From Event: SPIE Organic Photonics + Electronics, 2017
We designed the fast switching & low driving voltage principle with nano slippery interfaces in nematic gels. Confinement effect by the gel network can accelerate the response time of nematic due the localization of director motion as similar way to the cholesteric blue phase. However, the anchoring of the director on the gel network induces the driving voltage. Slippery effect on the nano interface of the gel network can reduce the driving voltage due to the lubrication of the director motion. Since azo dye acrylates are co-polymerized with nematic gels (Azo-NGel), we can demonstrate the UV-switchable nano-slippery interface on the nematic gels.
Dynamic Light Scattering (DLS) provides us the information of the dynamics of director rotation. Dispersion relation of the pure 7CB-T15 mixture completely satisfies the prediction of hydrodynamic modes in the nematic. On the contrary, the relaxation frequency of the Azo-NGel keeps fast response in the low wave-number region due to the confinement effect.
Electro-Optic response (EO) of the Azo-Ngel without UV illumination shows the serious increase of the driving voltage compared to the pure 7CB-T15 mixture. When the Azo-Ngel is illuminated by UV-light Slippery interfaces can be created by the trans-cis isomerization of the Azo dye of the side-chain on the nano network of nematic gels. EO under UV illumination shows the drastic reduction of the driving voltage keeping the fast response time. We have also confirmed that the dispersion relation of the UV illuminated Azo-Ngel is almost the same as that of Azo-Ngel without UV illumination by the DLS measurement. Thus, the confinement effect for the nematic gels is still effective after the slippery interface is created by the UV illumination.
We success to demonstrates that the acceleration of the response time is compatible with reduction of the driving voltage by the localization and lubrication of director motions due to the design of the nano-slippery interfaces in the nematic gels.
Jun Yamamoto and Isa Nishiyama, "Nano slippery interfaces in nematic gels -localization and lubrication of director motions (Conference Presentation)," Proc. SPIE 10361, Liquid Crystals XXI, 103610B (Presented at SPIE Organic Photonics + Electronics: August 06, 2017; Published: 19 September 2017); https://doi.org/10.1117/12.2273254.5581138447001.
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