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Rheological behavior of mixed system of ionic liquid [C

Zimeng HE,Ling YUE,Meng LI,Yazhuo SHANG,Honglai LIU

《化学科学与工程前沿（英文）》 2015年第9卷第2期页码 232-241 doi: 10.1007/s11705-015-1511-9

摘要： We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [C mim]Br (1-octyl-3-methylimidazolium bromide) and anionic surfactant sodium oleate (NaOA) in aqueous solution. The effects of surfactant composition, total surfactant concentration, added salts, and temperature were investigated. The prevailing surfactant effect at lower concentration and the leading cosolvent effect at higher concentration of [C mim]Br may be the main reasons for appearance of well-established maximum in key rheological parameters with variation of surfactant composition and total surfactant concentration. The Cole-Cole plots demonstrate that the systems (total surfactant concentration falls within 0.17–0.35 mol·L and molar ratio 0.33≤ ≤0.50) fit the Maxwell’s mechanical model as linear viscoelastic fluid. The addition of NaBr or sodium salicylate decreases significantly the viscosity and the relaxation time of the wormlike micelle solution but cannot change the value of plateau modulus . The present system has low rheological tolerance to temperature. The increase of temperature decreases the average contour length and viscosity of wormlike micelles and thus strengthens the relaxation progress of diffusion and weakens the relaxation progress of reptation. Increasing the temperature also decreases the value of plateau modulus and shifts the minimum value of the loss modulus to higher frequencies.

关键词： rheological behavior ionic liquid surfactant sodium oleate wormlike micelles viscoelasticity

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Formation of reverse micelles in supercritical carbon dioxide and its thermodynamics

WEN Zhen, DANG Zhi, ZHU Zhixin, ZONG Minhua

《化学科学与工程前沿（英文）》 2007年第1卷第3期页码 283-286 doi: 10.1007/s11705-007-0051-3

摘要： The solubilization behavior of methyl orange as a solvation probe in multiple systems composed of supercritical carbon dioxide, surfactants and co-solvents, is studied. It is concluded that some surfactants, such as sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) and isooctyl phenol polyethoxylate (TX-10), could form reverse micelles in supercritical carbon dioxide under the action of butanol. The formation of reverse micelles is a spontaneous process thermodynamically. Specifically for the nonionic surfactant TX-10, the formation of reverse micelles is dependent on the entropy increase in the system, while for the anionic surfactant AOT, the micellization is mainly dominated by the increase in enthalpy at higher temperatures, but by the increase in entropy at lower temperatures.

关键词： micellization surfactant AOT TX-10 sulfosuccinate solubilization

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Dissolution and enzymatic hydrolysis of casein micelles studied by dynamic light scattering

LIU Rui, QI Wei, SU Rongxin, ZHANG Yubin, JIN Fengmin, HE Zhimin

《化学科学与工程前沿（英文）》 2007年第1卷第2期页码 123-127 doi: 10.1007/s11705-007-0023-7

摘要： The effects of temperature, ionic strength, and enzymatic hydrolysis on the average hydrodynamic radius () of casein micelles in phosphate buffer were studied by using dynamic light scattering. The results showed that the average value of casein micelles decreased irreversibly during the heating, decreased with the increase of ionic strength in lower ionic strength solution (less than 0.05 mol/L), but opposite in higher ionic strength solution (above 0.1 mol/L). The value of casein increased rapidly during the process of enzymatic hydrolysis, and the structural model of casein micelles in the enzymatic hydrolysis process was also proposed, i.e. the casein micelle changed from compact sphere into unfolded and regularly flocky peptides.

关键词： compact strength temperature regularly flocky heating