Nanoscale Research Letters
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2014
·Vol. 9
·期 1
·1-7
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IF 2.481
Ji Jianwei,Wang Guan,You Xiaozeng,Xu Xiangxing
Silicon quantum dots (Si QDs) attract increasing interest nowadays due to their excellent optical and electronic properties. However, only a few optoelectronic organic molecules were reported as ligands of colloidal Si QDs. In this report, N -vinylcarbazole - a material widely used in the optoelectronics industry - was used for the modification of Si QDs as ligands. This hybrid nanomaterial exhibits different spectroscopic properties from either free ligands or Si QDs alone. Possible mechanisms were discussed. This type of new functional Si QDs may find application potentials in bioimaging, photovoltaic, or optoelectronic devices.
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SUPRAMOLECULAR CHEMISTRY
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2015
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IF 2.394
Bo Xiao,Ying Fan,Ning-Ning Ji,Xiao-Jie Cheng,Chuan-Zeng Wang,Jia-Jia Zhou,Sai-Feng Xue,Zhu Tao,Qian-Jiang Zhu
Using the one-pot, direct strategy reported by Su and co-workers, we have synthesised a series of cucurbit[n]urils (Q[n], n = 5–8) and alkyl-substituted cucurbit[6]urils (SQ[6]s) anchored on polymers. Acrylamide, as a typical monomer, was used to synthesise a series of Q[n]s (n = 5–8) and SQ[6]-anchored polyacrylamides (PAMs) using a persulfate salt as initiator and oxidant. The Q[n]s (n = 5–8) and SQ[6]-anchored PAM samples have been characterised by 1H NMR, 1H NMR titrations of probe guests, Fourier-transform infrared and thermogravimetric analyser. The results confirmed that PAM chains had been successfully grafted on the back of the Q[n]s (n = 5–8) and SQ[6]s through an in situ radical polymerisation approach. It was further confirmed that the hydrophobic cavities of the Q[n]s on the polymers were still freely accessible. This synthetic approach may be extended to a variety of Q[n]s that are difficult to functionalise.
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JOURNAL OF APPLIED POLYMER SCIENCE
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2014
·Vol. 131
·期 23
·
IF 1.64
Nenmei Jian,Tao Xu
In this article, we report that thermoresponsive poly( N -isopropyl acrylamide) (PNIPAAm) was successfully grafted onto a cotton fabric (CF) surface by free-radical solution grafting polymerization; we obtained a thermoresponsive CF-grafted PNIPAAm. This reaction system only contained four constituents: the monomer, solvent, initiator, and CFs. Ammonium peroxydisulfate was chosen as the initiator, and water was chosen as the solvent. A series of initiator concentrations and grafting polymerization temperatures were used in the experiments, and their effects on the grafting ratio ( G ) were also studied. Also, the effects of the G of CF- g -PNIPAAm on their corresponding thermoresponses was studied further. The structure of CF- g -PNIPAAm was characterized by Fourier transform infrared spectroscopy–attenuated total reflectance analysis and scanning electron microscopy analysis. The G of CF- g -PNIPAAm was measured by a gravimetric method. The thermoresponse of CF- g -PNIPAAm was characterized by modulated differential scanning calorimetry, water contact angle measurements, and wetting time measurements. The experiments manifested the following results: (1) the initiator concentration and grafting polymerization temperature both influenced G, (2) the grafted PNIPAAm covered the CF surface, (3) the CF- g -PNIPAAm showed thermoresponsive hydrophilicity/hydrophobicity, and (4) a relationship existed between the thermoresponse of CF- g -PNIPAAm and the corresponding G . © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 41193.
