COLLOID AND POLYMER SCIENCE
·
2016
·Vol. 295
·期 1
·205-213
·
IF 1.89
Tao Huiwen,Zhang Xueqin,Sun Ying,Yang Hong,Lin Baoping
To clarify the influence of molecular weight of siloxane macromonomer on phase separation morphology, oxygen permeability, and mechanical properties, silicone hydrogels were prepared by copolymerizing mixtures of methacrylate-terminated siloxane macromonomer (MTSM), silicon-containing monomers tris(trimethylsiloxy)-3-methacryloxpropylsilane, and three hydrophilic monomers N , N -dimethylacrylamide, N -vinylpyrrolidone, and hydroxypropyl methacrylate. The number of Si–O–Si repeating units was equal in every silicone hydrogel while the molecular weight of MTSM ranged from 1000 to 10000 g/mol. The oxygen permeability coefficient (Dk), equilibrium water content (EWC), light transmittance, mechanical properties, and internal morphologies of obtained silicone hydrogels were characterized, and their relationships were discussed in detail. The results showed that the Dk value increased first and then decreased with the chain length of MTSM increasing. The EWC presented an increasing trend and the light transmittance decreased with the increase of MTSM chain length. The elongation increased while the modulus and the tensile strengths of the silicone hydrogels decreased along with the MTSM molecular weight increasing. The internal morphologies of the silicone hydrogels were observed by transmission electron microscope. The results indicated that the silicone hydrogels presented different phase separation structures depending on the molecular chain length of MTSM. The continuous silicone phase formed and made significant contributions to high Dk value as the molecular chain length of MTSM was moderate. Besides, a model was proposed to explain the effect mechanism of the MTSM chain length on the oxygen permeability and the EWC. This work provided a facile method to preparing the silicone hydrogel materials with desirable water absorption and high oxygen permeability by adjusting the molecular weight of macromonomers.
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高影响因子
MICROCHIMICA ACTA
·
2016
·Vol. 184
·期 3
·677-686
·
IF 4.831
Zhao Shuang,Zhang Jun,Li Zhengping,Zhang Peixin,Li Yunxiao,Liu Guohua,Wang Yong,Yue Zhao
Nanocomposites consisting of gold nanoclusters and graphene oxide (AuNC/GO) were prepared and investigated with respect to the design of new sensors for hydrogen peroxide (H 2 O 2 ). The AuNC/GO hybrid nanomaterials were deposited on a gold electrode by the layer-by-layer assembly method, where they showed enhanced photoelectrical and sensing properties. The presence of graphene oxide improves the photoinduced electron separation efficiency of the AuNCs, as well as the catalytic effect of AuNCs on the electroreduction of H 2 O 2 . Compared to an electrode modified with AuNCs only, the new electrodes display a more than ten-fold enhanced photocurrent at a working voltage of -500 mV (vs. Ag/AgCl), higher sensitivity for H 2 O 2 (25.76 nA⋅mM −1 ), lower LOD (2 μM) and extended linear range (from 30 μM to 5 mM). The sensors were applied to the determination of H 2 O 2 extracted from living human umbilical vein endothelial cells stimulated by angiotensin II.
Graphene oxide (GO) not only improves the photoinduced charge separation efficiency of fluorescent gold nanoclusters (AuNCs) based photoelectrochemical sensors, but also enhances the catalytic property of AuNCs on the detection of hydrogen peroxide (H 2 O 2 ).
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高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2016
·Vol. 28
·期 3
·2867-2876
·
IF 1.798
Yu Libo,Li Zhen,Song Hai
Based on translucent TiO 2 nanotube (NT) film, CdS quantum dots (QDs) were anchored onto TiO 2 NT film using different linker molecules including thioglycolic acid (TGA), mercaptopropionic acid (MPA) and cysteine via hydrothermal method. The CdS QDs sensitized TiO 2 NT (CdS/TiO 2 NT) electrodes were constructed to quantum dots-sensitized solar cells (QDSSCs). The photovoltaic performance analysis results of the QDSSCs show that the linker molecule plays a significant role in the solar cell performance. The QDSSC using cysteine as linker molecule exhibits best power conversion efficiency than the other QDSSCs using TGA or MPA as linker molecules. The incident photon-to-current conversion efficiency (IPCE) and the electrochemical impedance spectroscopy (EIS) analysis results indicate that amino group of cysteine may has two aspects of the role to improve the power conversion efficiency of the QDSSC, one is that the good charge transfer properties of the cysteine might depend on the good donor–acceptor abilities of the free electron pair of the amino group, another is that distance between the TiO 2 NT and the CdS QDs could be slightly decreased due to the cysteine could anchor the CdS QDs via both amino and thiol group.
