Development of electrical conjugated polymers with liquid crystalline and magnetic properties

具有稳定基团的侧链液晶共轭聚合物有望在侧链自发取向和外力宏观取向的帮助下提供平行的自旋取向。本研究旨在通过液晶取向实现宏观自旋取向，为此，侧链上带有液晶基团和稳定基团的二取代聚乙炔是有用的，其中链内平行自旋排列可以基于满足Ovchinnikov规则的拓扑立构规整性容易地构造。通过在侧链上引入液晶基团和稳定基团，合成了取代聚乙炔。二叔丁基苯酚衍生物，其中苯基的羟基部分被三甲基硅基保护，被采用作为稳定的自由基前体。用TaCl_5-（n-Bu）_4Sn复分解催化剂进行了LC基取代乙炔单体和自由基前体的聚合。合成的聚合物可溶于有机溶剂，并显示出对映近晶相。通过对自由基前体脱保护和氧化后的聚合物的ESR自旋强度的测定，证实了由于液晶侧链的自发排列导致的自旋强度的各向异性。在150 ~ 160 ℃范围内，自由基取代的多烯链段比例小于10%的共聚物为近晶相，ESR强度随液晶温度的升高而增强。这归因于LC畴内苯氧基自由基电子的自旋排列。

Side-chain liquid crystalline (LC) conjugated polymer with stable radical group is expected to afford a parallel spin alignment with aids of spontaneous orientation and externally forced macroscopic alignment of LC side chains. The present study is aimed to achieve a macroscopic spin alignment through LC orientation, For this aim, di-substituted polyacetylene with LC group and stable radical group in side chains is useful, where the intrachain parallel spin alignment can be easily constructed on the basis of topological stereoregularity satisfying Ovchinnikov rule.Di-substituted polyacetylene was synthesized by introducing both liquid crystalline LC group and stable radical group into side chains. Di-tert-butylphenol derivative, where the hydroxy moiety of the phenyl group was protected by trimethylsilyl group, was adopted as a stable radical precursor. Acetylene monomer substituted with the LC group and the radical precursor was polymerized using metathesis catalyst of TaCI_5-(n-Bu)_4Sn. The polymer synthesized was soluble in organic solvents and showed an enantiotropic smectic phase. ESR spin intensity of the polymer was evaluated after the radical precursor was deprotected and oxidized, Anisotropy in spin intensity, owing to spontaneous alignment of LC side chains, was confirmed.Next, the mono-substituted polyacetylene copolymer was synthesized, where either the LC group or the radical group was substituted into the unit cell of main chain. The copolymer, in which the ratio of radical group-substituted polyene segment is less than 10 %, showed a smectic phase in 150 - 160ﾟC.The ESR intensity increased in the LC temperature. This is ascribed to the spin alignment of phenoxy radical electrons within LC domains.