Nonspherical Uniaxial Azobenzene Polymer Particles and Their Shape Changes under UV- or White-Light Irradiation for Stimuli-Response Applications
Nonspherical Uniaxial Azobenzene Polymer Particles and Their Shape Changes under UV- or White-Light Irradiation for Stimuli-Response Applications
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DOI：
10.1021/acsapm.0c00475
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发表时间：
2020-06-01
影响因子：
5
通讯作者：
Ihara, Eiji
中科院分区：
文献类型：
--
作者：
Itoh, Tomomichi;Tamamitsu, Tetsuo;Ihara, Eiji
在这项研究中，我们开发了偶氮苯聚合物颗粒，显示出几种光诱导的形状变化。传统的偶氮苯颗粒需要在基底上暴露于偏振白光或蓝光下以实现形状伸长。首先，6-[4-(4'-甲氧基苯基偶氮)苯氧基]己基甲基丙烯酸酯的分散聚合提供了独特的椭圆形或短圆柱形形状，具有受控的尺寸和窄的尺寸分布。然后，偏光光学显微镜观察和广角X射线衍射测量表明偶氮苯部分在颗粒中形成单轴取向的近晶层状结构。差示扫描量热测量表明堆积结构和颗粒形状彼此密切相关。最后，偶氮苯的反式-顺式光异构化改变了颗粒形状，同时伴随着偶氮苯堆积结构的变形。有趣的是，紫外线和白光照射增加了它们的形状各向异性。通过非偏振光改变分散介质中和基底上的颗粒形状。因此，光源和位置的组合改变了偶氮苯颗粒的光诱导形状变化。
In this study, we developed azobenzene polymer particles showing several light-induced shape changes. Conventional azobenzene particles require exposure to polarized white or blue light on a substrate for shape elongation. First, the dispersion polymerization of 6-[4-(4'-methoxyphenylazo)phenoxy]hexyl methacrylate afforded unique oval or short cylindrical shapes with controlled sizes and narrow size distributions. Then, polarized optical microscopic observations and wide-angle X-ray diffraction measurements suggest that the azobenzene moiety formed a uniaxially orientated smectic-layered structure in the particles. Differential scanning calorimetric measurements indicated that the packing structures and particle shapes were closely related to each other. Finally, the particle shape was altered by the trans-cis photoisomerization of azobenzene accompanied by the deformation of the azobenzene packing structure. Interestingly, their shape anisotropy was increased by ultraviolet and white-light irradiation. The particle shape was changed in a dispersed medium and on a substrate by unpolarized light. Consequently, the combination of a light source and site varied the light-induced shape changes of the azobenzene particles.