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高影响因子
Waste and Biomass Valorization
·
2016
·Vol. 9
·期 1
·95-101
·
IF 0.915
Ning Liangmin,Liao Shengyun,Sun Yongfa,Yu Linhao,Tong Xinli
Abstract The catalytic synthesis of 2,5-diformylfuran (DFF) from 5-hydroxymethylfurfural (HMF) attracts extensive attention in the research of biomass conversion. However, it is a challenge to achieve high conversion of HMF under mild conditions with a heterogeneous catalyst, which can be easily separated and recycled. Herein, we report a novel cobalt-based catalyst (Co x O y -N@TiO 2 ) for the oxidation of HMF to DFF with 30 % aqueous tert -butyl hydroperoxide as the oxidant. A series of Co-based catalysts were prepared by a typical impregnation method, and detected by XRD, TEM and FT-IR techniques. Based on the experimental results of catalytic test, it is found that a 91 % conversion of HMF and 40 % selectivity of DFF was obtained with the Co x O y -N@TiO 2 catalyst at 80 °C within 5 h. In addition, the Co x O y -N@TiO 2 can be recycled up to five times without significant loss of activity. Graphical Abstract The efficient oxidation of 5-hydroxymethyl furfural, a biomass-derived platform compound, to produce 2,5-diformylfuran is achieved using Co x O y -N@TiO 2 catalyst under mild conditions.
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2016
·Vol. 52
·期 4
·1823-1830
·
IF 2.302
Liu Zhi,Ang Koon Keong Jeremy,He Jihuan
Point discharge is a natural phenomenon which principle and application are both under active investigation. In this work, a needle-disk electrode spinneret was designed through the combination of the point discharge concept and the merits of typical needleless electrospinning (disk as spinneret). The desired outcome for point electrode system is to produce a controllable process of jet formation, with respect to the control of jet site and amount of jets under a lower applied voltage value. Two comparisons were used: (i) in comparison to the typical needleless electrospinning method (disk electrospinning), the needle-disk electrospinning produce finer and more uniform nanofibers. Further numerical simulation results confirmed that the needle-disk electrode induced electric field intensity which is 5.33 times higher than that of disk electrode under the same parameters; (ii) both the numerical simulation and experimental results showed that needle-disk electrospinning can produce competitive quality of nanofibers accompanied by enhanced throughput, compared with the traditional single-needle electrospinning method. Finally, we demonstrate that needle-disk electrospinning produces nanofiber with super-high throughput of 13.5 g/h, which is 183 times higher than traditional electrospinning under similar spinning conditions.
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高影响因子
POLYMER BULLETIN
·
2016
·Vol. 74
·期 6
·2099-2116
·
IF 1.371
Wu Lu,Guo Jingfeng,Zhao Shu
A series of flame-retardant waterborne polyurethanes were synthesized with 4,4′-diphenylmethane diisocyanate and polyethylene glycol600 (PEG600) and modified with different level of diethylbis(2-hydroxyethyl)aminomethylphosphonate (fyrol-6); besides, 1,1,1-Tris(hydroxymethyl)propane was introduced as chain extender and crosslinking agent. The structures of these waterborne polyurethanes were confirmed by Fourier transform-infrared spectroscopy. Thermal degradation properties and flame retardancy were investigated by thermal gravimetric analysis (TGA), limiting oxygen index (LOI), and vertical burning test (UL-94). Wettability and mechanical property of film were measured with contact angle analyzer and universal mechanical machine, respectively. The results showed that when the mass of fyrol-6 was 12.0 % and the TMP was 1.7 %, an LOI value of 28.1 % and a UL-94V-2 rating could be achieved. Besides, the mechanical properties, including tensile strength, 100 % modulus and impact strength, are also relatively good. Simultaneously, the TGA analysis indicated that the incorporation of fyrol-6 enhanced the carbon residue from 8.9 to 19.9 %.