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JOURNAL OF MOLECULAR STRUCTURE
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2013
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IF 1.404
Zhihua Cui,Xin Li,Xidong Wang,Kemei Pei,Weiguo Chen
Two N -heterocycle-containing benzotriazole compounds ( CBHDCP , CBMPP ) were synthesized and their structures were confirmed by FT-IR, 1 H NMR, mass spectroscopy and elemental analysis. Their spectral properties compared with that of a common commercial benzotriazole UV absorber Tinuvin 326 in solvents were measured and analyzed using molecular orbital calculations. It was found that the experimentally obtained optical properties were in close agreement with the theoretically obtained results. Besides, CBMPP is much superior to CBHDCP acting as an effective UV absorber on polyethylene terephthalate fabric due to its combinative higher exhaustion and higher molar extinction coefficient. The exhaustion difference on polyethylene terephthalate fabric among N -heterocycle-containing benzotriazoles ( CBHDCP , CBMPP ) and Tinuvin 326 were then measured and explained by the solubility parameter theory. The results agreed with the rule that compounds with higher exhaustion on fiber have solubility parameter much closer to that of fiber polymer.
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PROCEEDINGS OF THE COMBUSTION INSTITUTE
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2016
·
IF 4.12
Anne Rodriguez,Olivier Herbinet,Zhandong Wang,Fei Qi,Christa Fittschen,Phillip R. Westmoreland,Frédérique Battin-Leclerc
The reactions of chain-branching agents, such as H 2 O 2 and hydroperoxides, have a decisive role in the occurrence of autoignition . The formation of these agents has been investigated in an atmospheric-pressure jet-stirred reactor during the low-temperature oxidation of n- pentane (initial fuel mole fraction of 0.01, residence time of 2 s) using three different diagnostics: time-of-flight mass spectrometry combined with tunable synchrotron photoionization, time-of-flight mass spectrometry combined with laser photoionization, and cw- cavity ring-down spectroscopy. These three diagnostics enable a combined analysis of H 2 O 2 , C 1 –C 2 , and C 5 alkylhydroperoxides, C 3 –C 5 alkenylhydroperoxides, and C 5 alkylhydroperoxides including a carbonyl function (ketohydroperoxides). Results using both types of mass spectrometry are compared for the stoichiometric mixture. Formation data are presented at equivalence ratios from 0.5 to 2 for these peroxides and of two oxygenated products, ketene and pentanediones, which are not usually analyzed during jet-stirred reactor oxidation. The formation of alkenylhydroperoxides during alkane oxidation is followed for the first time. A recently developed model of n- pentane oxidation aids discussion of the kinetics of these products and of proposed pathways for C 3 –C 5 alkenylhydroperoxides and the pentanediones.
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JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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2016
·
IF 3.958
Huan Chen,Ting Li,Fang Jiang,Zhe Wang
Catalytic reduction of N -nitrosodimethylamine (NDMA) was investigated over γ-Al 2 O 3 supported bimetallic Pd-Ni catalysts (3%(Pd x Ni 1−x )). NDMA could be reduced to dimethylamine over 3%(Pd 0.8 Ni 0.2 ) with a metal-loading-normalized pseudo-first-order rate constant of 836 ± 21 L g me −1 h −1 . Characterization results showed that the reducibility of PdO (or NiO) was improved by addition of Ni (or Pd) in 3%(Pd x Ni 1−x ); Pd-Ni ensembles were formed in 3%(Pd x Ni 1−x ) and there was an electronic transfer from Pd to Ni; metal dispersion was affected by the formation of Pd-Ni ensembles and a volcano curve of metal dispersion via Pd/Ni ratio was observed. The activity profiles demonstrated that TOF had a significant positive relationship with metal dispersion of 3%(Pd x Ni 1−x ), indicating high metal dispersion favor NDMA reduction. NDMA reduction over 3%(Pd 0.8 Ni 0.2 ) catalyst could be described by Langmuir-Hinshelwood model, reflecting an adsorption controlled reduction mechanism. The reduction mechanism of NDMA over 3%(Pd 0.8 Ni 0.2 ) catalyst was proposed to be that H 2 was activated by Pd, and H spillover from Pd to Ni/NiO reduced NDMA though N-N cleavage.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2016
·Vol. 80
·期 1
