中文摘要：

离子表面活性剂的头基化学对其所形成的离子液晶的性能有重要影响。合成了一种新型的头基附近含3个羟基基团的季铵盐表面活性剂N,N,N-三（2-羟乙基）-N-十二烷基溴化铵（简写为THDAB）,并用热重分析（TG）、差热扫描量热法（DSC）、原位X射线粉末衍射（XRD）和偏光显微镜研究了其所形成的热致液晶相的性能。结果表明,THDAB可以在很宽的温度区间范围内（至少为96.9℃）形成近晶A相液晶（SmA相）。在液晶层内疏水链相互交错并呈周期性排列,层间距为3.06nm,极性层的厚度为1.39nm。分子结构中羟基的存在促使THDAB的SmA相的温度区间向低温延伸了近30℃且在最高温度160℃仍处于液晶区间。由此可见,多个羟基的存在对于液晶相的形成与稳定起着重要作用。

英文摘要：

The head group chemistry of ionic surfactants has a tremendous effect on the properties of the ionic liquid crystals formed.A new kind of quaternary ammonium surfactant with the head group containing three hydroxyl groups,namely N,N,Ntris（2-hydroxyethyl）-N-dodecylammonium bromide（abbreviated as THDAB）,has been synthesized.Its thermotropic liquid crystal properties were investigated by TG,in-situ XRD and polarizing microscopy.The results showed that THDAB can form the smectic A phase in a wide range of temperature（at least 96.9℃）.The interlamellar spacing is 3.06nm and the thickness of the polarized layer is 1.39nm.Hydroxyl groups in THDAB molecule lower the temperature range of SmA phase by nearly 30℃and the liquid crystal phase is still existing at the highest temperature 160 ℃.Obviously,the existence of multiple hydroxyl groups plays an important role in the formation and stabilization of liquid crystal phases.