Rheology of defect networks in cholesteric liquid crystals
Rheology of defect networks in cholesteric liquid crystals
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DOI：
10.1103/physreve.66.031711
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发表时间：
2002-09-01
影响因子：
2.4
通讯作者：
Weitz, DA
中科院分区：
文献类型：
--
作者：
Ramos, L;Zapotocky, M;Weitz, DA
研究了含缺陷网络的胆甾液晶的流变性能。当胶体颗粒分散到胆甾液晶中时，“油条纹”型线性缺陷网络就稳定了。该网络将预剪切胆甾液晶的流变反应从类流体转变为类固体，并导致“缺陷介导”固体的形成。频率相关的复合剪切模量G(*)（omega）被测量，在线性和非线性粘弹性制度下，有和没有夹杂的样品。用类似于橡胶弹性理论的模型讨论了缺陷网络介导的线弹性响应。G(*)（ω）的所有数据都拟合为简化的理论形式，并且根据样品中存在的缺陷结构的性质讨论了在所研究的各种制度下的拟合参数的值和变化。类似的流变性能预计会出现在层状体系中的颗粒稳定的油条纹缺陷网络中，如smic -a相和lyotropic l - α相。
The rheological properties of cholesteric liquid crystals containing networks of defects are investigated. A network of linear defects of the "oily-streak" type is stabilized when colloidal particles are dispersed into the cholesteric liquid crystals. This network converts the rheological response of a presheared cholesteric liquid crystal from fluidlike to solidlike and leads to the formation of a "defect-mediated" solid. The frequency-dependent complex shear modulus G(*)(omega) is measured, for samples with and without inclusions, in both the linear and nonlinear viscoelastic regimes. The linear elastic response mediated by the defect network is discussed in terms of a model analogous to the theories of rubber elasticity. All our data for G(*)(omega) are fitted to a simplified theoretical form, and the values and variations of the fitting parameters, in the various regimes investigated, are discussed in terms of the properties of defect structure present in the samples. Similar rheological properties are expected to arise from particle-stabilized oily-streak defect networks in layered systems such as smectic-A and lyotropic L-alpha phases.