·239-248
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IF 1.473
Cui Yuheng,Kang Xin,Zhang Jie,Zhang Liqun,Yue Dongmei
Abstract Thermoreversible gels were obtained from the well-defined triblock terpolymer poly(n-hexyl isocyanate)-b-polybutadiene-b-poly(n-hexyl isocyanate) (PHIC-b-PB-b-PHIC). PHIC-b-PB-b-PHIC adopted a helical conformation and exhibited florescence in solution. The gels were prepared in both n-heptane and n-octane. The gelation concentration and temperature could be affected by various factors. Hydrogen bonding and intermolecular aggregation were the driving forces to form stable thermoreversible gels. Atomic force microscopy (AFM) showed that the microstructure of the gels consisted of aggregates of fibrous nanoribbons. Because of their thermosensitivity and fluorescence, the thermoreversible gels have potential applications in sensors and temperature-sensitive switches. Graphical Abstract
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CHEMICAL ENGINEERING JOURNAL
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2017
·
IF 6.216
Yunyun Xie,Wenxiu Yang,Mozhen Wang,Xuewu Ge
The creation of high surface area and effective active sites is the key problem for the synthesis of high-performance porous carbon materials. In this work, polyacrylonitrile-coated fibrous silica (F-SiO 2 @PAN) microspheres were prepared by in situ polymerization of acrylonitrile on fibrous mesoporous silica microspheres induced by γ-ray radiation. After F-SiO 2 @PAN microspheres were carbonized and etched with hydrofluoric acid, uniform fibrous N-doped porous carbon (FNC) microspheres with an average size of 286 nm and a molar ratio of C/N of 5.2 were successfully prepared. As revealed by TEM, SEM, and N 2 adsorption-desorption isotherms analysis, FNC microspheres have a hierarchal micro-macroporous structure with a particular high surface area of 554.5 m 2 /g. The FNC microspheres also exhibit a good water dispersibility and an excellent adsorption ability to rhodamine B in water. The equilibrium adsorption capacity of FNC microspheres could reach 95.4 mg/g, which is 1.6 times as that of the primary silica template microspheres. The adsorption kinetics and thermodynamics of FNC microspheres are in accord with the pseudo-second-order kinetic equation and Freundlich isotherm model, respectively. This work provides a facile synthesis method for novel N-doped hierarchical micro-macroporous carbon microsphere as a potential high-performance adsorbent material.
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Journal of Materials Chemistry B
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2017
·Vol. 5
·期 39
·7974-7984
·
IF 4.543
Yuzheng Wu,Haifeng Li,Zhouquan Rao,Huaqiang Li,Yan Wu,Jianhao Zhao,Jianhua Rong
The controlled protein adsorption and delivery of thermosensitive poly(N-isopropylacrylamide) (PNIPAM) nanogels were investigated under different temperatures, pH values and ionic strengths by using bovine serum albumin (BSA) as a model protein. The BSA adsorption in deionized water was due to one or several of four contributions, i.e. the electrostatic attraction between BSA and nanogels, the seizing action of nanogels to BSA, the hydrophobic interaction between BSA and nanogels, and the physical diffusion of BSA, depending on the temperature and pH value. At 37 °C and pH 4.0, the largest BSA adsorption of 23.5 μg mg−1 was achieved by the above four contributions following electrostatic attraction (48%) > seizing action (21%) > hydrophobic interaction (16%) > physical diffusion (15%). The BSA adsorption in different sodium chloride solutions exhibited a maximum of 17.2 μg mg−1 at 0.03 M, which was influenced by the charge shielding of Na+ ions, salting out of BSA and nanogel aggregation. Most adsorbed BSA molecules were distributed on the nanogel surface except a few standing in the nanogel interior. The adsorbed BSA could be controllably delivered by tailoring the temperature and pH value, and with the aid of sodium dodecyl sulfate. The conformation of BSA adsorbed in hydrochloric acid solution (pH 4.0) significantly changed due to the acid environment and the electrostatic attraction between BSA and nanogels, but it could be completely recovered when BSA was delivered in deionized water or physiological saline. This work is instructive to design the controllable adsorption and delivery of proteins by using PNIPAM-based hydrogels as carriers.
