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  • 1
    Electronic Resource
    Electronic Resource
    Rheology of Cetyltrimethylammonium Tosylate-Water System. 1. Relation to Phase Behavior (1995)
    s.l. : American Chemical Society
    Langmuir 11 (1995), S. 3337-3346 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00009a013
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  • 2
    Electronic Resource
    Electronic Resource
    Rheological behavior in the didodecyldimethylammonium bromide/water system (2000)
    Springer
    Colloid & polymer science 278 (2000), S. 37-47 
    Details
    ISSN: 1435-1536
    Keywords: Key words Vesicles ; Lamellar liquid crystals ; Viscoelasticity ; Thixotropic-antithixotropic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The phase behavior in the dilute region of the didodecyldimethylammonium bromide (DDAB)/water system is studied with a battery of techniques. The critical vesicle concentration (cvc), measured by tensiometry, conductimetry, ion-selective-electrode potentiometry and dye solubilization, is similar to the value reported in the literature. Moreover, the combination of surfactant-ion-selective- electrode and bromide-ion-selective-electrode potentiometry indicates that the vesicles are substantially ionized (α ≈ 0.5) in the proximity of the cvc. The transition from small unilamellar vesicles to larger multilamellar liposomes was detected at 0.2 wt% by viscometry, conductimetry and dye solubilization measurements. The rheology of the DDAB/water system was studied as a function of surfactant concentration and temperature. Non- Newtonian behavior, viscoelasticity, yield stresses and time-dependent flow behavior were observed. Maxima and minima in the dynamic moduli and in conductivity are related to structural changes and phase transitions. Moreover, in time-dependent shear flow, the microstructure is modified and the rheological response shifts from thixotropic to antithixotropic or vice versa, depending on the DDAB concentration and the level and duration of the final applied stress. The conductivity behavior in the Lam1 phase region can be qualitatively explained by the capillary superconductivity theory. This conductivity behavior occurs when the thickness of the aqueous lamella is of the same order of magnitude as the Debye length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050006
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  • 3
    Electronic Resource
    Electronic Resource
    The aggregation of the sodium dodecyl sulfate –n - octanol–water system at low concentration (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 735-742 
    Details
    ISSN: 1435-1536
    Keywords: Key words Mixed micelles ; Octanol ; Sodium dodecyl sulfate ; Surfactants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Micelle formation in sodium dodecyl sulfate (SDS)–n-octanol mixtures was studied by several techniques and the results were interpreted using regular solution theory for mixed-micelle formation. Octanol was considered as a nonionic surfactant. The composition of micelles at the critical micelle concentration (cmc) was computed together with the interaction parameter and the activity coefficient of the components of the micelles. The fluorescence quenching technique with pyrene was employed to obtain the SDS and octanol aggregation numbers at the cmc. The results were in agreement with similar studies on other alcohol–SDS systems. At the cmc spherical, almost fully ionized micelles formed, while at a higher concentration there was a transition to anisometric (probably rodlike) micelles which pushed sodium counterions into their Stern double layer. Mixed anisometric micelles were more ionized than pure SDS micelles. When the octanol:SDS total ratio exceeded 0.85:1, an emulsion of octanol appeared in equilibrium with the micelles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050447
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  • 4
    Electronic Resource
    Electronic Resource
    Hydration of dodecyltrimethyl- ammonium hydroxide micelles (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 396-399 
    Details
    ISSN: 1435-1536
    Keywords: Key words Micelles ; hydration ; hydroxide surfactants ; cationic surfactants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The hydration of dodecyltrimethylammonium hydroxide (DTAOH) micelles was determined by viscosity measurements, giving 39.2±7.0 water molecules per micellized dodecyltrimethylammonium ion. This result is lower than the hydration of DTAB micelles, which is about 65. This difference may be due to the effect of the electrorestrictive structure-making hydroxide ion on the hydration of the alkyltrimethylammonium head group, in comparison with the less hydrated structure-breaking bromide ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050097
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of surfactant charge on micellization behavior (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 754-759 
    Details
    ISSN: 1435-1536
    Keywords: Key words Micelle charge ; alkanephosphonates ; cmc ; micellization ; micelle composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The influence of the surfactant charge on micellization was studied on sodium n-dodecane-phosphonates, varying the charge of the surfactant ion from 0 to 2. The effects on the cmc, hydrolysis, micelle composition, and micelle ionization degree were studied. The increase of one e unit in the charge of the surfactant species reduces the cmc by about one order of magnitude.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050144
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  • 6
    Electronic Resource
    Electronic Resource
    Zeta potential of dodecyltrimethylammonium hydroxide micelles in water (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 802-805 
    Details
    ISSN: 1435-1536
    Keywords: Key words Micelles ; zeta potential ; micellar electrophoresis ; electrophoretic mobility ; micelle ionisation degree
