Frustration Between Two- and Three-Dimensional Smectic Ordering Leads to a Biaxial Nematic Phase
Frustration Between Two- and Three-Dimensional Smectic Ordering Leads to a Biaxial Nematic Phase
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二维和三维近晶有序之间的挫败导致双轴向列相
DOI：
10.1039/c9sm01809c
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Noel A. Clark
中科院分区：
文献类型：
--
作者：
Dong Chen;David A. Coleman;Chenhui Zhu;Nattaporn Chattham;Frank Jenz;Xiaohong Cheng;Carsten Tschierske;Matthew A. Glaser;Joseph E. Maclennan;Noel A. Clark
The bola-amphiphilic, T-shaped mesogen CT2 has an aromatic, biphenyl core terminated on both ends by hydrophilic groups and a semi-perfluorinated, aliphatic side chain. Upon cooling from the isotropic phase, the fluorinated tails and the polar, rod-like cores nanophase-segregate to form a fluid lamellar phase. At high temperatures, the biphenyl cores are orientationally disordered in two dimensions (2D) in the lamellar planes but on further cooling the cores order orientationally, giving a biaxial lamellar phase with 2D nematic in-plane ordering. At lower temperature, the aromatic and hydrophilic parts of the cores nanosegregate within the lamellae and 2D smectic correlations of the head groups develop. X-ray diffraction shows that this 2D smectic ordering is incompatible with the initial lamellar structure, with both structures becoming short-ranged, resulting in a 3D biaxial nematic phase with macroscopic orthorhombic symmetry featuring strong smectic correlations in two orthogonal spatial dimensions. Freeze-fracture transmission electron microscopy enables direct visualization of the resulting short-ranged periodic structures.
