The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Yoshikiyo Moroi - One of the best experts on this subject based on the ideXlab platform.
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Solubility and micelle formation of bolaform-type surfactants: hydrophobic effect of counterion
The Journal of Physical Chemistry, 1992Co-Authors: Yoshikiyo Moroi, Yoshio Murata, Yuji Fukuda, Yoshifumi Kido, Wataru Seto, Mitsuru TanakaAbstract:Aqueous solubility and critical micelle concentration (cmc) of 1,1'-(1,ω-tetradecanediyl)bis(pyridinium) alkane-1-sulfonates ... were measured at various temperatures, and the effect of hydrophobicity of counterion on solubility, the critical micelle concentration (cmc), the micelle temperature (MTR or Krafft Point), and aggregation number of micelle was examined. The MTR was determined as 36, 39, and 36 o C for decane, dodecane, and tetradecanesulfonates, respectively, while the one for the rest was below 5 o C
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Micelle Temperature Range (MTR or Krafft Point)
Micelles, 1992Co-Authors: Yoshikiyo MoroiAbstract:Detergent action, colloid formation, and surface activity are different manifestations of the same characteristics of surfactant solutions. Detergency is the most important and conventional function of soaps, and is closely connected with their solubility. Because typical surfactant molecules (including soaps) have both a hydrophilic group and a bulk hydrophobic group, their aqueous solubility is not expected to be high. That is true below a certain narrow temperature range called the Krafft Point. Above this range, the solubility of the surfactant increases very steeply because surfactant aggregation is taking place.
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Cationic surfactants with perfluorocarboxylates as counterion: Solubility and micelle formation
Colloids and Surfaces, 1991Co-Authors: Gohsuke Sugihara, Shigem Nagadome, Tamami Yamashita, Naomi Kawachi, Hiroyuki Takagi, Yoshikiyo MoroiAbstract:Abstract The aqueous solubility and critical micelle concentration (CMC) of dodecylammonium perfluorocarboxylates (trifluoroacetate, pentafluoropropionate, and heptafluorobutyrate) were measured, and the effects of the extent of hydrophobicity of counterion on solubility, CMC, and the Krafft Point (the micelle temperature range, MTR) were examined. The aqueous solubilities were smaller than those of ionic surfactants with the same dodecyl chain, and the enthalpy changes of dissolution into aqueous media, while positive, were also reduced. The Krafft Point of the butyrate was too high to be determined. From the dependence of CMC on counterion concentration, the-degrees of counterion association to micelle were deduced to be 0.83–0.93 for acetate ion and 0.98–1 for propionate ion. These higher values resulted in their lower CMC values. Thermodynamic parameters for micelle formation indicated substantial differences in micellar structure between acetate and butyrate counterions.
Xia Xin - One of the best experts on this subject based on the ideXlab platform.
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Property Prediction on Surfactant by Quantitative Structure‐Property Relationship: Krafft Point and Cloud Point
Journal of Dispersion Science and Technology, 2005Co-Authors: Yuxia Luan, Shiling Yuan, Xia XinAbstract:General empirical relationships have been developed for estimating the Krafft Point of anionic surfactants and cloud Point of nonionic surfactants using the quantitative structure‐property relationship (QSPR) method. For the Krafft Point, a six‐parameter structure‐property relationship (R2=0.941) was obtained for a diverse set of 46 anionic hydrocarbon surfactants and a three‐parameter relationship (R2=0.864) for 19 linear fluorocarbon anionic surfactants by employing topological, thermodynamic, and structural descriptors. For the cloud Point of 64 nonionic surfactants with six representative structures, the best multiple linear regression model involved five parameters and had a correlation coefficient of R2=0.921. From these relations Krafft Point or cloud Point of surfactants can be estimated based on their molecular structure.
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property prediction on surfactant by quantitative structure property relationship Krafft Point and cloud Point
Journal of Dispersion Science and Technology, 2005Co-Authors: Yuxia Luan, Shiling Yuan, Xia XinAbstract:General empirical relationships have been developed for estimating the Krafft Point of anionic surfactants and cloud Point of nonionic surfactants using the quantitative structure‐property relationship (QSPR) method. For the Krafft Point, a six‐parameter structure‐property relationship (R2=0.941) was obtained for a diverse set of 46 anionic hydrocarbon surfactants and a three‐parameter relationship (R2=0.864) for 19 linear fluorocarbon anionic surfactants by employing topological, thermodynamic, and structural descriptors. For the cloud Point of 64 nonionic surfactants with six representative structures, the best multiple linear regression model involved five parameters and had a correlation coefficient of R2=0.921. From these relations Krafft Point or cloud Point of surfactants can be estimated based on their molecular structure.
