Development of electrical conjugated polymers with liquid crystalline and magnetic properties

具有稳定自由基团的侧链液晶共轭聚合物有望借助液晶侧链的自发取向和外力宏观取向实现平行的自旋取向。本研究的目的是通过液晶取向来实现宏观的自旋排列，为此目的，侧链上带有LC基团和稳定自由基的二取代聚乙炔是有用的，在满足Ovchinnikov规则的拓扑立体规则的基础上，可以很容易地构建链内平行自旋排列。采用二叔丁基苯酚衍生物作为稳定的自由基前驱体，其中苯基的羟基部分由三甲基硅基保护。在TaCl5-(n-Bu)4Sn复分解催化剂作用下，用LC基团取代乙炔单体和自由基前驱体进行聚合。合成的聚合物可溶于有机溶剂，呈对映异构近晶相。对自由基前驱体进行去保护和氧化后，对聚合物的ESR自旋强度进行了评估，证实了由于LC侧链的自发排列而导致的自旋强度各向异性。然后，合成了单取代聚乙炔共聚物，其中LC基团或自由基团被取代到主链的单元格中。自由基多烯链段比例小于10%的共聚物在15 0~16 0ﾟC范围内为近晶相，随LC温度升高，ESR强度增大。这归因于苯氧基电子在LC结构域内的自旋排列。

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.