Dielectric and Electro-Optical Properties of Nematic Liquid Crystals Dispersed with Carboxylated Nanodiamond: Implications for High-Performance Electro-Optical Devices

High Resolution Image Download MS PowerPoint Slide This study explores the enhancement of dielectric, electro-optical, and dynamic response properties of nematic liquid crystal (NLC) E7 by physical dispersion of carboxyl-functionalized nanodiamonds (NDs). At an optimal concentration of 0.10 wt %, ND incorporation reduced ionic concentration by 42.61% via an ion-trapping mechanism, resulting in a 61% decrease in rotational viscosity. Dielectric anisotropy (Δε) increased by 28.5%, attributed to the anisotropic self-assembly of nanodiamonds along the LC director, consistent with prior observations of field-induced ND alignment enhancing molecular ordering. The pretilt angle decreased significantly from 3.2° to 0.6°, improving LC alignment uniformity and contributing to enhanced optical performance at wider viewing angles. Switching dynamics improved with a 35.64% reduction in rise time and a 79% decrease in fall time (from 11.16 ms to 2.35 ms), surpassing the improvements anticipated from viscosity reduction alone. Finite element simulations using ANSYS Maxwell, conducted under a 5 V applied field (above the threshold and operating voltage), confirmed that smaller NDs (<10 nm) generate strong local electric fields (2.049 V/μm) and displacement fields (10.3 nC/cm 2 ), facilitating efficient LC reorientation. However, at concentrations above 0.10 wt %, ND aggregation led to a 46.49% increase in viscosity and a partial loss of electro-optical efficiency, validating the existence of an optimal ND concentration threshold. These findings demonstrate that carboxylated nanodiamond dispersion enables substantial improvement in dielectric and electro-optical properties of nematic LCs, positioning them as strong candidates for advanced, low-voltage, fast-response, and wide-viewing-angle liquid crystal displays (LCDs).