In-plane and tilt reorientation of p-methoxyazobenzene side chains tethered to liquid crystalline polymethacrylates by irradiation with 365 nm light
In-plane and tilt reorientation of p-methoxyazobenzene side chains tethered to liquid crystalline polymethacrylates by irradiation with 365 nm light
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DOI：
10.1021/ma0009303
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发表时间：
2001-01-02
期刊：
影响因子：
5.5
通讯作者：
Ichimura, K
中科院分区：
文献类型：
--
作者：
Han, M;Ichimura, K
通过线性极化的365 nm光和斜辐射，用非极化的365 nm光辐射引起的光学各向异性的产生，随后的退火，用P-甲氧亚苯二甲苯侧链进行了液晶多甲基丙烯酸酯。聚合物的自旋涂层膜暴露于10-20 mJ/cm（2）剂量的线性极化紫外线，并在接近玻璃过渡温度（T-g）的聚合物的温度下进行退火，导致了Azimuthal的明显增强偶氮苯的重新定位使双膜膜表现出极好的光学各向异性热稳定性。当聚合物的自旋涂层膜被倾斜的365 nm光（2）剂量（2）剂量（2）剂量并随后将其退火时，伴随H-凝集的形成，实现了偶氮苯基团的空间操纵重新定位。方向的方向仅由紫外光的入射方向控制。当暴露剂量超过约50 mJ/cm时，两种情况的光生态各向异性都大大降低或消失（2）。通过与线性极化365 Nm Light的线性极化365 Nm Light平行的过渡偶极矩平行，讨论了通过两种光照射模式诱导的光学各向异性的光学各向异性的机制或垂直于非极化紫外光的入射方向。
The generation of optical anisotropy induced by irradiation with linearly polarized 365 nm light and by oblique irradiation with nonpolarized 365 nm light and subsequent annealing was described for liquid crystalline polymethacrylates with p-methoxyazobenzene side chains. Exposure of the spin-coated films of the polymers to linearly polarized UV light of 10-20 mJ/cm(2) doses and subsequent annealing at temperatures close to the glass transition temperatures (T-g) of the polymers led to a marked enhancement of azimuthal reorientation of the azobenzene to give birefringent films exhibiting excellent thermostability of the optical anisotropy. When the spin-coated films of the polymers were irradiated obliquely with nonpolarized 365 nm light of about 15 mJ/cm(2) dose and annealed subsequently, spatially manipulated reorientation of the azobenzene groups was realized, accompanied by the formation of H-aggregation. The orientational direction was controlled simply by the incident direction of UV light. The photogenerated optical anisotropy for both cases was considerably reduced or disappears when exposure doses exceed about 50 mJ/cm(2). The mechanism for the thermally enhanced generation of optical anisotropy induced by both modes of photoirradiation was discussed on the basis of photoselective E-to-Z photoisomerization of the E-isomer with a transition dipole moment parallel to the electric vector of linearly polarized 365 nm light or perpendicular to the incident direction of nonpolarized UV light.