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苯并菲类盘状液晶的合成以及应用研究

The Synthesis and Applications of Triphenylene-based Discotic Liquid Crystals

【作者】 张春秀

【导师】 王永生; 何志群;

【作者基本信息】 北京交通大学 , 光学, 2009, 博士

【摘要】 本研究合成了基于苯并菲基元的盘状液晶材料2,3,6,7,10,11-六戊烷氧基苯并菲、2,7-二乙酰基-3,6,10,11-四戊氧基苯并菲、一个系列的16种基于倾向于形成柱状相的盘状液晶基元苯并菲和倾向于形成向列相的氰基联苯的盘状-棒状分子、基于2,6,10-三羟基-3,7,11-三戊氧基苯并菲基元的超支化盘状聚酯和超支化盘状聚醚以及基于单羟基苯并菲和杯芳烃的一种新型的苯并菲-杯芳烃二聚体25,27-二羟基杯[4]芳烃-26,28-二(氧基戊酸)苯并菲酯;通过核磁共振氢谱(1HNMR)、核磁共振碳谱(13CNMR)、红外(IR)、元素分析确认了所合成化合物的结构,对所合成的超支化聚醚和聚酯进行了核磁和红外以及凝胶色谱测试,计算了超支化聚酯的支化度为0.85,说明超支化聚酯是高度支化的分子;并通过POM、DSC和XRD手段对各种化合物的液晶性能进行了表征;2,7-二乙酰基-3,6,10,11-四戊氧基苯并菲化合物呈现柱状液晶相并且可以保持至室温;通过三氧化二铝模板空间限制来控制盘状液晶2,3,6,7,10,11-六戊烷氧基苯并菲的取向,即将HAT5、甲基丙烯酸甲酯和二氯甲烷的溶液在三氧化二铝模板中、在受限空间中制备了纳米管;借助扫描电子显微镜观察发现所制备的纳米管的直径在150~200nm之间、纳米管的壁厚在20~30nm之间;XRD结果显示空间限制对盘状液晶的取向有一定的辅助作用;对于盘状-棒状分子的液晶性能进行了考察,发现这个系列分子的相行为相当复杂,存在着奇偶效应,棒状分子的行为更具有主导作用,在TNF的诱导下,盘状-棒状分子还会表现出柱状分子的堆叠特性;对超支化聚醚的液晶性能的考察发现,超支化聚醚具有液晶性,呈柱状相;超支化聚酯呈现向列相,有序性较差;25,27-二羟基杯[4]芳烃-26,28-二(氧基戊酸)苯并菲酯不具备盘状液晶性能,仅存在由结晶向液态的转变;最后,对2,3,6,7,10,11-六戊烷氧基苯并菲、2,7-二乙酰基-3,6,10,11-四戊氧基基苯并菲和超支化苯并菲聚酯三种液晶材料的光电导性能进行了测试。六戊醚耿代苯并菲的载流子迁移率最高为1.47x 10-4cm2v-1s-1;3,7,11-三戊氧基-2,6,10-三酯基苯并菲的载流子迁移率为1.1×10-4cm2v-1s-1;超支化苯并菲聚醚的薄膜的载流子迁移率低于测量范围,而未能被测试到;超支化苯并菲聚醚/六戊醚取代苯并菲以摩尔比1:1掺杂而制备的薄膜的载流子迁移率为5.74×10-5cm2v-1s-1。载流子迁移率的结果与在前面文献报道的要低1~2个数量级,但较之一般的电荷传输材料的载流子迁移率在10-(5)~10-6cm2v-1s-1,这个迁移率的数值应该高出了1~2个数量级。

【Abstract】 Different discotic liquid crystals based on triphenylene including 2,3,6,7, 10,11-hexapentaloxytriphenylene,2,7-dicarbetboxy-3,6,10,11-tetrapentyloxyt riphenylene,a series of triphenylene-based liquid crystals which combined one discotic-shaped mesogen and three rod-shaped mesogens through alkyl,two triphe nylene-based hyperbranched ester and ether macromolecule was synthesized and a triphenylene-calixarene compound named 25,27-2-calix[4]arene-26,28-2(-valerate) triphenylene ester were synthesized.The chemical structrures of these materials synthesized here were characterized by using IR,1HNMR,13CNMR,elernentary analysis.The molecular weights and the distribution of the two hyperbranched discotic ester and ether were also characterized by using GPC.The degree of thehyperbranched discotic ester was 0.85.The liquid crystalline properties of the materials synthesized here were characterized by using polarized optical microscopy,differential scanning calorimetry and x-ray diffractometry.2,7-dicarbetboxy-3,6,10,11-tetrapentyloxytriphenylene displayed columnar phase during cooling process at the temperature range from 99℃to 160℃and the columnar phase can be preserved even at room temperature. The series of triphenylene-based liquid crystals showed multi-mesomorphism withchanging the carbon atoms of the linked alkyl and odd-even effect and the odd-even effect should be the character of rod-like liquid crystal,it can be concluded that these disc-rod molecules behaved as rod-like and the triphenylene was only the linkage of the three rod-like moieties,but the columnar phase of sample with 11 carbon number spacer can be induced by TNF.The hyperbranched discoticether showed columnar phase that was disordered to some degree and the hyperbranched discotic ester showed nematic phase.25,27-2-calix[4]arene -26,28-2(-valerate) triphenylene ester showed only crystalline phase.We have fabricated poly methyl methacrylate /2,3,6,7,10,11- hexapentaloxytrip henylene composite nanotubes by wetting an ordered porous anodic alumina temp late.The nanotubes formed by the template were characterized by SEM and XR D showed that the nanotubes had a diameter distribution from 150-200nm and the thickness of the walls of the nanotube is 20-30nm.The results showed that the geometric confinement can promote the growth of the discotic liquid crystal columns along the long axes of the nanotube.The charge carrier mobilities of 2, 3,6,7,10,11-hexapentyloxytriphenylene,2,7-dicarbetboxy-3,6,10,11-tetrapentyloxytriphenylene, the hyperbranched ester and the composite of 2,3,6, 7,10,11- hexapentyloxytriphenylene and the hyperbranched ester were measured using time-of-flight method and they were 1.47×10-4cm2v-1s-1,1.1×10-4cm2v-1s-1, 5.74×10-4cm2v-1s-1,respectively.The results were lower 1-2 magnitude than those reported in other references due to the lower orientational orders of these discotic molecules in the film,but they also higher 1-2 magnitude than general hole transport molecules with a charge carrier mobilities of 10-5-10-6 cm2v-1s-1.

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