Co-reporter:Jiaxiang Qin, Weikeng Luo, Meng Li, Pin Chen, Shuanjin Wang, Shan Ren, Dongmei Han, Min Xiao, and Yuezhong Meng
ACS Sustainable Chemistry & Engineering July 3, 2017 Volume 5(Issue 7) pp:5922-5922
Publication Date(Web):June 4, 2017
DOI:10.1021/acssuschemeng.7b00634
A kind of new biodegradable materials with high performance in a wide range of temperatures was effectively developed via the combination of theoretical calculations and experimental works. The new polymer of poly(propylene carbonate)-multiblock-poly(butylene succinate) (PPC-mb-PBS) was designed and synthesized from poly(propylene carbonate) (PPC) and poly(butylene succinate) (PBS) segments. The simulation was successfully performed based on their multiblock topology structure. On the basis of the calculation, the Tg of PPC-mb-PBS calculated by molecular dynamics (MD) simulation ranges from −42 to −38 °C that is independent of the block size of PPC segments. The end-to-end distance and mean square displacement (MSD) calculations indicate an inversion behavior of the PPC and PBS between hard and soft segments at different temperatures. The stress–strain behavior of PPC-mb-PBS was also calculated by the MD simulation of uniaxial deformation. The simulated stress of PPC-mb-PBS copolyesters is higher than that of pure PPC under uniaxial extension with the same strain and is found to increase with decreasing PPC block size. To verify the validity of the simulation, the PPC-mb-PBS multiblock copolyesters with various designed block length were synthesized and characterized by 1H NMR, DOSY, and GPC. Meantime, their thermal and mechanical properties were determined, respectively, by DSC and tensile testing. The measured Tg data and the variation tendency of tensile strength are in very good agreement with the simulated results, demonstrating the ability of the fully atomic-scale MD simulations to well predict the mechanical properties of the synthesized biodegradable polymers.Keywords: Biodegradable materials; Deformation; Mean square displacement; Mechanical properties; Molecular dynamics simulation; Multiblock copolyester;
Co-reporter:Weikeng Luo, Jiaxiang Qin, Min Xiao, Dongmei Han, Shuanjin Wang, and Yuezhong Meng
ACS Omega July 2017? Volume 2(Issue 7) pp:3205-3205
Publication Date(Web):July 7, 2017
DOI:10.1021/acsomega.7b00183
High-molecular-weight poly(propylene carbonate) (PPC) [number-average molecular mass (Mn): 80 000–100 000] is readily alcoholized into PPC macrodiols in the presence of 1,2-propanediol (PDO), 1,4-butanediol (BDO), or 1,6-hexanediol (HDO). The high-molecular-weight PPC and small amount of diols, such as PDO, BDO, or HDO, were stirred at elevated temperatures to convert the extremely viscous high-molecular-weight polymer to low-molecular-weight macrodiols with gel permeation chromatography-measured Mn of about 3000 Da. The chopping reaction of the high-molecular-weight PPC was studied in detail, such as the influences of the catalyst residue, the kinds of alcoholysis agents, reaction temperature, and time. The reaction mechanism of alcoholysis is proposed according to the experimental results. The results indicate that the presence of a trace residue of zinc catalyst (Zn-G-III) in PPC, excess diol feeding, and higher temperature can accelerate the alcoholysis. Moreover, different diols can produce different PPC macrodiols with varying end-capping. Finally, polycarbonate ether urethane can be successfully synthesized using as-synthesized PPC macrodiols and poly(propylene glycol) (Mn ≈ 3000) as the soft segment and 4,4′-diphenylmethane diisocyanate or BDO as the hard segment. The full evaluation for the synthesized PPC macrodiols demonstrates their potential applications in the polyurethane industry.Topics: Mechanical properties; Polyesters; Polyoxyalkylenes; Solvolysis; Thermal properties;
Co-reporter:Lei Zhong, Kai Yang, Ruiteng Guan, Liangbin Wang, Shuanjin Wang, Dongmei Han, Min Xiao, and Yuezhong Meng
ACS Applied Materials & Interfaces December 20, 2017 Volume 9(Issue 50) pp:43640-43640
Publication Date(Web):November 27, 2017
DOI:10.1021/acsami.7b13247
Rechargeable lithium–sulfur (Li–S) batteries have been expected for new-generation electrical energy storages, which are attributed to their high theoretical energy density, cost effectiveness, and eco-friendliness. But Li–S batteries still have some problems for practical application, such as low sulfur utilization and dissatisfactory capacity retention. Herein, we designed and fabricated a foldable and compositionally heterogeneous three-dimensional sulfur cathode with integrated sandwich structure. The electrical conductivity of the cathode is facilitated by three different dimension carbons, in which short-distance and long-distance pathways for electrons are provided by zero-dimensional ketjen black (KB), one-dimensional activated carbon fiber (ACF) and two-dimensional graphene (G). The resultant three-dimensional sulfur cathode (T-AKG/KB@S) with an areal sulfur loading of 2 mg cm–2 exhibits a high initial specific capacity, superior rate performance and a reversible discharge capacity of up to 726 mAh g–1 at 3.6 mA cm–2 with an inappreciable capacity fading rate of 0.0044% per cycle after 500 cycles. Moreover, the cathode with a high areal sulfur loading of 8 mg cm–2 also delivers a reversible discharge capacity of 938 mAh g–1 at 0.71 mA cm–2 with a capacity fading rate of 0.15% per cycle and a Coulombic efficiency of almost 100% after 50 cycles.Keywords: 3D cathode structure; cycling stability; fordable cathode; high sulfur loading; lithium−sulfur battery;
Co-reporter:Shuanjin Wang;Min Xiao;Dongmei Han;Shan Ren;Kuirong Deng
ACS Applied Materials & Interfaces December 14, 2016 Volume 8(Issue 49) pp:33642-33648
Publication Date(Web):November 23, 2016
DOI:10.1021/acsami.6b11384
This work demonstrates the facile and efficient synthesis of a novel environmentally friendly CO2-based multifunctional polycarbonate single-ion-conducting polymer electrolyte with good electrochemistry performance. The terpolymerizations of CO2, propylene epoxide (PO), and allyl glycidyl ether (AGE) catalyzed by zinc glutarate (ZnGA) were performed to generate poly(propylene carbonate allyl glycidyl ether) (PPCAGE) with various alkene groups contents which can undergo clickable reaction. The obtained terpolymers exhibit an alternating polycarbonate structure confirmed by 1H NMR spectra and an amorphous microstructure with glass transition temperatures (Tg) lower than 11.0 °C evidenced by differential scanning calorimetry analysis. The terpolymers were further functionalized with 3-mercaptopropionic acid via efficient thiol–ene click reaction, followed by reacting with lithium hydroxide, to afford single-ion-conducting polymer electrolytes with different lithium contents. The all-solid-state polymer electrolyte with the 41.0 mol % lithium containing moiety shows a high ionic conductivity of 1.61 × 10–4 S/cm at 80 °C and a high lithium ion transference number of 0.86. It also exhibits electrochemical stability up to 4.3 V vs Li+/Li. This work provides an interesting design way to synthesize an all-solid-state electrolyte used for different lithium batteries.Keywords: all-solid-state electrolyte; CO2-based multifunctional polycarbonate; environmentally friendly; ionic conductivity; single-ion-conducting polymer electrolyte; thiol−ene click chemistry;
Co-reporter:Kirill A. Alferov, Gennadiy P. Belov, Yuezhong Meng
Applied Catalysis A: General 2017 Volume 542(Volume 542) pp:
Publication Date(Web):25 July 2017
DOI:10.1016/j.apcata.2017.05.014
•Recent progress in the field of selective ethylene tri- and tetramerization in the presence of chromium catalysts is reviewed.•Patent and scientific publications are analyzed.•Activities and selectivities of different catalytic systems are provided.•Results of experimental and theoretical mechanistic studies for past years are covered.The objective of this review is the analysis and comment of recent publication results (from July 2010 until February 2017) obtained for selective ethylene oligomerization toward 1-hexene and 1-octene catalyzed by chromium-based catalytic systems. Both the scientific and patent literature was taken into the consideration. The catalytic systems for ethylene oligomerization are classified on the basis of the ligand type employed. The activities and selectivities of the catalysts are provided throughout the text. Despite a big success in the field, there is still rather limited choice of catalysts affording simultaneously high activity, selectivity and low polymer proportion. This is especially true for ethylene to 1-octene tetramerization reaction. The results of the studies concerning oligomerization mechanisms obtained over the recent years are also included in this review.Download high-res image (82KB)Download full-size image
Co-reporter:Kuirong Deng, Shuanjin Wang, Shan Ren, Dongmei Han, Min Xiao, Yuezhong Meng
Journal of Power Sources 2017 Volume 360(Volume 360) pp:
Publication Date(Web):31 August 2017
DOI:10.1016/j.jpowsour.2017.06.006
•Boron-based single-ion conducting gel polymer electrolytes are designed.•The electrolytes are fabricated by facile in situ thiol-ene click reaction.•Ionic conductivity reaches 1.47 × 10−3 S cm−1 at 25 °C.•High lithium transference number of 0.89 is obtained.•The LiFePO4 cell delivers a capacity of 124 mA h g−1 at 1 C rate after 500 cycles.Electrolytes play a vital role in modulating lithium ion battery performance. An outstanding electrolyte should possess both high ionic conductivity and unity lithium ion transference number. Here, we present a facile method to fabricate a network type sp3 boron-based single-ion conducting polymer electrolyte (SIPE) with high ionic conductivity and lithium ion transference number approaching unity. The SIPE was synthesized by coupling of lithium bis(allylmalonato)borate (LiBAMB) and pentaerythritol tetrakis(2-mercaptoacetate) (PETMP) via one-step photoinitiated in situ thiol-ene click reaction in plasticizers. Influence of kinds and content of plasticizers was investigated and the optimized electrolytes show both outstanding ionic conductivity (1.47 × 10−3 S cm−1 at 25 °C) and high lithium transference number of 0.89. This ionic conductivity is among the highest ionic conductivity exhibited by SIPEs reported to date. Its electrochemical stability window is up to 5.2 V. More importantly, Li/LiFePO4 cells with the prepared single-ion conducting electrolytes as the electrolyte as well as the separator display highly reversible capacity and excellent rate capacity under room temperature. It also demonstrates excellent long-term stability and reliability as it maintains capacity of 124 mA h g−1 at 1 C rate even after 500 cycles without obvious decay.Download high-res image (141KB)Download full-size image
Co-reporter:Sheng Huang;Chao Meng;Min Xiao;Shan Ren;Shuanjin Wang;Dongmei Han;Yuning Li
Sustainable Energy & Fuels (2017-Present) 2017 vol. 1(Issue 9) pp:1944-1949
Publication Date(Web):2017/10/24
DOI:10.1039/C7SE00355B
Tin phosphide (Sn4P3) combined with the good conductivity of tin (Sn) and high capacity of phosphorus has been reported to be a potential anode material for the sodium ion battery (SIB). However, the preparation of Sn4P3 is limited to ball-milling and compositing with carbon materials. The novel and detailed structure of Sn4P3 itself has so far not been revealed. In this research, the multi-shell Sn4P3 nano-structure was obtained, for the first time, using a simple and general low temperature solvothermal method. The multi-shell structure with a larger specific surface area and interlayer space endows this new anode material with a short cut pathway for sodium ion diffusion and a buffer space for volume expansion during sodiation, thus avoiding electrode pulverization and improving the cycling performance of the SIB. The as-prepared multi-shell Sn4P3 delivers an excellent specific capacity of 770 mAh g−1 with capacity retention of 96% after 50 cycles at the current density of 50 mA g−1, demonstrating the superiority of structure optimization in SIB anode preparation.
Co-reporter:Longlong Yan;Dongmei Han;Min Xiao;Shan Ren;Yuning Li;Shuanjin Wang
Journal of Materials Chemistry A 2017 vol. 5(Issue 15) pp:7015-7025
Publication Date(Web):2017/04/11
DOI:10.1039/C7TA01400G
To eliminate capacity fading effects due to the loss of sulfur in cathode materials for lithium–sulfur batteries (LSBs), a polymer of poly(1,3-diethynylbenzene) (PAB) with good solubility was synthesized by an oxidative coupling reaction. This polymer can be instantaneously carbonized into highly conductive carbon, which can then be used as both an immobilizer host and conductivity enhancer for sulfur cathodes. The cathode material of S/PAB-C was prepared via a rapid dissolution–precipitation method combined with an in situ and instantaneous carbonization process to obtain 3D graphene-like PAB-C with an artificial honeycomb-like morphology. Benefitting from this particular design, the S/PAB-C cathode with an optimal content of 75% sulfur exhibits excellent discharge–charge performance, which shows initial discharge capacities of 1449 mA h g−1 at 0.1C and 1087 mA h g−1 at 0.5C, and retains a stable capacity of 900 mA h g−1 after 500 cycles with a high retention of 82.6% at 0.5C. The strategy which utilizes instantaneous carbonization of PAB and an in situ sulfur trapping process offers a new way to enhance the cycling stability and enriches the architectural design of LSBs. To the best of our knowledge, this is the first report about the brand new methodology to in situ synthesize highly conductive carbon for application in LSBs.
Co-reporter:Yonghang Xu;Limiao Lin;Chun-Ting He;Jiaxiang Qin;Zhong Li;Shuanjin Wang;Min Xiao
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 23) pp:3632-3640
Publication Date(Web):2017/06/13
DOI:10.1039/C7PY00403F
The trizinc complexes Zn3(OAc)4(Ln)2, 1a and 1b, which were coordinated with Schiff-base ligands via a simple and economical method, have been examined and found to be highly effective and efficient toward the copolymerization of CO2 and cyclohexene oxide (CHO). In this work, the kinetics for the copolymerization of CO2 and CHO using 1b as the catalyst was monitored via in situ ATR-FTIR spectroscopy. The reaction orders’ dependencies on catalyst concentration, initial CHO concentration and CO2 pressure, as well as activation energies (Ea) of polycarbonate and cyclic carbonate formation, were investigated in detail. The practical amount of active zinc sites in the copolymerization was calculated using the parameters obtained from 1H NMR and GPC measurements. The initiating reaction details were simulated using density functional theory, and the potential energy surfaces were obtained. Based on the results of all characterizations and kinetic investigations, a unique initiating reaction and copolymerizing mechanism were proposed when using Zn3(OAc)4(Ln)2 as the catalyst.
Co-reporter:Lesi Zhang, Ling Ling, Min Xiao, Dongmei Han, Shuanjin Wang, Yuezhong Meng
Journal of Power Sources 2017 Volume 352(Volume 352) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.jpowsour.2017.03.124
•Nafion-[PDDA/ZrP]n with nacre-like nanostructures was fabricated by LbL method.•The lamellar structure and Donnan exclusion suppress vanadium ion permeability.•Nafion-[PDDA/ZrP]3 exhibits higher performance in VRFB than pristine Nafion.A novel self-assembled composite membrane, Nafion-[PDDA/ZrP]n with nacre-like nanostructures was successfully fabricated by a layer-by-layer (LbL) method and used as proton exchange membrane for vanadium redox flow battery applications. Poly(diallyldimethylammonium chloride) (PDDA) with positive charges and zirconium phosphate (ZrP) nanosheets with negative charges can form ultra-thin nacre-like nanostructure on the surface of Nafion membrane via the ionic crosslinking of tightly folded macromolecules. The lamellar structure of ZrP nanosheets and Donnan exclusion effect of PDDA can greatly decrease the vanadium ion permeability and improve the selectivity of proton conductivity. The fabricated Nafion-[PDDA/ZrP]4 membrane shows two orders of magnitude lower vanadium ion permeability (1.05 × 10−6 cm2 min−1) and 12 times higher ion selectivity than those of pristine Nafion membrane at room temperature. Consequently, the performance of vanadium redox flow batteries (VRFBs) assembled with Nafion-[PDDA/ZrP]3 membrane achieved a highly coulombic efficiency (CE) and energy efficiency (EE) together with a very slow self-discharge rate. When comparing with pristine Nafion VRFB, the CE and EE values of Nafion-[PDDA/ZrP]3 VRFB are 10% and 7% higher at 30 mA cm−2, respectively.Download high-res image (237KB)Download full-size image
Co-reporter:Longlong Yan, Min Xiao, Shuanjin Wang, Dongmei Han, Yuezhong Meng
Journal of Energy Chemistry 2017 Volume 26, Issue 3(Volume 26, Issue 3) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.jechem.2016.12.001
Lithium–sulfur batteries have great potential for high energy applications due to their high capacities, low cost and eco-friendliness. However, the particularly rapid capacity decay owing to the dissolution and diffusion of polysulfide intermediate into the electrolyte still hamper their practical applications. And the reported preparation procedures to sulfur based cathode materials are often complex, and hence are rather difficult to produce at large scale. Here, we report a simple mechano-chemical sulfurization methodology in vacuum environment applying ball-milling method combined both the chemical and physical interaction for the one-pot synthesis of edge-sulfurized grapheme nanoplatelets with 3D porous foam structure as cathode materials. The optimal sample of 70%S–GnPs-48 h (ball-milled 48 h) obtains 13.2 wt% sulfur that chemically bonded onto the edge of GnPs. And the assembled batteries exhibit high initial discharge capacities of 1089 mAh/g at 0.1 C and 950 mAh/g at 0.5 C, and retain a stable discharge capacity of 776 mAh/g after 250 cycles at 0.5 C with a high Coulombic efficiency of over 98%. The excellent performance is mainly attributed to the mechano-chemical interaction between sulfur and grapheme nanoplatelets. This definitely triggers the currently extensive research in lithium–sulfur battery area.A simple sulfurization methodology applying both the chemical and physical interaction is studied for the one-pot synthesis of edge-sulfurized GnPs with porous structure for cathode materials.Download high-res image (177KB)Download full-size image
Co-reporter:Yingjie Zhou;Jingjing Liu;Rongcai Huang;Meng Zhang;Min Xiao;Luyi Sun
Dalton Transactions 2017 vol. 46(Issue 38) pp:13126-13134
Publication Date(Web):2017/10/03
DOI:10.1039/C7DT01510K
Ionic liquids (ILs) have attracted significant attention because of their unique chemical and physical properties. Immobilization of ILs on solid materials helps increase their efficiency and facilitate their recycling. In our present work, ILs were immobilized on α-zirconium phosphate (ZrP) single layer nanosheets by a post-grafting method. The immobilized ILs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The characterization results supported that the ILs were covalently grafted onto ZrP nanosheets via the chemical reaction of ethoxyl silane groups in ILs with the surface hydroxyl groups on ZrP nanosheets. A high density of grafting of ILs on individual ZrP nanosheets was achieved. The immobilized ILs on individual ZrP nanosheets can be uniformly dispersed in polar chemicals and are readily accessible. When applied as a heterogeneous catalyst for Knoevenagel condensation under a solvent-free condition, such immobilized ILs exhibited high efficiency and can be easily recycled and reused.
