RSC Advances
·
2016
·Vol. 6
·期 79
·75793-75804
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IF 3.289
Haiming Cheng,Huafei Xue,Changqing Hong,Xinghong Zhang
Organic aerogels generally exhibit poor thermal, mechanical and hydrophilic properties, which seriously restrict their large-scale applications. In this study, siliane was introduced into resorcinol-furfural (RF) aerogels due to the enhancement of silicone to thermal stability and hydrophobicity of polymer molecules. Resorcinol-furfural/silicone (Si–RF) hybrid aerogels were synthesized by sol–gel polycondensation of resorcinol, furfural, (3-aminopropyl) triethoxysilane (ATPES) and methyltrimethoxysilane (MTMS), followed by ambient pressure drying (APD). The Si–RF aerogels showed an interpenetrating framework with high mesoporosity. Silicon-containing functional groups were successfully incorporated into the RF aerogels in dehydration reactions. Surface area, characteristic thermal degradation temperature and char yield of the Si–RF aerogels are higher than that of the as-prepared RF aerogels. In order to improve the mechanical properties, carbon fabric reinforced Si–RF aerogel composites were prepared by impregnating a carbon-bonded carbon fiber (CBCF) composite with the hybrid aerogels. The obtained composites possessed a low bulk density (0.309–0.375 g cm−3), high compressive strength (0.759–2.940 MPa for different directions) and low thermal conductivity (0.085–0.136 W (m−1 K−1)). Hydrophobic aerogels were also fabricated by –Si(CH3)3 (trimethylsilyl substituent) modification via immersing fresh Si–RF aerogels in trimethylethoxysilane (TMES)/hexane solution followed by aging and APD. The hydrophobic property was promoted by the concentrations of solutions (water contact angle of about 108–135°), also the thermal stability.
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FIBERS AND POLYMERS
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2017
·Vol. 18
·期 11
·2204-2211
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IF 1.113
Xu QingBo,Gu JiaYuan,Zhao Yang,Ke XiaTing,Liu XiangDong
L-cysteine (Cys) and silver nanoparticles (Ag NPs) were successfully linked onto the cotton fabric surfaces. The Cys molecules were covalently linked to the cotton fibers via esterification with the cellulose hydroxyl groups, and the Ag NPs tightly adhered to the fiber surface via coordination bonds with the Cys thiol groups. As a result, the Ag NPs coating on the cotton fabric showed an excellent antibacterial function with an outstanding laundering durability. The bacterial reduction rates (BR) efficiency reached 100 % for Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ). After 50 consecutive laundering cycles, the bacterial reduction rates (BR) against E. coli and S. aureus were maintained over 97 %. It has potential applications in a wide variety of fields such as sportswear, socks, and medical textile.
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RSC Advances
·
2017
·Vol. 7
·期 17
·10564-10569
·
IF 3.108
Xiaowen Zhang,Yang Li,Zhongliang Hu,Zhi Chen,Jianrong Qiu
The second near-infrared window (NIR-II, 1000–1400 nm) is ideal for fluorescence imaging owing to negligible tissue scattering and minimal autofluorescence. NIR-II luminescence nanophosphors are promising materials for fluorescence imaging. Mn5+ is emerging as a new luminescent indicator owing to its typical NIR-I (800 nm) to NIR-II (1190 nm) downconversion luminescence. Herein, we report a facile synthesis approach to prepare Mn5+ doped Ba3(MO4)2 (M = V, P) nanoparticles with a remarkably sharp emission peak around 1190 nm in the NIR-II region for the first time to our knowledge. The developed two-step approach based on efficient anion exchange reaction is able to not only stabilize the valence but also keep the controlled morphology and uniform size. It is highly possible that the general approach will provide a new perspective on synthesizing special valence ion doped nanosized materials.
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JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
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2013
·
IF 2.145
Rui-tang Guo,Yue Zhou,Wei-guo Pan,Jie-nan Hong,Wen-long Zhen,Qiang Jin,Cheng-gang Ding,Shi-yi Guo
CeO 2 /Al 2 O 3 catalysts prepared by three methods were investigated for selective reduction of NO with NH 3 . It was found that the catalyst prepared by the single step sol–gel method had the best SCR activity and SO 2 resistance performance. From the results of BET, XRD, TPD and TPR, it can be concluded that large surface area, strong interaction, highly dispersed nano-crystalline ceria , high NH 3 adsorption capacity and good redox ability might be the main reasons for the excellent performance of CeO 2 /Al 2 O 3 catalyst prepared by the single step sol–gel method.
