Light-Driven Rotation and Pitch Tuning of Self-Organized Cholesteric Gratings Formed in a Semi-Free Film

Ling-Ling Ma; Wei Duan; Ming-Jie Tang; Lu-Jian Chen; Xiao Liang; Yan-Qing Lu; Wei Hu

doi:10.3390/polym9070295

Polymers (Jul 2017)

Light-Driven Rotation and Pitch Tuning of Self-Organized Cholesteric Gratings Formed in a Semi-Free Film

Ling-Ling Ma,
Wei Duan,
Ming-Jie Tang,
Lu-Jian Chen,
Xiao Liang,
Yan-Qing Lu,
Wei Hu

Affiliations

Ling-Ling Ma: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
Wei Duan: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
Ming-Jie Tang: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
Lu-Jian Chen: Department of Electronic Engineering, School of Information Science and Engineering, Xiamen University, Xiamen 361005, China
Xiao Liang: Department of Chemistry, Tsinghua University, Beijing 100084, China
Yan-Qing Lu: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
Wei Hu: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China

DOI: https://doi.org/10.3390/polym9070295
Journal volume & issue: Vol. 9, no. 7
p. 295

Abstract

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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.

Published in Polymers

ISSN: 2073-4360 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Chemistry: Organic chemistry
Website: http://www.mdpi.com/journal/polymers/

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