Electrically controllable microstructures and dynamic light scattering properties of liquid crystals with negative dielectric anisotropy

Abstract

In this paper thin films which can potentially function as novel electrically switchable shutters were fabricated based on a commercially available liquid crystal media with negative dielectric anisotropy, and their microstructures and dynamic light scattering properties were investigated in detail by the in situ formation of polymer networks. It was found that the light transmittance of the prepared films in the wavelength range from 400 nm to 3000 nm can be expediently controlled on demand by felicitously applying an electric field with an appropriate strength. Compared to the ultraviolet (UV) and visible (Vis) regions, the light transmittance in the near infrared (NIR) region was much higher when a voltage over 30 V was applied. Continually raising the applied voltage would, however, increase the NIR transmittance without noticeable changes in the UV and Vis regions. Furthermore, we have also explored the relationship between the dynamic light scattering properties and the corresponding microstructures of the polymer network. The velocity of the flow of dynamic scattering increased with the increase of the applied voltage, which led to the gradual appearance of large sized pores followed by oversized connected pores with many tiny holes in the boundary. Accordingly, the dynamic light scattering of the samples increased with the increasing microstructures of the polymer network.