Supramolecular liquid crystals displaying competitive hydrogen bonding: Mesogenic associative chain structures using rigid and flexible pyridyl groups
Supramolecular liquid crystals displaying competitive hydrogen bonding: Mesogenic associative chain structures using rigid and flexible pyridyl groups
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DOI：
10.1080/15421406.2019.1685740
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发表时间：
2019-09
影响因子：
0.7
通讯作者：
E. A. John;Michael D. Heltne;Evan C. Bornowski;David J Lindberg;J. D. Carli;Seth B. Legare;John T. Carli;K. Wiegel
中科院分区：
文献类型：
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作者：
E. A. John;Michael D. Heltne;Evan C. Bornowski;David J Lindberg;J. D. Carli;Seth B. Legare;John T. Carli;K. Wiegel
摘要合成了一系列通过氢键形成的液晶超分子共聚物。这些聚合物由一个双苯甲酸和两个不同的吡啶物种组成-一个小的刚性双吡啶，当组装时能够形成中间相，以及一对柔性的双吡啶非介晶性“破坏者”物种之一。后一组分子由六个或十个亚甲基单元(分别为6BPD和10BPD)隔开的吡啶官能团组成。研究发现，缔合链状聚合物表现出与亚甲基间隔基长度相关的单向性特征。六亚甲基链产生近晶相，含量高达15%，在70%的载荷量下消除了向列相特征。当载量为5%时，十亚甲基团消除了近晶相，并出现了高达40%夹杂物的向列相。人们认为，烷基链长度的增加和柔性的增加允许太多的构象迁移率和自由度，从而在高浓度下有效地形成液晶相。
Abstract A series of liquid–crystalline supramolecular copolymers formed through hydrogen bonding has been created. These polymers are composed of a bis-benzoic acid and two different pyridyl species - a small rigid bispyridyl capable of forming a mesophase when assembled and one of a pair of flexible bis pyridyl non-mesogenic “disruptor” species. The latter set of molecules consist of the pyridyl functionality separated by six or ten methylene units (6BPD and 10BPD, respectively). It was found that the associative chain polymers display monotropic characteristics depending upon the length of the methylene spacer group. The hexamethylene chain produced smectic phases up to 15% composition and cleared nematic characteristics at 70% loading. The decamethylene species eliminated smectic phases at 5% loading and displayed nematic phases up to 40% inclusion. It is believed that the increased length and flexibility of the alkyl chain allows for too much conformational mobility and freedom to efficiently form liquid–crystalline phases at high concentrations.