Effect of Gold Nanoparticle on Electro _ Optical Properties of Polysiloxane Liquid Crystal Polymer
Journal of Industrial Engineering Research, 1(4) July 2015, Pages: 99-108
10 Pages Posted: 8 Jul 2017
Date Written: July 16, 2015
We investigate the nonlinearity of a liquid crystal cell doped with gold nanoparticles by considering their selective absorption. Such nonlinearities are promising for optical processing applications and optical limiters. Systems displaying thermal nonlinearities are particularly attractive as the maximum nonlinearity may occur in the absence of an applied field and additionally this nonlinearity can be controlled by the reorientation of the liquid crystal. This study focuses on the electro-optic properties of polymers with a different molecular weights based on the polysiloxane backbone, It is found that there is a strong coupling between the mesogenic side chain groups and the polymer chain that the elasticity of the polymer chain plays a strong role even in the static electro–optic properties. The switching times (on) and (off) have been measured through the period between planer and homotropic alignment which happens under the electrical field effect. Additionally, it is found that adding gold nanoparticles moieties will decrease the phase transition temperatures and thus decreasing of switching times. The variation of the threshold voltage is measured at constant steps below nematic–isotropic transition temperature (TNI) for series of polymers. It is found that the high molecular weights of polymers have great threshold voltage of the electro-optic response and this is related to the intrinsic elastic constant of the liquid crystal polymers. The performance of the electro-optical cells has improved after add the gold would reduce the contribution of the dibole moment of the cyano-groub baralle to the molecular long axis of the mesogenic unit and thus reduce density of the mesognic unit attached to polymer chaine and lead to a Increases of dielectric anisotropic ( ∆Ԑ) and thus enhanced backbone mobility for the system.
Keywords: gold nanorod, polysiloxane, electro–optic properties
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