Mesomorphic Behavior and Optical Properties of Liquid-Crystalline Polysiloxanes Bearing Different Chiral Groups
Mesomorphic Behavior and Optical Properties of Liquid-Crystalline Polysiloxanes Bearing Different Chiral Groups
复制标题
带有不同手性基团的液晶聚硅氧烷的介晶行为和光学性质
DOI：
10.1002/app.30437
复制
发表时间：
2009-11-15
影响因子：
3
通讯作者：
Yao, Dan-Shu
中科院分区：
文献类型：
--
作者：
Meng, Fan-Bao;Zhang, Bao-Yan;Yao, Dan-Shu
以胆甾型液晶单体胆甾醇2-(4-烯丙氧基苯甲氧基)琥珀酸酯和手性单体2-异丙基-5-甲基-环烯基4-烯丙氧基苯甲酸酯合成了一系列带有不同手性基团的侧链液晶聚硅氧烷。所有手性聚合物均表现出胆甾型中间相，具有非常宽的中间相温度范围。随着相形态从固态到各向同性态的变化，样品表现出不同的光谱图像，表明中间相和各向同性态之间不同的相行为。通过圆偏振光谱和旋光分析来表征聚合物的光学性质。手性液晶聚合物的比旋光度均为负值，并且随着聚合物体系中薄荷基组分的增加而增加。与相应的单体相比，聚合物表现出明显较低的比旋光度，表明聚硅氧烷主链的存在影响了分子极性。随着胆固醇成分的减少，相同温度下聚合物的选择性光反射最大波长向短波长移动，表明由于具有高手性的薄荷基的诱导，螺距变得更短。随着温度降低，选择性光反射最大波长的温度依赖性向更长的波长区域移动。 (C) 2009 年 Wiley 期刊公司 J Appl Polym Sci 114: 2195-2203, 2009
A series of side-chain liquid crystalline polysiloxanes bearing different chiral groups were synthesized with a cholesteric liquid crystalline monomer cholesteryl 2-(4-allyloxy-benzoxy)-succinate and a chiral monomer 2-isopropyl-5-methyl-cycloliexyl 4-allyloxy-benzoate. All the chiral polymers showed cholesteric mesophase with very wide mesophase temperature ranges. Along with phase morphology varied from solid state to isotropic state, the sample exhibited varied spectroscopic images, indicating different phase behaviors between mesophase and isotropic state. Optical properties of the polymers were characterized with circular polarization spectra and optical rotation analysis. The specific rotations of the chiral liquid crystalline polymers were all negative values and increased with increase of menthyl component in the polymer systems. As compared with corresponding monomers, the polymers showed significantly lower specific rotations, suggesting that the existence of polysiloxane main chains affect the molecule polarity. The selective light reflection maximum wavelength of the polymers at the same temperature shifted to short wavelength with decrease of cholesteryl component, indicating that the helical pitch becomes shorter due to induction of menthyl groups with high chiral properties. The temperature dependence of selective light reflection maximum wavelength was shifted to a longer wavelength region as the temperature decreased. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 2195-2203, 2009