Molecular Aspects of Mesophase Formation of Polymer Liquid Crystals As Revealed by ^2H NMR Analyzes and PVT Measurements

^2H NMR 分析和 PVT 测量揭示了聚合物液晶中间相形成的分子方面

• 批准号: 07405045
• 负责人: ABE Akihiro
• 金额: $ 16.13万
• 依托单位: Tokyo Institute of Polytechnics
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07405045/
• 关键词: mainchain liquid crystals; order-disorder transition; PVT properties; spacer conformation; conformational entropy; phase diagrams for binary mixtures; constant volume transition entropy; chiral spacers; エーテル型液晶; カーボネート型液晶

Our interest is to study the conformation and the thermodynamic role of flexible chains involved in an anisotropic environment. Mainchain-type liquid crystals (LC) involve flexible segments as a unit connecting two mesogenic cores. From the accumulated experimental data, transition entropies of such LCs at the nematic-isotropic interphase remain nearly invariant when divided by the number of spacers. Our study thus started from dimer and trimer model compounds having a spacer such as -O (CH_2)_nO- with n=9 and 10. These LCs can be synthesized with a precise constitution. Binary mixtures of these LCs allow us to investigate the effect of molecular weight distribution. The results of our research, supported by the Monbusho grant for a two-year period, are summarized as follows :1. The ^2H NMR analysis provided a technique to elucidate the orientational order parameter of the individual components of a given mixture. When dimer or timer LCs were dissolved in a monomer LC,the order paramet … More er of the mosogenic units of the former were found to be lower than those of the monomeric LC.In the mainchain-type LCs, bond angles conneting the mosogenic units to the spacer play an important role in determining the orientational order of the mosogenic core.2. The equation of state analysis (Flory's expression) indicated that the free volumes of the dimer and trimer LCs are about 20% of the core volume in the isotropic state just above the NI transition point. The volume changes at the NI transition were found to be about 10-20%.3. Combined use of the ^2H NMR and PVT measurements revealed that variation of the spacer conformation is largely responsible for the latent entropy at the NI as well as CN transitions. This observation immediately suggests that the stereochemical constitution of the spacer involved in the mainchain LCs effectively determines various thermodynamic properties of the system. Along this line, computer design of chiral-spacers is in progress in our laboratory. Some of them have been synthesized and tested. Less

我们的兴趣是研究的构象和热力学作用的柔性链在一个各向异性的环境。主链型液晶（LC）包括柔性链段作为连接两个介晶核的单元。从积累的实验数据，过渡熵的液晶在向列型各向同性界面时，保持几乎不变的间隔的数量划分。因此，我们的研究从具有间隔基如-O（CH_2）_nO-（n=9和10）的二聚体和三聚体模型化合物开始。这些LC可以以精确的组成合成。这些LC的二元混合物使我们能够研究分子量分布的影响。我们的研究结果，支持的Monbusho赠款为期两年，总结如下：1。^2 H NMR分析提供了一种技术，可以阐明给定混合物中各个组分的取向序参量。当二聚体或三聚体LC溶解在单体LC中时， ...更多信息 在主链型液晶中，键合单元与间隔基之间的键角在决定键合核的取向顺序中起着重要的作用.状态方程分析（Flory的表达式）表明，二聚体和三聚体LC的自由体积约为各向同性状态下核心体积的20%，刚好在NI转变点之上。发现NI转变时的体积变化约为10- 20%。结合使用^2 H NMR和PVT测量结果表明，间隔区构象的变化在很大程度上是NI和CN跃迁的潜熵的原因。这一观察结果立即表明，主链LC中的间隔基的立体化学结构有效地决定了系统的各种热力学性质。沿着这条路线，我们的实验室正在进行手性间隔区的计算机设计。其中一些已经合成和测试。少

项目成果

A.Abe: "Calculation of the Conformation Entropy of Dimer Liquid Crystals and Comparison with the Observed Transition Entropies at Constant Volume" Macromolecules. 28. 96-103 (1995)

A.Abe：“二聚体液晶构象熵的计算以及与恒定体积下观察到的转变熵的比较”大分子。

A.Abe, H.Furuya, N.Ichimura, and S.Kawauch: "Gas Phase NMR and ab Initio Molecular Orbital Calculations of 5-Methoxy-1,3-dioxanes : A Critical Survey on the Gauche Effect" J.Mol.Struct. (in press).

A.Abe、H.Furuya、N.Ichimura 和 S.Kawauch：“5-甲氧基-1,3-二恶烷的气相 NMR 和从头算分子轨道计算：对 Gauche 效应的批判性调查”J.Mol。

H.Furuya: "Dipole Moment and Optical Anisotropy Studies of Mesogenic Twin Compounds, α, ω-Bis【(4, 4'-cyanobiphenyl)oxy】alkanes" J. Phys. Chem.99. 6483-6486 (1995)

H.Furuya：“介晶孪晶化合物的偶极矩和光学各向异性研究，α, ω-双【(4, 4-氰基联苯)氧基】烷烃”J. Phys. 6483-6486 (1995)。

Y.Maeda: "High Pressure Differential Themal Analysis of Dimer Liquid Grystals : α,ω-Bis[(4,4′-cyanobiphenylyl) ox ylalkanes" Liquid Crysyals. 21. 365-371 (1996)

Y.Maeda：“二聚体液态晶体的高压差热分析：α,ω-双[(4,4′-氰基联苯基)氧基烷烃”，Liquisyals 21. 365-371 (1996)。

A.Abe and S.-Y.Nam: "PVT Studies on Dimer Liquid Crystals and Estimation of Transition Entropies at Constant Volume" Macromolecules. 28. 90-95 (1995)

A.Abe 和 S.-Y.Nam：“二聚体液晶的 PVT 研究和定体积过渡熵的估计”大分子。