Influence of azo dye concentration on dielectric response in polymer dispersed liquid crystal composites

Abstract

In this paper, we have investigated dielectric properties of azo dye methyl red (MR) doped polymer dispersed liquid crystal (PDLC) composites. Norland optical adhesive (NOA 65) and nematic liquid crystal (E63) materials were used to construction of PDLC composite. In order to observe the effect of MR concentration, PDLC was dispersed with 1, 3 and 5% wt/wt MR. Dielectric properties have been investigated using the dielectric spectroscopy method in the frequency range of 500 Hz to 10 MHz at room temperature. Dielectric constant (ε′ and ε″), dielectric anisotropy (Δε′), relaxation frequency (fR), relaxation time (τ), threshold voltage (Vth) and also splay elastic constant (K11) have been determined for the pure PDLC and its doped version PDLC + 1% MR, PDLC + 3% MR and PDLC + 5% MR composites by using experimental data. Dispersal of increasing MR concentration caused τ, Vth, K11 are decreased whereas fR is increased for the investigated samples. Results show that different MR concentrations significantly affect the dielectric properties of PDLC composites and make it suitable to design new based on PDLC device applications.