Polymer Chemistry
·
2016
·Vol. 7
·期 18
·3172-3178
·
IF 5.687
Zikun Wang,Youhua Tao,Zhen Wang,Jingling Yan
Four N-vinyl-1,2,3-triazole monomers were prepared in high yields from 2-aminoethanol and α-diazo-β-oxoamides via modified Wolff's cyclocondensation reactions. Then a series of poly(N-vinyl-1,2,3-triazole)s were synthesized through conventional free radical polymerization of these monomers. The chemical structures of these monomers and polymers were confirmed by proton and carbon nuclear magnetic resonance (1H and 13C NMR). The properties of poly(N-vinyl-1,2,3-triazole)s were systematically characterized by a variety of analytical techniques including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and solubility testing. The results indicated that these polymers exhibited higher glass transition temperatures (196–212 °C) than most of the commodity vinyl polymers such as polystyrene (100 °C) and poly(methyl methacrylate) (110 °C). Moreover, these polymers can be further functionalized through hydrolysis of amide groups. These results revealed that this methodology has great potential for constructing 1,2,3-triazole-containing monomers and polymers.
研究领域:
有机化学
·
高分子科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Xiangrui Zheng,Zhenhao Xi,Ling Zhao
Living cationic polymerization provides a controllable route to prepare a versatile hybrid biomaterial, poly(dichloro)phosphazene. However, the conversion of this multi-step reaction is limited and the mechanistic understanding of the process is incomplete. Thus, the geometric and energetic properties of three process models were designed to determine the interaction mechanism based on Density Functional Calculations. The internuclear distance among counterions and monomers visually demonstrated that [PCl 6 ] − restricted the reactivity of cationic polymerization through interacting with cationic species. The counterion effect was ascertained to be obvious at the beginning of the propagation on the basis of NBO, frontier molecular orbital and thermodynamic analysis. Besides, solvent effect was quantitatively described and solvents were effective for regulating the negative interaction. Therefore, a rational solvent screening model was established based on the solvent polarity and reactivity of monomers. Selected solvents were carried out to prepare oligomeric dichlorophosphazenes and poly(dichloro)phosphazenes to prove the reliability and practicability of the model, showing a significant improvement in conversion and molecular weight of product with the increase in solvent polarity. The findings of this study will provide new insights into the living cationic polymerization of trichloro(N-silyl)phosphoranimine and will be very relevant for a broader community working on polymerization with rational solvent screening via Density Functional Calculations.
研究领域:
高分子化学
·
计算化学
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2022
·
IF 6.057
Yaping Wang,Dengwen Hu,Xiaohua Chang,Yutian Zhu
Shape-tunable particles in response to external stimuli have gained unprecedented opportunities for their great and remarkable potential in catalysts, sensors, and clinical systems. Especially, temperature-responsive particles are highly worthwhile due to their simplicity for manipulation. Herein, we incorporated thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) into the self-assembly of block copolymers (BCPs) within confined emulsion droplets, which generated novel temperature-triggered shape-switchable particles. At a temperature higher than the lower critical solution temperature (LCST) of PNIPAM, raspberry-like particles are formed initially. Interestingly, the raspberry-like particles can automatically transform into onion-shaped particles as the temperature is lower than the LCST of PNIPAM. This shape transformation is attributed to the temperature-mediated hydrophobic–hydrophilic transition of the anchored PNIPAM in BCP domains. This successful immobilization of PNIPAM within BCP domains is ascribed to the hydrogen bonds between them. Afterward, the onion-shaped BCP particles turn into raspberry-like particles again when the temperature is switched back to higher than the LCST of PNIPAM. More importantly, the change in BCP particle shape is reversible and can be repeated over many cycles upon adjusting the ambient temperature. In addition, the temperature-driven shape-switching BCP particles can be utilized to regulate temperature-triggered drug release, demonstrating their promising applications in clinical and biomedical systems.
