JOURNAL OF APPLIED POLYMER SCIENCE
·
2013
·Vol. 129
·期 6
·3185-3191
·
IF 1.395
Yu Chen,Fengju Wang,Dongran Yun,Yanwen Guo,Yanchun Ye,Yanxi Wang,Huimin Tan
In this study, we explored a new method for preparing C 6 quaternary ammonium chitosan (CTS) derivatives. The C 2 NH 2 of CTS was first protected by benzaldehyde. The C 6 OH of CTS was then transformed into a sulfonyl ester, which was then reacted with NaN 3 through nucleophilic substitution to introduce the N 3 group at the CTS C 6 position. This intermediate was reacted in a click chemistry reaction with a terminal alkynyl quaternary ammonium salt; this was followed by the deprotection of C 2 NH 2 with acid to furnish the C 6 quaternary ammonium CTS derivative. The structures and properties of synthesized products in the reactions were characterized by Fourier transform infrared spectroscopy, NMR, X-ray diffraction, and thermogravimetric analysis, respectively. The effects of the reaction conditions on the degree of Schiff-base CTS quaternization were evaluated by elemental analysis. The largest inhibition zone test and the minimum inhibitory concentration test showed that compared with CTS, the prepared CTS derivative had significantly improved antibacterial activity toward Staphylococcus aureus and Escherichia coli . © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
研究领域:
高分子化学
·
药物化学
·
生物材料
·
抗菌材料
·
天然产物化学
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DOI
高影响因子
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2016
·Vol. 31
·期 1
·157-163
·
IF 0.4
Liu Rongpeng,Wan Liqiang,Huang Farong,Du Lei
The reaction kinetics between diazide(4,4’-biphenyl dibenzyl azide) and different diynes (dipropargyl bisphenol A and 1,3-diethynylbenzene) were studied by means of differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy ( 1 H-NMR). DSC was adopted to analyze the reactions under bulk polymerization condition, while 1 H-NMR for solution reaction polymerization was conducted. The apparent activation energies ( E
α ) calculated by Kissinger’s method were 77.96, 81.24 kJ/mol, which were confirmed by Friedman’s method, and 65.45, 69.36 kJ/mol by 1 H-NMR for dispropargyl bisphenol A/4,4’-biphenyl dibenzyl azide and 1,3-diethynylbenzene/4,4’-biphenyl dibenzyl azide, respectively. The polymerizations between the diazide and diynes were first-order reactions based on calculation from both DSC and 1 H-NMR. The results showed that the reaction between dipropargyl bisphenol A and 4,4’-biphenyl dibenzyl azide was easier than that between 1,3-diethynylbenzene and 4,4’-biphenyl dibenzyl azide, verifying that the reactivity of aliphatic alkyne was higher than that of aromatic alkyne.
研究领域:
高分子化学
·
物理化学
·
材料科学
·
有机化学
·
反应动力学
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DOI
高影响因子
INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES
·
2016
·
IF 1.956
Abbas Hasan Faris,Mohamad Nasir Mohamad Ibrahim,Afidah Abdul Rahim
Tannin-glyoxalated Kraft lignin (TGKL) resin is a successful substitution for phenol formaldehyde resin in the production of wood adhesives, however it has a poor water resistance. To overcome this obstacle, this research was focused on scalable adhesive through the modified tannin adhesive and oligomeric precursors of a hyperbranched poly (amine-ester) (HBPAE). The prepared glyoxalated Kraft lignin resin (MTGKL), TGKL, HBPAE and commercial phenol formaldehyde (CPF) resin were evaluated by FTIR , 1 H and 13 C NMR spectroscopy . The tensile strengths and thermal stability were determined. The results indicated that the addition of HBPAE to tannin adhesive could improve the water resistance of MTGKL. This was evident when soaking plywood bonded with TGKL in cool water, where delamination occurred, but it was not evident with MTGKL. The tensile results indicated that the adhesive strengths of MTGKL, 39.72 MPa (dry) and 27.62 MPa (wet), were higher compared to TGKL and CPF resins.