Co-reporter:Lizhen Long, Shuanjin Wang, Min Xiao and Yuezhong Meng
Journal of Materials Chemistry A 2016 vol. 4(Issue 26) pp:10038-10069
Publication Date(Web):25 May 2016
DOI:10.1039/C6TA02621D
In this review, state-of-the-art polymer electrolytes are discussed with respect to their electrochemical and physical properties for their application in lithium polymer batteries. We divide polymer electrolytes into the two large categories of solid polymer electrolytes and gel polymer electrolytes (GPE). The performance requirements and ion transfer mechanisms of polymer electrolytes are presented at first. Then, solid polymer electrolyte systems, including dry solid polymer electrolytes, polymer-in-salt systems (rubbery electrolytes), and single-ion conducting polymer electrolytes, are described systematically. Solid polymer electrolytes still suffer from poor ionic conductivity, which is lower than 10−5 S cm−1. In order to further improve the ionic conductivity, numerous new types of lithium salt have been studied and inorganic fillers have been incorporated into solid polymer electrolytes. In the section on gel polymer electrolytes, the types of plasticizer and preparation methods of GPEs are summarized. Although the ionic conductivity of GPEs can reach 10−3 S cm−1, their low mechanical strength and poor interfacial properties are obstacles to their practical application. Significant attention is paid to the incorporation of inorganic fillers into GPEs to improve their mechanical strength as well as their transport properties and electrochemical properties.
Co-reporter:Yingjie Zhou, Jingjing Liu, Min Xiao, Yuezhong Meng, and Luyi Sun
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 8) pp:5547
Publication Date(Web):February 3, 2016
DOI:10.1021/acsami.5b11249
A new methodology was developed for the immobilization of ionic liquids (ILs) on α-zirconium phosphate (ZrP) and montmorillonite (MMT) single-layer nanosheets via a facile coassembly process. The coassembled inorganic nanosheet/1-n-butyl-3-methylimidazolium chloride (BMIMCl) hybrids were systematically characterized. The results showed that the ILs were successfully assembled with ZrP or MMT single-layer nanosheets to form an intercalated structure. The inorganic nanosheet/IL hybrids can serve as efficient CO2 absorbents. The CO2 sorption of BMIMCl could be made up to 21 times more efficient because of the high exposure of the functional groups of BMIMCl in the coassembled hybrids. CO2 was physically absorbed by the hybrids with a slow equilibrium time at lower temperatures, whereas higher temperatures allowed for faster diffusion and chemical absorption of CO2. The best CO2 capture capacities of the hybrids were 0.73 mmol/g at 60 °C for ZrP/BMIMCl and 0.42 mmol/g at 70 °C for MMT/BMIMCl.Keywords: CO2 capture; coassembly; immobilization; ionic liquids; α-zirconium phosphate
Co-reporter:Meng Zhang, Zhongwei Fu, Min Xiao, Yuehong Yu, Shuanjin Wang, Myoung Jae Choi and Yuezhong Meng
Chemical Communications 2016 vol. 52(Issue 6) pp:1151-1153
Publication Date(Web):04 May 2015
DOI:10.1039/C5CC02230D
A new catalyst Co1.5PW12O40 was synthesized with exceptional catalytic performance of converting methanol to ethylene. Under the optimal conditions, both the conversion of methanol and the selectivity of ethylene are almost 100%, which can thus avoid a product separation process.
Co-reporter:Zhenjie Sun, Shuanjin Wang, Longlong Yan, Min Xiao, Dongmei Han, Yuezhong Meng
Journal of Power Sources 2016 Volume 324() pp:547-555
Publication Date(Web):30 August 2016
DOI:10.1016/j.jpowsour.2016.05.122
•Mesoporous carbon materials (MCMs) were synthesized from waste litchi shells.•The as-prepared MCMs exhibit a similar conductivity to conductive carbon black.•MCMs-S cathode delivers a very high initial specific capacity of 1667 mAh g−1.•The MCMs-S cathode material treated at 300 °C remains 612 mAh g−1 after 200 cycles.Novel mesoporous carbon materials (MCMs) with excellent electron conductivity and high surface area are successfully synthesized from waste litchi shells. The as-prepared MCMs possess a narrow pore size distribution (0.5–2.0 nm) and exhibit similar electron conductivities to conductive carbon black (Super P, Timcal). Because of the unique properties of MCMs, they are used as host matrixes to encapsulate sulfur for lithium-sulfur cathodes. The obtained MCMs-sulfur (MCMs-S) composite cathodes deliver a high initial specific capacity of 1667 mAh g−1. Moreover, 300 °C treated MCMs-S composite cathode shows a more stable discharge capacity than the untreated MCMs-S composite cathode, it remains 612 mAh g−1 after 200 cycles at a high current density of 0.5 C.
Co-reporter:Limiao Lin, Yonghang Xu, Shuanjin Wang, Min Xiao, Yuezhong Meng
European Polymer Journal 2016 Volume 74() pp:109-119
Publication Date(Web):January 2016
DOI:10.1016/j.eurpolymj.2015.09.029
•A gradient poly(lactide-grad-caprolactone) was synthesized at first time.•Both copolymer composition and structure have great impacts on their properties.•This method can be used to synthesize biodegradable aliphatic polyester with a diverse range of properties.An economic and biocompatible Schiff base tri-zinc catalyst was used to synthesize homo/copolymers of l-lactide (LA) and ε-caprolactone (CL) in bulk at first time. Both 1H and 13C NMR analyses show that LA is more active than CL, resulting in a poly(LA-grad-CL) copolymer with gradient sequence structure. A series of copolymers containing varying LA/CL ratios were readily synthesized. The chemical structure of poly(LA-grad-CL) was fully investigated using NMR and GPC technologies. TGA, DSC, DMA and nanoindentation instruments were employed to evaluate thermal and mechanical properties of these polymers. The results indicate that polymer composition and chain structure have a great impact on the crystallization behavior and crystallinity, as well as the thermal and mechanical properties of the copolymers. Therefore, the performance of the copolymer can be then tailored by simply adjusting the ratios of LA to CL.Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Yingjie Zhou, Zhongwei Fu, Shuanjin Wang, Min Xiao, Dongmei Han and Yuezhong Meng
RSC Advances 2016 vol. 6(Issue 46) pp:40010-40016
Publication Date(Web):18 Apr 2016
DOI:10.1039/C6RA04150G
Electro-assisted dimethyl carbonate (DMC) formation from CO2 and methanol over carbonaceous material supported 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU) was first performed under solvent-free conditions in a capacitor-like cell reactor designed by our group. The effects of applied voltage modes and conductivities of the catalysts on the catalytic performances were fully investigated. The experiment results demonstrated that the catalytic activities can be obviously boosted when the voltages were applied to the catalyst fixed-bed. The constant working potential presented better catalytic activity than the metabolic voltages, and the higher conductivity of catalysts leads to a better catalytic performance. Furthermore, the supported DBU displayed good recyclable properties in the specially designed electrochemical apparatus. We proposed a reaction mechanism of the electrocatalysis for DMC formation.
Co-reporter:Wenhan Luo, Min Xiao, Shuanjin Wang, Dongmei Han, Yuezhong Meng
European Polymer Journal 2016 Volume 84() pp:245-255
Publication Date(Web):November 2016
DOI:10.1016/j.eurpolymj.2016.09.029
•One-pot synthesis of terpolymers from PO, CO2 and CL by ZnGA catalyst is described.•Formation rates of PPC and PCL moieties were examined by in situ infrared monitoring.•The terpolymers are a kind of semicrystalline polymers with long CL rich sequence.•The terpolymers show excellent melt processibility and mechanical properties.We report here an efficient one-pot synthesis of terpolymers from propylene oxide (PO), carbon dioxide (CO2), and ε-caprolactone (CL) with long CL rich sequence using zinc glutarate as catalyst. The terpolymer yields increase significantly from 50 to 103 (g polymer per g catalyst) with the introduction of CL as a third monomer. The propylene oxide conversion increases by nearly 44% at relatively low polymerization temperature (60 °C). Moreover, the differences in reaction rates of polycarbonate and polyester moieties were examined by in situ infrared monitoring. 1H NMR, GPC and DOSY NMR results show the as-prepared polymer being a gradient terpolymer. As confirmed by XRD and DSC methods, the synthesized terpolymers are a kind of semicrystalline polymer in which the crystalline domains consist mainly of PCL rich segment. Consequently, the semicrystalline terpolymers exhibit much better thermal properties and superior mechanical strength compared with amorphous polycarbonate PPC.An efficient one-pot synthesis of terpolymers from propylene oxide (PO), carbon dioxide (CO2) and ε-caprolactone (CL) with long CL rich sequence using zinc glutarate as catalyst.
Co-reporter:Gao-feng Li;Wen-han Luo;Min Xiao
Chinese Journal of Polymer Science 2016 Volume 34( Issue 1) pp:13-22
Publication Date(Web):2016 January
DOI:10.1007/s10118-016-1720-9
Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides (LDHs) were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH (OLDH) in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A series of poly(propylene carbonate) (PPC)/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient (OP) and water vapor permeability coefficient (WVP) is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.
Co-reporter:Yang Zhao;Guiji Chen;Min Xiao;Shuanjin Wang
Journal of Polymer Research 2016 Volume 23( Issue 4) pp:
Publication Date(Web):2016 April
DOI:10.1007/s10965-016-0970-0
Biodegradable films of poly(propylene carbonate)/poly(vinyl alcohol)-thermoplastic polyurethane [PPC/(PVA-TPU)] ternary blends were successfully prepared by melting blending method. The mechanical properties of poly(propylene carbonate) blown film were greatly improved by blending PPC with PVA-TPU. In order to afford the melt processing of PVA, the PVA-TPU binary blend was firstly prepared using thermoplastic polyurethane as a polymeric plasticizer. The rheological behavior, mechanical properties and morphology of these blends were studied. Considering its melt viscosity and thermally processing temperature, the PVA-50%TPU, as a modifier, was blended with PPC to prepare PPC/(PVA-TPU) ternary blend. SEM observation revealed a basic one-phase morphological structure with very good interfacial adhesion between the extremely blurred PPC and PVA-TPU two components. Meanwhile, the miscibility of the ternary components was verified by only one glass-transition temperature obtained from DMA tests. The tensile strength and tear strength of PPC/(PVA-TPU) blown films were determined at different temperatures. The results demonstrate that the mechanical properties of PPC/(PVA-TPU) films were enhanced dramatically at low temperature when compared with neat PPC. At room temperature, PPC/30 %(PVA-50%TPU) blown film exhibited a tensile strength of 26 MPa, and an elongation at break of 484.0 %. Its tear strength in the take-up direction is 124.1 kN/m, and the one in machine direction is 141.9 kN/m. At a low temperature of 0 °C, PPC/30 %(PVA-50%TPU) exhibited a tensile strength of 40.7 MPa and tear strength of 107 kN/m, which are 153 % and 142 % of those of neat PPC respectively. The blending of PPC with the PVA plasticized with TPU provides a practical way to extend the application of the new biodegradable polymer of PPC in the area of blown films.
Co-reporter:Yingjie Zhou, Alex D. Brittain, Deyuan Kong, Min Xiao, Yuezhong Meng and Luyi Sun
Journal of Materials Chemistry A 2015 vol. 3(Issue 27) pp:6947-6961
Publication Date(Web):09 Jun 2015
DOI:10.1039/C5TC01377A
Diamondoids, a group of hydrocarbon cage molecules that resemble diamond lattice, are attracting increasing interest in the past decade. Their diamond-like structure warrants that diamondoids inherit the superior properties of diamond at nanoscale, including exceptional hardness and stiffness, high thermal stability, high chemical resistance, unique optical properties and fluorescence, and excellent biocompatibility. To effectively take advantage of the fascinating properties of diamondoids, they must be properly functionalized so that they can be covalently incorporated into the host systems or compatibly mixed with the hosts. Herein, the origin, synthesis, derivatization, and application of diamondoids are reviewed. In particular, how the derivatized diamondoids for various functional applications, including pharmaceuticals, polymers, fine chemicals, nanomaterials, and optical devices, are discussed. It is hoped that this review article can attract more interest in diamondoids, which in turn helps motivate the development of new synthesis and application of diamondoids and their derivatives so that this group of unique molecules can bring more benefits.
Co-reporter:Zhenjie Sun, Min Xiao, Shuanjin Wang, Dongmei Han, Shuqin Song, Guohua Chen, Yuezhong Meng
Journal of Power Sources 2015 Volume 285() pp:478-484
Publication Date(Web):1 July 2015
DOI:10.1016/j.jpowsour.2015.03.138
•A carbon black-sulfur composite material with a novel structure was synthesized.•The as-prepared cathode material with a high sulfur content of 84 wt%.•The stable capacity retention is of 865 mAh g−1 after 100 cycles.Sulfur is a promising cathode material with a high theoretical capacity of 1672 mAh g−1, but the challenges of the low electrical conductivity of sulfur and the high solubility of polysulfide intermediates still hinder its practical application. In this work, we design and synthesize a special carbon black nanoparticle–sulfur composite cathode material (NCB-S@NCB) with a novel structure and a high sulfur content of 84 wt% for lithium–sulfur battery application. The NCB-S@NCB composite cathode delivers a high initial discharge capacity of 1258 mAh g−1 and still maintains a reversible capacity of 865 mAh g−1 after 100 cycles with a relatively constant Coulombic efficiency around 98.0%.
Co-reporter:Yulei Liu, Kuirong Deng, Shuanjin Wang, Min Xiao, Dongmei Han and Yuezhong Meng
Polymer Chemistry 2015 vol. 6(Issue 11) pp:2076-2083
Publication Date(Web):13 Jan 2015
DOI:10.1039/C4PY01801J
Terpolymerizations of CO2, propylene epoxide (PO) and maleic anhydride (MA) using zinc adipate (ZnAA) as a catalyst were carried out in a toluene solution. A series of biodegradable terpolymers (PPCMAs) with different polyester and polycarbonate contents were synthesized. The molecular chain sequence structure of these terpolymers was proved to be a gradient one based on 1H NMR investigation combined with in situ infrared technology monitoring the reaction process. The sulfonation of biodegradable PPCMAs was carried out by the addition of sodium hydrogen sulphite into ethylenic double bonds of the unsaturated polyester unit. The surface activities and the aggregation of these sulfonated biodegradable terpolymers in aqueous solution were investigated by surface tension measurement and dynamic light scattering (DLS) technology. The results indicate that the sulfonated biodegradable terpolymer with comparable hydrophilic and hydrophobic segment contents tends to adsorb at the air/water interface and thus exhibits the best surface activities. The surface tension of the aqueous solution of the polymer with 56.8% hydrophilic segments reaches 47.5 mN m−1 at its critical micelle concentration (CMC).
Co-reporter:Yonghang Xu, Shuanjin Wang, Limiao Lin, Min Xiao and Yuezhong Meng
Polymer Chemistry 2015 vol. 6(Issue 9) pp:1533-1540
Publication Date(Web):01 Dec 2014
DOI:10.1039/C4PY01587H
Novel semi-crystalline terpolymers with varying chain sequence structures derived from cyclohexene oxide (CHO), CO2 and ε-caprolactone (CL) have been firstly synthesized and reported. The terpolymerization is catalyzed by Schiff base tri-zinc complexes via a one-step route. The tri-zinc complexes also exhibit a very high catalytic activity for the homopolymerization of ε-caprolactone in the absence of CHO. A series of terpolymers with varying content of crystalline segments are produced by adjusting the feedstock ratio of CHO/ε-CL. The reactivity of different monomers was investigated by experimental methodology. The results indicate that ε-CL is much more active than CHO in this terpolymerization system. Therefore, the incorporation of ε-CL can dramatically improve the TONs of terpolymer containing ε-CL moieties. Moreover, the thermal properties of the resulting terpolymers were also studied by DSC and TGA. Finally, the polymerization mechanism of this ternary system is extensively discussed based on experimental phenomena. To the best of our knowledge, this is the first report on novel catalysts capable of synthesizing polycarbonates, polyesters and poly (carbonate-ester) via a one-step polymerization.
Co-reporter:Bin Zhang, Shuanjin Wang, Min Xiao, Dongmei Han, Shuqin Song, Guohua Chen and Yuezhong Meng
RSC Advances 2015 vol. 5(Issue 48) pp:38792-38800
Publication Date(Web):22 Apr 2015
DOI:10.1039/C5RA06825H
Novel sulfur-rich polymeric materials were readily prepared via facile solution vulcanization of the commercial butadiene rubber (BR) and sulfur element, and were investigated as cathode materials for lithium–sulfur batteries. During the solution vulcanization procedure, the double bonds (CC) in butadiene rubber are chemically cross-linked with sulfur. Moreover, the sulfur canalso self-polymerize into polymeric sulfur with long molecular chain. The polymeric sulfur chains penetrate into the cross-linked BR network to form a unique semi-internal penetration network (semi-IPN) confinement structure, which can effectively alleviate the dissolution and diffusion of intermediate polysulfide into electrolytes. Meanwhile, the obtained sulfur-rich polymeric composites have high sulfur contents even over 90%. As a result, the as-prepared sulfur-rich polymeric composites (BR-SPC) with network confine caged structure exhibit excellent cycling stability and high coulombic efficiency. An initial discharge specific capacity of 811 mA h g−1 is reached, and retains 671 mA h g−1 after 50 cycles at 0.1 C. The capacity retention rate and coulombic efficiency are 83%, 100%, respectively. Additionally, Super P (carbon black) was added in situ before vulcanization to increase the conductivity of BR-SPC composites. The BR-SPC composite containing Super P (BR-SPC-SP) reveals higher capacity retention of 85% over 50 cycles at 0.5 C than the BR-SPC composite without Super P.
