REACTIVE & FUNCTIONAL POLYMERS
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2016
·
IF 2.725
Liang Chen,Jun Tang,Qi Zhang,Jianli Wang
In this study, we report the development of a novel recyclable polymer-supported interfacial catalyst for Montanari oxidation . The catalyst was prepared by immobilization of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) on poly(ether sulfone) (PES) bridged by imidazole groups and characterized by 1 H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, elemental analysis , contact angle measurement, and transmission electron microscopy (TEM). This well-designed polymer was self-assembled into nanoaggregates in CH 2 Cl 2 . It was then used as Pickering emulsifier in Montanari oxidation system (NaClO/NaBr/immobilized TEMPO) for selective oxidation of different alcohols, which exhibited higher activity due to the enhanced mass transfer through microreactor mechanism. Moreover, this polymeric interfacial catalyst was pH-sensitive and could be easily recycled by adding small amount of acid, and subsequent cycles of alcohol oxidation showed no loss on either conversion or selectivity. This study represents an innovative approach for developing polymeric interfacial catalyst.
研究领域:
材料科学
·
催化化学
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产品关联
DOI
高影响因子
IONICS
·
2017
·Vol. 23
·期 6
·1375-1382
·
IF 2.062
Xu Lihuan,Guo Pengju,He Huihui,Zhou Ningning,Ma Jiaojiao,Wang Guosheng,Zhang Cheng,Su Chang
Composite electrodes based on the nitroxide free radical-contained pyrrole copolymer (PPy- co -PPy-C-TEMPO) as active material were one-step synthesized by in situ electrochemical polymerization, which was then directly applied as the cathode of lithium ion batteries. The structure, morphology, electrochemical property, and charge-discharge performances of prepared copolymers were characterized by FTIR, SEM, cyclic voltammogram, electrochemical impedance spectroscopy, and galvanostatic charge-discharge testing, respectively. The results demonstrated that PPy- co -PPy-C-TEMPO-based composite cathodes have been successfully prepared by in situ electrochemical method, and the introduction of the nitroxide free radical (TEMPO) could obviously affect the morphology and electrochemical characteristics of the obtained electroactive polymers. And the charge/discharge tests showed that with the introduction of the TEMPO, PPy- co -PPy-C-TEMPO-based composite cathodes exhibited an improved specific capacity of 70.9 mAh g −1 for PPy- co -PPy-C-TEMPO (4:1) and 62.6 mAh g −1 for PPy- co -PPy-C-TEMPO (8:1) as measured at 20 mA g −1 between 2.5 and 4.2 V, which were remarkably higher than that of the pure PPy cathode of 41.0 mAh g −1 under the same experimental conditions. Also, the obtained PPy- co -PPy-C-TEMPO copolymers demonstrated an acceptable cycling stability during the charge-discharge process. These obtained cell performances for the composite cathodes were attributed to the application of the in situ electrochemical polymerization technology, which enhanced the intimate integration between conductive polymer film and electrode. Furthermore, the introduction of TEMPO-contained pyrrole (Py-C-TEMPO) improved the morphology of the composite cathode, which was in favor of the utilization of active materials and the improved electrochemical performances.
研究领域:
材料科学
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电化学
·
能源存储
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2019
·
IF 7.65
Shengpeng Liu,Gen Cheng,Yun Xiong,Yigang Ding,Xiaogang Luo
Due to strong activity, it is very difficult to remove low concentrations of bromide in medical wastewater by traditional method, thus highly effective and greener adsorbents should be utilized to design. In this work, the cellulose beads (CBs) were modified by the TEMPO-mediated oxidation and then bonded with Fe 3+ to fabricate Fe(III)-complexed carboxylated cellulose beads (Fe-CCBs) adsorbents. Structure and properties of Fe-CCBs were analyzed using Energy dispersive spectrum (EDS), Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), total acidity and basicity groups, X-ray diffraction (XRD), N 2 adsorption-desorption and Thermogravimetric (TGA). Moreover, batch adsorption experiments showed that the adsorption of Br − was better consistent with general-order kinetic model and Liu isotherm model, which could also further clarify the adsorption process mechanism. Meanwhile, the results revealed that removal of Br- was a spontaneous exothermic process and was more suitable to be carried out under neutral or acidic conditions. Furthermore, the mechanism of adsorption behavior of bromide ions on Fe-CCBs was based on a combination of electrostatic attraction and outer-sphere complexation. The results of this study can provide guidance for the design of novel material adsorbents and the removal of harmful anions from aqueous solutions.
