Phase classification of side chain nematic polymers

Phase classification of side chain nematic polymers 

In the Ni phase, Sa 0, but SB 0. The conformation of the backbone chain is discus-like, i.e., is oblate shape, in which the mean square end-to-end distance along the director, (R%) is less than the perpendicular component (R%). In the smectic phase the anisotropy of two components is greater than that in the nematic phase. At the extreme case the backbone is surpassed in a plane, which was predicted by Renz Warner (1986) to exist in smectic polymers where backbones become confined between smectic layers formed by side chains, and has been seen by Moussa et al. (1987). In the extreme case, the backbone becomes a two-dimensional random walk when SB = — and Sa = 1. 

In the latter two phases backbones have the spindle-like conformation, i.e., the prolate shape with (R%) R p), the characteristic of main chain liquid crystalline polymers. Important means of investigating the conformations of side chain liquid crystalline polymers include small angle neutron scattering from deuterium-labeled chains (Kirst Ohm, 1985), or small angle X-ray scattering on side chain liquid crystalline polymers in a small molecular mass liquid crystal solvent (Mattossi et al., 1986), deuterium nuclear resonance (Boeffel et al., 1986), the stress- or electro-optical measurements on crosslinked side chain liquid crystalline polymers (Mitchell et al., 1992), etc. Actually, the nematic (or smectic modifications) phases of the side chain liquid crystalline polymers have been substantially observed by experiments. 

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