Regulation of refractive index of polymer matrix and its effect on properties of polymer-dispersed liquid crystal films

• The effect of brominated monomers on the electro-optical properties of PDLCs was investigated. • Contrast ratio modulation of PDLC films by adjusting the refractive index of the polymer matrix . • The influence of the refractive index of the polymer matrix on the viewing angle of PDLC films was investigated. • PDLC films with high contrast (71.4) and low driving voltage (4.9 V) of only 8 μm thickness were prepared. Currently, thin polymer-dispersed liquid crystal (PDLC) films used in display applications have rarely been studied because the contrast ratio (CR) considerably decreases with decreasing thickness. Herein, the refractive index of the polymer matrix ( n p ) is adjusted by introducing bromine atoms and benzene rings into the acrylate, and the on-state transmittance is enhanced by improving the matching degree between n p and the ordinary refractive index of the liquid crystal. Simultaneously, the dissimilarity between n p and the average refractive index of LC is also elevated, which increases off-state scattering. This ultimately results in a 123 % increase in CR. Appropriate n p also broadens the viewing angle. In addition, further introduction of the methyl group on the acrylate monomer significantly increases the polymer pore size, resulting in a voltage reduction of 52 %. This study provides a new approach for enhancing the CR of PDLC films, expanding their potential applications.