Bilayers in nanoparticle-doped polar mesogens.
Bilayers in nanoparticle-doped polar mesogens.
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纳米颗粒掺杂极性介晶中的双层
DOI：
10.1103/physreve.88.062505
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
H.-S. Kitzerow
中科院分区：
文献类型：
--
作者：
A. Lorenz;N. Zimmermann;S. Kumar;D. R. Evans;G. Cook;H.-S. Kitzerow
用X射线散射法研究了5种4-烷基-4 ′-氰基联苯同系物（4-丁基-4 ′-氰基联苯到4-辛基-4 ′-氰基联苯）掺杂BaTiO_2纳米粒子的中间相结构.首先在庚烷中制备每种4--烷基-4 ′-氰基联苯的澄清溶液，然后用庚烷/纳米颗粒分散体掺杂，这导致凝胶化。在每种情况下，纳米凝胶被发现是一维的，多层的，近晶纳米结构。令人惊讶的是，在所有五种同系物中观察到4.5 nm的特征层间距。用同步辐射X射线散射研究了掺杂4-戊基-4 ′-氰基联苯和4-辛基-4 ′-氰基联苯多层膜的结构，发现了9级布拉格反射，并通过傅里叶分析计算了多层膜的电子密度分布。发现多层膜由分子双层组成，其中介晶被布置在极性头基团的头对头组装中。介晶分子的烷基尾是自由移动的，尾对尾组装体被庚烷稳定。溶解的纳米颗粒明显诱导了一种新的自组装纳米结构，其中分子的刚性芳香部分而不是总长度定义了层间距。
Structures of the mesophases of five members of the 4--alkyl-4′-cyanobiphenyl homologous series (4--butyl-4′-cyanobiphenyl to 4--octyl-4′-cyanobiphenyl) doped with milled BaTiOnanoparticles were investigated by x-ray scattering. Clear solutions of each of the 4--alkyl-4′-cyanobiphenyls were first prepared in-heptane and then doped with an-heptane/nanoparticle dispersion, which led to gelation. The nanogels were found to be one-dimensional, multilayered, smectic nanostructures in each case. Surprisingly, a characteristic layer spacing of 4.5 nm was observed in all five homologues. Synchrotron x-ray scattering study of the multilayer structures of doped 4--pentyl-4′-cyanobiphenyl and 4--octyl-4′-cyanobiphenyl revealed nine orders of the primary Bragg reflection which were used to calculate the electron density profiles of the multilayers by Fourier analysis. The multilayers were found to consist of molecular bilayers wherein the mesogens were arranged in a head-to-head assembly of the polar head groups. The alkyl tails of the mesogenic molecules were freely movable and the tail-to-tail assembly was stabilized by heptane. The dissolved nanoparticles clearly induced a new self-assembled nanostructure in which the rigid aromatic part, and not the overall length, of the molecules defined the layer spacing.
DOI：
--
发表时间：
2012
期刊：
影响因子：
--
作者：
W. Sun;Q. He;L. Lu;H. Liu
通讯作者：
H. Liu