研究领域:
材料科学
·
生物医学工程
·
纳米技术
✓ 已验证
DOI
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Guanhua Xing,Siyang Liu,Qingxin Guan,Wei Li
This paper focused on the isomerization and cracking of n -alkanes to synthesize bio-jet fuel. A series of SAPO-11 supports with different Si/Al molar ratio (0.2, 0.4, 0.6) were prepared, characterized, and evaluated by the hydroisomerization on hydrodeoxygenation product of castor oil. As a result, a Ni-Mo/SAPO-11(0.4) catalyst with hollow tubular structure and moderate acidic strength exhibited optimum conversion (97.2%) and jet fuel selectivity (81.6%) in the reaction. Subsequently, Ni-Mo/SAPO-11(0.4) was selected to carry out further experiments on studying the hydroisomerization and hydrocracking of long chain n -alkanes. The results show that increasing temperature may promote hydroisomerization and hydrocracking. Temperature is more favorable for the reaction with the length of the carbon chain decreasing, no matter conversion, hydrocracking degree or isomerization tendency. The product selectivity of different n -alkanes is associated with the carbon number. In reaction to n -C 18 , Ni-Mo/SAPO(0.4) surpassed the other two catalysts in the conversion and i/n ratio at 623 K which is the optimum temperature.
研究领域:
催化化学
·
能源科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2020
·
IF 5.162
Chen Su,Jia Liu,Zhuoran Yang,Lei Jiang,Xiufeng Liu,Wei Shao
Carboxymethyl cellulose (CMC)/pPoly-N-isopropylacrylamide (PNIPAM) hydrogels were prepared using nanoclay as physical cross-linker by UV irradiation . PNIPAM/CMC hydrogels exhibit 3D network structures with high porosity. PNIPAM/CMC hydrogels exhibit not only high water absorption capacity , but also temperature, pH and salt mutiple-responsive swelling performance. Besides, they exhibit reversible swelling behavior in alternate de-ionized water and NaCl solution. Moreover, the fabricated PNIPAM/CMC hydrogels display great compression mechanical property. Then, tetracycline hydrochloride (TCH) was loaded into the PNIPAM/CMC hydrogels to endow their antibacterial ability. TCH loaded PNIPAM/CMC hydrogels exhibit excellent antibacterial activity against E. coli and B. subtilis and good biocompatibility . Thus, the PNIPAM/CMC composite hydrogels with triple stimuli-responsive swelling performances reported herein have great potentials in many biomedical applications .
研究领域:
材料科学
·
生物医学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2024
·
IF 3.3
Nan Wang,Yuanyuan Huang,You Zi,Mengke Wang,Weichun Huang
A practical and regioselective direct N-alkylation of 2-pyridones is enabled by use of α-keto esters in the P(NMe2)3-mediated deoxygenation process. The reaction proceeds under mild conditions to produce N-alkylated 2-pyridones with high selectivity and generality, and the protocol is shown to be applicable for the scale-up synthesis, which makes it promising for practical applications.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
PubMed
高影响因子
AICHE JOURNAL
·
2017
·Vol. 63
·期 8
·3395-3403
·
IF 2.836
Min Xiao,Ding Cui,Helei Liu,Paitoon Tontiwachwuthikul,Zhiwu Liang
In this work, the equilibrium CO 2 solubility in the aqueous tertiary amine, N-methyl-4-piperidinol (MPDL) was measured over a range of temperatures, CO 2 partial pressures and amine concentrations. The dissociation constant of the MPDL solution was determined as well. A new thermodynamic model was developed to predict the equilibrium CO 2 solubility in the MPDL-H 2 O-CO 2 system. This model, equipped with the correction factor (C f ), can give reasonable prediction with an average absolute deviation of 2.0%, and performs better than other models (i.e., KE