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  • critical micelle concentration  (6)
  • aggregation  (3)
  • 1
    Digitale Medien
    Digitale Medien
    Counterion specificity of the micelle surface and its implications on micellar catalysis (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 662-668 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Micellar catalysis ; critical micelle concentration ; micellization ; counterion distribution constants ; hydroxide surfactants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Dodecyltrimethylammonium bromide — Dodecyltrimethyl-ammonium hydroxide — water mixtures were studied with ion-selective electrodes, and the aggregation behavior, degree of ionization of the micelles and the distribution constants of bromide and hydroxide ions between water and micelles were found, showing that some suppositions about the interpretation of micellar catalysis are incorrect, and these interpretations must be revised. The results support the mass action model for the theoretical treatment of micellar catalysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00653065
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  • 2
    Digitale Medien
    Digitale Medien
    The aggregation in dodecyltrimethylammonium hydroxide aqueous solutions (1995)
    Springer
    Colloid & polymer science 273 (1995), S. 959-966 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Hydroxide surfactants ; critical micelle concentration ; aggregation ; cationic surfactants ; micelle charge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The aggregation of dodecyltrimethylammonium hydroxide (DTAOH) aqueous solutions has been studied by several methods. It is stepwise and four critical points were found. AtC T=(2.51±0.10)×10−4 mol · dm−3 the surface excess becomes zero, atC T=(1.300±0.041)×10−3 mol · dm−3 small aggregates from, which grow with concentration. AtC T=(1.108±0.010)×10−2 mol · dm−3 true micelles form (CMC) and at (3.02±0.28)×10−2 mol · dm−3 the structure of micelles probably changes affecting their properties. The DTAOH micelles are highly ionized (α=0.8) at the CMC, and decreases to reach very small values when the total concentration increases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00660374
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  • 3
    Digitale Medien
    Digitale Medien
    The aggregation ofn-dodecanephosphonic acid in water (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 1089-1093 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Micelles ; critical micelle concentration ; dodecanephosphonic acid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Several techniques were employed to study the aggregation ofn-Dodecanephosphonic Acid (DPA) in water. At 22°C, the solubillity of DPA increases, probably due to the formation of small premicellar aggregates. The CMC is (5.4±2.4) ×10−4 mol·dm−3 and the solubility reaches the CMC value at 26°C. At 30°C and at a concentration of about 9×10−3 mol·dm−3, a lamellar mesophase appears. Both micelles and liquid crystal lamellae are almost uncharged. Their polar heads have strong hydrogen bonds between them. The ionization of DPA molecules in micelles and mesophase structures is strongly reduced in comparison with monomerically dissolved molecules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00658374
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  • 4
    Digitale Medien
    Digitale Medien
    The aggregation of aqueous dodecylphosphonic acid in dodecyltrimethylammonium hydroxide mixtures (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 669-677 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Dodecanephosphonic acid ; dodecyltrimethylammonium hydroxide ; mixed micelles ; critical micelle concentration ; aggregation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The aggregation of aqueous dodecylphosphonic acid (DPA) and dodecyltrimethylammonium hydroxide (DTAOH) mixtures was studied by several methods. The behavior of DPA-rich mixtures is close to that of pure DPA. This is probably due to the preservation of the hydrogen-bonded structure of the micellar headgroup layer. The behavior is almost ideal. Betweeny DPA =0.5 and 0.33 (y DPA being the mole fraction of DPA in the surfactant mixture), the hydrogen-bonded structure of the micellar headgroup layer is destroyed. A sort of “micellar azeotrope” is formed, and the maximum of non-ideal interaction between the two surfactants is attained aty DPA =0.4. Fory DPA 〈0.33 the system behaves as a common mixture of a cationic surfactant and a non-ionic one (DPA.2LTA). There is a phenomenon of counterion “condensation” on aggregates at concentrations over the CMC.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00653066
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  • 5
    Digitale Medien
    Digitale Medien
    The effect of NaOH on dodecyltrimethylammonium hydroxide aggregation in aqueous solutions (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 854-859 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Hydroxide surfactants ; critical micelle concentration ; aggregation ; cationic surfactants ; counterion effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The aggregation of dodecyltrimethylammonium hydroxide (DTAOH) in aqueous NaOH solutions was studied as a function of NaOH concentration. As in NaOH-free DTAOH aqueous solutions, the surfactant underwent a stepwise aggregation mechanism. Changes in the structure of aggregates produced an increase of the concentration at which premicellar aggregates could solubilize hydrophobic dyes and also in the concentration at which hydroxide inons join the aggregates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00654743
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  • 6
    Digitale Medien
    Digitale Medien
    Study of the required HLB for the solubilization of cholesterol in aqueous solution (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 87-91 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Key words Cholesterol ; solubilization ; HLB ; mixed micelles ; emulsions ; critical micelle concentration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract  The solubilization of cholesterol by anionic surfactant mixtures was studied as a function of their HLB values. The relationship between the logarithm of the critical micelle concentration and the HLB value of the mixtures was not linear, which was attributed to a lack of strict additivity of the HLB values. The solubilized cholesterol/surfactant ratio was determined and it was found to be higher than that in bile salts in all the studied surfactant mixtures. Below HLB=24, emulsions were obtained, and the remaining cholesterol was solid. Above that value, limpid solutions were obtained, giving a solubility maximum at HLB≈35. The non-solubilized cholesterol was mainly in the form of lamellar mesophase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003960050213
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