研究领域:
高分子材料
·
林产化学加工
·
胶体与界面科学
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可持续材料
·
生物质转化
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DOI
高影响因子
PHOTOCHEMISTRY AND PHOTOBIOLOGY
·
2012
·Vol. 88
·期 4
·840-843
·
IF 2.413
Zhan Zhou,Qianming Wang,Jintai Lin,Yanna Chen,Chuqin Yang
Herein, a novel fluorescent indicator for the real-time monitoring of amines is described. This probe contains a complex of europium-(thenoyltrifluoroacetone) 3 (Eu(TTA) 3 ) that efficiently reacts with primary and secondary amines. The electron-withdrawing trifluoroacetyl undergoes a nucleophilic addition with amines, and the complex was used to selectively detect BuNH 2 and Et 2 NH (quenching concentration for BuNH 2 : 10 −4 m , for Et 2 NH: 1.2 × 10 −3 m ) by monitoring emission; no changes were observed in the emission spectrum of Eu(TTA) 3 in the presence of Et 3 N, [Bu 4 N]Cl, or PhNH 2 in aqueous solution (THF/H 2 O = 1:1). The ratio of emission intensity to amine concentration was linear by the least-squares fitting method.
研究领域:
分析化学
·
生物传感
·
分子探针
·
稀土化学
·
有机合成
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DOI
高影响因子
ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Libo Deng,Wenhua Zhong,Jubei Wang,Peixin Zhang,Haoming Fang,Lei Yao,Xuqing Liu,Xiangzhong Ren,Yongliang Li
Biomass-derived carbons have been extensively researched as electrode material for energy storage and conversion recently. However, most of the previous works convert crude biomass directly into carbon and the electrochemical capacitances for the resultant carbons are quite often underestimated as well as large variations in capacitances exist in literatures due to the complex nature of biomass, which practically hinder their applications. In this work, polysaccharide nanofibers were extracted from an inexpensive natural fungus using a hydrothermal method and were converted to porous carbon nanofibers (CNFs) by potassium hydroxide activation. The porous carbons were assembled into symmetric supercapacitors using both potassium hydroxide and an ionic liquid (IL) as electrolytes. Solid state nuclear magnetic resonance characterization showed that the micropores of the as-prepared carbons are accessible to the IL electrolyte when uncharged and thus high capacitance is expected. It is found in both electrolytes the electrochemical capacitances of CNFs are significantly higher than those of the porous carbon derived directly from the crude fungus. Furthermore, the CNFs delivered an extraordinary energy density of 92.3 Wh kg −1 in the IL electrolyte, making it a promising candidate for electrode materials for supercapacitors.
研究领域:
材料科学
·
能源化学
·
纳米技术
·
电化学
·
可再生能源
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DOI
高影响因子
FLAVOUR AND FRAGRANCE JOURNAL
·
2012
·Vol. 27
·期 5
·378-385
·
IF 1.424
Zhangfu Zeng,Yanxiong Fang,Hongbing Ji
The reason for low encapsulation efficiency of vanillin compared to p -hydroxybenzaldehyde within β -cyclodextrin was investigated. Fourier transform infrared spectra proved intermolecular interaction between guest and β -cyclodextrin. UV–visible studies indicated that vanillin and p -hydroxybenzaldehyde form 1:1 inclusion complexes with β -cyclodextrin. Nuclear magnetic resonance and quantum computational methods gave the most favourable orientation in which the guest molecule (vanillin or p -hydroxybenzaldehyde) is totally sequestered in the hydrophobic cavity of the cyclodextrin with the phenolic end located near the primary hydroxyls of the β -cyclodextrin and the aldehyde group near the secondary hydroxyls with hydrogen bonding formation. Encapsulation efficiency of the β -cyclodextrin inclusion with vanillin is about 29% lower than that with p -hydroxybenzaldehyde. This result could be attributable to the effect that the side chain methoxy group weakened the guest/host non-covalent intermolecular interaction, specifically, hydrogen bond interaction. Copyright © 2012 John Wiley & Sons, Ltd.
