Ferromagnetic nanoparticles in a ferroelectric liquid crystal: Properties of stable colloids in homogeneous cells

Stable colloids in ferroelectric liquid crystal (FLC) of fine ferromagnetic CoFe2O4 nanoparticles (NPs) coated with specially designed promesogenic ligands were obtained. The studying of FLC properties for these nanocomposite materials revealed significant changes in dielectric spectra and increase in rotational viscosity of FLC accompanied with noticeable degradation of texture. The changes in dielectric parameters have a pronounced NPs concentration dependence although it was shown that the cell surface contribute to these changes significantly, thus, the role of NPs in changing of the properties was critically revised. Monitoring of dielectric properties and other physical parameters of FLC with time confirmed a high stability of the material upon storage. The influence of magnetic field on basic parameters of FLC in NPs-FLC colloids was examined and explained taking into account highly developed and strongly interacting with LCs organic shell on the NPs surface. Despite a high stability and homogeneity of the composites, in magnetic field the materials do not reveal any significant changes from properties of pure FLC except of increase in viscosity which as a result of alignment of magnetic NPs along with magnetic field and strong interpenetration of LC molecules and NPs ligands.