含联苯基团热致液晶聚脲的合成与表征

Synthesis and characterization of thermotropic liquid crystal polyureas containing biphenyl group

为合成新型热致液晶聚脲 ,以含液晶基元的联苯二胺 (或联邻甲苯胺 )、1,6 -己二胺、2 ,4-甲苯二异氰酸酯为原料进行合成。通过改变单体加料顺序发现 ,仅当先加入己二胺与 2 ,4-甲苯二异氰酸酯预聚 ,再加入芳香二胺聚合 ,所得的聚合物才有液晶性。采用这种加料顺序 ,通过改变芳香 ,脂肪两种二胺的配比 ,合成了两个系列的热致液晶聚脲 ,并确定了合成热致液晶聚脲的最佳配比范围。所得聚合物用偏光显微镜 ,示差扫描量热分析 ,广角、小角 X射线衍射等方法进行表征 。

Two series of thermotropic liquid crystalline polyureas were synthesized by the copolymerization of benzidine (or o tolidine), 1,6 hexane diamine and 2,4 toluene diisocyanate. The resulting copolymers were thermotropic liquid crystals only when the 1,6 hexane diamine mole ratio was in a certain range and only by using aliphatic diamine with 2,4 diicocyanate to prepolymerize followed by the addition of aromatic diamine. The thermotropic liquid crystals were determined to be nematic using a polarizing microscope with a hot stage (POM), a differential scanning calorimeter (DSC), wide angle X ray diffraction (WAXD) and small angle X ray diffraction (SAXD).