Co-reporter:Guojia Huang, Yingnan Zou, Min Xiao, Shuanjin Wang, Weikeng Luo, Dongmei Han, Yuezhong Meng
Polymer Degradation and Stability 2015 Volume 117() pp:16-21
Publication Date(Web):July 2015
DOI:10.1016/j.polymdegradstab.2015.03.020
Thermal degradation behaviors of poly(lactide-co-propylene carbonate)s (PLAPCs) with different PC contents were studied at various pyrolysis temperatures by the combination of thermo gravimetric analysis/Fourier transform infrared spectrometry (TG/FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques. The activation energies of thermal degradation are calculated by Kissinger method. The experimental results indicate that increasing PC content in PLAPC chain lead to a decrease of maximum decomposition temperature. The activation energy of degradation increases with increasing PC content. The dominant degradation pathway is a backbiting ester interchange reaction involving OH chain ends of PLAPCs, resulting in the formation of cyclic oligomers. In addition, at a relative higher pyrolysis temperature, besides the major products propylene carbonate and lactide, small amounts of propenoic acid and acetaldehyde were also detected, showing a main intramolecular trans-esterification accompanied with chain scission decomposition mechanism.
Co-reporter:Lipeng Zhai;Gaofeng Li;Yan Xu;Min Xiao;Shuanjin Wang
Journal of Applied Polymer Science 2015 Volume 132( Issue 11) pp:
Publication Date(Web):
DOI:10.1002/app.41663
ABSTRACT
A series of poly(propylene carbonate) (PPC)/aluminum flake (ALF) composite films with different ALF contents were prepared via a melt-blending method. Their cross-section morphologies, thermal properties, tensile strength (TS), and gas barrier properties were investigated as a function of ALF contents. SEM images reveal the good dispersion and orientation of ALF along with melt flow direction within PPC matrix. The oxygen permeability coefficient (OP) and water vapor permeability coefficient (WVP) of the composite films decrease continuously with ALF contents increasing up to 5 wt %, which are 32.4% and 75.2% that of pure PPC, respectively. Furthermore, the TS and thermal properties of PPC/ALF composite film are also improved by the incorporation of ALF particles. The PPC/ALF composite films have potential applications in packaging area due to its environmental-friendly properties, superior water vapor, and oxygen barrier characteristics. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41663.
Co-reporter:Lei Tang;Wenhan Luo;Min Xiao;Shuanjin Wang
Journal of Polymer Science Part A: Polymer Chemistry 2015 Volume 53( Issue 14) pp:
Publication Date(Web):
DOI:10.1002/pola.27617
ABSTRACT
We report here an efficient one-port synthesis of terpolymers from PO, CO2, and l-lactide (LLA) with long LLA rich sequence using the cheapest zinc adipate as catalyst. The copolymerizations were carried out under various experimental conditions to find out the optimal conditions. The terpolymer yields increase significantly from 151 to 417 (g polymer per g zinc) by the introduction of LLA as a third monomer. The polycarbonate moiety selectivity increases by nearly 60% at relatively high polymerization temperature (80 °C). Moreover, the differences in reaction kinetic of polycarbonate and polyester moieties were observed by in situ infrared monitoring. As confirmed by XRD and DSC, the synthesized terpolymers are a kind of semicrystalline polymer in which the crystalline PLA segment function as strong noncovalent crosslinking domains. Consequently, it exhibits much better thermal properties as well as remarkable higher mechanical strength compared with amorphous polycarbonate PPC. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1734–1741
Co-reporter:Zhenjie Sun, Min Xiao, Shuanjin Wang, Dongmei Han, Shuqin Song, Guohua Chen and Yuezhong Meng
Journal of Materials Chemistry A 2014 vol. 2(Issue 38) pp:15938-15944
Publication Date(Web):31 Jul 2014
DOI:10.1039/C4TA03570D
Sulfur has a very high theoretical specific capacity of 1672 mA h g−1 when used in lithium–sulfur batteries. However, the particularly rapid capacity reduction owing to the dissolution of intermediate polysulfide anions into the electrolyte still hinders practical application. In this respect, we report a novel core–shell structured sulfur–poly(sodium p-styrenesulfonate) (S@PSS) composite cathode material with a sulfur content as high as 93 wt% for lithium–sulfur batteries, which is the highest sulfur content disclosed in the literature. Due to the effective transport of lithium cations while blocking polysulfide anions by common ion Coulombic repulsion of the negatively charged –SO3− groups in the PSS protective layer, the S@PSS composite cathode exhibits a high initial specific capacity of 1159 mA h g−1 at a 0.1 C rate, and retains a stable discharge capacity of 972 mA h g−1 after 70 cycles and 845 mA h g−1 after 120 cycles with a high Coulombic efficiency of over 99%. To our knowledge, this new methodology for lithium–sulfur cathodes has not been reported so far; the initial specific capacity is the highest value calculated based on total composite mass, which has not been disclosed in the literature.
Co-reporter:Shaoyun Chen, Bin Sun, Wei Hong, Zhuangqing Yan, Hany Aziz, Yuezhong Meng, Jon Hollinger, Dwight S. Seferos and Yuning Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 9) pp:1683-1690
Publication Date(Web):10 Dec 2013
DOI:10.1039/C3TC31753F
Two diketopyrrolopyrrole (DPP)–carbazole (Cz) based π-conjugated copolymers, PDBTCz-H (P1) and PDBTCz-Me (P2), were designed and synthesized to study the effects of N-substitution of the carbazole unit on the molecular ordering, main chain conjugation, and charge transport properties of these polymers. It was found that the existence of hydrogen bonding interaction between the N–H group in the carbazole unit and the CO group in the DPP unit has a significant impact on the UV absorption, crystallinity, thin film morphology, as well as charge transport characteristics of P1. The hydrogen bonding is a very competitive force with the π–π stacking interaction, leading to the more twisted backbone structure and poorer molecular ordering of P1 in the solid state. Although the crystallinity of the P1 thin films could be somewhat improved by thermal annealing, the polymer main chains of P1 remain rather twisted and less conjugated in comparison with P2. The poorer main chain conjugation of P1 caused by the hydrogen bonding led to a dramatic drop in charge transport performance in organic thin film transistors (OTFTs). The highest hole mobility achieved for P1 is 8.9 × 10−3 cm2 V−1 s−1, which is almost two orders of magnitude lower than that of P2 (0.53 cm2 V−1 s−1).
Co-reporter:Zhenjie Sun, Min Xiao, Shuanjin Wang, Dongmei Han, Shuqin Song, Guohua Chen and Yuezhong Meng
Journal of Materials Chemistry A 2014 vol. 2(Issue 24) pp:9280-9286
Publication Date(Web):16 Apr 2014
DOI:10.1039/C4TA00779D
Novel polymeric materials with a very high content of sulfur were successfully synthesized via a facile copolymerization of elemental sulfur with 1,3-diethynylbenzene (DEB). For the as-prepared sulfur-rich polymeric materials (C–S copolymer), diynes or polydiynes are chemically cross-linked with a large amount of polymeric sulfur to form a cage-like semi-interpenetrating network (semi-IPN) structure. Due to the strong chemical interaction of sulfur with the carbon framework and the unique cage-like structure in C–S copolymers, the dissolution and diffusion of polysulfides out of the cathode is effectively suppressed through chemical and physical means. As a result, the sulfur-rich C–S polymeric materials with semi-IPN structure exhibit excellent cycling stability and high coulombic efficiency. The initial discharge capacity is 1143 mA h g−1 at a 0.1 C rate. The capacity still remains at 70% even after about 500 cycles at a high current density of 1 C. In addition, a high coulombic efficiency of over 99% is obtained during the entire range of cycling.
Co-reporter:Shaoyun Chen, Bin Sun, Wei Hong, Hany Aziz, Yuezhong Meng and Yuning Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 12) pp:2183-2190
Publication Date(Web):06 Jan 2014
DOI:10.1039/C3TC32219J
The influence of the side chain on the molecular organization and charge transport performance of diketopyrrolopyrrole-quaterthiophene copolymers (PDQTs) was studied. It was found that, by increasing the side chain length from 2-octyldodecyl (PDQT-20) to 2-decyltetradecyl (PDQT-24), the mobility increased from 2.10 cm2 V−1 s−1 up to 3.37 cm2 V−1 s−1 in organic thin film transistors (OTFTs). The increase was found to be due to the improved surface morphology, rather than the changes in crystallinity and π–π stacking distance. A new side chain substituent, 4-decylhexadecyl, was developed for studying the effects of the bifurcation point of the branched side chains in comparison with 2-octyldodecyl and 2-decyltetradecyl. The 4-decylhexadecyl substituted PDQT (PDQT-26) showed a surge in mobility up to 6.90 cm2 V−1 s−1. The remarkably enhanced charge transport performance observed for PDQT-26 was believed to originate from its much shorter π–π distance (3.68 Å) than those of PDQT-20 (3.79 Å) and PDQT-24 (3.86 Å). The improvement was the result of a farther distance of the bifurcation point of 4-decylhexadecyl from the polymer backbone, which could effectively minimize the steric interference of the bulky side chain branches with the backbone to facilitate the co-facial π–π stacking.
Co-reporter:Shaoyun Chen, Bin Sun, Chang Guo, Wei Hong, Yuezhong Meng and Yuning Li
Chemical Communications 2014 vol. 50(Issue 49) pp:6509-6512
Publication Date(Web):25 Apr 2014
DOI:10.1039/C4CC02840F
3,3′-(Ethane-1,2-diylidene)bis(indolin-2-one) (EBI) was used as a new electron-acceptor building block for conjugated polymers. Copolymers of EBI and bithiophene exhibited p-type semiconductor performance with hole mobility of up to 0.044 cm2 V−1 s−1 in organic thin film transistors.
Co-reporter:Yingjie Zhou, Rongcai Huang, Fuchuan Ding, Alex D. Brittain, Jingjing Liu, Meng Zhang, Min Xiao, Yuezhong Meng, and Luyi Sun
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 10) pp:7417
Publication Date(Web):April 7, 2014
DOI:10.1021/am5008408
Solid acids have received considerable attention as alternatives to traditional corrosive and hazardous homogeneous acids because of their advantages in practical applications, including their low corrosion of equipment and high catalytic activity and recyclability. In this work, a strong solid acid was prepared by anchoring thiol group terminated chains on layered α-zirconium phosphate (ZrP) single-layer nanosheets, followed by oxidation of thiol groups to form sulfonic acid groups. The obtained solid acids were thoroughly characterized and the results proved that sulfonic acid group terminated chains were successfully grafted onto the ZrP nanosheets with a high loading density. Such a strong solid acid based on inorganic nanosheets can be well-dispersed in polar solvents, leading to high accessibility to the acid functional groups. Meanwhile, it can be easily separated from the dispersion system by centrifugation or filtration. The strong solid acid can serve as an effective heterogeneous catalyst for various reactions, including the Bayer–Villiger oxidation of cyclohexanone to ε-caprolactone in the absence of organic solvents.Keywords: Baeyer−Villiger oxidation; heterogeneous catalysis; solid acid; α-zirconium phosphate;
Co-reporter:Bin Zhang, Min Xiao, Shuanjin Wang, Dongmei Han, Shuqin Song, Guohua Chen, and Yuezhong Meng
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 15) pp:13174
Publication Date(Web):July 15, 2014
DOI:10.1021/am503069j
Novel hierarchically porous carbon materials with very high surface areas, large pore volumes and high electron conductivities were prepared from silk cocoon by carbonization with KOH activation. The prepared novel porous carbon-encapsulated sulfur composites were fabricated by a simple melting process and used as cathodes for lithium sulfur batteries. Because of the large surface area and hierarchically porous structure of the carbon material, soluble polysulfide intermediates can be trapped within the cathode and the volume expansion can be alleviated effectively. Moreover, the electron transport properties of the carbon materials can provide an electron conductive network and promote the utilization rate of sulfur in cathode. The prepared carbon–sulfur composite exhibited a high specific capacity and excellent cycle stability. The results show a high initial discharge capacity of 1443 mAh g–1 and retain 804 mAh g–1 after 80 discharge/charge cycles at a rate of 0.5 C. A Coulombic efficiency retained up to 92% after 80 cycles. The prepared hierarchically porous carbon materials were proven to be an effective host matrix for sulfur encapsulation to improve the sulfur utilization rate and restrain the dissolution of polysulfides into lithium–sulfur battery electrolytes.Keywords: biopolymers; carbon−sulfur composites; cyclical stability; electron conductivity; hierarchically porous carbon materials; lithium−sulfur batteries
Co-reporter:Yonghang Xu, Min Xiao, Shuanjin Wang, Mei Pan and Yuezhong Meng
Polymer Chemistry 2014 vol. 5(Issue 12) pp:3838-3846
Publication Date(Web):12 Feb 2014
DOI:10.1039/C4PY00008K
A series of salicylaldiminato-zinc and -tri-zinc complexes containing various Schiff base ligands were prepared using quick methods and then well identified by full characterization. All zinc complexes were examined as catalysts for the copolymerization of CO2 and cyclohexene oxide. Many factors such as electron-donating or -withdrawing substituents on the benzene rings of the ligands, as well as chloride anions or acetate groups bound to the zinc centers, are found to greatly influence on the insertion of CO2 and ring-opening of epoxides. Tri-metallic complexes 2a and 2b exhibited excellent catalytic activities, and thus the copolymerization conditions such as temperature, pressure and reaction time were optimized. The molecular weights of the resulting copolymers determined by gel permeation chromatography display a bimodal distribution with relatively wide polydispersities. The results of the investigation indicate that the catalytic activities of zinc complexes are highly dependent on the electronic density and steric environment around the Zn metal centers.
Co-reporter:Yufei Wang, Shuanjin Wang, Min Xiao, Shuqin Song, Dongmei Han, Michael A. Hickner, Yuezhong Meng
International Journal of Hydrogen Energy 2014 Volume 39(Issue 28) pp:16123-16131
Publication Date(Web):23 September 2014
DOI:10.1016/j.ijhydene.2014.04.049
•Amphoteric ion exchange membrane synthesized by direct polymerization for VRBs.•Vanadium ion permeability was suppressed by introducing quaternary ammonium groups.•AIEM-20% has the highest selectivity and columbic efficiency of 88.1% at 50 mA/cm2.Novel sulfonated poly (fluorenyl ether ketone) with pendant quaternary ammonium groups (SPFEKA) was successfully synthesized by one-pot copolymerization of bis(4-fluoro-3-sulfophenyl)sulfone disodium salt, 4,4′-difluorobenzophenone, bisphenol fluorene and 2,2′-dimethylaminemethylene-9,9′-bis(4-hydroxyphenyl) fluorene (DABPF). The chemical structures were confirmed by FT-IR, and 1H NMR. The thermal properties were fully investigated by TGA. The synthesized copolymers SPFEKAs are soluble in aprotic solvents, and can be cast into membranes on a glass plate from their N,N′-dimethylacetamide (DMAc) solution. A new kind of amphoteric ion exchange membrane (AIEM) was obtained by immersed SPFEKA into 1 M sulfuric acid. The proton conductivities of these membranes are comparable to the most reported sulfonated polymers under the same conditions. The permeability of vanadium ions in vanadium redox flow battery (VRB) was effectively suppressed by introducing quaternary ammonium groups for Donnan exclusion effect. AIEM-20% possess a only 4.4% vanadium ion permeability of Nafion 115. Cell performance tests showed that the VRB assembled with AIEM-20% shows the highest coulombic efficiency (CE) at the current density of 50 mA/cm2, because of its lowest VO2+ permeability. In conclusion, these ionomers could be promising candidates for ion-exchange membranes for VRB applications.
Co-reporter:Yufei Wang, Shuanjin Wang, Min Xiao, Dongmei Han, Yuezhong Meng
International Journal of Hydrogen Energy 2014 Volume 39(Issue 28) pp:16088-16095
Publication Date(Web):23 September 2014
DOI:10.1016/j.ijhydene.2014.02.100
•LbL/porous-SPFEK composite membrane was prepared by a facile approach.•The pore was produced by introducing imidazole followed by extraction removing.•The pores introduced into the membrane can make the proton conductivity increased.•The LbL bilayers can reduce vanadium ions diffusion of the composite membranes.•VRB-SPFEK-20.7imidazole-(PDDA/PSS)8 showed the highest CE of 92.5% at 30 mA cm−2.By the solution casting method, a novel porous membrane has been prepared for VRB by doping sulfonated poly(fluorenyl ether ketone) (SPFEK) with imidazole, and then imidazole was washed out by extraction with solution. The proton conductivity of porous membrane increased with increasing the content of imidazole, but proton/vanadium ion (H/V) selectivity decreased. Layer-by-layer (LbL) technique was used to improve the porous membrane with high selectivity. Moreover, the performance of VRB using SPFEK-20.7imidazole-(PDDA/PSS)8 membrane which is doped with 20.7 wt.% content of imidazole and then removed imidazole, and then deposited with eight LbL bilayers exhibits the highest columbic efficiency (CE) of 92.5% at 30 mA cm−2.
Co-reporter:Dongmei Han, Bin Zhang, Min Xiao, Peikang Shen, Shuanjin Wang, Guohua Chen, Yuezhong Meng
International Journal of Hydrogen Energy 2014 Volume 39(Issue 28) pp:16067-16072
Publication Date(Web):23 September 2014
DOI:10.1016/j.ijhydene.2014.04.046
•Sulfur-rich polysulfide rubber composites were prepared by facile vulcanization.•Sulfur(S8) trapped in the network of vulcanized rubber(C-Sm-C) and polysulfide(Sn).•The composites showed good electrochemical activity and cycle stability.Novel sulfur-rich polymer composites were prepared from the commercial polysulfide rubber through facile vulcanization methods and were firstly used as cathode material for lithium/sulfur batteries. The sulfur enriched in the composites includes three parts, the first part was inserted into the main chains of the polysulfide rubber, the second part formed insoluble polysulfide (-Sn-)through self-polymerization and the third part was trapped inside the network of the above two polymer chains. The obtained sulfur-rich polymer composites have high sulfur content over 80%. Compared with the pure sulfur electrode, the composites showed better cycle stability and coulomb efficiency.
