surface, CMPSF was used to prepare the microporous membrane by phase-inversion process. Attachment of the PAM chains on membrane surface was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The grafted density of PAM was calculated to be 0.08 chains nm−2. Field emission scanning electron microscopy (FESEM) and atomic force microscope (AFM) were used to characterize the surface morphology of the CMPSF membrane and modified membrane. The number-average molecular weight (Mn) of PAM linearly increased with the polymerization time, while the static water contact angle (θ) of the membrane grafted with PAM linearly decreased. This indicated the hydrophilic property of the membrane was linearly correlated with the chain length of graft polymer. Therefore linear control of PSF membrane's hydrophilic property was realized through adjusting polymerization time.

Co-reporter:Yanwu Zhang;Junqing Jiang;Qihui Liang ;Bing Zhang
Journal of Applied Polymer Science 2010 Volume 117( Issue 5) pp:3054-3059
Publication Date(Web):
DOI:10.1002/app.32087

Abstract

Halloysite nanotubes (HNTs) were grafted with poly(styrene–butyl acrylate–acrylic acid) (P-SBA) via an in situ soap-free emulsion polymerization. To introduce double bonds into the HNTs, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane was first used to modify the HNTs and render amino groups, and then, the double bonds were anchored through an amidation reaction between acryloyl chloride and amino groups. P-SBA chains were grafted onto HNTs because of participating of double bonds in the copolymerization of styrene, butyl acrylate, and acrylic acid. Fourier transforms infrared spectroscopy, transmission electron microscopy, specific surface area measurements, and thermogravimetric analysis were used to characterize the HNTs grafted with P-SBA. The results indicate that 25.21% of P-SBA was grafted onto the outer walls of the HNTs and filled into the inner spaces of the HNTs. The modification dramatically decreased the surface area of the HNTs. The property study of the HNTs grafted with P-SBA focused on the dispersion behavior in the biphase system. The results show that the grafted HNTs dispersed stably in the water/cyclohexane biphase system and were a potential emulsifier. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Silane, trimethyl[3-(oxiranylmethoxy)propyl]-
Halloysite(Al2(Si2O7).xH2O)