Thermotropic Liquid Crystalline Polyimides with Siloxane Linkages: Synthesis, Characterization, and Liquid Crystalline Behavior
Thermotropic Liquid Crystalline Polyimides with Siloxane Linkages: Synthesis, Characterization, and Liquid Crystalline Behavior
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DOI：
10.1021/ma9021828
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发表时间：
2010-02
期刊：
影响因子：
5.5
通讯作者：
Yu Shoji;R. Ishige;Tomoya Higashihara;J. Watanabe;M. Ueda
中科院分区：
文献类型：
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作者：
Yu Shoji;R. Ishige;Tomoya Higashihara;J. Watanabe;M. Ueda
热致液晶 (LC) 半脂肪族聚酰亚胺是由含有硅氧烷间隔单元的二胺与均苯四甲酸二酐 (PMDA) 或 3,3',4,4'-四羧基联苯二酐 (BPDA) 开发而成。具有硅氧烷单元的单体二胺通过三个步骤制备，包括威廉姆森合成、氢化硅烷化和还原。聚合通过常规方法、溶液聚合、随后热酰亚胺化进行。得到高粘度聚酰胺酸溶液，其比浓对数粘度为0.65−1.73 dL/g。与已报道的含有亚烷基或氧乙烯间隔单元的聚酰亚胺相比，这些新型聚酰亚胺表现出高热稳定性和较低的晶体液晶转变温度。进行X射线研究以研究每种聚酰亚胺的定向近晶中间相。在衍生自 PMDA 的聚酰亚胺中，从各向同性液相逐渐冷却时形成近晶 A (SmA) 相。另一方面，聚酰亚胺...
Thermotropic liquid crystalline (LC) semialiphatic polyimides have been developed from diamines containing siloxane spacer units with pyromellitic dianhydride (PMDA) or 3,3′,4,4′-tetracarboxybiphenyl dianhydride (BPDA). Monomer diamines with siloxane units were prepared by three steps, which include Williamson’s synthesis, hydrosilylation, and reduction. The polymerization was conducted by the conventional method, solution polymerization, followed by thermal imidization. A highly viscose poly(amic acid) solution was obtained and its inherent viscosities were 0.65−1.73 dL/g. These novel polyimides exhibited high thermal stability and a lower crystal-LC transition temperature compared to reported polyimides containing alkylene or oxyethylene spacer units. X-ray studies were performed for investigating the oriented smectic mesophases of each polyimide. In the polyimides derived from PMDA, a smectic A (SmA) phase was formed on gradual cooling from the isotropic liquid phase. On the other hand, the polyimides ...