Development and Dynamics of Liquid Crystalline Structures Studied by Heterodyne Dynamic Light Scattering Spectroscopy

外差动态光散射光谱研究液晶结构的发展和动力学

• 批准号: 07651108
• 负责人: TSUNASHIMA Yoshisuke
• 金额: $ 1.41万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 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-07651108/
• 关键词: Heterodyne method; Lyotropic liquid crystals; Dynamic light scattering; Cellulose acetates; Dimethylacetamide; Selfassembly; Conformational transition; 形態転移; トリフルオロ酢酸; ジメチルホルムアミド; 液晶形成臨界濃度; みみず鎖; セルフアセンブルー

The transition from the isotropic to anisotropic phase occured in lyotropic liquid crystalline polymers such as celllulose acetates were examined in view of the polymer chain stiffness, the chain dynamics, and the intermolecular associations which depend strongly on the polymer concentration in solution and on the solvent quality. The critical concentration v_2 where the lyotropic liquid crystals (LLC) appear was 24-26wt% for cellulose triacetates (CTA,degree of substitution DS=2.9) and higher for cellulose diacetates (DS=2.40) in trifluoroacetic acid (TFA), whereas in demethylacetamide (DMAc) v_2 was more than 50wt% for CTA and 45wt% for CDA.LLC was never observed for CTA in chloroform and for CDA in dimethylformamide. The difference in v_2 with solvents indicates that CTA and CDA take a molecular conformation specific to the solvent. Indeed, the chain stiffness of CTA and CDA analyzed on the basis of the wormlike chain model revealed that they are semiflexible chains with q=10 and 8 … More nm in TFA and DMAc, respectively, and flexible chains in other solvents. Here q is the persistence length which represents the chain stiffness. Dynamic light scattering measurements for CDA fractions in DMAc in the dijute and semidilute solution regions showed that the CDA single molecule coexists with the intermolecular associations which may be formed with the hydrogen bonding between the intermolecular C-6 position OHs in the glucose unit. The CDA association was in two states, the selfassembly of four (State II) and 13-40 (State III) times as long as the single CDA chain. State II transformed to State III with increasing the CDA concentration. In addition, State III took three states, depending on the CDA concentration ; a long rigid-like structure and two huge structures, the latter being not so rigid and long as the former. The former long-rigid structure is considered to be a prototype of LLC formed by CDA in DMAc. The selfassemblies described above, however, disappeared in the external field such as the viscometric shear and the ultracentrifugal fields : the associations might be transient structures which cann't be retained under weak forces and collapse easily to a single chain. It is interesting that the CDA has a conformation six times stiffer than that in the shear field. Less

从各向同性到各向异性相的转变发生在溶致液晶聚合物，如纤维素醋酸酯检查鉴于聚合物链刚度，链动力学，和分子间的协会，强烈依赖于溶液中的聚合物浓度和溶剂质量。三醋酸纤维素出现溶致液晶的临界浓度v_2为24-26wt%（CTA，取代度DS=2.9）和更高的二乙酸纤维素（DS=2.40）在三氟乙酸（TFA）中，而在DMAc中，CTA的v_2大于50wt%，对于CTA在氯仿中和CDA在二甲基甲酰胺中，从未观察到LLC。v_2随溶剂的不同表明CTA和CDA具有溶剂特异性的分子构象。实际上，基于蠕虫状链模型分析CTA和CDA的链刚度表明，它们是半柔性链，q=10和8 ...更多信息 nm，分别在TFA和DMAc，和柔性链在其他溶剂中。这里q是表示链刚度的持续长度。动态光散射测量结果表明，CDA单分子与葡萄糖单元中分子间C-6位OH之间的氢键形成的分子间缔合共存。CDA协会是在两个国家，自我组装的4（状态II）和13-40（状态III）倍，只要单一的CDA链。随着CDA浓度的增加，状态II向状态III转变。此外，根据CDA的浓度，状态III有三个状态;一个长的刚性结构和两个巨大的结构，后者没有前者那么刚性和长。前者的长刚性结构被认为是由CDA在DMAc中形成的LLC的原型。然而，在外场如剪切粘度场和超离心场中，上述的自组装体消失了：缔合物可能是在弱力作用下不能保持的瞬态结构，很容易坍缩成单链。有趣的是，CDA的构象比在剪切场中的构象硬六倍。少

项目成果

T.Tsunashima: "Dynamics and Structures of Polymers in Solution" Proc. 1st Intl. Sympo., ICRIS '96. 1. 14-19 (1996)

T.Tsunashima：“溶液中聚合物的动力学和结构”Proc。

Y.Tsunashima: "Stiff Chain Behavior and Strucure Formation of Cellulose Diacetate in N, N-Dimethylacetamide Solution" Macromolecules. in press (1997)

Y.Tsunashima：“二醋酸纤维素在 N,N-二甲基乙酰胺溶液中的刚性链行为和结构形成”大分子。

Y.Tsunashima: "Hydrodynamic Behavior and Semiflexibility of a Disubstituted Polyacetylene with Silyl Group, Poly [(1-trimethylsilyl)-1-propyne), in Dilute Solution" ICR Annual Report 1995. 2. 28-29 (1996)

Y.Tsunashima：“稀溶液中带硅烷基的二取代聚乙炔、聚[(1-三甲基甲硅烷基)-1-丙炔)的流体动力学行为和半柔性”ICR 年度报告 1995. 2. 28-29 (1996)

Y.Tsunashima: "Dilute Solution Properties of Functional Polysaccharides" Molecular Properties of Functional Polysaccharides: Proceeding of 1st Microsymposium of the Cellulose Society of Japan. 1. 7-10 (1995)

Y.Tsunashima：“功能性多糖的稀释溶液特性”功能性多糖的分子特性：日本纤维素学会第一届微型研讨会论文集。

Y.Tsunashima: "Stiff Chain Behavior and Structure Formation of Cellulose Diacetate in N,N-Dimethylacetamide Solution" Macromolecules. (in press). (1997)

Y.Tsunashima：“二醋酸纤维素在 N,N-二甲基乙酰胺溶液中的刚性链行为和结构形成”大分子。