Co-reporter:Yulei Liu, Min Xiao, Shuanjin Wang, Liang Xia, Dongmei Hang, Guofeng Cui and Yuezhong Meng
RSC Advances 2014 vol. 4(Issue 19) pp:9503-9508
Publication Date(Web):27 Jan 2014
DOI:10.1039/C3RA46343E
The terpolymerizations of carbon dioxide (CO2), propylene oxide (PO) and phthalic anhydride (PA) using zinc glutarate (ZnGA) as the catalyst were carried out in toluene solution. The monomer reactivity ratios of carbon dioxide and phthalic anhydride (rCO2 = 5.94 and rPA = 0.21) were experimentally evaluated by Fineman–Ross methodology. The results indicate that the reactivity of CO2 is much higher than that of PA, resulting in a random sequence structure of ester and carbonate units in the terpolymer. It is found that the introduction of a small amount of the third monomer PA can significantly increase PO conversion and the molecular weight of the terpolymer. Terpolymers with very high number-average molecular weight (Mn), up to 221 kg mol−1, can be obtained at the optimal reaction conditions (PA/PO molar ratio: 1/8, temperature: 75 °C, CO2 pressure: 5 MPa). This is the highest Mn reported to date for the terpolymerization of CO2, epoxides and cyclic anhydrides, together with very high PO conversion of 72.5%. Moreover, the synthesized terpolymers exhibit a high Tg of about 41 °C and higher thermal stabilities compared with the copolymer of PO and CO2.
Co-reporter:Min Xiao, Miao Huang, Songshan Zeng, Dongmei Han, Shuanjin Wang, Luyi Sun and Yuezhong Meng
RSC Advances 2013 vol. 3(Issue 15) pp:4914-4916
Publication Date(Web):13 Feb 2013
DOI:10.1039/C3RA00017F
Sulfur@GO core–shell composites were prepared by the self-assembly of sulfur particles stabilized by a cationic surfactant and anionic graphene oxide nanosheets through electrostatic interaction. Due to the effective entrapment of polysulfide intermediates by the GO shell, the composites exhibit high cycling stability with 81% capacity maintenance over 210 cycles as the cathode for Li–S batteries.
Co-reporter:Shakil Mulani, Min Xiao, Shuanjin Wang, Yawen Chen, Junbiao Peng and Yuezhong Meng
RSC Advances 2013 vol. 3(Issue 1) pp:215-220
Publication Date(Web):23 Oct 2012
DOI:10.1039/C2RA21951D
A tris-cyclometalated iridium(III) complex [Ir(DMP)3] containing 2,6-dimethoxy phenol and an ancillary ligand was successfully prepared and used in the fabrication of organic light-emitting diodes (OLEDs). The absorption, emission, cyclic voltammetry and thermostability of the complex were systematically investigated. The structure of this complex was also characterized using single crystal X-ray diffraction analysis. Its crystal shows a cubic structure. Our device exhibits a yellow emission at 576 nm with a maximum luminescence efficiency of 10564 cd m−12 at a voltage of 7 V and a current density of 118 mA cm−2 respectively. The maximum quantum efficiency is 8.7% at 5.93 mA cm−2. The Commission Internationale de l′Eclairage (CIE) coordinates were (0.49, 0.50) at a 2 wt% doping concentration and show typical rectifying diode characteristics in the ITO/PEDOS:PSS/PVK:PBD:Ir(DMP)3/TPBI/Ba/Al device.
Co-reporter:Yufei Wang, Shuanjin Wang, Min Xiao, Dongmei Han, Michael A. Hickner and Yuezhong Meng
RSC Advances 2013 vol. 3(Issue 35) pp:15467-15474
Publication Date(Web):27 Jun 2013
DOI:10.1039/C3RA41670D
Sulfonated poly(fluorenyl ether ketone) (SPFEK) membranes have been first modified by layer-by-layer (LbL) self-assembly of positively charged polyelectrolyte PDDA (poly(diallyldimethylammonium chloride)) and negatively charged PSS (poly(sodium styrene sulfonate)). The membranes were investigated as an ion exchange membrane for vanadium redox flow batteries (VRBs). The permeability of the vanadium ions in VRBs was effectively suppressed by depositing the LbL thin film on the SPFEK membrane. The permeability decreased with increasing the number of PDDA/PSS bilayers. For the membrane with two self-assembly bilayers of PDDA/PSS, 50% and 10% of vanadium ion permeability of a pristine SPFEK and Nafion 117 membranes can be afforded, respectively. Moreover, the oxidative stability of the PDDA/PSS-SPFEK composite membrane is improved remarkably compared with the pristine one. Consequently, the performance of VRBs using the PDDA/PSS-SPFEK composite membrane exhibits the highest coulombic efficiency (CE) of 82.1% at 30 mA cm−2 and the longest duration stability in the self-discharge test.
Co-reporter:Ying-Jie Zhou, Min Xiao, Shuan-Jin Wang, Dong-Mei Han, Yi-Xin Lu, Yue-Zhong Meng
Chinese Chemical Letters 2013 Volume 24(Issue 4) pp:307-310
Publication Date(Web):April 2013
DOI:10.1016/j.cclet.2013.02.001
The Mo-promoted Cu–Fe bimetal catalysts were prepared and used for the formation of dimethyl carbonate (DMC) from CO2 and methanol. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), laser Raman spectra (LRS), energy dispersive spectroscopy (EDS) and temperature programmed desorption (TPD) techniques. The experimental results demonstrated that the Mo promoters can decrease the reducibility and increase the dispersion of Cu–Fe clusters. The concentration balance of base–acid sites can be readily adjusted by changing the Mo content. The moderate concentration balance of acid and base sites was in favor of the DMC formation. Under optimal experimental conditions, the highest methanol conversion of 6.99% with a DMC selectivity of 87.7% can be obtained when 2.5 wt% of Mo was loaded.The concentration balance of base–acid sites of Cu–Fe bimetal catalysts can be readily adjusted and thus the catalytic activities for the formation of dimethyl carbonate (DMC) from CO2 and methanol were significantly enhanced by the introduction of Mo. The highest methanol conversion of 6.99% with a DMC selectivity of 87.7% was obtained when 2.5 wt% Mo was loaded.
Co-reporter:Jie Luo, Wenqin Wu, Li-Wen Xu, Yuezhong Meng, Yixin Lu
Tetrahedron Letters 2013 Volume 54(Issue 21) pp:2623-2626
Publication Date(Web):22 May 2013
DOI:10.1016/j.tetlet.2013.03.028
A straightforward and practical method for the direct fluorination and chlorination of various β-ketoesters employing a phase-transfer catalyst is developed. The desired products with fluorine/chlorine-substituted quaternary chiral centers are prepared with good to excellent enantioselectivities.
Co-reporter:S. J. Wang;Y. Chen;M. Xiao ;Y. Z. Meng
Journal of Applied Polymer Science 2013 Volume 127( Issue 3) pp:1981-1988
Publication Date(Web):
DOI:10.1002/app.37579
Abstract
Two series of sulfonated poly(arylene ether nitrile ketone) ionomers containing potential crosslinkable nitrile groups were synthesized in high yield by direct aromatic nucleophilic polycondensation of 1,4-bis-(4-hydroxyphenyl)-2,3-dicyano -naphthalene (3) with different molar ratio of disodium 5,5′-carbonyl-bis-(2-fluorobenzene-sulfonate) (4) to 5,5′-carbonyl-bis-(2-fluorobenzene) (5) or 4,4-biphenol (7). Subsequently, the sulfonated polymeric ionomers were in situ crosslinked when cast into membranes from solution at 180°C under nitrogen protection. The structure of the synthesized polymers was characterized by 1H-nuclear magnetic resonance (NMR), Fourier-transform infrared spectra, and elemental analysis. Comparing with the original polymeric membranes, the crosslinked membranes showed much better thermal and hydrolytic stabilities and superior mechanical properties as well as much lower swelling behavior, which were even better than Nafion 117 membrane. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Lei Tang;Min Xiao;Yan Xu;Shuanjin Wang
Journal of Polymer Research 2013 Volume 20( Issue 7) pp:
Publication Date(Web):2013 July
DOI:10.1007/s10965-013-0190-9
The copolymerization of carbon dioxide and propylene oxide to generate poly (propylene carbonate) (PPC) were efficiently catalyzed by zinc adipate (ZnAA) in the presence of various tertiary amines as cocatalyst. The influences of temperature, pressure as well as cocatalyst concentration on the copolymerization were studied. The ZnAA/4,4′-methylenebis (N,N-dimethylaniline) composite catalyst shows reasonable high polymer productivity (>280 g polymer/g zinc), high selectivity (>95 %, PPC/cyclic carbonate), especially considerable high molecular weight (Mn > 250 k). Because of the high molecular weight, the as-prepared PPC exhibits apparently improved thermal properties as contrast to the one reported elsewhere previously. Furthermore, the effects of the steric and electronic properties of various tertiary amine derivatives on cocatalytic performance have also been discussed. The experimental results suggest that the tertiary amine cocatalysts with the rigid and bulky aromatic structure are more favorable for the copolymerization.
Co-reporter:Jingjing Pan, Shuanjin Wang, Min Xiao, Michael Hickner, Yuezhong Meng
Journal of Membrane Science 2013 443() pp: 19-27
Publication Date(Web):
DOI:10.1016/j.memsci.2013.04.068
Co-reporter:Wei Liu, Shuanjin Wang, Min Xiao, Dongmei Han and Yuezhong Meng
Chemical Communications 2012 vol. 48(Issue 28) pp:3415-3417
Publication Date(Web):26 Jan 2012
DOI:10.1039/C2CC16952E
A composite proton exchange membrane containing electrospun nanofibers shows excellent oxidative stability and high proton conductivity as well as an extremely low activation energy of 1.30 kJ mol−1.
Co-reporter:Dongyang Chen, Michael A. Hickner, Shuanjin Wang, Jingjing Pan, Min Xiao, Yuezhong Meng
Journal of Membrane Science 2012 Volumes 415–416() pp:139-144
Publication Date(Web):1 October 2012
DOI:10.1016/j.memsci.2012.04.048
Fluorinated sulfonated poly(fluorenyl ether ketone) (F-SPFEK) membranes and composites with 3-aminopropyltriethoxylsilane (F-SPFEK–APTES) were prepared for evaluation in vanadium redox flow battery (VRB) devices. Improved oxidative stability as well as increased water uptake and proton conductivity were found after direct fluorination of a sulfonated poly(fluorenyl ether ketone) (SPFEK) sample with fluorine gas. The incorporation of a polysilsesquioxane network within the fluorinated membrane effectively suppressed vanadium permeation without a large decrease in proton conductivity, leading to a membrane with a more optimized balance of proton conductivity and VO2+ permeability for good VRB performance. Both F-SPFEK and F-SPFEK–APTES membranes showed promising characteristics for VRB application, but the coulombic efficiency of the VRB with the F-SPFEK–APTES composite membrane was 21.5% higher than the VRB with a SPFEK membrane.Highlights▸ Fluorinated sulfonated membranes and composites were used in flow batteries. ▸ Enhanced oxidative stabilities were observed as compared to non-fluorinated samples. ▸ Polysilsesquioxane composite formation suppressed vanadium permeation. ▸ Improved flow battery performance was achieved with low permeability membranes.
Co-reporter:S.J. Wang, Y.F. Zhang, D. Shu, S.H. Tian, D.H. Mei, M. Xiao, Y.Z. Meng
International Journal of Hydrogen Energy 2012 Volume 37(Issue 5) pp:4539-4544
Publication Date(Web):March 2012
DOI:10.1016/j.ijhydene.2011.09.138
Portable polymer electrolyte membrane fuel cells (PEMFCs) stack was assembled with sulfonated poly(fluorenyl ether ketone) (SPFEK) ionomer membranes. The portable PEMFC stack was studied by means of cell performance tests at high temperatures under low relatively humidity (RH). The experimental results showed that the output power of the stack increased from 28.74 W to 37.11 W with increasing operating temperature from 30 to 90 °C under 100% RH. When the operating temperature was over 100 °C, the output power decreased with further increasing temperature from 27.68 W (100 °C, 85% RH) to 19.87 W (120 °C, 50% RH). The output at 120 °C and under 50% RH was 69% output power of the stack at 30 °C and under 100% RH. These results demonstrated that the self-prepared SPFEK ionomer membrane was a promising PEM for the application in high-temperature PEMFC.
Co-reporter:S.J. Wang, J.J. Luo, M. Xiao, D.M. Han, P.K. Shen, Y.Z. Meng
International Journal of Hydrogen Energy 2012 Volume 37(Issue 5) pp:4545-4552
Publication Date(Web):March 2012
DOI:10.1016/j.ijhydene.2011.09.095
A series of the poly(ether ether ketone)s with hydrophobic and hydrophilic long blocks were successfully synthesized by nucleophilic displacement condensation. The polyaromatics with different size of sulfonic acid group clusters were cast from their solutions to produce accordingly membranes. The comprehensive properties of these membranes were then fully characterized by determining the ion-exchange capacity, water uptake, proton conductivity, dimensional stabilities and mechanical properties. The experimental results show that the main properties of the membrane can be tailored by changing the cluster size of sulfonic acid groups or the length of hydrophilic units. The membrane of Block-6c has good mechanical, oxidative and dimensional stabilities together with high proton conductivity (2.09 × 10−2 S cm−1) at 80 °C under 100% relative humidity. The membranes also possess excellent thermal and dimensional stabilities, therefore, these polymers are potential and promising proton conducting membrane material for PEM full cell applications.
Co-reporter:Hang Hu, Wei Liu, Liu Yang, Min Xiao, Shuanjin Wang, Dongmei Han, Yuezhong Meng
International Journal of Hydrogen Energy 2012 Volume 37(Issue 5) pp:4553-4562
Publication Date(Web):March 2012
DOI:10.1016/j.ijhydene.2011.09.085
A series of Sulfonated Poly (fluorenyl ether ketone) ionomers containing aliphatic functional segments were synthesized and characterized. The monomer 4,4′-Dihydroxy-α, ω-diphenoxydecane with aliphatic group was conveniently prepared from hydroquinone and 1,10-dibromodecane. A series of sulfonated aliphatic functional groups containing poly(fluorenyl ether ketone)s with different aliphatic group content were successfully synthesized and characterized in detail, in particular with respect to properties relevant for their application as membrane materials in proton exchange membrane (PEM) fuel cells. Tough and transparent membranes were formed by casting from their solutions. The effects of alkyl groups were investigated by comparison of the PEM properties of the copolymers with different content of aliphatic component on the copolymer chain. The introduction of aliphatic segments can provide an enhanced water uptake, increased proton conductivities, but worse oxidative stability. Transmission electron microscope (TEM) images of j and f revealed an improved phase separation structure under the effect of aliphatic groups. The as-made membranes can also exhibit comparable or much better single cell performance than Nafion@ 117 at 75 °C–95 °C under full or partial relative humidification.
Co-reporter:Yingjie Zhou, Shuanjin Wang, Min Xiao, Dongmei Han, Yixin Lu and Yuezhong Meng
RSC Advances 2012 vol. 2(Issue 17) pp:6831-6837
Publication Date(Web):22 May 2012
DOI:10.1039/C2RA20359F
A novel Cu–Fe bimetal supported catalytic system was prepared and applied to the direct dimethyl carbonate (DMC) formation from methanol and CO2. The prepared catalysts were characterized by means of temperature-programmed reduction (TPR), X-ray powder diffraction (XRD), laser Raman spectra (LRS), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Metallic Cu, Fe and oxygen deficient Fe2O3−x (0 < x < 3) were formed during the reduction and activation step. The supported Cu–Fe bimetal catalysts exhibited good catalytic activity and high stability for the direct DMC formation. Under the reaction conditions at 120 °C and 1.2 MPa with space velocity of 360 h−1, the highest methanol conversion of 5.37% with DMC selectivity of 85.9% could be achieved. The high catalytic performance of the Cu–Fe bimetal catalysts in the DMC formation could be attributed to the interaction of base sites functioned by metallic Cu and Fe with acid sites provided by oxygen deficient Fe2O3−x (0 < x < 3) in the activation of methanol and CO2. The moderate concentration balance of acid and base sites was in favor of DMC formation.
Co-reporter:Dongyang Chen, Michael A. Hickner, Shuanjin Wang, Jingjing Pan, Min Xiao, Yuezhong Meng
International Journal of Hydrogen Energy 2012 Volume 37(Issue 21) pp:16168-16176
Publication Date(Web):November 2012
DOI:10.1016/j.ijhydene.2012.08.051
Soluble quaternary ammonium functionalized poly(fluorenyl ether)s (PFEQAs) with a wide range of ion exchange capacities (IECs) were successfully synthesized from a novel tertiary amine group containing cardo monomer. Complete conversion of tertiary amine group to quaternary ammonium group was established, which enables precise control over IEC of the resultant polymers by adjusting monomer-loading ratio. The influence of IEC on the thermal stability, mechanical integrity, water uptake and ion conductivity of the PFEQAs were investigated. Furthermore, four counter ions were selected and their influences on the water uptake and ion conductivity of PFEQAs were studied in detail in order to give a comprehensive view of the transport properties of these anion exchange membranes. It was observed that the water uptakes of the membranes with different counter ions followed the trend: OH− > SO42− > Cl− > I− while their ion conductivities followed another trend: OH− > SO42− > Cl− > I−. These membranes exhibited promising characteristics for anion exchange membrane water electrolyzers working with neutral PH water with or without supporting electrolytes.Highlights► Soluble cardo polymers containing quaternary ammonium groups were synthesized. ► High thermal stability and robust mechanical properties were obtained. ► Water uptakes and ion conductivities with different counter ions were correlated. ► These membranes are promising for neutral PH water electrolysis.
Co-reporter:Shaoyun Chen;Min Xiao;Shuanjin Wang;Dongmei Han
Journal of Polymer Research 2012 Volume 19( Issue 2) pp:
Publication Date(Web):2012 February
DOI:10.1007/s10965-011-9800-6
Block copolymers of poly (propylene carbonate—cyclohexyl carbonate) (PPC-PCHC) were successfully synthesized by a one-pot method with the zinc complex catalyst (Zn2G). The IR and 1H-NMR and 13C-NMR spectra verified the introducing of PCHC segments in the copolymers. The GPC curves of the copolymers appeared only one peak and the DSC results showed three glass transition temperatures at 40 °C, 66 °C and 115 °C, indicating the three-block copolymer structure. TGA tests revealed that the thermal decomposition temperature of the synthesized block copolymers increased up to about 300 °C. The mechanical properties proved to be also enhanced greatly as evidenced by static and dynamic mechanical tests. The thermal and mechanical properties of the resultant block copolymers lay between those of PPC and PCHC, demonstrating the desired properties of a polymer can be achieved via block copolymerization.
