Contact angle between black film and bulk liquid

Abstract

The contact angles between black film and bulk liquid from aqueous solutions of NaLS are measured at different NaCl concentrations both by topographical and expansion methods. The contact angles increase about 10 times during the transition from first to second black films. The rate of expansion of the black films is studid; the critical thickness of the films by which black spots are formed coincide with the critical thickness of rupture. The data for the contact angles and for the kinetics of expansion of the black films are interpreted with the aid of the concept for the film tensi0n.l

Techniques in the Formation and Examination of “Black” Lipid Bilayer Membranes

“…The determination of () for aqueous soap films has been extensively discussed during the past few years, and several methods are available (Mysels et al, 1966;Princen, 1968;Kolarov et aI., 1968;Prins, 1969;Clint et al, 1969;Princen and Frankel, 1971). In principle, these methods may also be applied to lipid films, but in fact only an interference technique comparable to that of Kolarov et al (1968) has so far been described Kruglyakov et al, 1972;Requena, 1974). In this technique, interference fringes, arising from the illumination of the regions adjacent to the edge of the black film, are used to ascertain the profile of the oil-water interface, and hence the angle of this interface with the film.…”

“…20. These may be analyzed by the topographical method proposed by Scheludko (1967), and later applied by Scheludko et al (1968) and Kolarov et al (1968). Figure 21 illustrates the geometry of the border region.…”

A measurement of line tension in a common black soap film

“…In the light of this some alterations of the earlier described experimental technique (6)(7)(8) were made. In order to obtain measurable effect of the line tension on the contact angles we faced the problem to study films with too small radii.…”

Profile of the plateau border in a vertical free liquid film

“…We therefore thought it profitable to learn more about pressure and flows in Plateau borders, by extending the optical interference method developed by Scheludko et al (2)(3)(4)(5) and Haydon et al (9,10) for measuring contact angles in horizontal films, to vertical films, and to larger distances from the film into the Plateau border. EXPERIMENTAL Materials CTAB (cetyltrimethylammonium bromide, Sigma Chemical Co.).…”

“…Later studies of film thinning concentrated in most cases on contact angles at the transition film/Plateau border (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) and on the influence of surface waves on film drainage (18)(19)(20)(21)(22)(23). Thus, the paradoxes mentioned in the previous paragraph remained, to the knowledge of the present authors, unsolved.…”