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JOURNAL OF POLYMER RESEARCH
·
2015
·Vol. 22
·期 11
·1-7
·
IF 1.92
Gao Lijun,Luo Yucheng,Lin Yongjia,Su Ting,Su Riping,Feng Jiuying
In order to improve the catalytic efficiency of zinc glutarate (ZnGA) used in the CO 2 /propylene oxide (PO) copolymerization, silica-supported zinc glutarate catalysts (ZnGA/SiO 2 ) are prepared via a rheological phase reaction with a little toluene as a reaction medium. Wide-angle X-ray diffraction (WAXD) tests of the catalysts illustrate that the crystal quality increases and the overall crystallinity declines after supporting. The scanning electron microscope (SEM) images show that the proportion of supported ZnGA increases with increasing the SiO 2 proportion. Accordingly, the polymer yields increase from 12.7 Kg polymer/mol Zn of ZnGA to 25.6 of ZnGA/SiO 2 . And the almost alternating poly(propylene carbonasstes) (PPCs) with the carbonate content of above 97 % and the M
n s of above 10, 000 g/mol are obtained. This work illustrates that the catalytic efficiency does not increase sharply like the supported catalysts used in olefin polymerization because of the decline in overall crystallinity of ZnGA. The catalytic efficiency is expected to be enhanced significantly if it can be improved for ZnGA/SiO 2 .
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Journal of Nanomaterials
·
2015
·
IF 1.644
Qiufang Yao,Chunde Jin,Huanhuan Zheng,Zhongqing Ma,Qingfeng Sun
Magnetic NiFe2O4 nanoparticles were successfully deposited on the wood surface via a hydrothermal process at 70°C. The surface of the as-prepared magnetic NiFe2O4/wood hybrids (MWHs) was covered by spherical-like NiFe2O4 particles with an average size of 50 nm. MWH exhibited the thermostability, microwave absorbability, and superparamagnetism with saturation magnetization () of 1.79 emu·g−1. With further modification by 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS-17), MWH expressed superhydrophobic performances with a water contact angle of 158°. Its superparamagnetism stably remained under harsh conditions after chemical solutions corrosion and physical frozen test.
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JOURNAL OF CHEMICAL THERMODYNAMICS
·
2013
·
IF 2.297
Chaoyuan Wang,Yonghong Hu,Wenge Yang,Kai Wang,Yihua Li,Song Guo
The solubility of 2,3,4,5-tetrabromothiophene in (ethanol + tetrahydrofuran) binary solvent mixtures was measured within the temperature range from (278.15 to 322.15) K. The solubility increases with the rise of temperature, while it decreases with increasing ethanol content at constant temperature. The experimental data were fitted using the two variants of the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) equation and the Jouyban–Acree equation, respectively. All the three equations were proven to give good representations of the experimental values. Computational results showed that the variant two of CNIBS/R–K equation was superior to the other two equations. The thermodynamic properties of the solution process, including the Gibbs free energy, enthalpy, and entropy, were calculated by the van’t Hoff analysis. The values of both the enthalpy change and the standard molar Gibbs free energy change of solution were positive, which indicated that the process was endothermic.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2015
·Vol. 133
·期 11
·
IF 1.768
Fei Qu,Shuwen Niu,Jinmao You
Hyperbranched poly(ethylene imine) (PEI)-capped Ag nanoclusters, synthesized starting from an aqueous environment, dispersed well in water and most polar organic solvents. However, with the addition of 1,4-dioxane, the PEI-capped Ag nanoclusters could be separated completely to obtain hydrophilic and hydrophobic Ag nanoclusters. Through this facile method, the successful phase transfer of PEI-capped Ag nanoclusters from the aqueous phase to the nonpolar organic phase, such as from water to carbon tetrachloride, chloroform, and methylene bichloride, was easily realized. The polarity reversal of Ag nanoclusters were considered to be associated with the conformational change of PEI on the basis of the hydrophobic methylene groups of polymer backbone facing the external side or internal side, and this polarity reversal was irreversible. Moreover, PEIs with higher molecular weights showed a higher efficiency of phase transfer of the Ag nanoclusters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43206.
