【摘要】 利用几种含不同生色团和具有不同生色团密度的偶氮聚合物刻写了表面起伏光栅(SRGs),研究了偶氮聚合物结构、不同起伏深度、周期和写入偏振态的表面起伏光栅对液晶取向性能的影响.对线偏振p+p干涉激光在BP-AZ-CN膜上刻写的表面起伏光栅,随着表面起伏深度增加,对5CB液晶的取向能力逐渐增强.在BP-AZ-CA和PA-AZ-CA薄膜上刻写的周期为800和1200 nm的光栅,在光栅深度从16~100 nm都能诱导液晶均一取向排列.对起伏深度接近的BP-AZ-CA膜SRGs,周期为800 nm的SRGs诱导液晶的取向的能力明显优于周期1200 nm的SRGs.对周期同样为1200 nm,PA-AZ-CA表面光栅比BP-AZ-CA光栅具有更好的液晶取向能力.对于用圆偏振RCP+LCP干涉激光在PA-AZ-CA膜上刻录的SRGs,则观察不到液晶在SRGs表面的单轴取向.基于上述结果,对不同偶氮聚合物的分子结构及其SRGs的表面沟槽和膜内分子取向等因素对液晶取向的影响进行了讨论.更多还原

【Abstract】 The liquid-crystal( LC) alignment properties of surface relief gratings( SRGs) of different azo polymers and their correlations with grating parameters and polarizations of writing beams were studied. Three azo polymers with different kinds of azo chromophores and different chromophore densities were used in this study. The contrasts( T max/ T min) and optical photographs of different liquid crystal cells were compared to determine the alignment properties. For the gratings with a period of 800 nm recorded by p + p interfering Ar+laser beams on the epoxy based azo polymer containing 4-cyanoazobenzene chromophores( BP-AZ-CN) films,the ability for aligning liquid crystal increased with the increase of grating depths. For gratings of the epoxy based azo polymer containing 4-carboxylazobenzene chromophores( BP-AZ-CA) with a period of 800 nm and the gratings of the polyacrylate based azo polymer containing 4-carboxylazobenzene chromophores( PA-AZCA) with a period of 1200 nm,the liquid crystal showed uniform alignment when the grating depth was in a range from 16 to 100 nm. For the BP-AZ-CA gratings with a similar depth,the liquid crystal showed better alignment on the gratings with a period of 800 nm than gratings with a period of 1200 nm. Compared with BPAZ-CA and PA-AZ-CA gratings with a period of 1200 nm,liquid crystal shows a better alignment on the PAAZ-CA gratings. For the PA-AZ-CA gratings inscribed by RCP + LCP interfering Ar+laser beams,no unidirectional alignment was observed even for the gratings depths over 100 nm. Above results can offer a better understanding of the effect of polymer structures and grating parameters on the liquid crystal alignment performance.更多还原