Characteristics of Liquid Crystal Droplet of Polymer Dispersed Liquid Crystal

• Main Authors: Chao-Yu Hu, 胡昭宇
• Other Authors: Jy-Shan Hsu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/95196115701384915691

碩士 === 中原大學 === 物理研究所 === 99 === Polymer dispersed liquid crystal (PDLC) consists of the liquid crystal droplets which are uniformly dispersed in the polymer matrixes. When there is no external electric field, the light is scattered from the droplets because of the mismatched refractive index between the polymer and LC droplets, so that the appearance of PDLC is white. When an electric field is applied across the PDLC, the LC molecules rotate to the direction of the electric field, and the PDLC is transparent because the refractive index of polymer and LC droplet are matched. Therefore, we can manipulate the opaque and transparent states by the external electric field through the changes of the refractive index of the LC droplet. In this study, we explore the optical, electrical and surface characteristics of the liquid crystal droplets. When we increase the intensity of the curing light or temperature of the curing environments, the liquid crystal droplet size becomes smaller, the threshold voltage of PDLC is higher and scattered light is stronger. The threshold voltage is also higher in larger cell thickness. By controlling all the parameters, the dielectric anisotropy (Δε) of PDLC increases and hence the threshold voltage decreases as the concentration of BaTiO3 increases. In addition, that the contact angel between the polymer and LC increases as the concentration of BaTiO3 increases is due to the decrease of the surface energy.