Preparation of dye-doped polymer-dispersed liquid crystals using acrylic monomers, and enhancement of contrast by using THF solvent as a cleaning agent

Polymer-dispersed liquid crystal (PDLC), with characteristics of high contrast and low driving voltage, has found many product applications and is an important material for new generations. In this experiment, we used 2-phenoxy ethyl acrylate (2-PEA) and tripropylene glycol diacrylate, two acrylic monomers, to prepare PDLC, and we compared various preparation conditions in order to investigate the impact of structural properties on the optical behavior of PDLC. While maintaining the low driving voltage and high contrast of a PDLC, a dichroic dye was added to turn the device into a dye-doped PDLC. Using a polarized light microscope, it was observed that direct injection of the dye resulted in an overflow of the dichroic dye outside the thin film, reducing the contrast of the PDLC. Therefore, we utilized tetrahydrofuran solvent to wash away the liquid crystal (LC) from the PDLC, followed by re-addition of the dye-containing LC. This successfully solved the dye overflow problem and was found to enhance the PDLC contrast effectively.