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ENERGY & FUELS
·
2017
·
IF 3.091
Zhongqi Ren,Mengyao Wang,Yong Li,Zhiyong Zhou,Fan Zhang,Wei Liu
The designer nature of ionic liquids (ILs) has driven their exploration and application in countless fields because of their unique phiscochemical properties. In this work, two ester-functionalized ionic liquids (ILs), N-ethyl acetate-N-methylimidazole bis(trifluoromethylsulfonyl)imide ([Eamim][NTf2]) and N-ethyl acetate-N-methylimidazole sulfocyanide([Eamim][SCN]), were prepared. Two ternary systems, benzene-hexane-[Eamim][NTf2] and benzene-hexane-[Eamim][SCN], were investigated in terms of both quantum chemical calculation and liquid–liquid extraction experiments. Quantum chemical calculation results showed that the interaction between ILs and benzene was larger than that between ILs with n-hexane. The liquid–liquid extraction results showed that the selectivity reached 29.55 with [Eamim][NTf2], while the selectivity reached 61.44 with [Eamim][SCN] at 25 °C. The vapor permeation process was conducted through a supported membrane with ILs. The influences of operating temperature and the feed concentration of benzene were investigated. With the increase of temperature, the selectivity of benzene increased at first and then decreased. When the concentration of benzene was 0.5 and the temperature was 35 °C, the selectivity of benzene reached 16.05, while the flux was 22.14 g·h–1·m–2. The stability of the membrane in the vapor permeation was also tested and could remain steady for 60 h.
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TALANTA
·
2024
·
IF 5.6
Qing Liu,Si Chen,Yiming Nie,Qian Li,Fang Chen
4- n -butylresorcinol (4nBR) is a frequently utilized as whitening ingredients in skincare cosmetics. Compared with other whitening ingredients, it can effectively inhibit tyrosinase with lower toxicity and superior inhibition efficacy. Under alkaline conditions, an induced oxidative coupling reaction can occur between 4nBR and dopamine (DA) to generate strong fluorescent substance azamonardine with an intense emission band centering at 476 nm when excited at 440 nm. This phenomenon can be used to establish a fluorescence analysis method for 4nBR. The results indicated that the linear range of the method was 1.0–24.0 nmol L −1 , and the detection limit was as low as 0.25 nmol L −1 . The method showed high sensitivity, good selectivity, mild experimental conditions and low cost. The proposed method was successfully used to detect 4nBR in cosmetics, and the results were consistent with those of HPLC. The spiking recoveries were between 98.2% and 108 %.
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MACROMOLECULES
·
2024
·
IF 5.1
Wenxiao Liu,Xuehua Deng,Yutong Dong,Sunting Xuan,Zhengbiao Zhang
The synthesis of N-substituted polypeptides is challenging due to steric hindrance. Here, N-alkyl poly(l-alanine)s, with controlled molecular weights (Mns) and narrow distributions, were efficiently synthesized by primary amine-initiated and acetic acid-catalyzed ring-opening polymerizations of N-alkyl-(l)-alanine N-carboxyanhydrides [NAlkyl-(l)-Ala-NCAs] in toluene of low polarity and low proton-accepting ability. The N-alkyl poly(l-alanine)s, with chiral centers at backbones and different alkyl substituents at side chains, showed a relatively extended helical structure similar to that of the PPII-helix of poly(l-proline). The elongation of the alkyl side chains and the increase in temperatures had negligible effects on the helix structure, as revealed by the circular dichroism measurements. The differential scanning calorimetry and X-ray diffraction measurements showed that the polymers were crystalline. Besides, the NAlkyl-(l)-Ala-NCAs were capable of copolymerizing with other monomers, producing structurally diverse copolymers. The efficient synthesis of N-alkyl poly(l-alanine)s, combined with the structural tunability, hydrophobicity, crystallinity, protein-like skeleton, enzymatic stability, and stable helix, makes the polymers attractive structural units in self-assembly and the biomedical field.
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