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The electrophoretical mobility of dodecyltrimethyl-ammonium hydroxide micelles has been measured at two different concentrations giving values similar to that determined in other surfac-tants. There is a good agreement between micelle ionization degrees computed from zeta potential measurements and those from ion-selective electrodes experiments. This demonstrates that electrophoresis experiments may be replaced by the simpler ion-selective electrode measurements to determine micelle surface potential. It has also been concluded that ion-selective electrodes detect only the non-micellised ions, that only free ions contribute to the intermicellar solution ionic strength, and micelles do not affect the result, and that the dependence of the electrophoretic mobility on the soap concentration is due to the reduction of the micelle net charge when the ionic strength of the intermicellar solution arises.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050151
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  • 7
    Electronic Resource
    Electronic Resource
    Emulsification properties of chitosan (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 1159-1165 
    Details
    ISSN: 1435-1536
    Keywords: Key words Chitosan ; HLB ; food emulsions ; cationic polyelectrolytes ; multiple emulsions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The chitosans use as an emulsifier in food emulsions was explored. The properties of chitosan (air/solution surface activity, electrical conductivity, HLB) were studied. The obtained emulsions were stable multiple w/o/w emulsions, whose characteristics were explained on the basis of the emulsifier structure and solution properties. The reaction with an anionic surfactant, sodium dodecylsulfate, was also studied, giving a water-insoluble complex at a given surfactant/chitosan ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050359
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  • 8
    Electronic Resource
    Electronic Resource
    Aggregation effects on evaporation and the air/water interface of dodecyltrimethylammonium hydroxide solutions (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 232-238 
    Details
    ISSN: 1435-1536
    Keywords: Key words Dodecyltrimethyl-ammonium hydroxide ; soluble monolayer ; air/water interface ; evaporation ; ion-selective electrodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The system dodecyltrimethylammonium hydroxide (DTAOH)–water was studied by surface tension, ion-selective electrodes and evaporation in an electrobalance. Results confirmed earlier conclusions about a stepwise aggregation mechanism in DTAOH solutions. The aggregation process started at a total concentration C T=(2.51±0.10)×10-4 mol dm-3) which probably corresponds to the formation of dimers. At C T= (1.300±0.041)×10-3 mol dm-3 there was a change in the surface and evaporation behavior, corresponding to the formation of small, fully ionized aggregates which grew with increasing concentration. At C T= (1.108±0.010)×10-2 mol dm-3 the formation of true micelles with hydroxide counterions in the Stern layer did not change significantly the evaporation and adsorption behavior. This means that between this concentration and C T=(3.02±0.28)× M28.8n10-2 mol dm-3, the changes in structure were gradual. At the latter concentration there was a sudden change in the monolayer state at the air/water interface, with a strong surfactant desorption, and a major change in evaporation behavior. The changes are compatible with the formation of few, large aggregates reducing the total concentration of kinetically independent solute units, which in turn increased the activity of the solvent. This phenomenon is in agreement with literature information. The reduction in the evaporation rate of water was mainly due to the reduction of the water activity, caused by colligative effects. The reduction of the effective area available for evaporation had only a slight effect in water evaporation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050233
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  • 9
    Electronic Resource
    Electronic Resource
    Partial molar volume of dodecyltrimethylammonium hydroxide in water and NaOH aqueous solutions (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 738-742 
    Details
    ISSN: 1435-1536
    Keywords: Key words Hydroxide surfactants ; micelles ; partial molar volume ; Dodecyltrimethylammonium hydroxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The partial molar volume of dodecyltrimethylammonium hydroxide in water and aqueous NaOH solutions was measured. The addition of NaOH did not affect either the micellized or the unmicellized molecules. The expansion on micellization is much larger than in dodecyltrimethylammonium bromide systems, which reflects the stronger ionization of the hydroxide surfactant micelles, when compared with that of the bromide amphiphile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050304
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  • 10
    Electronic Resource
    Electronic Resource
    Distribution of emulsified monomers with different water solubility (1990)
    Springer
    Colloid & polymer science 268 (1990), S. 778-785 
    Details
    ISSN: 1435-1536
    Keywords: Monomersdistribution ; micellarphase ; emulsioncopolymerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The location and distribution of acrylic acid and styrene in emulsions made with a cationic surfactant, cetyltrimethylammonium bromide (CTAB), or an anionic surfactant, sodium dodecylsulfate (SDS), were determined with ultra-violet spectroscopy, conductivity, and potentiometry. In these systems, the acrylic acid remains in the aqueous phase near the micelle surface, whereas the styrene is located in the micelles or in emulsified droplets. In the absence of acrylic acid, some of the styrene is solubilized in the micelle interior and some is adsorbed at the micelle inner surface. Upon addition of acrylic acid, all the styrene is displaced to the center of the micelles. The interaction between acrylic acid and CTAB micelles is stronger than that between acrylic acid and SDS micelles. With CTAB, acrylic acid is adsorbed at the micelle surface, whereas with SDS, acrylic acid remains in the intermicellar solution. These differences can account for the differences reported in the emulsion copolymerization of acrylic acid and styrene using CTAB or SDS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411110
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