Photochromism of Azopyridine Side Chain Polymer Controlled by Supramolecular Self-Assembly
Photochromism of Azopyridine Side Chain Polymer Controlled by Supramolecular Self-Assembly
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DOI：
10.1080/15226514.2011.586279
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发表时间：
2011-07
期刊：
影响因子：
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通讯作者：
T. Michinobu;Rinako Eto;H. Kumazawa;Nozomu Fujii;K. Shigehara
中科院分区：
文献类型：
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作者：
T. Michinobu;Rinako Eto;H. Kumazawa;Nozomu Fujii;K. Shigehara
以甲基丙烯酸酯为单体，通过自由基聚合法合成了含偶氮吡啶侧链的聚甲基丙烯酸甲酯。用UV/Vis光谱研究了偶氮吡啶部分在溶液和固体薄膜中的反式顺式光异构化反应。母体聚甲基丙烯酸甲酯在四氢呋喃溶液中的光致变色行为略好于薄膜状态。当基于聚合物侧链的吡啶部分和客体分子的羧酸之间的氢键形成超分子组装时，这种差异变得显著。因此，超分子聚合物在薄膜状态下的反式-顺式光异构化反应显著减少，这可能是由于在受限的聚合物结晶环境中以氢键的形式固定了反式-偶氮吡啶基团。DSC热图和偏光显微镜图像表明客体分子的脂肪族侧链具有高度的结晶性。在设计新型功能超分子聚合物时，更好地了解偶氮吡啶部分的光致变色性和弱分子间相互作用是非常重要的。
Polymethacrylate bearing azopyridine side chains was prepared by the radical polymerization of the corresponding methacrylate monomer. The trans-cis photoisomerization of the azopyridine moieties was studied by UV/Vis spectroscopy in both the solution and solid thin film states. The parent polymethacrylate displayed a slightly better photochromic behavior in the THF solution than in the thin film state. This difference became significant when the supramolecular assemblies, based on the hydrogen-bond between the pyridine moieties of the polymer side chain and carboxylic acids of the guest molecule, were formed. Thus, the supramolecular polymer showed a dramatically reduced trans-cis photoisomerization in the thin film state, probably due to the immobilized trans-azopyridine moieties in the confined polymer crystalline environment in terms of the hydrogen bonds. The highly crystalline features of the aliphatic side chains of the guest molecule were demonstrated by the DSC thermograms and polarized optical microscopic images. A better understanding of the photochromism and weak intermolecular interactions of the azopyridine moiety is very important when designing novel functional supramolecular polymers.