研究领域:
环境科学
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材料科学
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产品关联
DOI
PubMed
高影响因子
E-POLYMERS
·
2014
·Vol. 15
·期 1
·39-44
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IF 0.33
Danjie Li,Xianbo Shen,Liang Chen,Huanchang Jiang,Jianli Wang
Covalently immobilizing the active sites or ligands on a polymer surface is an efficient strategy to achieve a full use of expensive organic parts. In this work, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was anchored onto polystyrene beads through an ether bond or an ionic liquid bridge. We quantitatively compared their thermal stabilities at nitrogen atmosphere and their chemical stabilities in a biphasic oxidation surrounding. It was found that the ionic liquid-bridged TEMPO exhibited an additional advantage of stability and could be reused for 30 consecutive recycles with a conversion ratio above 90% without any significant loss under the condition of the Montanari oxidation system (NaClO/NaBr, CH 2 Cl 2 /water), and the overall reaction time exceeded 2700 min.
研究领域:
材料科学
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有机化学
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产品关联
DOI
高影响因子
ACTA PHYSICO-CHIMICA SINICA
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2017
·Vol. 33
·期 7
·1390-1398
·
IF 0.767
YIN Lu,LIANG Cheng,CHEN Ke-Xian,ZHAO Chen-Xuan,YAO Jia,Li Hao-Ran
A novel Pt(II)-based metallointercalator terpyridine complex linked with a 2,2,6,6-tetramethyl-1-piperidinyl N-oxide (TEMPO) derivative was prepared by a reaction between 4'-TEMPO-terpyridine (L) and a Pt(II) salt. This complex presented unusual luminescence quenching owing to
the effect of the stable nitroxide radical. The crystal structure of[Pt(terpy-TEMPO)Cl]Cl·H2O·CH3OH (terpy=2,2':6',2"-terpyridine) was elucidated by X-ray crystallography. Additionally, the effect of TEMPO on the photophysical properties of[Pt(terpy-TEMPO)Cl]
Cl·H2O·CH3OH was investigated by UV-Vis, fluorescence emission, and electron paramagnetic resonance (EPR) spectroscopy. Data from the absorption and luminescence properties (298 K) of the[Pt(terpy-TEMPO)Cl]+ complex indicated the presence of two
groups of typical bands:an intense band B with distinct vibronic structures (270-350 nm, ε>104 dm3·mol-1·cm-1) and a less intense band A (370-450 nm, ε~103 dm3·mol-1·cm-1).
These two bands are generally assigned to ligand-to-ligand charge transfer (LLCT) and metal-to-ligand charge transfer (MLCT) excited states, respectively. Furthermore, efficient photoluminescent quenching behavior was observed in the emission spectra of this complex system. Quantum calculations
of the molecular energy gaps and bands were performed by Gaussian 09 software. The calculated results verified that TEMPO greatly affects the energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. Thus, the relationship between efficient photoquenching
and molecular structure was theoretically interpreted. EPR results indicated that when TEMPO is attached to a macrocyclic terpyridine platinum complex, e.g.,[Pt(terpy)Cl]+, the terpyridine platinum complex does not affect the hyperfine coupling constant (A value) and g
factor (g values) but the rotation and relaxation times of the TEMPO radical.
研究领域:
无机化学
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材料科学
·
光谱学
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产品关联
DOI
高影响因子
CHEMICAL PHYSICS LETTERS
·
2021
·
IF 2.328
Jingwei Gong,Yanzhu Guo,Jie Lu,Yi Cheng,Haisong Wang
Carbon quantum dots/titanium dioxide (CQDs/TiO 2 ) nanocomposites were synthesized with TEMPO oxidized cellulose as carbon source via a facile method. In this eco-friendly system, the photocatalytic activity of CQDs/TiO 2 were evaluated through photo-degradation of methylene blue (MB) under visible light. The results show that CQDs/TiO 2 composites possess high photocatalytic degradation efficiency up to 92%. The enhanced degradation efficiency of MB was probably attributed to that the photoelectrical properties of CQDs can lead to effective separation of photo-generated electrons-holes pairs. Moreover, the TEMPO oxidized cellulose has abundant amino groups, which can significantly improve the photophysical properties of CQDs.
