Investigations on the effect of polymer precursors chain lengths on the electro-optical properties of polymer dispersed liquid crystal (PDLC) films

In this study, the effects of various chain lengths of polymer precursors on the electro-optical properties of polymer-dispersed liquid crystal (PDLC) films have been investigated. For this purpose, PDLC- films were prepared by inserting the three different precursor of different chain lengths into mixtures of liquid crystal (LC) and polymers. Such mixtures were dropped on ITO-glass and were cured under the UV irradiation to make PDLC films. The electro-optical (EO) properties of the PDLC films were characterized by measuring their haze, transmittance and contrast ratio (CR). Further, the relationship between the electro-optical properties according to the chain length of the precursor liquid crystal (LC) droplet size was measured. The obtained results revealed that the longer the chain length of the monomer, the larger the size of the liquid crystal droplet. Also, for the viscous the polymer matrix, the lower the threshold voltage and the higher the ON transmittance was observed.