New article: Smart liquid crystal defects

22 avril 2021
Micrometric, electrically irreversible smectic A liquid crystal defect patterns can be used as active films for smart windows with voltage-adjustable and reversible haze levels.

Smectic A liquid crystals are layered anisotropic fluids. They can form self-organized defect patterns such as assemblies of focal conic domains with unconventional optical features. However, such defect structures have long been known to be essentially electrically irreversible, limiting their potential applications.
In the lab, we managed to circumvent that longstanding issue by transferring these smectic defect textures into more electrically responsive nematic liquid crystals through a polymer network. With this approach applicable to any smectic A defect patterns, new and previously desired uses of these structures can now be seriously envisaged.
For instance, we uncovered that specific arrays of smectic A focal conic domains could totally hide a background. By applying the above principles, we could make them instantaneously switch back and forth with low voltages between many textures ranging from totally hiding to transparent states. These findings may thus offer new possibilities for active glazing with dynamic adjustability of the privacy levels.

Published in Macromolecular Rapid Communications, Giuseppe Boniello, Victoria Vilchez, Emmanuel Garre, and Frédéric Mondiot (2021) https://doi.org/10.1002/marc.202100087

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