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首页> 外文期刊>Journal of Polymer Science, Part A. Polymer Chemistry >Siloxane polymers containing azo moieties synthesized by click chemistry for photo responsive and liquid crystalline applications
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Siloxane polymers containing azo moieties synthesized by click chemistry for photo responsive and liquid crystalline applications

机译：通过点击化学合成的包含偶氮基团的硅氧烷聚合物，用于光响应和液晶应用

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摘要

Three new types of siloxane-based photoactive liquid crystalline polymers containing azo side groups were synthesized through the click chemistry route. The polymers having molecular weight range of 14,000-34,000 g mol ~(-1) were soluble in most of the polar solvents like chloroform, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, and dichloromethane. The photoresponsive trans-cis photoisomerization under UV radiation and cis-trans relaxation process in dark for the polymers were studied. The isomerization rate constants were found to be 0.01-0.04 sec ~(-1) and 1.16*10 ~(-4)-4. 67*10 ~(-4) sec ~(-1), respectively. It has been noted that the polymers showed high intensity absorption for n-π* in chloroform. Both trans and cis forms of azide monomers having azo moiety exhibited molar extinction coefficient (?μ _(max)) in the range of 22,000-33,000 L mol ~(-1) cm ~(-1). The thermotropic behavior of the polymers was studied by polarizing optical microscope (POM) and differential scanning calorimetry (DSC) experiments. Polymer P1 showed liquid crystalline textures of nematic droplets, whereas P2 showed smectic focal conic texture and nematic droplets. Polymer P1 was also studied for photomechanical bending on exposure to UV radiation. The polymers showed initial degradation temperature in the range of 210-275°C.
机译：通过点击化学途径合成了三种新型的含偶氮侧基的硅氧烷基光敏液晶聚合物。分子量范围为14,000-34,000 g mol〜（-1）的聚合物可溶于大多数极性溶剂，如氯仿，四氢呋喃，二甲基甲酰胺，二甲基亚砜和二氯甲烷。研究了聚合物在紫外辐射下的光响应反式顺式光异构化和在黑暗中的顺式反式弛豫过程。发现异构化速率常数为0.01-0.04秒〜（-1）和1.16×10〜（-4）-4。 67 * 10〜（-4）秒〜（-1）。已经注意到，该聚合物在氯仿中显示出对n-π*的高强度吸收。具有偶氮部分的叠氮化物单体的反式和顺式都显示出在22,000-33,000 L mol〜（-1）cm〜（-1）范围内的摩尔消光系数（Δμ_（max））。通过偏光光学显微镜（POM）和差示扫描量热法（DSC）实验研究了聚合物的热致行为。聚合物P1显示向列液滴的液晶织构，而聚合物P2显示近晶焦点圆锥形织构和向列液滴。还研究了聚合物P1在暴露于紫外线辐射下的光机械弯曲。聚合物显示出初始降解温度为210-275℃。

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