研究领域:
材料科学
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环境科学
·
纳米技术
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产品关联
DOI
高影响因子
CELLULOSE
·
2021
·Vol. 28
·期 17
·10999-11011
·
IF 5.044
Si Rongrong,Wu Chaojun,Yu Dongmei,Ding Qijun,Li Ronggang
Abstract In this study, environmentally friendly TEMPO-oxidized cellulose nanofiber (TO-CNF)/polyvinyl alcohol (PVA)/polyethyleneimine (PEI) nanoparticles were obtained by assembling PEI into TO-CNF/PVA aerogel, which was prepared by freeze-drying method with the help of glutaraldehyde. FTIR results showed that PEI likely assembled into the TO-CNF/PVA aerogel due to appearances of bending vibration of the TO-CNF/PVA/PEI nanoparticles at 1615 cm −1 . BET results further demonstrated that PEI have successfully assembled into the aerogel since the specific surface area (22.93 m 2 /g) of TO-CNF/PVA /PEI nanoparticles was lower than that (56.37 m 2 /g) of TO-CNF/PVA aerogel. SEM results also showed that PEI could obviously regulate the morphology of TO-CNF/PVA aerogel. TGA indicated that TO-CNF/PVA/PEI nanoparticles were structurally stable at 216.4 °C. The adsorption kinetics of the TO-CNF/PVA/PEI nanoparticles for copper ion (Cu 2+ ) removal presented good correlations with the Pseudo-second-order kinetic and Langmuir model ( R 2 > 0.99). Its maximum adsorption capacity for Cu 2+ according to Langmuir model was 156.8 mg/g. The adsorption equilibrium could reach in near one hour, and the adsorption efficiency could still maintain more than 80% after 3 cycles. Graphic abstract
研究领域:
环境科学
·
材料科学
·
水处理
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产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2024
·
IF 10.7
Fang Tian,Shuyi Xu,Miaoyu Gan,Baihui Chen,Qian Luan,Luyun Cai
Fucoxanthin (FX) has various excellent biological properties but suffers from poor bioavailability. In this work, we build a bionic cell wall model using TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)-oxidized cellulose. The bionic cell wall enhances the environmental stability of the liposomes and serves as a pH-responsive mechanism. The coating processes protect the structure of liposomes and fucoxanthin under the acidic conditions of the stomach. The bionic cell wall disperses and releases the fucoxanthin in simulated intestinal fluid (SIF). Overall, the protective and release capabilities highlight the potential of cellulose in a bionic cell wall model and provide diversity for the structural design of carriers for delivering functional bioactive components.
研究领域:
材料科学
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药学
·
生物技术
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产品关联
DOI
PubMed
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2018
·
IF 2.829
Xubing Sun,Jianfa Zhu,Qiuyue Gu,Yaohui You
To introduce carboxyl groups on the surface of chitin and improve the adsorption performance of Cd(II) from aqueous solution, chitin was modified by 2, 2, 6, 6-tetramethylpiperidine-1-oxyl radical (TEMPO) with hypochlorite (NaClO) and sodium bromide (NaBr). Structure characterization demonstrated the carboxyl groups were successfully introduced on the surface of chitin. Batch experiments with various parameters of the content of carboxyl group, pH, contact time, initial concentration of Cd(II) and ionic strength on the adsorption performance were investigated. The surface-modified chitin exhibited enhancement for the Cd(II) adsorption capacity than original chitin. The Cd(II) adsorbed on carboxylated chitin increased rapidly in the first 30 min and reached equilibrium within 120 min. The dynamic data followed the pseudo-second-order kinetic model . Both Frendlich and Langmuir isotherm models fitted well to the equilibrium data and the maximum adsorption capacity calculated from Langmuir model was about 207.9 mg/g at 298 K. The adsorption of Cd(II) tended to increase with an increase of pH varying from 2.0 to 5.0, but decrease with an increase of ionic strength. The Cd(II) removal mechanism on carboxylated chitin was mainly through electrostatic interaction to form outer-sphere complexes and ion exchange.
