Intermediate ribbon phase

Ribbon phases have been the most comprehensively studied of the intermediate phases. They occur when the surfactant molecules aggregate to form long flat ribbons with an aspect ratio of about 0.5 located on two dimensional lattices of oblique, rectangular (primitive or centred), or hexagonal symmetry. Ribbon phases were first proposed by Luzzati [68,69] in aqueous sur-... 

Figure 4.S Phase diagram of binary water/ intermediate ribbon, distorted lamellar,...

Figure 5.43 Phase contrast optical micrographs of typical helical structures in chemically defined lipid concentrate system, (a) Low-pitch helical ribbon with pitch angle i r = 11 2°. (b) High-pitch helical ribbons with pitch angle t t = 54 2°. (c) Intermediate-pitch helical ribbons with pitch angle i r = 40.8 3.8°. Reprinted with permission from Ref. 162. Copyright 1999 by the National Academy of Sciences, U.S.A.

Phases with noncubic structures were first identified by X-ray scattering from aqueous soap mixtures [68, 69] and anhydrous soap melts in a series of papers by Luzzati and Skoulios [69-73]. In the first of these papers [68] the term intermediate was applied to a rectangular structure found in aqueous mixtures of potassium and sodium oleates and potassium laurate and pal-mitate. The structures found in the anhydrous soaps were reinterpreted as intermediate, tetragonal, rhombohedral, and ribbon structures in the paper by Luzzati and coworkers [74] in 1968. It was not until the early eighties that interest in these unusual phase structures was rekindled. 

Figure 8.41 Proposed structure of the ribbon-like units in the intermediate phases subwaxy, waxy, superwaxy, subneat of sodium soaps (Skoulios and Luzzati, 1961).

Kinetically controlled formation of helical mesoporous silica nanostructures correlated to a ribbon intermediate phase. RSCAdv., 1, 229-237. 

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