Disclinations electron microscopy

The textures in homeotropic lamellar phases of lecithin are studied in lecithin-water phases by polarizing microscopy and in dried phases by electron microscopy. In the former, we observe the La phase (the chains are liquid, the polar heads disordered)—the texture displays classical FriedeVs oily streaks, which we interpret as clusters of parallel dislocations whose core is split in two disclinations of opposite sign, with a transversal instability of the confocal domain type. In the latter case, the nature of the lamellar phase is less understood. However, the elementary defects (negative staining) are quenched from the La phase they are dislocations or Grandjean terraces, where the same transversal instability can occur. We also observed dislocations with an extended core these defects seem typical of the phase in the electron microscope. 

Figure 12. Electron microscopy—the layers are wound up into typical disclinations...

Fig. 7.19. Left The 180° slips in the grating structure ensure stability of the selected states as they pin the disclination lines. Right Scanning electron microscopy image of a surface grating showing the slips. The image also shows regions with different pitch gratings allowing for greyscale. Prom Jones,reproduced with kind permission of the Society for Information Display.

Optical measurements provide valuable information about alignment kinetics, and electron microscopy of aligned samples provides clues about the alignment process. Microtomed slices were taken fi om PS-PMMA block copolymer materials that were aligned in an electric field (far from the edges of the samples) [65]. Alignment was verified by SAXS. Some slice planes were parallel to the electrodes (parallel slices) and others perpendicular to the electrodes (perpendicular slices), as shown in Fig. 27. The slices were stained with ruthenium tetroxide and viewed with a transmission electron microscope. Several classes of defect structures were observed +1/2 disclination lines and defect walls were most prevalent, and... 

Hudson et al. 28 HBA/HNA Examined disclination defect density by electron microscopy and looked at in terms of skin-core morphology when filled with 20% glass. 

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