Synthesis of β-cyclodextrin Functionalized silica nanoparticles and their effects on the dielectric, optical and electro-optic properties of nematic liquid crystal

Abstract

ABSTRACT The present work reported the synthesis and characterisation of β-cyclodextrin (βCD) grafted into silica (SiO2@βCD) nanoparticles (NPs). Morphology analysis shows that the prepared NPs have a spherical shape with 170 nm of size. The electro-optic, dielectric and viscoelastic properties of SiO2@βCD doped nematic 5CB were examined in different concentrations of the NPs. A decrease in clearing temperature, birefringence and the order of the nanocomposite systems as compared to the pure system was observed. Dielectric parameters of pure and doped samples were measured in the frequency range of 1–2 MHz. Ionic conductivity and dielectric anisotropy increase significantly with NPs concentration due to the strong dipole moment and polarisability of SiO2@βCD. The advantage of dopedSiO2@βCDnematic 5CB is attributed to the significant decrements in threshold voltage by 32% and strong additional coupling of the electrical dipole moments in the spherical NPs with the nematic director field. On the other hand, it is found that the NPs exhibit a decreasing effect on the response time of the nematic liquid crystal, which is demonstrated by the decrement in the viscosity. The results indicate that doping SiO2@βCD is appropriate to fabricate a fast response LC device.