Electro-optical characterization of E48:PVP polymer dispersed liquid crystals

Authors

Claire Macale ⋅ PH National Institute of Physics, University of the Philippines Diliman
Cheryll Lei Mahinay ⋅ PH National Institute of Physics, University of the Philippines Diliman
Fairland Amos ⋅ PH National Institute of Physics, University of the Philippines Diliman
Zenaida Domingo ⋅ PH National Institute of Physics, University of the Philippines Diliman
Leonorina Cada ⋅ PH Institute of Chemistry, University of the Philippines Diliman

Abstract

SIn polymer dispersed liquid crystals, LC droplets are dispersed in a polymer matrix. The size, concentration, and birefringence of the LC droplets would determine the intensity of the off-state scattering. Several factors influence the size and shape of the droplets: solvent, temperature, and polymer.
Solvent Induced Phase Separation (SIPS) involves the evaporation of the solvent after dissolving the liquid crystal into the polymer. The solvent is evaporated at a controlled rate to begin phase separation. Thermally Induced Phase Separation (TIPS) is the process wherein the liquid crystal and polymer mixture is initially at a high temperature where they are isotropic then cooled to room temperature. Slow cooling rates yield larger droplets than droplets formed by fast cooling.
Polymer Dispersed Liquid Crystal (PLDC) films scatter light when light passes through considering there is no applied electric field. The directors of the droplets are oriented randomly so minimum transmittance is observed. When an electric field is applied, the directors align themselves in the direction of the field. As light passes through the film, optimum transmittance is noticed. Contrast ratio is the ratio between the intensity of the on state and off state of the PDLC.
This study aims to observe the transmittance behavior and contrast ratio of PDLCs in relation to the droplet size and cooling rate. This study also aims to determine if memory effects can be observed in the PDLC. The absence of a memory effect is preferred since optical switches are better if the switching time is fast.

Downloads

Issue

1999: Proceedings of the 17th National Physics Congress of the Samahang Pisika ng Pilipinas

Article ID

SPP-1999-MS-12

Section

Materials Science

Published

1999-10-22

How to Cite

[1]

C Macale, CL Mahinay, F Amos, Z Domingo, and L Cada, Electro-optical characterization of E48:PVP polymer dispersed liquid crystals, Proceedings of the Samahang Pisika ng Pilipinas 17, SPP-1999-MS-12 (1999). URL: https://proceedings.spp-online.org/article/view/SPP-1999-MS-12.