研究领域:
药物化学
·
超分子化学
·
分析化学
·
药剂学
·
分子识别
·
计算化学
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DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2011
·
IF 2.794
Yuanchao Pei,Jing Liu,Zhenning Yan,Zhiyong Li,Jing Fan,Jianji Wang
In this paper, the interactions between cationic dyes and the ionic liquids (ILs) have been studied by 31 P nuclear magnetic resonance (NMR), UV–Vis spectroscopy and conductometric measurements at different temperatures. It was shown that a decrease in the measured specific conductance of the (dye + IL) mixtures was caused by the formation of non-conducting or less conducting (dye + IL) associates. The associates were formed by 1:1 ratio of cation of the cationic dyes and anion of the ILs by using the 31 P NMR and UV–Vis spectroscopy methods. The association constants were calculated by theoretical model based on the deviation from linear behavior, and the association constants were as high as 10 6 (L · mol −1 ) 2 . Thermodynamic results imply that the formation process of association was exothermic nature. It is expected that the associates reported here would have promising application as active materials for the preparation of ion-selective electrode used in the determination of ILs concentrations.
研究领域:
物理化学
·
分析化学
·
胶体与界面化学
·
药物化学
·
分子生物学
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DOI
高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 9
·期 7
·3985-3994
·
IF 11.301
Ruidi Wang,Bei-Bei Xu,Jiachen Wang,Xue Lu Wang,Ye-Feng Yao
The relationship between the structural characteristics and photocatalytic reaction mechanisms of graphitic carbon nitride (g-C3N4) still remains unclarified at the molecular level, which severely hinders the further development of this field. The present study addresses this issue by employing an innovative strategy to investigate the relationship between the H-containing structures of g-C3N4 and its water splitting properties. The exchangeable and unexchangeable protons of the H-containing groups of g-C3N4 were differentiated by selective deuteration, providing a way to distinguish the hydrophilic and relatively non-hydrophilic H-containing groups of g-C3N4. A combination of advanced solid-state NMR approaches reveals that amino group defects (CN2(NHx)) on the C–N skeleton of the photocatalyst likely serve as hydrophilic active sites for facilitating the photocatalytic hydrogen evolution reaction. Accordingly, the newly synthesized g-C3N4 sample having a high concentration of CN2(NHx) by design demonstrates an enhanced H2 yield by a factor of 17 compared to that of pure g-C3N4.
研究领域:
材料化学
·
光催化
·
固体核磁共振
·
表面科学
·
能源材料
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DOI
高影响因子
Journal of Materials Chemistry A
·
2021
·Vol. 9
·期 38
·22064-22071
·
IF 12.732
Wenda Zhang,Jie Feng,Fengqi Lu,Alberto J. Fernández-Carrión,Hui Fu,Xiaojun Kuang
Na-doped melilite-type silicate Sr2MgSi2O7 was reported to display high oxide ion conductivity. In this work, through multiple complementary techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, solid-state 29Si and 23Na nuclear magnetic resonance spectroscopy, and DFT calculations of defect formation energies, we found that it is hard to replace Sr with Na in Sr2MgSi2O7, and the Sr2−xNaxMgSi2O7−0.5x compositions formed mixed crystalline Sr2MgSi2O7 and Na-containing glassy phases. AC impedance spectroscopy measurements indicated that the ionic conduction in Sr2−xNaxMgSi2O7−0.5x could be from Na+ ions in the glassy phase, instead of the oxide ions.
