Effect of nano particles on electro optic properties of polymer dispersed liquid crystal in normal mode

Abstract

Polymer dispersed liquid crystal (PDLC) is a striking material and have an enormous role in electro optic display devices. In this paper, nanoparticles (NPs) doped PDLCs in normal mode were prepared from a mixture of UV curable liquid polymer, nematic liquid crystal (LC) and silica NPs by the polymerization induced phase separation (PIPS) process. Morphological study shows the LC droplets cluster formation in pure PDLC and LC droplets with a more uniform phase separated polymer matrix in NPs doped PDLC due to the heterogeneous nucleation rate caused by the increased nucleation at the surface of NPs. Further, electro optic properties of doped and pure PDLC including transmittance, driving voltage, contrast ratio and sharpness as well as slope of the linear region of the transmittance-voltage were measured, compared and analyzed. Driving voltage of NPs doped PDLCs quite improved, however the slope of linear region and contrast ratio declined as compared to pure PDLC.