Liang Meng - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Performances of Quaternary Ammonium Cationic Surfactants with Dehydroabietyl Group
2000Co-Authors: Liang MengAbstract:N,N dimethyl N benzyl N dehydroabietyl ammonium chloride and N,N,N trimethyl N dehyroabietyl ammonium monomethyl sulfate were synthesized from dehydroabietyl amine. Their physical and interfacial properites, such as melting Point, Krafft Point, surface tension, emulfying ability, foaming ability were determined. The results showed they possess good surface activity and their germicidal ability are as good as alkyl quantery ammoniums cationic surfactants.
Jean-marie Aubry - One of the best experts on this subject based on the ideXlab platform.
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Amphiphilicity and salt-tolerance of ethoxylated and propoxylated anionic surfactants
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020Co-Authors: Estelle Illous, Jesús F. Ontiveros, Guillaume Lemahieu, Raphaël Lebeuf, Jean-marie AubryAbstract:Abstract The aqueous solubility of anionic surfactants is generally limited by their Krafft Point. However, the insertion of non-ionic spacers such as ethoxy or propoxy groups between the alkyl chain and the anionic head is known to improve the water solubility of these hybrid surfactants in pure water or the presence of electrolytes. In this work, the amphiphilicity of a series of ethoxylated or propoxylated sulfate surfactants is assessed by the PIT-slope method. Then, the phase behavior of these surfactants in concentrated aqueous solutions of NaCl or CaCl2 is investigated and compared with that of the typical nonionic (C12EO7) and ionic (SDS) surfactants. Surprisingly, sodium dodecyl sulfate presents a cloud Point at high salinities and temperatures. Adding ethoxy or propoxy groups greatly enhances the resistance to electrolytes due to the “disordered” structure of non-ionic spacers that hinders crystallization, leading to Krafft Point under 0 °C. Increasing the number of hydrophilic ethoxy groups increases the salt tolerance in contrast with the decrease observed with the slightly hydrophobic propoxy groups. Finally, the salt effect of CaCl2 and Ca(NO3)2. are compared Pointing out the salting-out effect of Cl- and showing a weak salting-in effect of Ca2+ on nonionics and its strong interaction with sulfate anionic function.
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Preparation, amphiphilic properties and lyotropic phase behaviour of new surfactants based on sodium monoalkyl α,ω-dicarboxylates
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006Co-Authors: Véronique Nardello, Nelly Chailloux, G. Joly, Jean-marie AubryAbstract:Abstract New surfactants based on sodium monoalkyl α,ω-dicarboxylates H 3 C(CH 2 ) n − 1 OC(O)(CH 2 ) m − 1 CO 2 Na (C n C m CO 2 Na) with various chain lengths were prepared from succinic anhydride ( m = 3), azelaic acid ( m = 8) and dodecanedioic acid ( m = 11). Their physico-chemical properties (Krafft Point, critical micelle concentration and kinetics of hydrolysis) were measured and their lyotropic aqueous phase behaviour was investigated by polarized light optical microscopy. To assess the influence of the ester function inside the hydrocarbon chain, sodium monoalkyl azelates and monoalkyl succinates were compared with sodium soaps ( m = 0) having a same carbon number. Insertion of an ester group within the surfactant alkyl chain considerably lowers the Krafft Point and slightly delays the formation of the first mesophase. The methylene units localized between the ester and the carboxylate groups are equivalent to 0.5 methylene group in their effect on CMC. The rate of hydrolysis of those monoesters depends heavily on the pH and on the CMC. The kinetics is fast and pseudo-first order below the CMC and it is slow and pseudo-zeroth order above the CMC because the ester function is protected from hydrolysis when it is embedded within the micelle core.
Reinhard Strey - One of the best experts on this subject based on the ideXlab platform.
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Solubility of sodium soaps in aqueous salt solutions.
Journal of Colloid and Interface Science, 2005Co-Authors: Bin Lin, Alon V. Mccormick, H. Ted Davis, Reinhard StreyAbstract:The solubility of sodium soaps in dilute aqueous salt solutions has been systematically investigated by direct visual phase behavior observations. The added electrolytes, including simple inorganic salts and bulky organic salts, influence the solubility of sodium soaps in water, as represented by the varied soap Krafft Point. Two inorganic salts, sodium chloride and sodium perchlorate, demonstrate a "salting-out" property. On the other hand, tetraalkylammonium bromides show an excellent ability to depress the soap Krafft Point and enhance the soap solubility in water. With increasing the tetraalkylammonium ionic size, the degree of "salting-in" of soaps in water increases. However, solubility of pure tetraalkylammonium bromide in water decreases as the length of the alkyl chains increases. Furthermore, in the ternary water-tetrapentylammonium bromide (TPeAB)-sodium myristate (NaMy) system, we observed an upper cloud Point phenomenon, which greatly shrinks the 1-phase micellar solution region in the phase diagram. This miscibility gap, together with the organic salt solubility limitation, restricts the use of tetraalkylammonium bromides with alkyl chains longer than 4 carbon atoms as effective soap solubility enhancement electrolytes. We also found that for sodium soap with a longer hydrocarbon chain, more tetrabutylammonium salt is required to reduce the soap Krafft Point to room temperature.
