Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
Philos Trans A Math Phys Eng Sci. 2013 Mar 4;371(1988):20120256. doi: 10.1098/rsta.2012.0256. Print 2013 Apr 13.
We examine for the first time how chemically and thermally stable gold nanoparticles (NPs), prepared by a silane conjugation approach, affect both the thermal and the electro-optical properties of a nematic liquid crystal (LC), when doped at concentrations ranging from 0.25 to 7.5 wt%. We find that the octadecylsilane-conjugated gold NPs stabilize both the enantiotropic nematic and the monotropic smectic-A phases of the LC host with a maximum stabilization of 2(°)C for the nematic and 3.5(°)C for the smectic-A phases for the mixture containing 1 wt% of the silanized particles. The same mixture shows the lowest values for the Fréedericksz transition threshold voltage and the highest value for the dielectric anisotropy. Generally, all NP-containing mixtures, except mixtures with NP concentrations exceeding 5 wt%, reduce the threshold voltage, increase the dielectric anisotropy and reduce both rise and decay time; the latter particularly at temperatures at least 10(°)C below the isotropic-nematic phase transition on cooling.
我们首次研究了在浓度范围为 0.25 至 7.5wt%时，通过硅烷偶联方法制备的化学和热稳定性好的金纳米粒子（NPs）如何影响各向异性向列液晶（LC）的热和电光性质。我们发现，十八烷基硅烷偶联的金 NPs 稳定了 LC 主体的向列相和单分子层各向异性相，对于含有 1wt%硅烷化颗粒的混合物，向列相的最大稳定度为 2°C，单分子层各向异性相的最大稳定度为 3.5°C。对于相同的混合物，Freedericksz 相变阈值电压最低，介电各向异性最大。通常，除了含有超过 5wt%纳米粒子的混合物外，所有含有纳米粒子的混合物都降低了阈值电压，增加了介电各向异性，并降低了上升和下降时间；后者特别是在冷却时低于各向同性-向列相转变温度至少 10°C 的温度下。
