Study on the electro-optical properties of polyimide-based polymer-dispersed liquid crystal films

Abstract

The reflectivity control device, initially developed for attitude control, is utilised to control the solar sail orbit by switching the states between absorption and specular reflection. Actually, the major parts of the device are the polymer-dispersed liquid crystal (PDLC) films. Here, PDLC films based on polyimide (PI) as polymer matrix and a low molecular weight LC can be prepared by the thermally induced phase separation (TIPS) method. The influences of cooling rate and the content of LC on the size and uniformity of LC droplets dispersed in a polymer matrix by a TIPS process were investigated. It was found that a fast cooling rate gave smaller droplet sizes and hence a more uniform distribution as compared to the ones produced under a slow cooling rate. If the LC content was increased, the droplet size would be increased. Furthermore, the effect of LC droplet size on the electro-optical properties of the PI-based PDLC films was discussed, such as transmittance, threshold voltage, driving voltage and contrast ratio (CR).

Keywords:

• liquid crystal
• polymer
• electro-optical properties
• reflectivity control

Additional information

Funding

This work was supported by the Major Project of International Cooperation of the Ministry of Science and Technology [grant number 2013DFB50340]; the National Key Basic Research Program of China [2014CB931804]; the National Natural Science Foundation of China [grant number 51173017], [grant number 51373024], [grant number 51473020], [grant number 61370048]; the Beijing Higher Education Young Elite Teacher Project [grant number YETP0356]; the Fundamental Research Funds for the Central Universities [grant number FRF-TP-14-001A2].