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高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2015
·Vol. 116
·期 2
·451-466
·
IF 1.17
Jiang Dahao,Mao Jun,Fang Zheng,Ni Jun,Zhang Qunfeng,Li Xiaonian
In this paper, the deactivation causes of the Pd/SiO 2 catalyst for continuous liquid-phase selective hydrogenation of 6,10,14-trimethylpentadeca-13-en-2-one in 2000 h of pilot plant test were systematically investigated by N 2 adsorption–desorption, thermogravimetric and differential thermal analyses, scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray fluorescence, experiments of CO poisoning and regeneration, and laboratory retests of the deactivated catalyst samples. The pore textures of Pd/SiO 2 catalysts were not destructed during the pilot test, while there were no obvious carbonaceous deposits appearing on the deactivated catalyst samples. The sintering and crystallization of Pd metal nanoparticles were found, which could be partially accountable for the deactivation of Pd/SiO 2 catalysts. Though Pd leaching did not take place in the pilot test, the Pd active phase could be slightly poisoned by sulfur impurities from feedstock hydrogen. Combining the results of CO poisoning and regeneration experiments with those of compositional analyses of fresh and circulating hydrogen in the pilot test, it could be concluded that CO poisoning should be another important reason for the deactivation of the Pd/SiO 2 catalyst due to high concentration of CO in the reaction system of pilot test and relatively low reaction temperature in the middle and at the bottom of the catalyst bed. Fortunately, the CO poisoned Pd/SiO 2 catalyst in the pilot test could be in situ regenerated by installing a purifier for CO elimination from the circulating hydrogen and increasing the temperature of the whole catalyst bed to slightly higher than 383 K.
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高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2015
·Vol. 31
·期 4
·645-650
·
IF 0.875
Geng Zhi,Zhu Suiyi,Yu Yang,Lu Ying,Lin Rao,Guo Shujun,Bian Dejun,Yang Xia,Huo Mingxin,Huo Hongliang
Novel matrix beads for the immobilization of strain Comamonas testosteroni sp. bdq06 to degrade quinoline were fabricated from polyethersulfone(PES). The beads have an average size of 3 mm and a surface dense layer of 20 microns. To help adhesion and proliferation of bacterial cells, the surfaces of the PES beads were etched, and numerous holes about 1.5 micrometers in diameter were generated as tunnels for cell colonizing in the larger internal cavities of about 5 micrometers in diameter. The quinoline degradation was remarkably enhanced by the cells immobilized in PES beads compared with that by the free cells at pH 5.0 or 10.0 and a temperature of 40 °C. The enhanced degradation of quinoline was contributed to the biofilm on the surface of PES beads, resulting in the significant reduction of retention time from 9 h to 2 h. Furthermore, the beads remain intact after the ultrasonic treatment of them for 30 min or recycling 50 times, indicating that they have excellent mechanical strength, flexibility and swelling capacity. Thus, PES beads have great potential to be matrix for the cell immobilization in bioaugmentation.
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高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2015
·Vol. 123
·期 3
·2485-2497
·
IF 2.042
Wang Xue-jie,You Jin-zong
The thermal decomposition of capecitabine (CAP) was measured with thermogravimetry, differential scanning calorimetry, and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The IR spectra, high-performance liquid chromatography, and liquid chromatography–mass spectrometry of CAP and the residue of its thermal decomposition at various temperatures were determined. The molecular bond orders were calculated using an ab initio method from the GAMESS program of quantum chemistry. The mode of thermal decomposition for CAP was discussed. The kinetic parameters for thermal decomposition such as activation energy E
a and the pre-exponential factor A were obtained using the Ozawa method. The prospective lifetime of CAP was estimated using the Dakin equation. The results indicated that the thermal decomposition of CAP is a three-step process, and the first mass loss stage is to lose pentyl formate. The initial decomposition temperature in either nitrogen or air is 120 °C. For decomposition in nitrogen, the E
a and A for the initial thermal decomposition are 105.1 kJ mol −1 and 9.12 × 10 11 min −1 , respectively. For decomposition in air, the corresponding E
a and A are 105.1 kJ mol −1 and 9.55 × 10 11 min −1 , respectively. The CAP has poor thermal stability under routine temperature.
