Electric-field-induced rotation of polymer cholesteric liquid crystal flakes: mechanisms and applications

Tanya Z. Kosc; Kenneth L. Marshall; Stephen D. Jacobs; John C. Lambropoulos

doi:10.1117/12.452489

12 December 2002 Electric field induced rotation of polymer cholesteric liquid crystal flakes: mechanisms and applications

Tanya Z. Kosc, Kenneth L. Marshall, Stephen D. Jacobs, John C. Lambropoulos

Author Affiliations +

Proceedings Volume 4799, Liquid Crystals VI; (2002) https://doi.org/10.1117/12.452489
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

Electric fields can induce motion of polymer cholesteric liquid crystal (pCLC) flakes suspended in a fluid medium. The platelet-shaped pCLC flakes with a Grandjean texture show strong selective reflection when lying flat in the plane of a conventional cell. As their orientation with respect to normally incident light changes, their selective reflection color shifts toward the blue and diminishes until the flakes are no longer easily visible beyond 7-12° of rotation. Reproducibility and control of motion has been observed in moderately conductive host fluid. Flakes in such hosts do not respond to a DC electric field, but they rotate 90° in an AC field within a given frequency band. The response times and frequency regions for motion depend partially on the field magnitude, the dielectric properties of the host fluid and the flake geometry. We observe flakes reorienting in less than 500 ms in an electric field of 0.17 V_rms/μm, while sub-second reorientation is seen in fields as low as 5x10^-2 V_rms/μm. This response time is comparable with typical electronic-paper applications, but with a significantly lower electric field. Displays using pCLC flakes would not require backlighting, sheet polarizers, color filters or alignment layers. Numerous additional applications for pCLC flakes are envisioned, including filters, polarizers, and spatial light modulators.

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Tanya Z. Kosc, Kenneth L. Marshall, Stephen D. Jacobs, and John C. Lambropoulos "Electric field induced rotation of polymer cholesteric liquid crystal flakes: mechanisms and applications", Proc. SPIE 4799, Liquid Crystals VI, (12 December 2002); https://doi.org/10.1117/12.452489

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