含胆甾基偶氮液晶聚合物的合成与表征

将合成的含偶氮基团的液晶单体M与含胆甾基团的手性液晶单体N接枝到含氢甲基硅油上，得到系列手性偶氮类侧链液晶聚合物PY₁~PY₆.利用红外光谱(IR)、核磁共振谱(¹HNMR)对其分子结构进行表征，采用差示扫描量热法(DSC)、偏光显微分析法(POM)、热重分析法(TG)对其介晶性能、相行为及热稳定性进行研究.结果表明，所合成的聚合物PY₁~PY₆为互变热致液晶，均呈现胆甾相的Grandjean织构.从PY₁到PY₆ 随着偶氮单体M含量的增加，t_g呈先降后升的趋势，而t_i则缓慢下降.该系列聚合物热稳定性良好，5%热失重温度在290℃以上，液晶区间在162~189℃之间.

Synthesis and Characterization of Azobenzene Liquid Crystalline Polymers Containing Cholesteryl Groups

The azo monomer 4-(allyloxybenzoyloxy)azobenzene-4′-ethyl formate(M)and chiral monomer 4-(allyloxybenzoyloxy)isopropionate cholesteryl(N)were grafted onto the backbone of polymethylhydrosiloxane. A new kind of azobenzene liquid crystalline polymers(PY₁~PY₆)containing cholesteryl groups was prepared. Their chemical structures were confirmed by FT-IR and ¹HNMR spectra， and mesomorphic properties， phase behavior and thermal stability were investigated by DSC， POM and TG. The results showed that PY₁~PY₆ are thermotropic cholesteric liquid crystal and display Grandjean texture. With the increasing content of M， t_g ascends after a decline， but t_i descends slowly. The temperatures when 5% weight loss occurred are higher than 290℃ and the mesomorphic temperature ranges are 162~189℃， which reveal that PY₁~PY₆ have a high thermal stability and remarkable liquid crystal properties.