研究领域:
材料科学
·
固体离子导体
·
无机非金属材料
·
能源材料
·
电化学
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·Vol. 43
·期 16
·14176-14182
·
IF 2.986
Lin Wang,Benxue Liu,Luyi Zhu,Yongshuai Xie,Yadong Lv,Chonghe Xu,Xiaotong Jin,Xinqiang Wang,Guanghui Zhang,Dong Xu
Polyaceticzirconium (PEZ) sol, which is the precursor of zirconia (ZrO 2 ) continuous fibers, has been synthesized by means of the reaction between zirconium oxychloride octahydrate (ZrOCl 2 ·8H 2 O) and potassium acetate (CH 3 COOK) in methanol. The polymeric structures and the rheological behaviors of the sols with different molar ratios of ZrOCl 2 ·8H 2 O/CH 3 COOK are different and would affect the spinnability and stability significantly. Herein, the polymeric structures and rheological behaviors of the PEZ sols with the molar ratios of 1:1, 1:1.5, 1:1.8 and 1:2 were investigated by Fourier transform infrared (FT-IR), 1 H nuclear magnetic resonance spectrum ( 1 H-NMR), thermogravimetry and differential thermal analysis (TG/DTA) and rheological measurements. The results showed the carboxyl group acted as a chelating ligand instead of bidentate ligand, and the water molecule coordinated to Zr 4+ was deprotoned gradually with the decrease of the molecular ratios. The different polymeric structures lead to a different rheological behaviors of the sols. It is divided into three types, the Newton fluid with a low viscosity produced by the charged linear polymeric structures, the shear thinning fluid with a high viscosity produced by the three-dimensional polymeric structures and the shear thinning fluids with a proper viscosity produced by the linear twining polymeric structures. Through the experimental guidance, we successfully synthesized a sol with suitable viscosity and stability, and used it to fabricate high quality ZrO 2 fibers.
研究领域:
材料科学
·
无机化学
·
高分子化学
·
纤维工程
·
溶胶-凝胶技术
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DOI
高影响因子
FOOD CHEMISTRY
·
2017
·
IF 4.529
Ting Shi,MengTing Zhu,Yi Chen,XiaoLi Yan,Qian Chen,XiaoLin Wu,Jiangnan Lin,Mingyong Xie
Proton nuclear magnetic resonance ( 1 H NMR) and chemometrics were employed to detect the adulteration of camellia oil (CAO) with 3 different cheap vegetable oils. With the intensity of 15 selected 1 H NMR signals as input variables, principal component analysis (PCA) showed good group clustering results for pure and nonpure CAO, but unsatisfied identification accuracy for the adulterated oil types, indicating relatively small difference among those oils. Whereas these difference could be revealed by orthogonal projection to latent structures discriminant analysis (OPLS-DA), with identification accuracy higher than 90%. Partial least squares (PLS) was further applied for the prediction of adulteration level in CAO. With less than 6 variables screened out by variable importance in the projection (VIP) scores as potential key markers, the developed PLS models showed better accuracy. The prediction results for 10 hold-out samples also confirmed that this method was accurate and fast for the detection of CAO adulteration.
研究领域:
食品科学
·
分析化学
·
食品安全
·
代谢组学
·
油脂化学
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DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2013
·Vol. 51
·期 9
·2016-2023
·
IF 3.543
CaiFei Wang,ChunHua Zhao,JiaQin Sun,SanQing Huang,XiangDong Liu,Takeshi Endo
A fully bio-based benzoxazine, 3-furfuryl-8-methoxy-3,4-dihydro-2H-1,3-benzoxazine (Bzf), has been prepared using guaiacol, furfurylamine, and paraformaldehyde as raw materials. Its chemical structure has been characterized by 1H and 13C NMR, FTIR, and elemental analysis. The polymerization behavior of Bzf in the presence of methyl p-toluenesulfonate (PTSM) has been studied by FTIR and DSC, and the thermal stability of the cured resin has been evaluated by thermogravimetric analysis. It was found that PTSM is a good promoter that serves to avoid thermal decomposition of the bio-based monomer during the curing process at high temperature. In contrast to the situation with neat Bzf, the presence of PTSM (5 mol % for Bzf) significantly improves the polymerization behaviors, including a decrease in the polymerization temperature from 240 to 174 °C, a shortening of the time required to reach the gel point on heating at 200 °C from 47 to 20 min, and an increase in the char yield of the cured resin from 53 to 62%. Moreover, these observed experimental results on the promoting effect of PTSM are interpreted in terms of several possible mechanistic schemes, which involve a catalytic effect on the dissociation of C O bonds in both the coordination ring-opening reaction and the rearrangement from a phenoxy structure to a phenolic structure. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
研究领域:
高分子化学
·
材料科学
·
热分析
·
绿色化学
·
功能高分子
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DOI
高影响因子
危险品化学品经营许可证（带存储）