self-organization as a function of the length and position of the lateral polar chain and the length of the terminal alkyl chains. Depending on the size of the polar and lipophilic segments, a series of unusual liquid crystalline phases was detected. In three of these phases, the space is divided into three distinct periodic subspaces. In addition to a hexagonal channeled layer phase (ChL(hex)) consisting of layers
T 形多亲三嵌段分子,由棒状对三联苯单元、以 1-acylamino-1-deoxy-D-山梨糖醇单元封端的亲水且柔性的侧向连接的低聚(氧乙烯)链和两个末端连接的亲脂烷基组成链,已通过钯催化的交叉偶联反应合成为关键步骤。通过偏光显微镜、差示扫描量热法 (DSC) 和 X 射线散射研究了这些化合物的热致液晶行为。我们研究了自组织模式作为横向极性链的长度和位置以及末端烷基链的长度的函数。根据极性和亲脂性片段的大小,检测到一系列不寻常的液晶相。在这三个阶段中,空间被划分为三个不同的周期性子空间。除了由极性柱穿透的层组成的六边形通道层相(ChL(hex))外,还有由方形(Col(squ)/p4mm)或五边形圆柱体(Col(方)/p4gm)。圆柱壁由由烷基链柱稠合的三联苯单元组成,内部包含极性侧链。此外,观察到六方柱状相,其中极性柱在三联苯和烷基链的连续体中组织,三联苯核在柱周围切向组织,长轴垂直于
A New Type of Square Columnar Liquid Crystalline Phases Formed by Facial Amphiphilic Triblock Molecules
A series of three novel liquid crystalline amphiphilic molecules is reported which are composed of three incompatible molecular parts, a rigid terphenyl core, two lipophilic decyloxy chains in the terminal 4- and 4' '-positions, and a polar group in the lateral 2'-position. The polar group comprises a polyether chain, an amide group, and a polyhydroxyalkyl end group (1-acylamino-1-deoxy-d-sorbitol derivatives). The self-organization of these compounds was studied by polarized light microscopy, differential scanning calorimetry, and different X-ray diffraction techniques. These investigations confirm a novel liquid crystalline phase with a square 2D-lattice (square columnar mesophase, plane group p4mm). This structure is built up by a set of three distinct columns, namely columns containing the polar lateral groups, columns incorporating the alkyl chains, and ribbons of the rodlike terphenyl units. The calamitic cores form walls bounding square-shaped channels occupied by the microsegregated polar lateral chains. The lipophilic columns containing alkyl chains are at the corners interconnecting the aromatic rods end-to-end.