Refractive Index Changes in Polymers Bearing Pendant Active Ester Groups by Thermal Rearrangement Reaction
作者:Makoto Miyasaka、Ayano Higurashi、Atsushi Kameyama
DOI:10.1246/cl.2011.1363
日期:2011.12.5
Linear and branched polymers bearing S-(2-benzoxazolyl) thioester groups were selectively synthesized by free radical and photoinitiated radical polymerization, respectively, of S-(2-benzoxazolyl)-4-vinylthiobenzoate. Upon heating, the pendant S-(2-benzoxazolyl) thioester groups were converted to 3-acylbenzoxazoline-2-thione groups, accompanied with a change of refractive index (Δn) of about +0.01 in both cases. The structural conversion was confirmed by UV–vis and IR spectroscopy, as well as comparison with authentic polymers bearing 3-acylbenzoxazoline-2-thione groups (similarly synthesized from 3-(4-vinylbenzoyl)benzoxazoline-2-thione). Application of such thermally induced rearrangement reactions may provide a new approach for obtaining materials whose refractive index can be changed by heat (e.g., generated by a laser beam).
分别通过自由基和光引发自由基聚合 S-(2-苯并恶唑基)-4-乙烯基硫代苯甲酸酯,选择性地合成了带有 S-(2-苯并恶唑基)硫酯基团的线性和支化聚合物。加热时,悬垂的 S-(2-苯并恶唑基)硫酯基团转化为 3-酰基苯并恶唑啉-2-硫酮基团,两种情况下的折射率(Δn)都发生了约 +0.01 的变化。紫外-可见光谱和红外光谱以及与含有 3-酰基苯并恶唑啉-2-硫酮基团(同样由 3-(4-乙烯基苯甲酰基)苯并恶唑啉-2-硫酮合成)的真实聚合物的比较证实了这种结构转换。应用这种热诱导重排反应可为获得折射率可受热(如激光束产生的热量)改变的材料提供一种新方法。