Influence of chromophoric electron-withdrawing groups on photoinduced deformation of azo polymer colloids
Influence of chromophoric electron-withdrawing groups on photoinduced deformation of azo polymer colloids
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DOI：
10.1016/j.polymer.2010.04.048
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发表时间：
2010-06
期刊：
影响因子：
4.6
通讯作者：
Junpeng Liu;Yaning He;Xiaogong Wang
中科院分区：
文献类型：
--
作者：
Junpeng Liu;Yaning He;Xiaogong Wang
研究了生色基团对三种偶氮聚合物胶体球光诱导变形行为的影响。以环氧基偶氮聚合物(BP-AZ-CA、BP-AZ-CN和BP-AZ-NT)为原料，在THF-H2O介质中进行疏水聚合，制备了胶体微球。通过调整初始四氢呋喃溶液中的聚合物浓度和制备过程中的加水速率，胶体球被控制为具有相似的平均尺寸。用动态光散射(DLS)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)对胶体进行了表征。用线偏振的Ar+激光(488 nm，130 mW/cm2)照射固体胶体球，研究了胶体的形变。为了比较，还用偏振半导体固体激光(532 nm，130 mW/cm2)照射研究了胶体。在光照射下，胶体球均沿激光偏振方向拉长。吸电子基团对与光照响应相关的胶体变形行为有显著影响。用波长介于偶氮生色团的λ最大吸收带和吸收带尾部之间的中间波长的激光照射，可以更有效地诱导胶体变形。当采用亲水性羧基作为吸电子基团时，在相同的光照条件下，聚合物的变形更明显，这可能是由于聚合物的亲水性较高所致。上述观察有助于更好地理解偶氮聚合物胶体的光诱导变形机理。
This study investigated the influence of chromophoric electron-withdrawing groups on photoinduced deformation behavior of colloidal spheres of three azo polymers. The colloidal spheres were prepared by using the epoxy-based azo polymers (BP-AZ-CA, BP-AZ-CN, and BP-AZ-NT) through gradual hydrophobic aggregation of the polymers in THF–H2O media. The colloidal spheres were controlled to have similar average sizes by adjusting both the polymer concentrations in the initial THF solutions and water-adding rates in the preparation processes. The colloids were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The colloid deformation was investigated by irradiating the colloidal spheres in solid state with a linearly polarized Ar+laser beam (488 nm, 130 mW/cm2). For comparison, the colloids were also studied by irradiation with a polarized diode solid state laser beam (532 nm, 130 mW/cm2). Upon the light irradiation, all the colloidal spheres were elongated along the polarization direction of the laser beams. The electron-withdrawing groups showed significant influence on the colloid deformation behavior related with the response to the light irradiation. The colloid deformation was more efficiently induced by irradiation with the laser beams having the intermediate wavelengths between the λmaxand the absorption band tails of the azo chromophores. When the hydrophilic carboxylic group was used as the electron-withdrawing groups, more significant deformation was induced under the same light irradiation condition, which could be attributed to the higher hydrophilicity of the polymer. Above observations can lead to a better understanding of the photoinduced deformation mechanism of azo polymer colloids.