Electric Field Induced Rotation of Polymer Cholesteric Liquid Crystal Flakes: Mechanisms and Applications
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14623
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{sup o} 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{sup o} 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 Vrms/mm, while subsecond reorientation is seen in fields as low as 5 x 10-2 Vrms/mm. 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.
- Research Organization:
- Laboratory for Laser Energetics, University of Rochester (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FC03-92SF19460
- OSTI ID:
- 806855
- Report Number(s):
- DOE/SF-194460-467; 1338; 2002-100
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
09 BIOMASS FUELS
99 GENERAL AND MISCELLANEOUS
ALIGNMENT
CHOLESTERIC
COLOR
DIELECTRIC PROPERTIES
DISPLAYS ''ELECTRIC FIELD INDUCED ROTATION FO POLYMER CHOLESTERIC LIQUID CRYSTAL FLAKES: MECHANISMS AND APPLICATIONS''....(OAK/B202).
ELECTRIC FIELDS
GEOMETRY
LIQUID CRYSTALS
ORIENTATION
PARTICLES
POLYMER
POLYMERS
REFLECTION
ROTATION
TEXTURE