液晶聚氨酯的合成及性能研究

以1,4-双(三甲基硅氧基)苯、对羟基苯甲酰氯为原料合成1,4-双(对羟基苯甲酸)苯酯(I),将(I)分别与3-溴丙醇、4-溴丁醇等反应合成一系列的1,4-双(对羟基烷氧基苯甲酸)苯酯(Ⅱ),(Ⅱ)再分别与2,4-TDI、MDI反应制得液晶聚氨酯。并用差热扫描量热分析仪(DSC)、红外光谱(IR)、偏光显微镜(POM)对液晶聚氨酯进行了表征。结果表明,所得聚氨酯产物在144~260℃均为热致性向列型液晶,其熔点(Tm)和清亮点(Ti)随着分子链柔顺性的增加而下降。

Synthesis and Properties of Liquid Crystal Polyurethanes

1,4-Bis(p-hydroxybenzoate) phenylene was prepared using 1,4bis(trimethylsiloxy) benzene and p-hydroxybenzoyl chloride as starting materials.A series of novel 1,4-bis(p-hydroxyalkoxybenzo-ate) phenylene were synthesized by reaction of 1,4-bis(p-hydroxybenzoate) phenylene with 3-bromopropanol and 4-bromobutanol respectively.The liquid crystal polyurethanes were prepared by 1,4-bis(p-hydroxyalkoxybenzoate) phenylene with MDI and 2,4-TDI respectively.The thermotropic properties,the melting point(T_(m)) and the isotropization temperature(T_(i)) of the synthesized polyurethanes were characterized by DSC,IR and POM.It showed that all of the polyurethane polymers exhibited thermotropic liquid crystalline properties between 144℃and 260℃.The transition temperature(T_(m) and T_(i)) decreased with an increase in the length of the methylene spacer.