Siloxane polymers containing azo moieties synthesized by click chemistry for photo responsive and liquid crystalline applications
作者:Someshwarnath Pandey、Balakrishna Kolli、Sarada P. Mishra、Asit B. Samui
DOI:10.1002/pola.25885
日期:2012.3.15
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
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性反式-顺式光致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 sec -1和1.16 * 10 -4 –4.67 * 10 -4 sec -1, 分别。已经注意到,该聚合物在氯仿中对n-π*表现出高强度吸收。两个反式和CIS具有偶氮基团的叠氮化物的单体的形式表现出的摩尔消光系数(ε最大为22,000-33,000大号mol的范围内)-1厘米-1。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P2显示近晶焦点圆锥纹理和向列液滴。还研究了聚合物P1在暴露于