排序方式: 共有28条查询结果,搜索用时 15 毫秒
1.
Yao Chen Wenchuan Wang Dong Xie Lili Wu Chaocan Zhang 《Journal of polymer science. Part A, Polymer chemistry》2021,59(14):1528-1539
TPPAlCl-PPN+Cl− binary catalyst (where TPPAlCl is 5,10,15,20-tetraphenylporphyrin aluminum chloride, PPN+Cl− is bis[triphenylphosphine] iminium chloride, the molar ratio of TPPAlCl to PPN+Cl− is 1 to 0.5) can initiate the effective one-pot/one-step ternary copolymerization of CO2, lactide and 4-vinyl-1-cyclohexene-1,2-epoxide, and the quaternary copolymerization of CO2, propylene oxide, lactide, 4-vinyl-1-cyclohexene-1,2-epoxide, to form multiblock poly(carbonate-co-lactide) products with pendant vinyl group. The ternary copolymerization product composes of polylactide (PLA) block and poy(vinylcyclohexylene carbonate) (PVCHC) block, and the quaternary copolymerization product composes of poy(propylene carbonate) (PPC) block, PLA block and PVCHC block, which are verified by 1H NMR, 13C NMR, 1H-1H cosy, hetero-nuclear multiple bond correlation, DTG, and Gel permeation chromatography analysis. The functionality and glass-transition temperature of the products can be easily adjusted by the copolymerization variables, such as the molar ratio of comonomers, copolymerization temperature, pressure of CO2, the concentration of the catalyst. 相似文献
2.
Liang Hu Fan Yang Chaocan Zhang Yuanyuan Hu Yanjun Chen 《Colloid and polymer science》2011,289(3):323-331
In this work, a functional gradient polymeric material derived from silicon-containing acrylate blend emulsion film is prepared
in two steps. Firstly, 3-[tris(trimethylsilyloxy)silyl] propyl methacrylate (TRIS)-modified acrylate latex is prepared using
multiple emulsifiers by the two-stage semicontinuous emulsion copolymerization method. Next, blend latexes composed of TRIS-containing
and TRIS-free acrylate latexes are obtained. Detailed studies on the effects of the film-formation temperature and the glass
transition temperature (T
g) differences on the compositional gradient film are conducted. Surface energy analysis shows that silicon elements enriched
at the film-air (F-A) interface and T
g differences facilitate the fabrication of silicon gradient in emulsion blend films. Scanning electron microscopy-energy dispersive
X-ray further reveals that the concentration of silicon components varies in a gradient-like manner along the overall transaction
of the film when the film-formation temperature is 55 °C. However, excessive temperature creates the formation of a segmental
gradient distribution of silicon in the emulsion blend films. 相似文献
3.
Jian Zhou Xi Li Linlin Yang Songlin Yan Mengmeng Wang Dan Cheng Qi Chen Yulin Dong Peng Liu Weiquan Cai Chaocan Zhang 《Analytica chimica acta》2015
A novel electrochemical sensor based on Cu-MOF-199 [Cu-MOF-199 = Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylicacid)] and SWCNTs (single-walled carbon nanotubes) was fabricated for the simultaneous determination of hydroquinone (HQ) and catechol (CT). The modification procedure was carried out through casting SWCNTs on the bare glassy carbon electrode (GCE) and followed by the electrodeposition of Cu-MOF-199 on the SWCNTs modified electrode. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were performed to characterize the electrochemical performance and surface characteristics of the as-prepared sensor. The composite electrode exhibited an excellent electrocatalytic activity with increased electrochemical signals towards the oxidation of HQ and CT, owing to the synergistic effect of SWCNTs and Cu-MOF-199. Under the optimized condition, the linear response range were from 0.1 to 1453 μmol L−1 (RHQ = 0.9999) for HQ and 0.1–1150 μmol L−1 (RCT = 0.9990) for CT. The detection limits for HQ and CT were as low as 0.08 and 0.1 μmol L−1, respectively. Moreover, the modified electrode presented the good reproducibility and the excellent anti-interference performance. The analytical performance of the developed sensor for the simultaneous detection of HQ and CT had been evaluated in practical samples with satisfying results. 相似文献
4.
5.
Yixiao Dong Chaocan Zhang Lili Wu Yanjun Chen Yuanyuan Hu 《Macromolecular rapid communications》2014,35(22):1943-1948
For most stimuli‐responsive polymer materials (SRPMs), such as polymer gels, micelles, and brushes, the responsive mechanism is based on the solubility or compatibility with liquid media. That basis always results in distorting or collapsing the material's appearance and relies on external liquids. Here, a novel kind of SRPMs is proposed. Unlike most SRPMs, liquid is stored within special domains rather than expelled, so it is deforming‐free and relying on no external liquid, which is referred to as self‐storage SRPMs (SS‐SRPMs). The facile and universal route to fabricate SS‐SRPMs allows for another novel family of SRPMs. Furthermore, it is validated that SS‐SRPMs can drastically respond to outside temperature like switchers, especially for optical and electrochemical responses. Those features hold prospects for applications in functional devices, such as smart optical lenses or anti‐self‐discharge electrolytes for energy devices.
