Polysiloxane textures

Fig. 4. Typical polysiloxane side-chain liquid crystal optical textures for (a) nematic, (b) cholesteric and (c) smectic A phases.

In an extensive work on polysiloxane polymer liquid crystals, Finkelmann et al. examined their performance in a twisted nematic electro-optical cell. In parallel with the polymer measurements, analogous studies were carried out on low molar mass nematic compounds of equivalent dielectric anisotropy (Ae). Both the low molar mass nematic materials and the polymer side-group moieties were mixtures of methoxy- (or alkyloxy-) and chlorine-terminated benzoate esters. Cells were prepared using rubbed polyimides and in the polymer case the samples were annealed for several hours to obtain defect-free aligned textures. Measurement of the threshold voltages, for both the low molar mass compounds and the polymer, showed ... 

In clinical practice, it has been observed that facial prostheses can cause irritation, abrasion and sometimes ulceration of the supporting tissues. If the tissue side of the facial prosthesis is left as a negative of the actual tissue texture, it will act as sandpaper as it abrades the tissue surface in function. Therefore, the tissue side of the prosthesis must be smoothed and polished to eliminate abrasion. In addition, the hydrophobic characteristics of polysiloxane... 

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