Nematic liquid crystal dispersed with two-dimensional functionalised graphene oxide (fGO): insights on improving the nematic ordering and reducing electro-optic response time

Doping a nematic liquid crystal (NLC) with nanoparticles (NPs) of varied dimensions and properties to form LC-NP nanocomposites with improved electro-optic and dielectric properties has recently been a much-explored field of work. But still, NLC nanocomposites based on two-dimensional (2D) NPs have not been studied vividly because of the high tendency of 2D NPs to aggregate together. In the present work, we have studied the effect of incorporating hexadecanethiol functionalised graphene oxide (fGO), a 2D NP, in a conventional NLC medium under varying doping concentrations. We found that at a lower doping concentration (similar to 10(-4) wt.%), the NLC nanocomposite showed a substantial increase in dielectric anisotropy (Delta epsilon) and birefringence (Delta mu) values as compared to pure NLC sample. A significant decrease (similar to 50%) in ionic conductivity as well as reduced electro-optic response time (similar to 75%) was also observed in this NLC nanocomposite. As the fGO doping concentration was increased (similar to 10(-2) wt.%), a reverse trend was observed for Delta epsilon, Delta mu and response time values, which declined sharply with increasing doping concentration. Hence, the present work highlights two different working mechanisms at low- and high-doping concentrations of 2D NPs. [GRAPHICS] .