Co-reporter:Dongyang Chen, Shuanjin Wang, Min Xiao, Yuezhong Meng and Allan S. Hay
Journal of Materials Chemistry A 2011 vol. 21(Issue 32) pp:12068-12077
Publication Date(Web):07 Jul 2011
DOI:10.1039/C1JM10950B
A novel dihydroxyl monomer bearing 18 electron rich phenyl rings were synthesized and polymerized with other monomers bearing electron deficient phenyl rings to give dense and selective sites in macromolecules for post-sulfonation, which was successfully conducted in ClSO3H/CH2Cl2 solution at room temperature in a subsequential step. The chemical structures were confirmed by 1H NMR and FT-IR spectra. The ionic exchange capacity (IEC) was controlled to be from 0.65 to 1.21 mequiv g−1 to afford considerable proton conductivity. Distinct phase separation was observed in the resulting membranes from SAXS profiles. The SPAEK-5 with an IEC of 1.21 mequiv g−1 gave better proton conductivity than Nafion 117 at all tested temperatures under 100% relative humidity. The membranes exhibited an exceeding stability when immersing in Fenton's reagent (3 wt.% H2O2 + 2 ppm FeSO4) at 80 °C. These properties make them promising candidates for electrochemical applications.
Co-reporter:Songshan Zeng, Shuanjin Wang, Min Xiao, Dongmei Han, Yuezhong Meng
Carbohydrate Polymers 2011 Volume 86(Issue 3) pp:1260-1265
Publication Date(Web):30 August 2011
DOI:10.1016/j.carbpol.2011.06.023
A series of starch acetates (SAs) with different degrees of substitution (DS) were prepared by chemically converting the hydroxyl group of natural cornstarch (NS) into an acetyl group. Biodegradable poly (propylene carbonate) (PPC) was melt blended with these SAs in a Haake mixer. The morphologies, mechanical and thermal properties of PPC/SA and PPC/NS blends were investigated. PPC/SA (DS < 0.88) showed better tensile property and impact strength than those of PPC/NS. Scanning electron microscopy (SEM) and Fourier transform infrared spectra (FTIR) revealed strong interfacial adhesion between the SA fillers and PPC matrix. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) demonstrated the addition of SA led to improved thermal stability of the blend. Among all the samples prepared, the PPC/SA (DS = 0.51) has the optimal mechanical and thermal properties. The methodology described here represents a promising approach for the production of cost competitive biodegradable polymer blends.Highlights• Starch acetate (SA) acts as reinforcement fillers for poly (propylene carbonate) (PPC). • Strong interfacial adhesion existed between SA and PPC. • Incremental enhancement in mechanical properties was dramatically obtained for PPC/SA (DS < 0.88) blend. • The introduction of SA led to the improvement in the thermal stability of PPC matrix.
Co-reporter:Dongyang Chen, Shuanjin Wang, Min Xiao, Dongmei Han, Yuezhong Meng
Polymer 2011 Volume 52(Issue 23) pp:5312-5319
Publication Date(Web):27 October 2011
DOI:10.1016/j.polymer.2011.09.021
High-molecular-weight bulky-block poly(fluorenyl ether thioether ketone)s were successfully synthesized by a two steps one-pot protocol using N,N′-dimethy-S-carbamate masked dithiols for vanadium redox flow battery (VRB) application. The followed sulfonation procedure gave birth to novel sulfonated block poly(fluorenyl ether thioether ketone)s (SPFETKs) with controlled ionic exchange capacities (IEC). Membranes with proton conductivities higher than (IEC > 1.66 mequiv. g−1) or comparable to (IEC < 1.66 mequiv. g−1) that of Nafion117 membrane were achieved. The VO2+ permeabilities of SPFETKs membranes were much lower than that of Nafion117 membrane. The thermal properties, mechanical properties, oxidative stability, water uptake, proton conductivity, VO2+ permeability and cell performance were investigated in detail.
Co-reporter:Jing-shu Wu;Min Xiao 肖敏;Hu He;Shuan-jin Wang
Chinese Journal of Polymer Science 2011 Volume 29( Issue 5) pp:
Publication Date(Web):2011 September
DOI:10.1007/s10118-011-1078-y
Using supported multi-component zinc dicarboxylate catalyst, poly(1,2-propylene carbonate-co-1,2-cyclohexylene carbonate) (PPCHC) was successfully synthesized from carbon dioxide (CO2) with propylene oxide (PO) and cyclohexene oxide (CHO). The conversion of epoxides dramatically increased up to 89.7% (yield: 384.2 g of polymer per g of Zn) with increasing reaction temperature from 60°C to 80°C. The optimized reaction temperature is 80°C. The chemical structure, the molecular weight, as well as thermal and mechanical properties of the resulting terpolymers were investigated extensively. When CHO feed content (mol%) is lower than 10%, the PPCHC terpolymers have number average molecular weight (Mn) ranging from 102 × 103 to 202 × 103 and molecular weight distribution (MWD) values ranging from 2.8 to 3.5. In contrast to poly(propylene carbonate) (PPC), the introduction of small amount of CHO leads to increase in the glass transition temperature from 38.0°C to 42.6°C. Similarly, the mechanical strength of the synthesized terpolymer is greatly enhanced due to the incorporation of CHO. These improvements in mechanical and thermal properties are of importance for the practical application of PPC.
Co-reporter:Hang Hu ; Jarett C. Martin ; Min Xiao ; Cara S. Southworth ; Yuezhong Meng ;Luyi Sun
The Journal of Physical Chemistry C 2011 Volume 115(Issue 13) pp:5509-5514
Publication Date(Web):March 3, 2011
DOI:10.1021/jp111646d
A facile mechanochemical intercalation approach was adopted to immobilize 1-butyl-3-methylimidazolium chloride (BMIMCl) in layered α-zirconium phosphate (ZrP). The intercalation compounds with an expanded layer distance were confirmed by X-ray diffraction. Thermogravimetric characterization revealed that a portion of the BMIMCl was intercalated into the ZrP galleries, while a portion was adsorbed on the layer surface. The immobilized BMIMCl was evaluated for catalysis evaluation of the coupling reaction of CO2 and propylene oxide to synthesize propylene carbonate. The immobilized BMIMCl exhibited similar reactivity as free BMIMCl. Overall, the mechanochemical approach proves to be effective in immobilizing ionic liquids in layered compounds and thus may expand the applications of ionic liquids and, meanwhile, improve catalyst separation and recycling.
Co-reporter:Dongyang Chen, Shuanjin Wang, Min Xiao and Yuezhong Meng
Energy & Environmental Science 2010 vol. 3(Issue 5) pp:622-628
Publication Date(Web):21 Dec 2009
DOI:10.1039/B917117G
High-molecular-weight poly(arylene thioether ketone) (PTK) and poly(arylene thioether ketone ketone) (PTKK) polymers were successfully synthesized by one-pot polymerization of N,N′-dimethy-S-carbamate masked dithiols with activated dihalo compounds, followed by post-sulfonation using chlorosulfonic acid as the sulfonation agent in dichloromethane solution to give the production of sulfonated poly(arylene thioether ketone) (SPTK) and sulfonated poly(arylene thioether ketone ketone) (SPTKK) with appropriate ion-exchange capacities. The chemical structures were confirmed by 1H NMR, FT-IR and elemental analysis (EA). The thermal properties were fully investigated by TGA-IR. The synthesized SPTK and SPTKK polymers are soluble in aprotic solvents such as N,N′-dimethylacetamide (DMAc), N,N′-dimethylformamide and dimethyl sulfoxide, and can be cast into membranes on a glass plate from their DMAc solution. The proton conductivities of these membranes are comparable to Nafion117 membranes under the same conditions. Cell performance tests showed that the vanadium redox flow batteries (VRBs) assembled with SPTK and SPTKK membranes possessed higher Coulombic efficiencies than VRBs assembled with Nafion117 membranes at the current density of 50 mA cm−2, because of their one-order-of magnitude lower VO2+ permeabilities. In conclusion, these ionomers could be promising candidates as proton-exchange membranes for vanadium redox flow battery (VRB) applications.
Co-reporter:Dongyang Chen, Shuanjin Wang, Min Xiao, Dongmei Han, Yuezhong Meng
Journal of Power Sources 2010 Volume 195(Issue 22) pp:7701-7708
Publication Date(Web):15 November 2010
DOI:10.1016/j.jpowsour.2010.05.026
A series of novel organic–inorganic hybrid membranes with special microstructure, based on sulfonated poly (fluorenyl ether ketone) ionomer (SFPEK, IEC = 1.92 mequiv. g−1) and SiO2 or sulfonic acid group containing SiO2 (SiO2–SO3H), has been successfully designed and prepared for vanadium redox flow battery (VRB) application. The SiO2–SO3H is synthesized by co-condensation of tetraethoxysilane and γ-propyl mercaptotrimethoxysilane via sol–gel process to control the same IEC with neat SPFEK. The hybrid membranes are prepared by simply adding the inorganic particles into the SPFEK solution in N,N′-dimethylacetamide, followed by ultrasonic dispersion, casting and profiled temperature drying process. The morphology is examined by SEM-EDX which is applied to the top surface, bottom surface and cross-section of the hybrid membranes. The water uptake, oxidative stability, thermal property, mechanical property, proton conductivity, VO2+ permeability and single cell performance are investigated in detail in order to understand the relationship between morphology and property of the membranes. All the hybrid membranes show dramatically improved proton selectivity at 20 °C and 40 °C when compared with Nafion117. The VRB assembled with the SPFEK/3%SiO2 and SPFEK/9%SiO2 membranes exhibit higher coulombic efficiency and average discharge voltage than the VRB assembled with the SPFEK membrane at all the tested current densities.
Co-reporter:Dongyang Chen, Shuanjin Wang, Min Xiao, Yuezhong Meng
Journal of Power Sources 2010 Volume 195(Issue 7) pp:2089-2095
Publication Date(Web):2 April 2010
DOI:10.1016/j.jpowsour.2009.11.010
In order to develop novel membranes for vanadium redox flow battery (VRB) with low self-discharge rate and low cost, sulfonated poly(fluorenyl ether ketone) (SPFEK) was synthesized directly via aromatic nucleophilic polycondensation of bisphenol fluorene with 60% sulfonated difluorobenzophenone and 40% difluorobenzophenone. The SPFEK membrane shows the lower permeability of vanadium ions. The open circuit voltage evaluation demonstrates that the SPFEK membrane is superior to Nafion 117 membrane in self-discharge test. Both energy efficiencies (EE) and power densities of the VRB single cell based on the SPFEK membrane are higher than those of the VRB with Nafion 117 membrane at the same current densities. The highest coulombic efficiency (CE) of VRB with SPFEK membrane is 80.3% while the highest CE of the VRB with Nafion 117 membrane is 77.0%. The SPFEK membrane shows the comparative stability to Nafion 117 membrane in VO2+ electrolyte. The experimental results suggest that SPFEK membrane is a promising ion exchange membrane for VRB.
Co-reporter:Zaoxue Yan, Zhuofeng Hu, Chan Chen, Hui Meng, Pei Kang Shen, Hongbin Ji, Yuezhong Meng
Journal of Power Sources 2010 Volume 195(Issue 21) pp:7146-7151
Publication Date(Web):1 November 2010
DOI:10.1016/j.jpowsour.2010.06.014
The synthesis procedure of the hollow carbon hemispheres (HCHs) using glucose as carbon source and polystyrene spheres (PSs) as templates and the formation mechanism of the HCHs have been presented. The HCHs have regular morphology and high BET surface area of 702.7 m2 g−1. The advantage of the HCHs compared to the hollow carbon spheres is that the HCHs can provide similar surface area at reduced volume. The electrocatalytic activity of ethanol oxidation on Pd supported on HCHs electrocatalyst (Pd/HCH) is 2.8 times higher than that of Pd supported on commercial Vulcan XC-72 carbon (Pd/C) electrocatalyst at the same Pd loadings. The high surface area is beneficial for the dispersion of the precious metal nanoparticles to increase their utilization. The hemispherical structure with hollow shell results in the improvement in the mass transfer and therefore more concentrated ethanol solution can be used to increase the energy density.
Co-reporter:S.H. Tian, D. Shu, S.J. Wang, M. Xiao, Y.Z. Meng
Journal of Power Sources 2010 Volume 195(Issue 1) pp:97-103
Publication Date(Web):1 January 2010
DOI:10.1016/j.jpowsour.2009.06.085
High molecular weight sulfonated poly(fluorenyl ether ketone nitrile)s with different equivalent weight (EW) from 681 to 369 g mequiv.−1 are synthesized by the nucleophilic substitution polycondensation of various amounts of sulfonated difluorobenzophenone (SDFBP) and 2,6-difluorobenzonitrile (DFBN) with bisphenol fluorene (BPF). The synthesized copolymers are characterized by 1H NMR, FT-IR, TGA, and DSC techniques. The membranes cast from the corresponding copolymers exhibit superior thermal stability, good oxidative stability and high proton conductivity, but low water uptake due to the strong nitrile dipole interchain interactions that combine to limit swelling. Among all the membranes, the membrane with EW of 441 g mequiv.−1 shows optimum properties of both high proton conductivity of 41.9 mS cm−1 and low water uptake of 42.6%. Accordingly, That membrane is fabricated into a membrane electrode assembly (MEA) and evaluated in a single proton exchange membrane fuel cell (PEMFC). The experimental results indicate its similar cell performance as that of Nafion® 117 at 70 °C, but much better cell performance at higher temperatures. At the potential of 0.6 V, the current density of fuel cell using the prepared membrane and Nafion® 117 is 0.46 and 0.25 A cm−2, respectively. The highest current density of the former reaches as high as 1.25 A cm−2.
Co-reporter:Z.P. Guan, M. Xiao, S.J. Wang, Y.Z. Meng
European Polymer Journal 2010 Volume 46(Issue 1) pp:81-91
Publication Date(Web):January 2010
DOI:10.1016/j.eurpolymj.2009.08.021
A series of parent poly(aryl ether ketone)s bearing different content of unsaturated pendant propenyl groups were synthesized via nucleophilic substitution polymerization from 3,3′-diallyl-4,4′-dihydroxybiphenyl, 9,9′-bis(4-hydroxyphenyl) fluorene and 4,4′-difluorobenzophenone. The polymers with pendant aliphatic sulfonic acid groups were further synthesized by free radical thiol-ene coupling reactions between 3-mercapto-1-propanesulfonic sodium and the parent propenyl functional copolymers. The resulting sulfonated polymers with high inherent viscosity (1.83–4.69 dL/g) were soluble in polar organic solvents and can form flexible and transparent membranes by casting from their solutions. The copolymers with different ion exchange capacity could be conveniently synthesized by varying the monomers ratios. Transmission electron microscopy (TEM) was used to examine the microstructures of the membrane and the results revealed that significant hydrophilic/hydrophobic microphase separation with spherical, uniform-sized (5–10 nm) and well-dispersed hydrophilic domains was afforded. The proton conductivities of the as-prepared membranes and the state-of-the-art Nafion 117 membrane in fully hydrated state were investigated. The results revealed that the proton conductivity of the synthesized membranes increased more remarkably than that of Nafion 117 membrane with increasing temperature. The membrane with 1.69 mequiv/g of IEC had a conductivity of 2.5 × 10−2 Scm−1 at 100 °C. The membranes also possessed excellent mechanical properties, good thermal, oxidative, hydrolytic and dimensional stabilities.
Co-reporter:H. Hu, M. Xiao, S.J. Wang, Y.Z. Meng
International Journal of Hydrogen Energy 2010 Volume 35(Issue 2) pp:682-689
Publication Date(Web):January 2010
DOI:10.1016/j.ijhydene.2009.10.103
A series of sulfonated poly(fluorenyl ether ketone) with different hydrophilic block lengths were synthesized via a two-step one-pot polymerization from 9,9'-bis(4-Hydroxypheyl) fluorine, 3,3'-disulfonated-4,4'-difluorobenzophenone, and 4,4'-difluorobenzophenone. The resulting sulfonated block polymers with high inherent viscosity (0.8–1.37 dL/g) were very soluble in polar organic solvents and can form flexible and transparent membranes by casting from their solutions. Transmission electron microscope (TEM) was used to examine the microstructure of the membranes and the results revealed that significant hydrophilic/hydrophobic microphase separation was produced. The effects of the multiblock structure and/or length were investigated by comparison of the properties of the multiblock copolymer and the corresponding random structure. The multiblock structure can provide enhanced proton transport, especially under partially hydrated conditions. The as-made membranes can also exhibit better oxidative stability and single cell performance than random copolymer. The multiblock structure design method provides a useful way to prepare proton exchange membrane used in PEM fuel cells.
Co-reporter:J.J. Luo, S.J. Wang, M. Xiao, D.M. Han, Y.Z. Meng
European Polymer Journal 2010 Volume 46(Issue 8) pp:1736-1744
Publication Date(Web):August 2010
DOI:10.1016/j.eurpolymj.2010.05.005
A series of sulfonated block poly(ether ether ketone)s with different sulfonic acid group clusters were successfully synthesized by nucleophilic displacement condensation. Membranes were accordingly cast from their DMSO solutions, and fully characterized by determining the ion-exchange capacity, water uptake, proton conductivity, dimensional stabilities and mechanical properties. The experimental results showed that the main properties of the membrane can be tailored by changing the cluster size of sulfonic acid groups. The membrane of block-7c(40) has good mechanical, oxidative and dimensional stabilities together with high proton conductivity (5.09 × 10−2 S cm−1) at 80 °C under 100% relative humidity. The membranes also possess excellent thermal and dimensional stabilities. These polymers are potential and promising proton conducting membrane material for PEM full cell applications.A series of sulfonated block poly(ether ether ketone)s with different sulfonic acid group clusters were successfully synthesized and characterized.