model, Li-Shen model, and Hu-Chakma). The second-order reaction rate constant (k 2 ) of MPDL and the heat of CO 2 absorption (–ΔH abs ) into aqueous MPDL solutions were evaluated as well. Based on the comparison with some conventional amines, MPDL revealed a high-equilibrium CO 2 loading, reasonably fast absorption rate when compared with other tertiary amines, and a low energy requirement for regeneration. It may, therefore, be considered to be an alternative solvent for CO 2 capture. © 2017 American Institute of Chemical Engineers AIChE J , 63: 3395–3403, 2017
研究领域:
化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
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2021
·
IF 3.196
Jiancheng Zhao,Rui Liu,Zhenzhou Zhang,Qianqian Xing,Honghong Chang,Xianglin Hou,Yingxiong Wang
The tautomer structure of monosaccharides plays an important role in its conversion and utilization, which is mainly manifested in the selectivity of the product and the reaction mechanism. The tautomer distributions of N -acetyl- D -glucosamine (GlcNAc), a natural nitrogen-containing monosaccharide were investigated by quantitative 1 H NMR ( 1 H qNMR) and 13 C NMR ( 13 C qNMR) at 298 K under the condition commonly utilized for biorefinery. Catalysts used for biorefinery, i.e. BaCl 2 , KCl, ZnCl 2 , MgCl 2 , B(OH) 3 , SnCl 4 ·5H 2 O and amino acid ionic liquid were introduced into D 2 O or DMSO‑ d 6 to explore the tautomer distributions of GlcNAc. The introduction of ZnCl 2 and SnCl 4 ·5H 2 O promoted the conversion of α-pyranose to β-pyranose. The introduction of amino acid ionic liquid has little effect on the percentage of tautomers in D 2 O. However, when the amino acid ionic liquid, such as [Thr]Cl, was introduced into DMSO‑ d 6 , the proportion of β-pyranose increased to 29.06%, compared with no catalyst introduced. Besides, we also studied the tautomer distributions of GlcNAc in commonly utilized reaction solvents for biorefinery, such as N,N -dimethylformamide, N , N -dimethylacetamide, N -methyl-2-pyrrolidinone, ethylene and glycerol. In these solvents, the proportion of β-pyranose in N,N -dimethylformamide and glycerol was reduced to 25.84% and 38.38%, respectively. This study provides the basic experimental data of tautomer distributions of GlcNAc, and guided the conversion and utilization of GlcNAc in the future.
研究领域:
生物化学
·
分析化学
✓ 已验证
DOI
高影响因子
SOLAR ENERGY
·
2018
·
IF 4.374
Xichuan Yang,Weihan Wang,Yanyun Zhang,Licheng Sun
P-type doping is a rational strategy for the enhancement of hole transporting properties of the organic semiconductors as well as the device performance of organic photo-electric devices. We originally introduce a stable and solution processed p-type dopant based on N-oxoammonium salts termed 2,2,6,6-tetramethyl-1-oxopiperidinebromide salt (TEMPO-Br) for 2,2′,7,7′-tetrakis(N, N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene (Spiro-OMeTAD) based solid state dye sensitized solar cells (ssDSC). By introducing TEMPO-Br doped Spiro-OMeTAD and a commercialized D-π-A sensitizer into ssDSCs, a promising device performance of 6.83% is achieved under simulated AM 1.5G solar irradiation (100 mW cm −2 ), which is significantly better than the control devices (∼1.7 times). The doping effect of TEMPO-Br on the photophysical and electrochemical properties of Spiro-OMeTAD, solid state device performance, cationic dye regeneration kinetics and preliminary long-term stability have been systematically investigated. This work indicates a potential application of N-oxoammonium salts as chemical P-type dopants for triphenylamine based hole transporting materials in solid state photo-electric devices.
