Bilayer, curling

Micellar solutions are isotropic microstructured fluids which form under certain conditions. At other conditions, liquid crystals periodic in at least one dimension can form. The lamellar liquid crystal phase consists of periodically stacked bilayers (a pair of opposed monolayers). The sheetlike surfactant structures can curl into long rods (closing on either the head or tail side) with parallel axes arrayed in a periodic hexagonal or rectangular spacing to form a hexagonal or a rectangular liquid crystal. Spherical micelles or inverted micelles whose centers are periodically distributed on a lattice of cubic symmetry form a cubic liquid crystal. 

The lamellar—.hexagonal transformation of Zr02 is likely to be initiated first by the removal of some of the surfactant species, followed by the curling of the surfactant bilayer in order to minimize the surface/interface energy as shown in Fig. 4(a) and (b).13,15 The curled bilayers transform to cylindrical rods to further minimize the surface energy as shown in Fig. 4(c) and the cylindrical rods assemble to give the ordered hexagonal structure shown in Fig. 4(d). In order to examine... 

FIGURE 11.21 Schematic showing the bilayer actuator design, wherein one layer in the device contracts or expands upon oxidation-reduction resulting in a bending or curling type motion. 

Table III. Curling time (min.) of bilayer sheets from DMAEMA-BMA...

Other types of bilayer sheet made from DMAEMA and BMA can be prepared by using the same method and changing the two layer compositions. The pH-responsive behavior of one kind of bilayer sheet (Layer A DMABMA BMA=1/1 Layer B DMABMA BMA=l/4, both are in molar ratio) was examined in detail by placing the sheets in deionized water as shown in Figure 6. It can be seen that the bilayer began to curl very quickly. Since Layer A is more hydrophilic than Layer B, the sheet bent gradually until a circle was formed. The curling time, the time when... 

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