Co-reporter:Jian Liu;Shu-Guang Bian;Min Xiao;Shuan-Jin Wang;Yue-Zhong Meng
Journal of Applied Polymer Science 2010 Volume 115( Issue 6) pp:3401-3408
Publication Date(Web):
DOI:10.1002/app.30910
Abstract
Poly(trimethylene terephthalate) (PTT) is an excellent fiber materials. Although it was synthesized as early as 1940s, obtaining high-molecular weight PTT suitable for spinning is not easy due to no evident breakthrough in the catalysts for PTT synthesis. Patents and literatures disclosed a lot of the catalysts of preparing PTT, but which are more or less disadvantageous. Based on acid catalytic mechanism of PTT preparation, a series of solid acid as x% MoO3/(50% Al2O3 − 50% TiO2) (briefly written as xM/(A − T), x = 0, 10, 15, 20 by weight) were prepared by sol–gel coprecipitation and wetting impregnation methods, and first used for PTT synthesis in this work. When 50% Al2O3 − 50% TiO2 (briefly written as A − T) was supported by MoO3 using wetting impregnation technique of (NH4)6Mo7O24.4H2O aqueous solution, a lot of Brφnsted acid and Lewis acid sites were formed on xM/(A − T) catalyst surfaces, which was confirmed by the characteristics of their NH3-TPD (temperature programmed desorption). All the prepared catalysts were highly active ones toward synthesis of PTT. PTT with high-intrinsic viscosity (IV) was obtained in the presence of trace amount of the catalysts. IV ranging of the PTT synthesized from 0.66 to 0.95 dL g−1 corresponds to weight average molecular weight from 49,197 to 73,004. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Xiaoyuan Yu;Min Xiao;Shuangjin Wang;Dongmei Han
Journal of Applied Polymer Science 2010 Volume 118( Issue 4) pp:2078-2083
Publication Date(Web):
DOI:10.1002/app.32480
Abstract
The poly(propylene carbonate maleate) (PPCMA) was synthesized by the terpolymerization of carbon dioxide, propylene oxide, and maleic anhydride. The PPCMA polymer can be readily crosslinked using dicumyl peroxide (DCP) as crosslinking agent and then actived by absorbing liquid electrolyte to fabricate a novel PPCMA gel polymer electrolyte for lithium-ion battery. The thermal performance, electrolyte uptake, swelling ratio, ionic conductivity, and lithium ion transference number of the crosslinked PPCMA were then investigated. The results show that the Tg and the thermal stability increase, but the absorbing and swelling rates decrease with increasing DCP amount. The ionic conductivity of the PPCMA gel polymer electrolyte firstly increases and then decreases with increasing DCP ratio. The ionic conductivity of the PPCMA gel polymer electrolyte with 1.2 wt % of DCP reaches the maximum value of 8.43 × 10−3 S cm−1 at room temperature and 1.42 × 10−2 S cm−1 at 50°C. The lithium ion transference number of PPCMA gel polymer electrolyte is 0.42. The charge/discharge tests of the Li/PPCMA GPE/LiNi1/3Co1/3Mn1/3O2 cell were evaluated at a current rate of 0.1C and in voltage range of 2.8–4.2 V at room temperature. The results show that the initial discharge capacity of Li/PPCMA GPE/LiNi1/3Co1/3Mn1/3 O2 cell is 115.3 mAh g−1. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Xiao-Yuan Yu;Min Xiao;Shuang-Jin Wang;Qi-Qiang Zhao ;Yue-Zhong Meng
Journal of Applied Polymer Science 2010 Volume 115( Issue 5) pp:2718-2722
Publication Date(Web):
DOI:10.1002/app.29915
Abstract
A new poly(propylene carbonate)/poly(ethylene oxide) (PEO/PPC) polymer electrolytes (PEs) have been developed by solution-casting technique using biodegradable PPC and PEO. The morphology, structure, and thermal properties of the PEO/PPC polymer electrolytes were investigated by scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry methods. The ionic conductivity and the electrochemical stability window of the PEO/PPC polymer electrolytes were also measured. The results showed that the Tg and the crystallinity of PEO decrease, and consequently, the ionic conductivity increases because of the addition of amorphous PPC. The PEO/50%PPC/10%LiClO4 polymer electrolyte possesses good properties such as 6.83 × 10−5 S cm−1 of ionic conductivity at room temperature and 4.5 V of the electrochemical stability window. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:J. Bian, M. Xiao, S.J. Wang, Y.X. Lu, Y.Z. Meng
Journal of Colloid and Interface Science 2009 Volume 334(Issue 1) pp:50-57
Publication Date(Web):1 June 2009
DOI:10.1016/j.jcis.2009.03.009
Novel Cu–Ni bimetallic catalysts supported on thermally expanded graphite (TEG) were prepared as an example to show the particular characteristics of TEG as a carbon support material. The structures of TEG and the synthesized Cu–Ni/TEG catalysts were characterized using BET, FTIR, TG, SEM, TEM, XRD and TPR techniques. The catalytic activities of the prepared catalysts were investigated by performing micro-reaction in the direct synthesis of dimethyl carbonate (DMC) from CH3OH and CO2. The experimental results indicated that the prepared Cu–Ni/TEG catalysts exhibited highly catalytic activity. Under the optimal catalytic conditions at 100 °C and under 1.2 MPa, the highest conversion of CH3OH of 4.97% and high selectivity of DMC of 89.3% can be achieved. The highly catalytic activity of Cu–Ni/TEG in DMC synthesis can be attributed to the synergetic effects of metal Cu, Ni and Cu–Ni alloy in the activation of CH3OH and CO2 and the particular characteristics of TEG as a carbon support material.Novel TEG supported Cu–Ni bimetallic catalyst was synthesized and utilized in the direct synthesis of DMC to illustrate the superior properties of TEG as a catalyst support.
Co-reporter:Jun Bian, Min Xiao, Shuan-Jin Wang, Yi-Xin Lu, Yue-Zhong Meng
Applied Surface Science 2009 Volume 255(Issue 16) pp:7188-7196
Publication Date(Web):30 May 2009
DOI:10.1016/j.apsusc.2009.03.057
Abstract
Multi-walled carbon nanotubes (MWCNTs) supported Cu–Ni bimetallic catalysts for the direct synthesis of dimethyl carbonate (DMC) from CH3OH and CO2 were synthesized and investigated. The supporting materials and the synthesized catalysts were fully characterized using FTIR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS) techniques. The catalytic activities were investigated by performing micro-reactions. The experimental results showed that the metal phase and Cu–Ni alloy phase in the catalyst were partially formed during the calcination and activation step. Active metal particles were dispersed homogeneously on the surface of the MWCNTs. Cu–Ni/MWCNTs catalysts were efficient for the direct synthesis of DMC. The highest conversion of CH3OH was higher than 4.3% and the selectivity of DMC was higher than 85.0% under the optimal catalytic conditions of 120 °C and around 1.2 MPa. The high catalytic activity of Cu–Ni/MWCNTs in DMC synthesis can be attributed to the synergetic effects of metal Cu, Ni and Cu–Ni alloy in the activation of CH3OH and CO2, the unique structure of MWCNTs and the interaction between the metal particles and the supports.
Co-reporter:Y.F. Zhang, S.J. Wang, M. Xiao, S.G. Bian, Y.Z. Meng
International Journal of Hydrogen Energy 2009 Volume 34(Issue 10) pp:4379-4386
Publication Date(Web):May 2009
DOI:10.1016/j.ijhydene.2008.12.092
The sulfonated poly(fluorenyl ether ketone)s (SPFEK) membranes doped with SiO2 and dispersed by hydroxypropyl methyl cellulose (HPMC) were prepared and investigated for polymer electrolyte membrane fuel cells (PEMFCs) used at high temperature and low relative humidity (RH). The above membrane was prepared by solution dispersion of SPFEK and SiO2 using HPMC as dispersant. The physio-chemical properties of the hybrid membrane were studied by means of scanning electron microscope (SEM), ion-exchange capacity (IEC), proton conductivity, and single cell performance tests. The hybrid membranes dispersed by HPMC were well dispersed when compared with common organic/inorganic hybrid membranes. The hybrid membranes showed superior characteristics as a proton exchange membrane (PEM) for PEMFC application, such as high ionic exchange content (IEC) of 1.51 equiv/g, high temperature operation properties, and the satisfactory ability of anti-H2 crossover. The single cell performances of the hybrid membranes were examined in a 5 cm2 commercial single cell at both 80 °C and 120 °C under different relative humidity (RH) conditions. The hybrid membrane dispersed by HPMC gave the best performance of 260 mW/cm2 under conditions of 0.4 V, 120 °C, 50% RH and ambient pressure. The results demonstrated HPMC being an efficient dispersant for the organic/inorganic hybrid membrane used for PEM fuel cell.
Co-reporter:Jun Bian, Min Xiao, Shuan Jin Wang, Yi Xin Lu, Yue Zhong Meng
Chinese Chemical Letters 2009 Volume 20(Issue 3) pp:352-355
Publication Date(Web):March 2009
DOI:10.1016/j.cclet.2008.11.034
Novel Cu–Ni/C has been prepared and utilized as an efficient catalyst system in direct synthesis of DMC from CH3OH and CO2.
Co-reporter:Jian Liu, Shu Guang Bian, Min Xiao, Shuan Jin Wang, Yue Zhong Meng
Chinese Chemical Letters 2009 Volume 20(Issue 4) pp:487-491
Publication Date(Web):April 2009
DOI:10.1016/j.cclet.2008.11.035
Poly(trimethylene terephthalate) (PTT) is an excellent fiber material. Its thermal degradation and isothermal crystalline behaviors were in this study investigated using thermogravimetric analysis (TGA), thermogravimetric analysis–Fourier transform infrared spectroscopy (TGA–FTIR) analysis, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The thermal degradation mechanism of PTT follows Mclafferty rearrangement principle. The PTT with intrinsic viscosity (IV) of 0.74 dl/g has a maximum crystallinity of about 55% at 190 °C, as demonstrated by DSC and XRD measurements consistently.
Co-reporter:Peng-fei Song;Shuan-jin Wang;Min Xiao;Feng-guang Du
Journal of Polymer Research 2009 Volume 16( Issue 2) pp:91-97
Publication Date(Web):2009 March
DOI:10.1007/s10965-008-9206-2
Poly(propylene carbonate maleate) (PPCMA) was successfully synthesized from carbon dioxide with propylene oxide and maleic anhydride using supported zinc glutarate as catalyst. The PPCMA can be readily cross-linked using dicumyl peroxide (DCP) as a cross-linking agent. The gel content, thermal performance and mechanical properties of the cross-linked PPCMA were then investigated. The results showed that the gel content increased with increasing DCP content and reaction temperature. The as-prepared PPCMA showed higher glass transition temperature (Tg) and decomposition temperature compared with uncross-linkable poly(propylene carbonate) (PPC). The introduction of small amount of cross-linkable moiety provides a very effective way to improve the thermal stability and to extend the molecular weight of PPC, consequently extending its application area.
Co-reporter:Shuanghong Tian;Allan S. Hay
Journal of Polymer Science Part A: Polymer Chemistry 2009 Volume 47( Issue 18) pp:4762-4773
Publication Date(Web):
DOI:10.1002/pola.23529
Abstract
Multiblock copolymers 1a (Mn = 31,500–47,400) of sulfonated poly(aryl ether)s were synthesized by polycondensation of 4,4′-difluorobenzophenone (DFBP), bis(4-hydroxyphenyl)sulfone (BHPS), and an hydroxy-terminated sulfonated oligomer, which was synthesized from DFBP and 2,2′,3,3′,5,5′-hexaphenyl-4,4′-dihydroxybiphenyl a. The copolymerization of trimeric monomer b with DFBP and BHPS gave a series of copolymers 1b (Mn = 26,200–45,900). The copolymers were then sulfonated with chlorosulfonic acid to give ionomers 3a with hydrophilic multiblock segments and ionomers 3b with segments containing clusters of 18 sulfonic acid groups. The proton exchange membranes cast from ionomers 3a and 3b were characterized with regard to thermal stability, water uptake, proton conductivity, and morphology. Transmission electron microscopy images of 3a-1 and 3b-1 revealed a phase separation similar to that of Nafion that may explain their higher proton conductivities compared with randomly sulfonated copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4762–4773, 2009
Co-reporter:Yuanyuan Liu;Yinghua Qi;Antisar R. Hlil;Allan S. Hay
Journal of Polymer Science Part A: Polymer Chemistry 2009 Volume 47( Issue 17) pp:4326-4331
Publication Date(Web):
DOI:10.1002/pola.23485
Abstract
1,3-Phthaloyl bis-9H-carbazole (MPC) and 1,4-phthaloyl bis-9H-carbazole (PPC) were synthesized by a Friedel-Crafts reaction of carbazole with terephthaloyl chloride or isophthaloyl chloride. Homopolymers were obtained by a CN coupling reaction with activated difluorides and copolymers were synthesized with 4,4′-biphenol as a comonomer by a nucleophilic substitution reaction between these NH- and OH-containing monomers and the activated difluoro monomers. The inherent viscosities of the polymers ranged from 0.35 to 1.03 dL/g. These polymers exhibited glass-transition temperatures greater than 238 °C with the PPC-containing homopolymer showing the highest value, 326.4 °C. The thermal stabilities indicated no significant weight loss below 450 °C and the temperatures of 5% weight loss ranged from 514.0 to 546.3 °C. The polymers showed reasonable solubility in organic solvents such as DMAC, DMSO, and NMP. UV absorption and fluorescence emission properties are presented. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4326–4331, 2009
Co-reporter:Shuanghong Tian, Yuezhong Meng and Allan S. Hay
Macromolecules 2009 Volume 42(Issue 4) pp:1153-1160
Publication Date(Web):January 30, 2009
DOI:10.1021/ma802456m
We report on the dependence of the properties on the morphologies of sulfonated polymers 3a and 3b (ηinh = 0.65−1.18) with segments containing clusters of 6 and 12 sulfonic acid groups, respectively. The larger sulfonated clusters in polymers 3b resulted in higher proton conductivity and much better cell performance than polymers 3a. The highest power density of a fuel cell using 3a-1 (IEC = 1.16 mequiv/g) and Nafion 117 was 0.23 and 0.21 W/cm2, respectively, at the effective work potential of 0.5 V, whereas that of 3b-1 (IEC = 1.16 mequiv/g) was 0.29 W/cm2 at even higher effective work potential of 0.6 V. The morphological structure of 3a-1 and 3b-1 was investigated by transmission electron microscopy (TEM) and compared with that of Nafion. TEM images of 3a-1 and 3b-1 revealed a phase separation similar to that of Nafion, which may explain their higher proton conductivities compared to those of randomly sulfonated copolymers.
Co-reporter:D.M. Han, Z.P. Guo, Z.W. Zhao, R. Zeng, Y.Z. Meng, D. Shu, H.K. Liu
Journal of Power Sources 2008 Volume 184(Issue 2) pp:361-369
Publication Date(Web):1 October 2008
DOI:10.1016/j.jpowsour.2008.03.051
A novel catalyst, polyoxometallate-stabilized platinum–ruthenium alloy nanoparticles supported on multiwalled carbon nanotubes (Pt–Ru–PMo12-MWNTs), was synthesized by a microwave-assisted polyol process. The effects of microwave reaction time, microwave reaction power, and pH value of the reaction solution on the electrocatalytic properties of Pt–Ru–PMo12-MWNTs catalysts were also investigated. The polyoxometallate (PMo12) formed a self-assembled monolayer on the surface of the Pt/Ru nanoparticles and MWNTs, which effectively prevented the agglomeration of Pt, Ru nanoparticles and MWNTs, due to the electrostatic repulsive interactions between the negatively charged PMo12 monolayers. Energy dispersive spectroscopy examination and electrochemical measurements showed that the loading content of Pt/Ru and their electrochemical activity vary with the synthesis conditions, such as pH, reaction time, and microwave power. It was found that the a Pt–Ru–PMo12-MWNTs electrocatalyst with high Pt loading content, small crystallite size, and good electrocatalytic activity could be synthesized using a long reaction time, intermediate microwave power, and a pH value of 7. The electrocatalysts obtained were characterized using X-ray diffraction, and scanning and transmission electron microscopy. Their electrocatalytic properties were also investigated by using the cyclic voltammetry technique.