研究领域:
材料科学
·
光电化学
✓ 已验证
DOI
高影响因子
Chemistry Africa-A Journal of the Tunisian Chemical Society
·
2021
·Vol. 5
·期 1
·79-87
·
IF 0
Naz Farah,Ciprian Matteo,Luo Zhixiong,Yan Shilin,Iqbal Shahzad Zafar,Zhu Meifang,Chaemchuen Somboon,Verpoort Francis
The synthesis and use of MOF-derived Co/NCF (N-doped carbon framework) material as a heterogeneous catalyst for copolymers synthesis via ring-opening polymerization (ROP) are reported for the first time. The Co/NCF material is applied for the copolymerization of L -lactides (LA) and ε-caprolactone (ε-CL) as monomers via ROP in bulk without any solvent or co-catalyst. The as-prepared catalyst is characterized using XRD, TPD, XPS, SEM, and TEM analytical techniques. At the same time, 1 H and 13 C-NMR spectroscopy were used to analyze the microstructure of the copolymer confirming the random copolymer structure. The average r values calculated from the heterodiad analysis of the 1 H NMR, data were r LA = 0.96 and r CL = 0.93 and L value calculated from the triads analysis of 13 C NMR, data were L LA = 3.17 and L CL = 2.79, respectively. It has been observed that the melting temperature and glass transition temperature of the copolymer increases with higher LA content. The XRD and DSC analyses also confirmed that the as-synthesized copolymer possesses two phases corresponding to the polylactide and polycaprolactone, respectively. Additionally, the activity of Co/NCF is also compared with other Co-based heterogeneous catalysts to demonstrate its ability. Graphic Abstract
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Kangfeng Pang,Wei Sun,Feng Ye,Lihui Yang,Mengjie Pu,Cao Yang,Qichun Zhang,Junfeng Niu
N,S-co-doped carbons were synthesized through the calcination of sulfur-modified chitosan for the first time, and utilized as persulfate activators for sulfamethoxazole (SMX) remediation in water. The chitosan and sulfonyl chloride underwent one-step sulfonylation reaction to generate S-modified chitosan. The catalyst NSC-3 showed both excellent adsorption and catalytic oxidation efficiency, corresponding 98.62% removal and 81.34% mineralization rate within 90 min. The rate constant ( k obs ) was up to 0.0578 min −1 , with 75.60-folders higher than that of sulfur-free catalyst NC (7.6580 ×10 −4 min −1 ). The synergy of N and S contributed to the improvement of removal efficiency. The adsorption and oxidation performance were highly depended on the S/N atomic ratio. At the S/N ratio of 0.18, the maximum adsorption and oxidation capability were obtained. The NSC-3/PS system exhibited outstanding adaptability at the wide pH range from 3.07 to 9.28, while the inhibitory effect occurred at strong basic conditions (pH = 11.01). The thiophene sulfur and structural defects were identified as the catalytic sites in activating PS. Both radical and non-radical pathways were responsible for degradation process, where 1 O 2 played a major role, SO 4 ·- exerted a minor contribution, and O 2 ·- acts as the precursor for the production of 1 O 2 . Another source of 1 O 2 was assigned to the activation of PS by structure defects . This work indicates that N,S-co-doped carbon at an optimal S/N atomic ratio effectively catalyzes persulfate, and provides an innovative method to construct bifunctional carbon materials of adsorption and oxidization.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2015
·
IF 1.964
Pengfei Zhang,Jiang Deng,Jianyong Mao,Haoran Li,Yong Wang
By combination of photocatalysis and organocatalysis, a metal-free system composed of mesoporous graphitic carbon nitride (mpg-C 3 N 4 ) and N -hydroxyphthalimide (NHPI) offers an efficient and environmentally friendly method for the oxidation of alcohols at room temperature. As a wide-band gap semiconductor, mpg-C 3 N 4 absorbs visible light and uses the energy to activate NHPI, resulting in high catalytic activity in the subsequent oxidation of alcohols. Interestingly, the main oxidation product of benzyl alcohol can be tuned from benzoic acid to benzaldehyde by increasing the ratio of mpg-C 3 N 4 in the catalyst system. To further understand the reaction route, electron spin resonance and Fourier transform infrared measurements were carried out, confirming that active oxygen and phthalimide N-oxyl radicals formed in the mpg-C 3 N 4 /NHPI system. Based on these results, a catalytic mechanism for the mpg-C 3 N 4 /NHPI system was proposed. Moreover, this metal-free system also works well for the oxidation of various aromatic alcohols with good selectivity for aldehydes or ketones.
研究领域:
化学
·
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）