研究领域:
环境化学
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材料科学
·
水处理
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2025
·
IF 7.3
Xiang Chen,Hao Li,Yichao Lu,Zhichun Liu,Zhongsen Ma,Yajie Zhang
2,5-Furandicarboxylic acid (FDCA) has been extensively verified as a biobased aromatic ring platform compound. The development of mild and efficient novel oxidation technologies is important for FDCA preparation technologies. In this study, the efficient oxidation of 5-hydroxymethylfurfural (HMF) to produce FDCA by the TEMPO/NaClO/KBr single-phase aqueous catalytic oxidation system was systematically investigated, and the mechanism was analyzed in detail. Under the optimal reaction conditions, TEMPO as the main catalyst directly catalyzed the oxidation of HMF to FDCA, and the HMF conversion and FDCA yield both reached 100%. The oxidant NaClO could achieve a quantitative reaction (NaClO/HMF = 3:1(mol)). In addition, the reaction was conducted at mild room temperature and innovatively utilized a single aqueous system as the reaction solvent. This establishes a new method for the oxidative preparation of FDCA with the potential for technical scale-up.
研究领域:
化学工程
·
生物化学
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产品关联
DOI
高影响因子
RUSSIAN JOURNAL OF ELECTROCHEMISTRY
·
2021
·Vol. 56
·期 12
·984-988
·
IF 1.078
Zhixing Xiong,Ouyang Dilan,Zhang Wenbin
Abstract The use of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and 4-acetamido-TEMPO (ACT) for electrochemical oxidation of L-sodium lactate (SL) was comparatively investigated by cyclic voltammetry, and it was proved that ACT is more effective as a mediator in these electrocatalytic reactions. A comprehensive investigation of electrooxidation performance of ACT toward SL through investigating the effect of pH, concentration of SL, the sensitivity of SL using this electroanalytical method was calculated to be 2.78 μA cm –2 /mM, the catalytic rate constant was determined to be 51.7 L/(mol s) by using chronoamperometry.
研究领域:
电化学
·
分析化学
·
催化
✓ 已验证
DOI
高影响因子
CELLULOSE
·
2021
·Vol. 28
·期 7
·4151-4164
·
IF 5.044
Sun Tingting,Wang Huimin,Liu Jiaye,Chu Xiaomeng,Xing Xuteng,Liu Shaojie,Tang Erjun,Liu Xinying,Hildebrandt Diane
In this work, a recoverable acrylamide-vinylamine copolymer immobilized TEMPO [P(AM-co-VAm)-T] catalyst for selective oxidation of cellulose with good catalytic performance and low cellulose degradation was developed. Firstly, the acrylamide-vinylamine copolymer [P(AM-co-VAm)] was prepared by Hofmann degradation of polyacrylamide (PAM). Then, the condensation reduction reaction between amine groups of P(AM-co-VAm) and carbonyl groups of 4-oxo-TEMPO yielded P(AM-co-VAm)-T. P(AM-co-VAm)-T was used as a catalyst for selective oxidation of C6 primary hydroxyl groups of cellulose to carboxyl groups. The carboxyl content of obtained oxidized cellulose was up to 1.114 mmol/g, which was equivalent to 76% of the free TEMPO level. This macromolecular catalyst was easily recycled and the recycling performance was excellent. Interestingly, it was found that P(AM-co-VAm)-T could effectively reduce the degradation of oxidized cellulose. The corresponding degradation degree was 21–27%, which was much lower than the degradation degree of free TEMPO (61–66%) and other macromolecular TEMPO catalysts, such as polyacrylic acid immobilized-TEMPO (41–53%) and polyamidoamine supported TEMPO (28–44%). P(AM-co-VAm)-T with positive charge and suitable size could effectively inhibit the formation of C6 aldehydes and C2/C3 ketones, which was the main reason that it could significantly inhibit cellulose degradation.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）