Co-reporter:M. Z. Pang;J. J. Qiao;J. Jiao;S. J. Wang;M. Xiao ;Y. Z. Meng
Journal of Applied Polymer Science 2008 Volume 107( Issue 5) pp:2854-2860
Publication Date(Web):
DOI:10.1002/app.27252
Abstract
Completely biodegradable blends of poly (propylene carbonate) (PPC) and poly(butylene succinate) (PBS) were melt-prepared and then compression-molded. The miscibilities of the two aliphatic polyesters, that is, PPC and PBS, were investigated by dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The static mechanical properties, thermal behaviors, crystalline behavior, and melt flowability of the blends were also studied. Static tensile tests showed that the yield strength and the strength at break increased remarkably up to 30.7 and 46.3 MPa, respectively, with the incorporation of PBS. The good ductility of the blends was maintained in view of the large elongation at break. SEM observation revealed a two-phase structure with good interfacial adhesion. The immiscibility of the two components was verified by the two independent glass-transition temperatures obtained from DMA tests. Moreover, thermogravimetric measurements indicated that the thermal decomposition temperatures (T−5% and T−10%) of the PPC/PBS blends increased dramatically by 30–60°C when compared with PPC matrix. The melt flow indices of the blends showed that the introduction of PBS improved the melt flowability of the blends. The blending of PPC with PBS provided a practical way to develop completely biodegradable blends with applicable comprehensive properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:L. J. Gao;M. Xiao;S. J. Wang ;Y. Z. Meng
Journal of Applied Polymer Science 2008 Volume 108( Issue 2) pp:1037-1043
Publication Date(Web):
DOI:10.1002/app.27271
Abstract
To enhance the thermal and mechanical properties of poly(propylene carbonate) (PPC), the terpolymers were synthesized from carbon dioxide, propylene oxide, and a third monomer, [(2-naphthyloxy)methyl]oxirane (NMO) using supported zinc glutarate as catalyst. The structure of these terpolymers was confirmed by 1H NMR spectroscopy. The catalytic activity, molecular weight, carbonate unit content, as well as thermal and mechanical properties were investigated extensively. The experimental results showed that the catalytic activity, molecular weight, and carbonate unit content decreased with the incorporation of NMO. DSC measurements indicated that the introduction of NMO increased the glass transition temperature from 38 to 42°C. TGA tests revealed that the thermal decomposition temperature (Tg−5%) of the synthesized terpolymer increased significantly, being 34°C higher than that of pure PPC. Accordingly, the mechanical properties proved also to be enhanced greatly as evidenced by tensile tests. These thermal and mechanical improvements are of importance for the practical process and application of PPC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:L. J. Gao;F. G. Du;M. Xiao;S. J. Wang ;Y. Z. Meng
Journal of Applied Polymer Science 2008 Volume 108( Issue 6) pp:3626-3631
Publication Date(Web):
DOI:10.1002/app.27994
Abstract
To improve the thermal and mechanical properties of poly(propylene carbonate) (PPC), the terpolymers were synthesized by the terpolymerization of CO2 with PO and a third monomer, N-(2,3-epoxylpropyl)carbazole (NEC) using supported zinc glutarate as catalyst. The catalytic activity, molecular weight, carbonate unit content, as well as the thermal and mechanical properties were investigated extensively. The experimental results showed that the catalytic activity, molecular weight, and carbonate unit content decreased with the incorporation of NEC. The introduction of NEC increased the glass transition temperature from 38.0 to 44.1°C. Moreover, the thermal decomposition temperature (Tg-5%) of the terpolymer (278°C) was much higher than that of pure PPC (238°C). Accordingly, the mechanical properties proved to be enhanced greatly as evidenced by tensile tests due to the incorporation of bulky carbazole moieties. These improvements in thermal and mechanical properties are of very importance for the process of PPC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:P. F. Song;M. Xiao;F. G. Du;S. J. Wang;L. Q. Gan;G. Q. Liu;Y. Z. Meng
Journal of Applied Polymer Science 2008 Volume 109( Issue 6) pp:4121-4129
Publication Date(Web):
DOI:10.1002/app.28449
Abstract
Terpolymerization of carbon dioxide (CO2) with propylene oxide (PO) and maleic anhydride (MA) was successfully carried out using supported zinc glutarate catalyst. Consequently giving high molecular weight poly(propylene carbonate maleate) (PPCMA) in a very high yield (72.5 g polymer/g catalyst). The resulting terpolymers were fully characterized by FTIR, 1H NMR, 13C NMR, and wide-angle X-ray diffraction (WAXD) techniques. NMR measurements showed that PPCMA had an almost alternating structure for the components of carbon dioxide and PO. The influence of molecular weight and MA content on the properties of PPCMA was also investigated. Differential scanning calorimetry (DSC) measurements revealed that the glass transition temperature (Tg) of PPCMA increased with increasing molecular weight. Thermogravimetric analysis (TGA) indicated that PPCMA51 exhibited a very high decomposition temperature (263°C) due to the introduction of the double bond of MA into the backbone of terpolymer. The terpolymers with double bonds can be readily subjected to crosslinking reaction in high temperature to give a slightly crosslinked PPCMA, which exhibit superior thermal stability. Tensile tests also showed that the mechanical properties of PPCMA increased with increasing molecular weight. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:S. J. Wang;S. G. Bian;H. Yan;M. Xiao;Y. Z. Meng
Journal of Applied Polymer Science 2008 Volume 110( Issue 6) pp:4049-4054
Publication Date(Web):
DOI:10.1002/app.29010
Abstract
A new effective method is presented for the easier preparation of macrocyclics from poly(phenyl sulfide)by two steps: (1) depolymerization reaction of poly(phenyl sulfide) with Na2S in the presence of weak base, and (2) oxidation reaction of depolymerization products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:F.C. Ding, S.J. Wang, M. Xiao, Y.Z. Meng
Journal of Power Sources 2007 Volume 164(Issue 2) pp:488-495
Publication Date(Web):10 February 2007
DOI:10.1016/j.jpowsour.2006.11.028
The cross-linkable sulfonated ploy(arylene ether)s derived from 3,3′-diallyl-4,4′-dihydroxybiphenyl, bisphthalazinone, 4,4′-difluorobenzophenone (DFBP) and sulfonated 4,4′-diflourobenzophenone (SDFBP) were synthesized over a wide range of DFBP/SDFBP molar ratios. The resulting sulfonated poly(arylene ether)s with high inherent viscosity (1.02–1.29 dL g−1) are soluble in polar organic solvents and can form flexible and transparent membranes by casting from their solution. Cross-linking reaction was carried out using the thermal activated radical cross-linking agent (TARC) at 140 °C. The comprehensive properties of the virgin and the cross-linked membranes were compared accordingly. The results showed that the cross-linked membranes revealed the better mechanical, oxidative and dimensional stabilities together with high proton conductivity (9.675 × 10−3 S cm−1) at 25 °C under 100% relative humidity.
Co-reporter:F.C. Ding, S.J. Wang, M. Xiao, X.H. Li, Y.Z. Meng
Journal of Power Sources 2007 Volume 170(Issue 1) pp:20-27
Publication Date(Web):30 June 2007
DOI:10.1016/j.jpowsour.2007.03.068
The cross-linkable sulfonated ploy(arylene ether)s derived from 3,3′-diallyl-4,4′-dihydroxybiphenyl, 9,9′-bis(3,5-dimethyl-4-hydroxypheyl)fluorene (DMHPF), 4,4′-difluorobenzophenone (DFBP) and sulfonated 4,4′-diflourobenzophenone (SDFBP) were synthesized over a wide range of DFBP/SDFBP molar ratios. The resulting sulfonated poly(arylene ether)s with high inherent viscosity (0.87–1.46 dl g−1) are soluble in polar organic solvents and can form flexible and transparent membranes by casting from their solution. The cross-linking reaction was carried out using a thermal activated radical cross-linking agent (TARC) at 100 °C. The comprehensive properties of the virgin and the cross-linked membranes were characterized and compared accordingly. The results showed that the cross-linked membranes had better mechanical, oxidative and dimensional stabilities together with high proton conductivity (5.41 × 10−2 S cm−1) at 80 °C under 100% relative humidity when compared with previously synthesized and similar membranes. These improvements were raised from the cross-linking structure and the fabrication procedure of the membranes.
Co-reporter:H.G. Chen, S.J. Wang, M. Xiao, Y.Z. Meng
Journal of Power Sources 2007 Volume 165(Issue 1) pp:16-23
Publication Date(Web):25 February 2007
DOI:10.1016/j.jpowsour.2006.12.044
Co-reporter:X.L. Wang, R.K.Y. Li, Y.X. Cao, Y.Z. Meng
Materials & Design (1980-2015) 2007 Volume 28(Issue 6) pp:1934-1939
Publication Date(Web):2007
DOI:10.1016/j.matdes.2006.05.003
Starch filled poly(propylene carbonate) composites are environmental friendly materials. In this study, the fracture toughness of composites under mode I loading was determined by the essential work of fracture concept. The specific essential fracture work of the poly(propylene carbonate)/starch composites decreases with increasing the starch content, while the non-essential work term, βwp increases with increasing the starch content. In addition, the morphologies, thermal properties, thermo-mechanical properties were studied by scanning electron microscope, thermogravimetric analysis, dynamic mechanical analysis, and differential scanning calorimetry, respectively. The thermal and thermo-mechanical measurements revealed that increasing starch content led to an increase in glass transition temperature and thermal stability. Morphology observation indicates that poly(propylene carbonate) and starch have weak interfacial adhesion.
Co-reporter:F. C. Ding;M. Xiao;S. J. Wang;Y. Z. Meng;D. M. Han
Journal of Applied Polymer Science 2007 Volume 106(Issue 3) pp:1821-1827
Publication Date(Web):18 JUL 2007
DOI:10.1002/app.26727
A novel class of crosslinkable poly(phthalazinone ether ketone)s with relative high molecular-weight and good solubility were successfully synthesized by the copolymerization of bisphthalazinone containing monomer, 3,3′-diallyl-4,4′-dihydroxybiphenyl and 4,4′-di- fluorobenzophenone. The synthesized polymers with inherent viscosities in the range of 0.42 to 0.75 dL/g can form flexible and transparent membranes by casting from their solution. The crosslinking reaction of these polymers can be carried out by thermally curing of the virgin polymers in or without the presence of crosslinking agent. The experimental results demonstrated that the crosslinking reaction also occurred to some extent during the polymerization. The crosslinked polymers exhibited equivalent glass transition temperature (Tg) at lower crosslinking density, and showed higher Tg than virgin polymers at higher crosslinking density. The crosslinked high-temperature polymer can be used as the base material for high temperature adhesive, coating, enamel material, and composite matrices. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Co-reporter:L. J. Gao;M. Xiao;S. J. Wang;F. G. Du;Y. Z. Meng
Journal of Applied Polymer Science 2007 Volume 104(Issue 1) pp:
Publication Date(Web):27 DEC 2006
DOI:10.1002/app.25587
To enhance the catalytic copolymerization of CO2 and propylene oxide catalyzed by zinc glutarate, the influence of trace of water, ethanol, and propanal on the catalytic activity, the resulted copolymer structure, and the molecular weight and molecular weight distribution of the copolymer were investigated extensively. The experimental results showed that the catalytic activity decreased remarkably in the presence of either trace of ethanol or water, but increased in the presence of trace of propanal. Both 1H-NMR and 13C-NMR spectra suggested that the content of carbonate linkages of resulted copolymer was not effected obviously in the presence of above-mentioned impurities, giving completely alternating poly(propylene carbonate) (PPC). GPC results indicated that these impurities reduced the molecular weights but broadened the molecular weight distributions of resulted copolymers. Finally, the byproduct contents including both propylene carbonate determined by GC and polyether increased with the increase of three impurity concentrations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Y. Xu;S.J. Wang;J. Jiao;M. Xiao;Y.Z. Meng
Polymer Engineering & Science 2007 Volume 47(Issue 2) pp:174-180
Publication Date(Web):17 JAN 2007
DOI:10.1002/pen.20694
Biodegradable blends of poly(propylene carbonate) (PPC) and poly(ethylene-co-vinyl alcohol) (EVOH) were melt compounded in a batch mixer followed by compression molding. The processability, mechanical properties, thermal behavior, and morphologies of the blends were investigated with torque rheometer, Fourier transform infrared spectroscopy, tensile tests, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Torque rheometry indicated good interfacial miscibility between PPC and EVOH phases, and then fourier transform infrared spectroscopy spectra demonstrated that a certain extent of hydrogen-bonding interactions between PPC and EVOH matrix in the blends. A study of the mechanical properties and thermal behavior showed that the EVOH incorporation can significantly enhance the tensile strength, thermal stability, and crystallinity of the blends. Moreover, dynamic mechanical analysis and differential scanning calorimetry both revealed that PPC and EVOH were compatible to some extent. Further, scanning electron microscopic examination also revealed the good interfacial adhesion between EVOH and PPC phases. POLYM. ENG. SCI., 47:174–180, 2007. © 2007 Society of Plastics Engineers
Co-reporter:X. L. Wang;F. G. Du;J. Jiao;Y. Z. Meng;R. K. Y. Li
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2007 Volume 83B(Issue 2) pp:373-379
Publication Date(Web):5 APR 2007
DOI:10.1002/jbm.b.30806
Biodegradable blends of poly(propylene carbonate)/ethylene–vinyl alcohol copolymers (PPC/EVOH) were melt prepared. The mechanical strength, crystallization and melting behavior, morphologies, and thermal properties of these blends were fully investigated using tensile tester, modulated differential scanning calorimetry, scanning electron microscopy, and thermogravimetric analysis, respectively. The results indicated that the thermal stability of blends could be enhanced by increasing EVOH content. No change was observed for the tensile strength when EVOH content was lower than 30 wt %. The tensile strength, however, increased obviously with increasing EVOH content when EVOH content was higher than 30 wt %. The crystallization behavior of the PPC/EVOH blends was studied accordingly. The degradability test showed that the weight loss of PPC/EVOH blends increased with increasing EVOH content because of the strong moisture sorption of EVOH. Morphology observation indicated that the PPC/EVOH blends exhibited a two-phase microstructure. The blends with EVOH contents ranging from 40 to 60 wt % showed the best comprehensive properties as biodegradable thermoplastic for many applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Co-reporter:Y. Z. Meng;J. Xu;S. J. Wang;A. S. Hay
Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 2) pp:262-268
Publication Date(Web):4 DEC 2006
DOI:10.1002/pola.21733
Novel sulfur-containing biphenol monomers were prepared in high yields by the reaction of 4-mercaptophenol with chloropyridazine or chlorophthalazine compounds. High-molecular-weight poly(arylene ether)s were synthesized by a nucleophilic substitution reaction between these sulfur-containing monomers and activated difluoro aromatic compounds. The inherent viscosities of these polymers ranged from 0.34 to 0.93 dL/g. The poly(pyridazine)s exhibited glass-transition temperatures greater than 165 °C. The poly(phthalazine)s showed higher glass-transition temperatures than the poly(pyridazine)s. A polymer synthesized from a bisphthalazinebiphenol and bis(4-fluorophenyl)sulfone had the highest glass-transition temperature (240 °C). The thermal stabilities of the poly(pyridazine)s and poly(phthalazine)s showed similar patterns of decomposition, with no significant weight loss below 390 °C. The poly(phthalazine)s were soluble in chlorinated solvents such as chloroform, and the poly(pyridazine)s were soluble in dipolar aprotic solvents such as N,N′-dimethylacetamide. The soluble poly(pyridazine)s and poly(phthalazine)s could be cast into flexible films from solution. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 262–268, 2007
Co-reporter:L. N. Song;M. Xiao;D. Shu;S. J. Wang;Y. Z. Meng
Journal of Materials Science 2007 Volume 42( Issue 4) pp:1156-1161
Publication Date(Web):2007 February
DOI:10.1007/s10853-006-1433-5
Mechanical and thermal properties of poly(arylene disulfide) synthesized by ring-opening reaction of cyclic(aromatic disulfide) oligomer were reported. These oligomers were prepared from 4,4′-oxybis(benzenethiol). Three-point bending tests were performed to measure the flexural properties of the poly(arylene disulfide). DSC and TGA techniques were used to characterize the thermal properties of these polymers. Ring-opening reactions were carried out by hot-press under atmosphere and nitrogen atmosphere, respectively. Oxidation reaction of these polymers was detected from Raman spectra under atmosphere. The glass transition temperature increased but 10% weight loss temperature decreased with increasing ring-opening temperature. The flexural strength decreased with increasing the temperature of ring-opening polymerization under both atmosphere and nitrogen atmosphere. The polydisulfides could be used as high temperature and thermally curing insulating materials to substitute epoxy resins.
Co-reporter:L. T. Guan;F. G. Du;G. Z. Wang;Y. K. Chen;M. Xiao
Journal of Polymer Research 2007 Volume 14( Issue 3) pp:245-251
Publication Date(Web):2007 June
DOI:10.1007/s10965-007-9103-0
Completely biodegradable foams of poly(propylene carbonate) (PPC) derived from carbon dioxide and propylene oxide were fabricated using N, N′-dinitroso pentamethylene tetramine (DPT) as chemical blowing agent, and urea as the activator to lower the decomposition temperature of DPT. Thermal decomposition behavior and gas evolution behavior of the DPT composite with various urea to DPT ratios were investigated to optimize the composition of the blowing agent. The formulation of blowing agent mixture and foaming condition, the foam morphologies, the molecular weight change, as well as the mechanical properties of produced PPC foams were studied extensively. The experimental results demonstrated that the greatest blowing ratio of 14.8 can be afforded in case 12 phr blowing agent was used at 170 °C for 30 min. Gel permeation chromatography (GPC) and thermal analysis revealed that DPT acted as both chain-extension agent and blowing agent for PPC matrix. The molecular weight of PPC subjected to foaming increased by 76%. The foamed PPC exhibited superior mechanical properties and can be used as packaging material for many practical applications.
Co-reporter:L.N. Song, M. Xiao, Y.Z. Meng
Composites Science and Technology 2006 Volume 66(Issue 13) pp:2156-2162
Publication Date(Web):October 2006
DOI:10.1016/j.compscitech.2005.12.013
Expanded graphite (EG) with different expansion ratios were prepared by the exfoliation of expandable graphite under microwave irradiation. Nanocomposite precursor was fabricated by direct solution blending of cyclic(arylene disulfide) oligomers with the EG fillers. Subsequently, the nanocomposite precursor was hot-molded at 200 °C to carry out simultaneously the in situ ring-opening polymerization (ROP) of these oligomers via free radical mechanism to prepare aromatic polydisulfide/EG nanocomposites. The resulting aromatic polydisulfide/EG nanocomposite exhibited a completely intercalated nanostructure as evidenced by TEM observation. Highly electrical conductivity of the composite was measured by a four-point probe resistivity determiner. Three-point bending tests were used to determine the flexural strength of the composites. The nanocomposite can be used as potential materials to prepare bipolar plate of polymer electrolyte membrane fuel cell due to its high electrical conductivity, recyclable properties of the matrix and nanoscale effect in gas barrier performance.
Co-reporter:H. Yan;X. H. Li;S. J. Wang;Y. Z. Meng
Journal of Applied Polymer Science 2006 Volume 100(Issue 1) pp:161-166
Publication Date(Web):26 JAN 2006
DOI:10.1002/app.22642
Well-crystal macrocyclic (arylene thioether ketone) oligomers were synthesized under high dilution condition by the reaction of Na2S with bis(4-fluoro-phenyl)-methanone in 1-methyl-pyrrolidone (NMP). The oligomers were fully characterized by Matrix-assisted laser desorption/ionization time-of-flight mass spectra (MALDI-TOF-MS), high-pressure liquid chromatography (HPLC), gel permeation chromatography (GPC), 1H NMR, 13C-NMR, and differential scanning calorimetry (DSC). According to DSC studies, uncatalyzed and rapid ring-opening polymerization (ROP) of the oligomers took place instantly when they were heated to melting point. Extracted by dichloro-methane, the obtained polymer neither loses any weight nor dissolves in boiling 1-chloro- naphthalene. These facts indicated that there are no residual oligomers within the resultant polymer. The as-prepared oligomers could be potentially used as high-temperature hot-melt adhesive at a high temperature > 350°C, and matrices for high-performance composites and nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 161–166, 2006
Co-reporter:J. Jiao;M. Xiao;D. Shu;L. Li;Y. Z. Meng
Journal of Applied Polymer Science 2006 Volume 102(Issue 6) pp:5240-5247
Publication Date(Web):28 SEP 2006
DOI:10.1002/app.24771
Biodegradable foams were successfully prepared from calcium carbonate reinforced poly(propylene carbonate) (PPC/CaCO3) composites using chemical foaming agents. The incorporation of inexpensive CaCO3 into PPC provided a practical way to produce completely biodegradable and cost-competitive composite foams with densities ranging from 0.05 to 0.93 g/cm3. The effects of foaming temperature, foaming time and CaCO3 content on the fraction void, cell structure and compression property of the composite foams were investigated. We found that the fraction void was strongly dependent on the foaming conditions. Morphological examination of PPC/CaCO3 composite foams revealed that the average cell size increased with increasing both the foaming temperature and the foaming time, whereas the cell density decreased with these increases. Nevertheless, the CaCO3 content showed opposite changing tendency for the average cell size and the cell density because of the heterogeneous nucleation. Finally the introduction of CaCO3 enhanced the compressive strength of the composite foams dramatically, which was associated with well-developed cell morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5240–5247, 2006
Co-reporter:Cao Min, Xiao Min, Lu Yixin, Meng Yuezhong
Materials Letters 2006 Volume 60(Issue 27) pp:3286-3291
Publication Date(Web):November 2006
DOI:10.1016/j.matlet.2006.03.005
A novel in situ crosslinking and foaming process for ethylene-vinyl alcohol copolymers (EVOH) by propylene carbonate was investigated. The crosslinking process was believed to result from the ester-exchange reaction between propylene carbonate and EVOH, during which the 1, 2-propanediol by-product subsequently acts as the foaming agent for the crosslinked EVOH. The effects of propylene carbonate content, foaming condition, nucleating agent as well as plasticizer on the expansion ratio, morphology, and mechanical properties of the crosslinked EVOH foams were explored. Propylene carbonate not only acted as both crosslinking agent and foaming agent but also worked as plasticizer for the EVOH foams. The addition of nucleating agent or plasticizer led to foams with higher cell density and smaller cell size. Gel content, crystallization behavior, and thermal stability of the crosslinked EVOH foams were determined. The results revealed that the gel content and decomposition temperature increased with increasing propylene carbonate content, while the melting point, crystallization temperature and crystallinity decreased.
