Study on the Property of Liquid-Crystalline Polyoxetanes Containing Ion-Conducting Domains Controllable for Driving the Pendant Mesogens

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Thermotropic side-chain liquid-crystalline polyoxetanes containing a tri(oxyethylene) segment in the pendant spacer or tail were synthesized. The isotropic phase transition temperature (T_i) of the resultant polymers were remarkably lowered, e.g., T_i at 14.9 ℃ on cooling scan of differential scanning calorimetry (DSC) for a polymer with a -CH_2O(CH_2)_4O(CH_2CH_2O)_3-spacer and a methoxy tail, and showed a spherulitic texture by polarized optical microscopy (POM). When these polymers were mixed with LiClO_4 (an equimolar amount with respect to the oxyethylene unit), they showed DSC peaks, although the polymer with a methoxy tail only indicated a needle-like texture on heating and cooling scans, suggesting that the short tail did not hinder the mesophase formation, although the longer tails repulsed each other to hinder the mesophase formation, since width among mesogens was narrowed by formation of Li^+-oxyethylene complexes. Possibly the structure desired in this study was constructed, since the needle-like texture was ascribed to structural change in the mesophase domain. On the other hand, a polymer with a -O(CH_2CH_2O)_3-C_6H_4-p-F tail indicated no DSC peak and no POM texture above room temperature, and these results were not influenced by the presence and absence of LiClO_4. The polymer charged in a holder equipped with a voltage impression apparatus did not indicated any change in mesophase texture under impression of 1〜3V. This is ascribed to the fact that the polymer was so viscous that the polymer did not charged up to a full level of holder. A manuscript concerning the influence of the structural segments on the liquid-crystalline property was submitted to a Journal.