カチオン開環重合による立体規則性を有する液晶性脂環型ポリエーテルの合成

要旨

We have synthesized main-chain type liquid-crystalline alicyclic polyethers, <I>i. e.</I>, 2-substituted poly (4-oxycyclohexane) s, by cationic ring-opening polymerization of racemic 7-oxa-bicyclo [2.2.1] heptanes (OBH's) as monomer. Optically pure (+) -<I>exo</I>-2-phenyl-7-oxabicyclo [2.2.1] heptane ((+) -POBH) and (-) -POBH were separated by optical resolution on a silica gel column coated with cellulose phenylcarbamate. The optically pure monomers and monomer mixtures with various proportions were polymerized by Lewis acid catalysts in high vacuum. The NMR data suggested that stereoregular polymers were obtained from optically pure monomers. The poly ((+) -POBH) and poly ((-) -POBH) had a high specific rotation of +536°, suggesting that the polymers take a helix conformation. The stereoregularity of polymers from optically pure monomers was higher than that of polymers from mixture monomers. The optically pure polymers exhibited liquid crystallinity. These polymers showed a nematic phase in the temperature range from <I>T</I><SUB>g</SUB> (152-195°C) to approximately 310°C.

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