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Micelle, interface

The prerequisite for templating is the presence of weak noncovalent interactions between the hydrophilic micelle interface and the precursor, so that the total interfacial energies of the resulting composite are lowered. Too strong interactions, as for example strong electrostatic ones, can lead to the... [Pg.284]

NaAOT-heptane and toluene-H20 reversed micelles Size-quantized CdS particles generated in situ in reversed micelles Low [H2Oj and reversed-micelle interface were important in controlling the size and polydispersity of CdS 617... [Pg.128]

The benzofuran epoxides 70 are found to be the most reactive epoxides functioning as alkylative agents. Polyunsaturated free fatty acids, namely linoleic, arachidonic, and eicosatrienic acids, and also their methyl esters have been epoxidized using lb <2006HCA2243>. When the reaction is performed in water, it has been found that due to supramolecular organization of fatty acids into a micelle, the C=C bonds closest to the aqueous-micelle interface are most prone to epoxidation. [Pg.656]

Critical micelle concentration ( >cmc is expected to decrease strongly with diminished diblock asymmetry rc as low rc values favor easier creation of highly curved micelle interfaces. Theory of micelle formation [231,260] also indicates that the overall copolymer degree of polymerization Nc, as well as the anchor -homopolymer interaction parameter %AP have to be considered to explain properly the onset of micelle segregation as observed by Shull et al. [260]. Using this theory, experimenters are able to choose systems where only individual copolymers segregate. [Pg.95]

This last observation deserves further consideration. Because any molecule exhibits a measurable volume, the parameter V is expected to be the most important variable in the MLR (Table 15.1) in comparison with other parameters, especially those representing specific interactions, properties that some of the solutes in the set might lack. If a three-compartment model can be invoked for the micelle structure (inner core, interface, and surface) as opposed to the Hartley model ( oil droplet, hydrophobic core encased by a hydrophilic region), remarkable differences in cavitation energy between the aqueous bulk and the micelle interface as well as between the aqueous bulk and the micelle inner core are anticipated. Thus, the parameter V coefficient in the MLR with the entire set of solutes is expected to be prominent as well. More importantly, the parameter V coefficient reflects an average behavior, that is, it is indicative of cavitation energy differences between a given micelle... [Pg.356]

These results can be explained by considering the electrostatic interactions between the cations, the structure of the AOT reversed micelle interface at varying co, and the transition states leading to the formation of the cyclobutane dimers. As mentioned above, p is the only photoproduct formed in studies with /V-octadecyl-trans-4-stilbazolium p-chlorobenzenesulfonate. This can be attributed to the packing constraints of the monomer within the crystal lattice. The fact that the ratio of p/a increases with decreasing co indicates that the way in which the stilbazolium monomer units pack at the interface is affected by to. [Pg.226]

Members of class I reduce the CMC. Shorter-chain members of the class are probably adsorbed mainly in the outer portion of the micelle close to the water-micelle interface. The longer-chain members are probably adsorbed mainly in the outer portion of the core, between the surfactant molecules. Adsorption of the additives in these fashions decreases the work required for micellization, in the case of ionic surfactants probably by decreasing the mutual repulsion of the ionic heads in the micelle. [Pg.146]

While the photosensitizer DCM serves as a probe into the micellar interior, DODCI provides a probe of a small region near the water-micelle interface. The time-resolved emission spectra for DODCI in TX-lOO, CTAB, and SDS above the critical micelle concentration showed a marked increase in the emission quantum yield (two to three times greater than in water). Also, a significant increase in the excited-state lifetime of DODCI was observed, from 0.70 ns in water to 2.25 ns in SDS, 2.36 ns in CTAB, and 2.55 ns in TX-lOO. The observations of increased fluorescence quantum yield are attributed to a decrease in the photoisomerization rate of DODCI as a result of the micellar environment. [Pg.655]

For AB-type polymers, the A-B junction point is taken at the micelle interface (Inoue et al., 910a,b), as before. The ends of the molecules are, admittedly, unrealistically placed for example, for spheres, the free end of the A block is at the center of the micelle and the bound end of the B block is constrained to a position on a sharply defined micelle spherical surface. Corresponding restrictions are placed on cylinder and lamellae formation. These assumptions, of course, lead to anomalous values for calculated densities, being high in the middle and low near the surface of the micelle. [Pg.136]

The subscripts ieS and ieM refer to the ion-exchange equilibria at the solution-stationary phase and the solution-micelle interface, respectively. The [C] concentrations are the counter anion concentration in the aqueous phase, aq, including added salts, and the one on the stationary phase, s. is the micellar counterion dissociation constant, (j) is the column phase ratio, [M] is the micellar concentration and k is the anion retention fector. Equation 13.6 obtained from ion-exchange equilibria resembles the classical Armstrong-Nome equation. The Pwm Partition coefficient of eq. 13.6 can be related to the KjeM constant by [30] ... [Pg.481]

Key words Force microscopy - self-assembly - double layer forces -micelles - interfaces... [Pg.232]

Figure 6 Top Cartoon illustrating locations of an organic substrate (see below), surfactant, colons, and counterions across a small cross section of a cationic micelle interface. Bottom Illustration of radial counterion distributions at three salt concentrations as described by the solution of the Poisson-Boltzmann equation in spherical symmetry (solid lines) and by the PIE model assuming that = 0.75, cmc = 0, and interfacial counterion concentration = 4 M (broken lines). A = 2.4 A, a typical assumed width of the reaction region in the PBE model. (Reproduced from Ref. 71 American Chemical Society, 1991.)... Figure 6 Top Cartoon illustrating locations of an organic substrate (see below), surfactant, colons, and counterions across a small cross section of a cationic micelle interface. Bottom Illustration of radial counterion distributions at three salt concentrations as described by the solution of the Poisson-Boltzmann equation in spherical symmetry (solid lines) and by the PIE model assuming that = 0.75, cmc = 0, and interfacial counterion concentration = 4 M (broken lines). A = 2.4 A, a typical assumed width of the reaction region in the PBE model. (Reproduced from Ref. 71 American Chemical Society, 1991.)...
Effect of Reverse Micelle Interfaces on the Entrapped Ionic Liquid Structure... [Pg.283]

A micelle comprises 50-100 molecules of surfactant and is approximately 40A across. The micelles form because the surfactant molecules orientate to remove the hydrophobic part as far as possible from the water and are stabilised at the water micelle interface by the electrical charge on the polar (hydrophilic) portion of the molecule. [Pg.106]


See other pages where Micelle, interface is mentioned: [Pg.2592]    [Pg.283]    [Pg.287]    [Pg.188]    [Pg.227]    [Pg.740]    [Pg.185]    [Pg.176]    [Pg.294]    [Pg.299]    [Pg.486]    [Pg.154]    [Pg.358]    [Pg.359]    [Pg.84]    [Pg.401]    [Pg.168]    [Pg.656]    [Pg.51]    [Pg.96]    [Pg.483]    [Pg.139]    [Pg.79]    [Pg.15]    [Pg.223]    [Pg.222]   
See also in sourсe #XX -- [ Pg.46 ]




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