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CARBOHYDRATE POLYMERS
·
2015
·
IF 4.074
Haizhen Chen,Jinping Ni,Jing Chen,Wenwen Xue,Jinggang Wang,Haining Na,Jin Zhu
Water and four small molecular alcohols are respectively used to activate corn cellulose (CN cellulose) with the aim to improve the dissolvability in DMAc/LiCl. Among all these activated agents, monohydric alcohols are found to produce the optimal effect of activation in the whole process including of activating, dissolving, and electrospinning of CN cellulose. Meanwhile, well distributed fibers with the diameter of 500 nm–2 μm are fabricated in electrospinning. Understanding the activation effect of monohydric alcohols with water and polyhydric alcohols, the most effective activated agent is ascertained with the characteristics of small molecular size, low viscosity, and single functionality. This work is definitely initiated to understand the critical principle of CN cellulose in dissolving. Accordingly, a feasible methodology is also established to prepare ultrafine cellulose fibers with good morphology in electrospinning.
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PubMed
高影响因子
JOURNAL OF POROUS MATERIALS
·
2017
·Vol. 25
·期 2
·373-382
·
IF 1.624
Wang Liang,Li Zhu,Jing Qiangshan,Liu Peng
The aim of this paper is to synthesis a new type of insulation material (EPA), which fill the aerogels into the expanded perlite (EP). EP is a kind of lightweight filler, its application is constrained by the character of absorbing water easily. The silicic acid is inhaled into the expanded perlite at −0.1 MPa, aging 24 h, it becomes aerogel after solvent exchanging/surface modifying and drying. The pores of EP are filled with aerogel which affects thermal conductivity of expanded perlite little and makes it hydrophobic. EPA has a wider use than EP for its hydrophobic character. A new recipe to synthesize aerogel, filled into EP, with the thermal conductivity of 0.034 W/m K in ambient pressure drying is found in this experiment. The time and reagents dosage for synthesizing EPA are less than large block of aerogel, while the thermal conductivity is close to it. The scanning electron microscopy is used to analyze EPA’s micro structure. The thermal conductivity tester is used for testing the thermal conductivity of silica aerogel, expanded perlite and EPA.
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THERMOCHIMICA ACTA
·
2015
·
IF 2.184
Sanguo Peng,Shi Zhang,Ying Zhang,Xiangyang Liu,Maogang He
Mutual diffusion coefficients of several short chain alcohols (ethanol, n -propanol and n -butanol) + n -octane mixtures in the temperature range from 283.2 K to 313.2 K at different concentrations were measured using holographic interferometry. The relation between the mutual diffusion coefficient with temperature, viscosity, concentration and molecular weight is investigated, respectively. The Onsager–Fuoss model is applied to analyse the various influence factors. A new correlation taking into account the effect of the temperature and concentration on the mutual diffusion coefficient is proposed to fit well the experimental data.
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ENERGY & FUELS
·
2017
·
IF 3.091
Guolin Jing,Zhengnan Sun,Ziyi Tu,Xudong Bian,Yu Liang
Nanohybrid pour-point depressants (PPDs) were prepared by organically modified nano-SiO2 in copolymers of ethylene and vinyl acetate (EVA) with various vinyl acetate contents. The effects of nanohybrid PPDs on the cold-flow properties of 25 wt % wax model oil were evaluated. The crystallization behavior and crystal morphology of the model oil at low temperatures were also observed using polarized optical microscopy. The results indicated that the co-crystallization and dispersion effects of EVA on wax crystals are the key factors in determining the heterogeneous nucleation effect of the nanohybrid PPDs. The vinyl acetate content in EVA strongly affects the compatibility between the modified nanosilica and EVA. As a result, the selection of an appropriate EVA according to the oils used and the compatibility factor is important. In this work, EVA (VA = 32%)/modified nano-SiO2 composite PPD [N-SiPPD(32)] provided the best cold-flow improvement for the model oil when doped at 500 ppm. The pour point of the model oil was reduced from 34 to 5 °C, which resulted in a regular, diamond-shaped, and uniform arrangement of wax morphologies.
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