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2007年03月06日

【期刊论文】Water in Carbon Dioxide Microemulsions with Fluorinated Analogues of AOT

刘昭铁, Zhao-Tie Liu , Can Erkey

Langmuir 2001, 17, 274-277,-0001,():

-1年11月30日

摘要

A series of fluorinated analogues of AOT, the sodium salt of bis(3,3,4,4,5,5,6,5,7,7,8,8,8-tridecafluorooctyl)-2-sulfosuccinate (CF3(CF2)5CH2CH2OOCCH2CH(SO3Na)COOCH2CH2(CF2)5CF3, di-HCF7),the sodium salt of bis(2,2,3,3,4,4,5,5-octafluoro-1-pentyl)-2-sulfosuccinate (H(CF2)4CH2OOCCH2CH-(SO3Na)COOCH2(CF2)4H, di-HCF4), and the sodium salt of bis(2,2,3,4,4,4-hexafluorobutyl)-2-sulfosuccinate(CF3CHFCF2CH2OOCCH2CH(SO3Na)COOCH2CF2CHFCF3, di-HCF3), were synthesized and characterized by 1HNMR. The pressure-temperature phase diagrams for W/CO2 microemulsions stabilized by the three surfactants were determined. At a fixed temperature, cloud point pressures increased with increasing water-to-surfactant ratio. The water solubilization capacity increased in the order di-HCF4 > di-HCF3 > di-HCF7.

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2008年11月16日

【期刊论文】Selective hydrogenation of cinnamaldehyde over Pt-supported multi-walled carbon nanotubes: Insights into the tube-size effects

刘昭铁

,-0001,():

-1年11月30日

摘要

The multi-walled carbon nanotubes (MWCNTs) having different outer diameters but similar inner diameters were loaded with 3.0 wt.% Pt via the reduction of H2PtCl6 by formaldehyde in the solution of ethanol and water. For both the MWCNT supports and catalysts, the BET surface areas and pore size distributions determined by N2 adsorption and desorption were varied significantly although type II adsorption isotherms with closed hysteresis loops were observed. The 3.0 wt.% Pt/MWCNT catalysts were investigated for the selective hydrogenation of cinnamaldehyde (CALD) in a batch reactor under the conditions of 80 8C and 2.0 MPa of hydrogen. All the catalysts showed reasonably high catalytic activity but significantly different product selectivities. The highly selective hydrogenation of C C bonds into hydrocinnamaldehyde (88% selectivity at 100% conversion) occurred over Pt-supported MWCNT4 with the biggest outer diameters (>50 nm). In the case of the other three catalysts, however, C O bonds were selectively hydrogenated showing about 60–80% selectivities to cinnamyl alcohol (CA) depending on the catalysts and CALD conversions. Irrespective of the catalysts, the results of X-ray diffraction and highresolution transmission electron microscopy indicated that the metallic Pt particles with an average size of about 11 nm were overwhelmingly deposited on the outer surface of the MWCNTs. The binding energies of Pt and the surface atomic ratios of oxygen to carbon determined by X-ray photoelectron spectroscopy were slightly varied for different catalysts. Based on these characterization results together with the hydrogenation results of CA, the different selective behaviors of the Pt/MWCNTs catalysts were discussed. Besides other factors, the electronic effects induced by the significantly varied tube diameters of the MWCNTs played the major role in determining the selective behaviors of different catalysts.

Multi-walled carbon nanotubes,, Cinnamaldehyde hydrogenation,, Hydrocinnamaldehyde,, Cinnamyl alcohol,, Platinum-supported catalysts

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2008年11月16日

【期刊论文】Benzylated Modification and Dyeing of Ramie Fiber in Supercritical Carbon Dioxide

刘昭铁

,-0001,():

-1年11月30日

摘要

The effects of pretreatment conditions, including the addition of a phase-transfer catalyst, on the benzylation of ramie fiber were investigated in this study. Raw and benzylated ramie fibers were dyed in supercritical carbon dioxide, and the color strength (K/S) of the ramie fiber was measured by ultraviolet–visible spectroscopy. An obviously improved dyeing capability of the benzylated ramie fiber, that is, a better level-dyeing property and a higher K/S, was achieved. Moreover, the color strength of the ramie fiber, indexed as the value of K/S, increased significantly with the degree of substitution of the benzylated ramie fiber. The raw and modified ramie fibers were characterized with Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry.

biofibers, degree of polymerization (, DP), , dyes/, pigments, modification, morphology

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2008年11月16日

【期刊论文】New Process for Synthesizing Fluorinated Polymers in Supercritical Carbon Dioxide

刘昭铁

,-0001,():

-1年11月30日

摘要

The typical polymerization process in supercritical fluids (SCFs) was improved through modifying the reaction system and designing and using sampling tubes. The efficacy of the newly developed procedure was demonstrated by the free radical homopolymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) and coplymerization of TFEMA and N-vinylpyrrolidone (NVP) in supercritical carbon dioxide (scCO2). Results indicate that the newly developed procedure has the characteristics of minimum loss of reactants and polymerization starting at the desired temperature and pressure. Furthermore, the polymerization process can be well tracked by analyzing the reaction mixtures online sampled from the reactor at certain reaction times by FT-IR, 1H NMR, and GPC. The reaction time and the product properties can be optimized based on the tracking results. For the first time, block copolymers by free radical polymerization in scCO2 was successfully synthesized by sequential addition of TFEMA and methyl methacrylate (MMA) into the reactor at different reaction stages. The synthesized polymers were characterized by FT-IR, 1H NMR, 13C NMR, GPC, TGA, and DSC, respectively. It was proved that the losing of monomer, pollution to the environment, and distribution of the molecular weight of the synthesized polymers decreased while the yield of product, the reproducibility, and the controllability of polymerization increased after improvement of the polymerization process.

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2008年11月16日

【期刊论文】Adjustable Wettability of Methyl Methacrylate Modified Ramie Fiber

刘昭铁

,-0001,():

-1年11月30日

摘要

The surface hydrophobicity/hydrophilicity of ramie fiber was regulated through the atom transfer radical polymerization of methyl methacrylate from initiators immobilized on the fiber. The optimal reaction conditions for preparing the macroinitiated ramie fiber were determined to be a temperature of 608C and a reaction time of 24 h. The grafted copolymers were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive analysis of X-rays, gel permeation chromatography, and thermogravimetric analysis. The results indicate that poly (methyl methacrylate) was covalently bonded onto the surface of the ramie fiber, and the polymerization of methyl methacrylate was a living/controlled process under the investigated conditions. The results of the contact angle measurements indicate that the wettability of the ramie fiber could be widely regulated by control of the grafted ratios of poly(methyl methacrylate) from 26 to 33 wt %.

atom transfer radical polymerization (, ATRP), , differential scanning calorimetry (, DSC), , fibers, graft copolymers, modification

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    陕西师范大学,陕西

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