Co-reporter:Y. F. Zhao;M. Xiao;X. C. Ge;S. J. Wang;Y. Z. Meng
Polymers for Advanced Technologies 2006 Volume 17(Issue 5) pp:386-390
Publication Date(Web):31 MAY 2006
DOI:10.1002/pat.724
Macrocyclic (arylene thioether ketone) oligomers together with a linear poly(phenylene sulfide ketone) oligomer were synthesized by a one-step reaction. The macrocycles and linear oligomer were fully characterized by 13C-NMR, H-NMR, matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), differential scanning calorimetry (DSC) and FT-IR. Uncatalyzed, simultaneously ring-opening polymerization (ROP) of the macrocycles and the mixture of macrocycles and linear oligomer were carried out under dynamic heating conditions. The ROP temperature of the macrocycles decreased upon mixing it with the linear oligomer. The ROP conditions and mechanism were investigated and discussed. The macrocycles and their mixture show potential applications in high temperature adhesives and sealants. Copyright © 2006 John Wiley & Sons, Ltd.
Co-reporter:Yulin Chen;Shuanjin Wang;Shuanghong Tian;Allan S. Hay
Macromolecular Chemistry and Physics 2006 Volume 207(Issue 7) pp:653-659
Publication Date(Web):22 MAR 2006
DOI:10.1002/macp.200500574
Summary: Nafion perfluorinated resins that contain perfluorosulfonic acid groups have outstanding properties as membranes in polymer electrolyte membrane (PEM) fuel cells when used only at temperatures lower than 80 °C. At higher temperatures, dehydration of the membrane occurs with a concomitant loss of conductivity. In this paper, we report a new approach to synthesize polyphthalazinone ionomers via an NC coupling reaction. The sulfonated polymers produced showed excellent thermal and oxidative stability because of their specially designed structure. Membranes cast from solution possessed good water affinity and high proton conductivity. Different bisphthalazinone monomers resulted in varying properties of the corresponding polymers. The membranes exhibited excellent resistance both to hydrolysis and oxidation, demonstrating their promising application as proton exchange membranes in PEM fuel cells. The relationship between the structure and properties for the synthesized polymeric ionomers was discussed.
Co-reporter:J. Xu;Y. Z. Meng;S. J. Wang;A. S. Hay
Journal of Polymer Science Part A: Polymer Chemistry 2006 Volume 44(Issue 10) pp:3328-3335
Publication Date(Web):31 MAR 2006
DOI:10.1002/pola.21441
A series of novel soluble pyridazinone- or pyridazine-containing poly(arylene ether)s were prepared by a polycondensation reaction. The pyridazinone monomer, 6-(4-hydroxyphenyl)pyridazin-3(2H)-one (1), was synthesized from the corresponding acetophenone and glyoxylic acid in a simple one-pot reaction. The pyridazinone monomer was successfully copolymerized with bisphenol A (BPA) or 1,2-dihydro-4-(4-hydroxyphenyl)phthalazin-1(2H)-one (DHPZ) and bis(4-fluorophenyl)sulfone to form high-molecular-weight polymers. The copolymers had inherent viscosities of 0.5–0.9 dL/g. The glass-transition temperatures (Tg's) of the copolymers synthesized with BPA increased with increasing content of the pyridazinone monomer. The Tg's of the copolymers synthesized from DHPZ with different pyridazinone contents were similar to those of the two homopolymers. The homopolymers showed Tg's from 202 to 291 °C by differential scanning calorimetry. The 5% weight loss temperatures in nitrogen measured by thermogravimetric analysis were in the range of 411–500 °C. 4-(6-Chloropyridazin-3-yl)phenol (2) was synthesized from 1 via a simple one-pot reaction. 2 was copolymerized with 4,4′-isopropylidenediphenol and bis(4-fluorophenyl)sulfone to form high-Tg polymers. The copolymers with less than 80 mol % pyridazinone or chloropyridazine monomers were soluble in chlorinated solvents such as chloroform. The copolymers with higher pyridazinone contents and homopolymers were not soluble in chlorinated solvents but were still soluble in dipolar aprotic solvents such as N-methylpyrrolidinone. The soluble polymers could be cast into flexible films from solution. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3328–3335, 2006
Co-reporter:Wenhan Luo, Min Xiao, Shuanjin Wang, Shan Ren, Yuezhong Meng
Polymer Testing (April 2017) Volume 58() pp:13-20
Publication Date(Web):April 2017
DOI:10.1016/j.polymertesting.2016.12.004
Co-reporter:Shaoyun Chen, Bin Sun, Wei Hong, Hany Aziz, Yuezhong Meng and Yuning Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 12) pp:NaN2190-2190
Publication Date(Web):2014/01/06
DOI:10.1039/C3TC32219J
The influence of the side chain on the molecular organization and charge transport performance of diketopyrrolopyrrole-quaterthiophene copolymers (PDQTs) was studied. It was found that, by increasing the side chain length from 2-octyldodecyl (PDQT-20) to 2-decyltetradecyl (PDQT-24), the mobility increased from 2.10 cm2 V−1 s−1 up to 3.37 cm2 V−1 s−1 in organic thin film transistors (OTFTs). The increase was found to be due to the improved surface morphology, rather than the changes in crystallinity and π–π stacking distance. A new side chain substituent, 4-decylhexadecyl, was developed for studying the effects of the bifurcation point of the branched side chains in comparison with 2-octyldodecyl and 2-decyltetradecyl. The 4-decylhexadecyl substituted PDQT (PDQT-26) showed a surge in mobility up to 6.90 cm2 V−1 s−1. The remarkably enhanced charge transport performance observed for PDQT-26 was believed to originate from its much shorter π–π distance (3.68 Å) than those of PDQT-20 (3.79 Å) and PDQT-24 (3.86 Å). The improvement was the result of a farther distance of the bifurcation point of 4-decylhexadecyl from the polymer backbone, which could effectively minimize the steric interference of the bulky side chain branches with the backbone to facilitate the co-facial π–π stacking.
Co-reporter:Shaoyun Chen, Bin Sun, Wei Hong, Zhuangqing Yan, Hany Aziz, Yuezhong Meng, Jon Hollinger, Dwight S. Seferos and Yuning Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 9) pp:NaN1690-1690
Publication Date(Web):2013/12/10
DOI:10.1039/C3TC31753F
Two diketopyrrolopyrrole (DPP)–carbazole (Cz) based π-conjugated copolymers, PDBTCz-H (P1) and PDBTCz-Me (P2), were designed and synthesized to study the effects of N-substitution of the carbazole unit on the molecular ordering, main chain conjugation, and charge transport properties of these polymers. It was found that the existence of hydrogen bonding interaction between the N–H group in the carbazole unit and the CO group in the DPP unit has a significant impact on the UV absorption, crystallinity, thin film morphology, as well as charge transport characteristics of P1. The hydrogen bonding is a very competitive force with the π–π stacking interaction, leading to the more twisted backbone structure and poorer molecular ordering of P1 in the solid state. Although the crystallinity of the P1 thin films could be somewhat improved by thermal annealing, the polymer main chains of P1 remain rather twisted and less conjugated in comparison with P2. The poorer main chain conjugation of P1 caused by the hydrogen bonding led to a dramatic drop in charge transport performance in organic thin film transistors (OTFTs). The highest hole mobility achieved for P1 is 8.9 × 10−3 cm2 V−1 s−1, which is almost two orders of magnitude lower than that of P2 (0.53 cm2 V−1 s−1).
Co-reporter:Zhenjie Sun, Min Xiao, Shuanjin Wang, Dongmei Han, Shuqin Song, Guohua Chen and Yuezhong Meng
Journal of Materials Chemistry A 2014 - vol. 2(Issue 38) pp:NaN15944-15944
Publication Date(Web):2014/07/31
DOI:10.1039/C4TA03570D
Sulfur has a very high theoretical specific capacity of 1672 mA h g−1 when used in lithium–sulfur batteries. However, the particularly rapid capacity reduction owing to the dissolution of intermediate polysulfide anions into the electrolyte still hinders practical application. In this respect, we report a novel core–shell structured sulfur–poly(sodium p-styrenesulfonate) (S@PSS) composite cathode material with a sulfur content as high as 93 wt% for lithium–sulfur batteries, which is the highest sulfur content disclosed in the literature. Due to the effective transport of lithium cations while blocking polysulfide anions by common ion Coulombic repulsion of the negatively charged –SO3− groups in the PSS protective layer, the S@PSS composite cathode exhibits a high initial specific capacity of 1159 mA h g−1 at a 0.1 C rate, and retains a stable discharge capacity of 972 mA h g−1 after 70 cycles and 845 mA h g−1 after 120 cycles with a high Coulombic efficiency of over 99%. To our knowledge, this new methodology for lithium–sulfur cathodes has not been reported so far; the initial specific capacity is the highest value calculated based on total composite mass, which has not been disclosed in the literature.
Co-reporter:Shaoyun Chen, Bin Sun, Chang Guo, Wei Hong, Yuezhong Meng and Yuning Li
Chemical Communications 2014 - vol. 50(Issue 49) pp:NaN6512-6512
Publication Date(Web):2014/04/25
DOI:10.1039/C4CC02840F
3,3′-(Ethane-1,2-diylidene)bis(indolin-2-one) (EBI) was used as a new electron-acceptor building block for conjugated polymers. Copolymers of EBI and bithiophene exhibited p-type semiconductor performance with hole mobility of up to 0.044 cm2 V−1 s−1 in organic thin film transistors.
Co-reporter:Meng Zhang, Zhongwei Fu, Min Xiao, Yuehong Yu, Shuanjin Wang, Myoung Jae Choi and Yuezhong Meng
Chemical Communications 2016 - vol. 52(Issue 6) pp:NaN1153-1153
Publication Date(Web):2015/05/04
DOI:10.1039/C5CC02230D
A new catalyst Co1.5PW12O40 was synthesized with exceptional catalytic performance of converting methanol to ethylene. Under the optimal conditions, both the conversion of methanol and the selectivity of ethylene are almost 100%, which can thus avoid a product separation process.
Co-reporter:Longlong Yan, Dongmei Han, Min Xiao, Shan Ren, Yuning Li, Shuanjin Wang and Yuezhong Meng
Journal of Materials Chemistry A 2017 - vol. 5(Issue 15) pp:NaN7025-7025
Publication Date(Web):2017/03/14
DOI:10.1039/C7TA01400G
To eliminate capacity fading effects due to the loss of sulfur in cathode materials for lithium–sulfur batteries (LSBs), a polymer of poly(1,3-diethynylbenzene) (PAB) with good solubility was synthesized by an oxidative coupling reaction. This polymer can be instantaneously carbonized into highly conductive carbon, which can then be used as both an immobilizer host and conductivity enhancer for sulfur cathodes. The cathode material of S/PAB-C was prepared via a rapid dissolution–precipitation method combined with an in situ and instantaneous carbonization process to obtain 3D graphene-like PAB-C with an artificial honeycomb-like morphology. Benefitting from this particular design, the S/PAB-C cathode with an optimal content of 75% sulfur exhibits excellent discharge–charge performance, which shows initial discharge capacities of 1449 mA h g−1 at 0.1C and 1087 mA h g−1 at 0.5C, and retains a stable capacity of 900 mA h g−1 after 500 cycles with a high retention of 82.6% at 0.5C. The strategy which utilizes instantaneous carbonization of PAB and an in situ sulfur trapping process offers a new way to enhance the cycling stability and enriches the architectural design of LSBs. To the best of our knowledge, this is the first report about the brand new methodology to in situ synthesize highly conductive carbon for application in LSBs.
Co-reporter:Wei Liu, Shuanjin Wang, Min Xiao, Dongmei Han and Yuezhong Meng
Chemical Communications 2012 - vol. 48(Issue 28) pp:NaN3417-3417
Publication Date(Web):2012/01/26
DOI:10.1039/C2CC16952E
A composite proton exchange membrane containing electrospun nanofibers shows excellent oxidative stability and high proton conductivity as well as an extremely low activation energy of 1.30 kJ mol−1.
Co-reporter:Lizhen Long, Shuanjin Wang, Min Xiao and Yuezhong Meng
Journal of Materials Chemistry A 2016 - vol. 4(Issue 26) pp:NaN10069-10069
Publication Date(Web):2016/05/25
DOI:10.1039/C6TA02621D
In this review, state-of-the-art polymer electrolytes are discussed with respect to their electrochemical and physical properties for their application in lithium polymer batteries. We divide polymer electrolytes into the two large categories of solid polymer electrolytes and gel polymer electrolytes (GPE). The performance requirements and ion transfer mechanisms of polymer electrolytes are presented at first. Then, solid polymer electrolyte systems, including dry solid polymer electrolytes, polymer-in-salt systems (rubbery electrolytes), and single-ion conducting polymer electrolytes, are described systematically. Solid polymer electrolytes still suffer from poor ionic conductivity, which is lower than 10−5 S cm−1. In order to further improve the ionic conductivity, numerous new types of lithium salt have been studied and inorganic fillers have been incorporated into solid polymer electrolytes. In the section on gel polymer electrolytes, the types of plasticizer and preparation methods of GPEs are summarized. Although the ionic conductivity of GPEs can reach 10−3 S cm−1, their low mechanical strength and poor interfacial properties are obstacles to their practical application. Significant attention is paid to the incorporation of inorganic fillers into GPEs to improve their mechanical strength as well as their transport properties and electrochemical properties.
Co-reporter:Zhenjie Sun, Min Xiao, Shuanjin Wang, Dongmei Han, Shuqin Song, Guohua Chen and Yuezhong Meng
Journal of Materials Chemistry A 2014 - vol. 2(Issue 24) pp:NaN9286-9286
Publication Date(Web):2014/04/16
DOI:10.1039/C4TA00779D
Novel polymeric materials with a very high content of sulfur were successfully synthesized via a facile copolymerization of elemental sulfur with 1,3-diethynylbenzene (DEB). For the as-prepared sulfur-rich polymeric materials (C–S copolymer), diynes or polydiynes are chemically cross-linked with a large amount of polymeric sulfur to form a cage-like semi-interpenetrating network (semi-IPN) structure. Due to the strong chemical interaction of sulfur with the carbon framework and the unique cage-like structure in C–S copolymers, the dissolution and diffusion of polysulfides out of the cathode is effectively suppressed through chemical and physical means. As a result, the sulfur-rich C–S polymeric materials with semi-IPN structure exhibit excellent cycling stability and high coulombic efficiency. The initial discharge capacity is 1143 mA h g−1 at a 0.1 C rate. The capacity still remains at 70% even after about 500 cycles at a high current density of 1 C. In addition, a high coulombic efficiency of over 99% is obtained during the entire range of cycling.
Co-reporter:Yingjie Zhou, Alex D. Brittain, Deyuan Kong, Min Xiao, Yuezhong Meng and Luyi Sun
Journal of Materials Chemistry A 2015 - vol. 3(Issue 27) pp:NaN6961-6961
Publication Date(Web):2015/06/09
DOI:10.1039/C5TC01377A
Diamondoids, a group of hydrocarbon cage molecules that resemble diamond lattice, are attracting increasing interest in the past decade. Their diamond-like structure warrants that diamondoids inherit the superior properties of diamond at nanoscale, including exceptional hardness and stiffness, high thermal stability, high chemical resistance, unique optical properties and fluorescence, and excellent biocompatibility. To effectively take advantage of the fascinating properties of diamondoids, they must be properly functionalized so that they can be covalently incorporated into the host systems or compatibly mixed with the hosts. Herein, the origin, synthesis, derivatization, and application of diamondoids are reviewed. In particular, how the derivatized diamondoids for various functional applications, including pharmaceuticals, polymers, fine chemicals, nanomaterials, and optical devices, are discussed. It is hoped that this review article can attract more interest in diamondoids, which in turn helps motivate the development of new synthesis and application of diamondoids and their derivatives so that this group of unique molecules can bring more benefits.
Co-reporter:Dongyang Chen, Shuanjin Wang, Min Xiao, Yuezhong Meng and Allan S. Hay
Journal of Materials Chemistry A 2011 - vol. 21(Issue 32) pp:NaN12077-12077
Publication Date(Web):2011/07/07
DOI:10.1039/C1JM10950B
A novel dihydroxyl monomer bearing 18 electron rich phenyl rings were synthesized and polymerized with other monomers bearing electron deficient phenyl rings to give dense and selective sites in macromolecules for post-sulfonation, which was successfully conducted in ClSO3H/CH2Cl2 solution at room temperature in a subsequential step. The chemical structures were confirmed by 1H NMR and FT-IR spectra. The ionic exchange capacity (IEC) was controlled to be from 0.65 to 1.21 mequiv g−1 to afford considerable proton conductivity. Distinct phase separation was observed in the resulting membranes from SAXS profiles. The SPAEK-5 with an IEC of 1.21 mequiv g−1 gave better proton conductivity than Nafion 117 at all tested temperatures under 100% relative humidity. The membranes exhibited an exceeding stability when immersing in Fenton's reagent (3 wt.% H2O2 + 2 ppm FeSO4) at 80 °C. These properties make them promising candidates for electrochemical applications.
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