Lamellar structures transmission electron micrograph

Figure 10.8. Transmission electron micrograph of the lamellar structure of Fluoro-PSB-LX. 

Figures 9a-c represent transmission electron micrographs of different lyotropic liquid crystals after freeze fracture without etching. The layer structure of the lamellar mesophase including confocal domains, hexagonal arrangement of rodlike micelles within the hexagonal mesophase, as well as close-packed spherical micelles within the cubic liquid crystal can be clearly seen.

Figure 12 Cryo-transmission electron micrographs of vitrified thin films of lamellar phase (brine 0.5 M-SDS 9%-pentanol 7%). Dark lines correspond to the contrast produced by the surfactant membranes. Micrographs a-c display a lamellar order with a variable characteristic distance, which is interpreted as the sign of strong fluctuations of the membranes. Micrograph d displays a disorganized structure that could be due to a modification of the labile lamellar organization by shear or during specimen preparation. Bar = 100 nm. (From Ref. 136.)...

The lamellar structures exhibit poor thermal stability. Upon removal of the template by thermal treatment, the structure collapses resulting in a dense phase with little structural order or porosity. The lamellar phase can be stabiHzed by subsequent treatment using an alkoxide [36]. Removal of the template after this stabihzation treatment resulted in a structure having an X-ray diffraction pattern of only hOO peaks consistent with the lamellar configuration. The X-ray diffraction pattern is illustrated in Fig. 4. The transmission electron micrograph also shown in Fig. 4 is of uniform layers having an interlayer separation ( 40 A) consistent with the X-ray diffraction data. 

Fig. 4. The X-ray diffraction pattern, transmission electron micrograph, and the proposed structure of MCM-50 (stabilized lamellar phase)...

Figure 12.2 Transmission electron micrograph showing the edge-on lamellar structure of syndiotactic polypropylene crystallized on a carbon surface at 90 °C. The film thickness is about 50 nm. Reproduced with permission from [70], copyright 2013, American Chemical Society.

Figure 11 Transmission electron micrograph of area of normal guinea pig trachea showing a lamellar body in the hypophase of the mucus The source of these lipid structures is unknown. An alveolar origin as well as local secretion have both been proposed (see text magnification X 20,000).

Recent developments have allowed atomic force microscopic (AFM) studies to follow the course of spherulite development and the internal lamellar structures as the spherulite evolves [206-209]. The major steps in spherulite formation were followed by AFM for poly(bisphenol) A octane ether [210,211] and more recently, as seen in the example of Figure 12 for a propylene 1-hexene copolymer [212] with 20 mol% comonomer. Accommodation of significant content of 1-hexene in the lattice allows formation and propagation of sheaf-like lamellar structure in this copolymer. The onset of sheave formation is clearly discerned in the micrographs of Figure 12 after crystallization for 10 h. Branching and development of the sheave are shown at later times. The direct observation of sheave and spherulitic formation by AFM supports the major features that have been deduced from transmission electron and optical microscopy. The fibrous internal spherulite structure could be directly observed by AFM. 

When the mucous layer is appropriately preserved, it shows a smooth or slightly undulating surface, as shown in scanning electron micrographs (Fig. 8). By transmission electron microscopy, the top-most layer can be seen to be coated with an osmiophilic film (Fig. 9), which may appear multilayered (Fig. 10). Lamellar bodies and other lipid structures may be present in the sol layer (6,86 Fig. 11). The periodicity of these osmiophilic lamellae has been measured at approximately 40 A (6), suggesting structural homology with the alveolar lining layer. 

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