Light-Driven Rotation and Pitch Tuning of Self-Organized Cholesteric Gratings Formed in a Semi-Free Film
by
Ling-Ling Ma 1, Wei Duan 1, Ming-Jie Tang 1, Lu-Jian Chen 2, Xiao Liang 3, Yan-Qing Lu 1 and Wei Hu 1,*
Ling-Ling Ma 1, Wei Duan 1, Ming-Jie Tang 1, Lu-Jian Chen 2, Xiao Liang 3, Yan-Qing Lu 1 and Wei Hu 1,*
1
National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
2
Department of Electronic Engineering, School of Information Science and Engineering, Xiamen University, Xiamen 361005, China
3
Department of Chemistry, Tsinghua University, Beijing 100084, China
*
Author to whom correspondence should be addressed.
Polymers 2017, 9(7), 295; https://doi.org/10.3390/polym9070295
Received: 29 June 2017 / Revised: 18 July 2017 / Accepted: 19 July 2017 / Published: 21 July 2017
(This article belongs to the Special Issue Photo-Responsive Polymers)
Cholesteric liquid crystal (CLC) has attracted intensive attention due to its ability to form a periodic helical structure with broad tunability. CLC gratings in open systems are especially promising in sensing and micromanipulation. However, there is still much to learn about the inherent mechanism of such gratings. We investigate the light-driven rotation and pitch-tuning behaviors of CLC gratings in semi-free films which are formed by spin-coating the CLC mixtures onto planarly photoaligned substrates. The doped azobenzene chiral molecular switch supplies great flexibility to realize the continuous grating rotation. The maximum continuous rotational angle reaches 987.8°. Moreover, dependencies of light-driven rotation and pitch tuning on the dopant concentration and exposure are studied. The model of director configuration in the semi-free film is constructed. Precise beam steering and synchronous micromanipulation are also demonstrated. Our work may provide new opportunities for the CLC grating in applications of beam steering, micromanipulation, and sensing.
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Keywords:
cholesteric liquid crystal; photoalignment; light-driven; isomerization; beam steering; micromanipulation; self-assembly; semi-free film
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MDPI and ACS Style
Ma, L.-L.; Duan, W.; Tang, M.-J.; Chen, L.-J.; Liang, X.; Lu, Y.-Q.; Hu, W. Light-Driven Rotation and Pitch Tuning of Self-Organized Cholesteric Gratings Formed in a Semi-Free Film. Polymers 2017, 9, 295.
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