Liquid crystal poly(glycidyl ether)s by anionic polymerization and polymer-analogous reaction

Two new series of liquid crystalline poly(glycidyl ether)s I and II containing a side-chain 4-alkoxy-azobenzene mesogenic unit were prepared according to two different synthetic routes. The former were prepared by ring-opening anionic polymerization of different mesogenic epoxides, while the latter were prepared by grafting the same mesogenic side chain onto preformed poly(epichlorohydrin) to different substitution extents. Poly(glycidyl ether)s I formed a sequence of different smectic mesophases and nematic mesophases, depending on the length of the alkoxy tail. For poly(glycidyl ether)s II the kind of the phase behavior (not liquid crystalline, nematic, nematic and smectic) was strongly correlated with the extent of mesogenic side-chain incorporation with greater degrees of substitution favoring the onset of more stable and ordered mesophases. No smectic monolayer arrangement was observed, but only bilayer smectic structures, either S_A2 or S_C2, were detected by X-ray diffraction investigations on powder or magnetically aligned samples.