Mesophase lamellar liquid crystal model

Figure 2. Lamellar liquid crystal model of the carbonaceous mesophase 977) 38,19 ...

For liquid crystals [319 326] and reversed micellar solutions [319j324j325] it seems also appropriate to analyse the data in terms of a two-site model. The study of counterion binding in the hexagonal and lamellar mesophases of the three-component system cetyltrimethyl-ammonium bromide - hexanol - water [319 321 326] revealed for the lamellar phase a partial release of counterions from the lamellae with increasing hexanol concentration. Studies of solutions containing reversed micelles are exemplified in Fig. 5.10 for the hexanol-rich... 

Here a simple extension of the master equation method developed for macromolecules in solution [8.4, 8.22] is used to model correlated internal motions in liquid crystals. By explicitly generating all of the possible conformations in a mesogen and weighing these conformers according to their equilibrium probabilities imposed by the nematic mean field [8.12, 8.14], those improbable conformations that were obtained based on the assumption of independent rotations about different C-C bonds may be effectively eliminated. Thus, internal rotations about different axes are considered to be highly correlated. A similar approach has been used to model correlated internal motions in lamellar mesophases of lyotropic liquid crystals [8.20]. All of the studies still retain the simplifying assumption of decoupling internal rotations from the reorientation of the whole molecule. First, the decoupled model of correlated internal motions is considered. 

FIG. 12 Variation of structural parameters of model liquid crystal aggregates as a function of volume fraction of (pentanol + dodecane), p+d, as derived from X-ray diffraction data. (Top) Size of the nonpolar compartment. R p is the radius of the nonpolar core in the hexagonal mesophase Hi, and is the thickness of the nonpolar layer in the lamellar mesophase L . (Middle) Thickness of the hydrophilic mantle, tm. (Bottom) Available surface area per surfactant head group, a . Swelling lines 4PD ( ) 5PD (A) 6PD (o) 7PD ( ). These swelling lines correspond to the designation PD, where n-(10%) is the initial weight fraction of surfactant. Open symbols refer to Hj and filled symbols refer to the L phase. (From Ref. 38.)... 

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