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高影响因子
Nanoscale Research Letters
·
2015
·Vol. 10
·期 1
·1-8
·
IF 2.779
Shi Chaohong,Zhu Nengwu,Cao Yanlan,Wu Pingxiao
The development of green procedure for the synthesis of gold nanoparticles (AuNPs) has gained great interest in the field of nanotechnology. Biological synthetic routes are considered to be environmentally benign and cost-effective. In the present study, the feasibility of AuNPs’ synthesis via intracellular protein extract (IPE) of Pycnoporus sanguineus was explored. The characteristics of generated particles of formation, crystalline nature, and morphology and dimension were analyzed by UV-vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. UV-vis spectra exhibited strong absorption peaks in 520 to 560 nm, indicating the formation of AuNPs. XRD analysis revealed that the formed AuNPs were purely crystalline in nature. TEM observation showed that AuNPs with various shapes including spherical, pseudo-spherical, triangular, truncated triangular, pentagonal, and hexagonal, ranging from several to several hundred nanometers, were synthesized under different conditions. The average size of AuNPs decreased from 61.47 to 29.30 nm as the IPE addition increased from 10 to 80 mL. When the initial gold ion concentration changed from 0.5 to 2.0 mM, the average size rose from 25.88 to 51.99 nm. As in the case of solution pH, the average size was 84.29 nm with solution pH of 2.0, which diminished to 6.07 nm with solution pH of 12.0. Fourier transform infrared (FTIR) analysis implied that the functional groups including hydroxyl, amine, and carboxyl were involved in the reduction of gold ions and stabilization of AuNPs. The catalysis results showed that 0.019 mg of AuNPs with average size of 6.07 nm could catalyze the complete degradation of 12.5 μmol of 4-nitroaniline within 6 min and the degradation rate increased drastically with the addition of AuNPs. All the results suggested that the IPE of P. sanguineus could be potentially applied for the eco-friendly synthesis of AuNPs.
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PubMed
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2015
·Vol. 33
·期 5
·732-742
·
IF 1.835
Dai Ting-yang,Wang Hong-juan,Cao Yi,Lu Yun
Composites of polyaniline (PAn) and epoxide polysiloxane (EPSi) are reported for the first time. EPSi is designed, synthesized and N -grafted onto the PAn backbone through covalent bonds. As-prepared EPSi- g -PAn composites are soluble in organic solvents and the corresponding films can be easily produced via a simple solution-casting procedure. The composite films combine the mechanical characteristics of EPSi and the chemical properties of PAn, enabling the facile introduction of the noble metal particles. The successful fabrication of the composites is confirmed by the investigation of the molecular structure, crystalline structure and microstructure of the materials. The resulting composite films containing noble metal particles are employed as the catalysts for the hydrogenation of phenol to produce cyclohexanone, which exhibit the convenience and recyclability for usage as well as the high catalytic activities, including the conversion ratio of 97%–100% and the selectivity as high as 84%–98%. The present work not only provides a new method to improve the processability of the conducting polymers but also describes a kind of composite materials that may display outstanding preformances in industrial catalysis.
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COLLOID AND POLYMER SCIENCE
·
2014
·Vol. 292
·期 12
·3223-3231
·
IF 2.41
Xing Pengyao,Chu Xiaoxiao,Du Guangyan,Ma Mingfang,Li Shangyang,Hao Aiyou
Here, we report a dual stimuli-responsive organogel which can stabilize graphene oxide (GO) in apolar solvents. The gelator 1-octadecyl-ureido-naphthalene (OUN) was synthesized, and it could form organogel in toluene and xylene. The resultant gels can respond to thermal and anion stimuli, bringing about fluorescent changes. Thin nanoribbons are entangled together to form three dimensional networks that can immobilize solvents in gel, providing large superficial area to interact with GO sheets. The addition of GO influences the gel properties, which are studied through rheological, fluorescent, and DSC measurements.
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高影响因子
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