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Area per headgroup

These deviations were accounted by Strey et al.,8 who carried out experiments with the binary water—C12E5 system, by noting that the amplitude of the thermal undulations increased with the repeat distance d. If one considers the total area of the interface a constants which depends only on the number of surfactant molecules, the projection So of the total area on a plane perpendicular to d will decrease with increasing d. Hence, the apparent area per surfactant molecule, which is defined as the ratio between So and the total number of surfactant molecules, decreases with increasing d, while the ideal dilution law implies that the apparent area per surfactant molecule is a constant. The excess area, defined as AS = S — So, was related to the bending modulus of the interface,8 and the experimental results for the deviations from the ideal dilution law were used to determine. Kc-3,11 However, it should be noted that there are binary systems for which the deviations from the ideal dilution law occur in the opposite directions. For instance, in the binary systems of fatty acid alkali soaps/water, the apparent area per headgroup increases with water dilution, because of the incorporation of water in the interface.1... [Pg.314]

Recently it has been also shown that the surface tension of micellar solutions above the CMC can respond to the transition between spherical and rodlike micelles taking place in micellar solutions of certain surfactants in the presence of multivalent ions, such as Al [65], The qualitative explanation of this phenomenon is connected with the ability of ion to bind three surfactant headgroups, and, consequently, to lower the area per headgroup. According to Israelachvili et al., [11] this can induce a transition from spherical to rodlike micelles. On the other hand, the new micelles adsorb additional Al ions from the bulk. This leads also to a lower adsorption of Al at the solution-gas interface because the competitive adsorption of the counterions follows the same tendency as their bulk concentration. The desorption of Ap causes sharp increase of the surface tension with increasing molar ratio. [Pg.442]

Numerous attempts have been made to control these self-organized structures and to characterize their macro- as well as microscopic properties [18]. The effect of modifications in the surfactant structure (hydrophilic or hydrophobic group) and the impact of an additional component on mesophase behavior have been examined [19-22]. It has been suggested that the interfacial curvature that determines the phase behavior depends on the relationship between three elements tail volume, tail length, and area per headgroup. [Pg.91]

Solid (S). The headgroups are largely dehydrated. Pressure-area isotherms are linear. Extrapolation to zero film pressure results in an area per molecule that corresponds to the molecular cross-section. For example, lipids with two long-chain fatty acids occupy an extrapolated area of 41 A2, which corresponds to the cross-sectional area of the molecule [585],... [Pg.284]

Fig. 5 Film thickness, R, of films at the water surface and transferred films of pol5isoprenes with hydrophilic headgroups and different chain lengths, AT as a function of the surface concentration, njA (=inverse area per head group). The straight lines represent the theoretical film thickness derived from Eq. (1) in the regime of surface concentration between onset of the isotherm and collapse. (Filled symbols) films on the water surfaee. X-ray reflection [18] (open symbol Transferred films, X-ray reflection [19], ( +) film on water surface neutron reflection [20]... Fig. 5 Film thickness, R, of films at the water surface and transferred films of pol5isoprenes with hydrophilic headgroups and different chain lengths, AT as a function of the surface concentration, njA (=inverse area per head group). The straight lines represent the theoretical film thickness derived from Eq. (1) in the regime of surface concentration between onset of the isotherm and collapse. (Filled symbols) films on the water surfaee. X-ray reflection [18] (open symbol Transferred films, X-ray reflection [19], ( +) film on water surface neutron reflection [20]...

See other pages where Area per headgroup is mentioned: [Pg.190]    [Pg.94]    [Pg.95]    [Pg.74]    [Pg.314]    [Pg.479]    [Pg.36]    [Pg.452]    [Pg.429]    [Pg.205]    [Pg.216]    [Pg.317]    [Pg.114]    [Pg.119]    [Pg.120]    [Pg.94]    [Pg.254]    [Pg.190]    [Pg.94]    [Pg.95]    [Pg.74]    [Pg.314]    [Pg.479]    [Pg.36]    [Pg.452]    [Pg.429]    [Pg.205]    [Pg.216]    [Pg.317]    [Pg.114]    [Pg.119]    [Pg.120]    [Pg.94]    [Pg.254]    [Pg.468]    [Pg.808]    [Pg.47]    [Pg.55]    [Pg.185]    [Pg.368]    [Pg.392]    [Pg.52]    [Pg.74]    [Pg.33]    [Pg.96]    [Pg.130]    [Pg.1004]    [Pg.1005]    [Pg.392]    [Pg.59]    [Pg.68]    [Pg.47]    [Pg.55]    [Pg.813]    [Pg.466]    [Pg.142]    [Pg.199]    [Pg.217]    [Pg.531]    [Pg.89]    [Pg.90]    [Pg.27]   
See also in sourсe #XX -- [ Pg.442 ]




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Headgroup

Headgroup area

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