6.
A Supramolecular Gel Approach to Minimize the Neural Cell Damage during Cryopreservation Process 下载免费PDF全文
The storage method for living cells is one of the major challenges in cell‐based applications. Here, a novel supramolecular gel cryopreservation system (BDTC gel system) is introduced, which can observably increase the neural cell viability during cryopreservation process because this system can (1) confine the ice crystal growth in the porous of BDTC gel system, (2) decrease the amount of ice crystallization and cryopreservation system's freezing point, and (3) reduce the change rates of cell volumes and osmotic shock. In addition, thermoreversible BDTC supramolecular gel is easy to be removed after thawing so it does not hinder the adherence, growth, and proliferation of cells. The results of functionality assessments indicate that BDTC gel system can minimize the neural cell damage during cryopreservation process. This method will be potentially applied in cryopreservation of other cell types, tissues, or organs and will benefit cell therapy, tissue engineering, and organs transplantation.
7.
Liang Hu Chaocan Zhang Yuanyuan Hu Yanjun Chen Wanyu Chen 《Colloid and polymer science》2012,290(8):709-718
The effect of annealing on the self-organized morphology and component gradient distribution of films prepared from bimodal latexes blend containing 1:1 silicon-containing acrylate copolymer/silicon-free acrylate copolymer blend was studied using attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy with X-ray energy-dispersive (SEM-EDX) spectrometry, and atomic force microscopy (AFM). The distribution of silicon through the whole thickness of the film as a function of annealing was investigated using confocal Raman spectroscopy (CRS). AFM results show that poly(methyl methacrylate-co-n-butyl acrylate) latex fuses to form a continuous film at 25?°C. The wettability of the acrylate components and the heterogeneous composition of poly(3-[tris(trimethylsilyloxy)silyl] propyl methacrylate-co-methyl methacrylate) result in a graded block film. ATR-FTIR and SEM-EDX measurements reveal silicon-containing components segregate at the film–air interface upon annealing. CRS further shows that the nonlinear model gradient distribution of silicon is obtained, where the content of silicon component is enhanced and it gradually varies in the bulk. When the annealing temperature increases to 120 and 180?°C, blend latexes films demonstrate varying topography and phase images, indicating phase separation is induced by annealing. Furthermore, CRS implies that the destruction of the gradient structure is attributed to the phase separation of the two blend components. 相似文献
8.
L. Peng X. Jiangjun M. Fangquan L. Xi Z. Chaocan 《Journal of Thermal Analysis and Calorimetry》2008,93(2):485-488
The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of Δr
U
mθ(−14358.4±20.65 kJ mol−1), Δr
H
mθ(−14385.7 kJ mol−1) of combustion reaction and Δf
H
mθ(2812.9 kJ mol−1) of cholesterol were obtained from the reaction equation. The enthalpy of combustion reaction of cholesterol was also estimated
by the average bond enthalpies. By design of a thermo-chemical recycle, the enthalpy of combustion of cholesterol were calculated
between 283.15∼373.15 K. Besides, molar enthalpy and entropy of fusion of cholesterol was obtained by DSC technique. 相似文献
9.
新型支化聚乙烯亚胺螯合树脂的制备及吸附性能研究 总被引:4,自引:0,他引:4
在聚乙烯亚胺(PEI)的胺基上接枝4种不同的侧链,制备出4种新型的螯合树脂。研究这些螯合树脂对重金属离子Hg(II)、Cd(II)、Co(II)、Cu(II)、Zn(II)、Pb(II)、Mg(II)的吸附性能以及选择性吸附,并对温度对Cu(II)的最大吸附量的影响进行了研究。结果表明:新型的螯合树脂对Hg(II)有很好的吸附性能和吸附选择性,对Cu(II)、Cr(III)重金属离子也有较好的吸附性能,随着温度的升高,树脂对金属离子的吸附量逐渐上升。 相似文献
10.
Hebao Tian Chaocan Zhang Lili Wu Yanjun Chen 《Journal of Thermal Analysis and Calorimetry》2010,101(3):959-964
Isothermal heat conduction microcalorimetry was adopted as a novel characterization method to investigate the polymerization
processes of silica when the combination of silica sol and potassium sodium silicate was stirred at 25.0, 35.0, and 45.0 °C.
Thermodynamic and kinetic parameters were simultaneously obtained. The enthalpy change was greater at each higher temperature.
The reaction orders (m, n) instantaneously varied, up and down in an alternate manner. At 25.0, 35.0, and 45.0 °C, the rate constants were different;
the maximum rate constant occurred at 25.0 °C. These phenomena reflect a two-stage oligomeric mechanism of silica monomers.
The measurements of particle size showed the complex chemical composition of aqueous silicates, which can be qualitatively
designated by the particle size distribution in two parts. The results further indicate that the colloidal particles in the
mixed silica sol and silicates first dissolved. Then the “active” silica in the silicates redeposited to make a distinct particle
size distribution influenced by K+ and Na+ ions as well as by temperature. 相似文献