Effect of magnetic nanoparticles with various geometrical shapes on morphology and dielectric properties of nanodispersions of nematic liquid crystal in polymer matrix

Abstract

Abstract. Prepared in this work are dispersions of nematic liquid crystal in polyvinyl alcohol with sizes of liquid phase inclusions less than one micrometer (nano-polymer dispersed liquid crystal (PDLC)) by changing technology of mixing the components. It was shown that, like to the case of earlier examined dispersions with the droplet sizes 6 to 10 μm (micro-PDLC), the conductivity of nano-PDLC has two components: the ion one, which value does not depend on frequency, and the electron one, the value of which depends on frequency according to a power law. It was found that the ion conductivity of nano-PDLC is three orders of magnitude higher than that for micro-PDLC, and the exponent for the electron components of nano-PDLC conductivity is less than that for micro-PDLC. It was shown that the spherical and rod-like magnetic nanoparticles (MNs) influence in a different manner on the conductivity components of nano-PDLC. If for the maximum concentration of spherical MNs .% wt 10 2 3   the ion conductivity is 2-fold increased, then at the same concentration of rod-like MNs the ion conductivity value increases by more than one order of magnitude.

Features of dielectric properties of medical thermal indicators based on dispersions of cholesteric liquid crystals in the polymer matrix

“…As we noted in [6], the reason for this dispersion of the ε' value is the influence of near-electrode processes. Quite a significant difference between the dielectric properties of the samples 1 and 2 at the frequencies less than 1 kHz can be explained by a significant difference in the parameters of the near-electrode processes in these samples.…”

“…Technology of manufacturing dispersions of CLCs in the polymer was practically the same as in the work [6]. To prepare dispersions, we used a 10% aqueous solution of polyvinyl acetate.…”

“…As in [7,8], the dielectric properties of the obtained sandwich samples were investigated within the frequency range 6…10 6 Hz by using the oscilloscopic method [9]. As electrodes, we used glass plates coated with a conductive layer of ITO (mixtures of tin and indium oxides).…”

“…The purpose of this work was to study the dielectric characteristics for two types of thermal indicators based on CLC dispersed in a polymer matrix with carbon black impurities, selective light reflection of which occurred at normal (36.5 C) and elevated (38.2 C) human body temperatures, and also to compare these results with our previously published data on the properties of NLC in the same polymer [6].…”

Peculiarities of nonadditive changes in conductivity of nano-PDLC under influence of magnetite and single-wall carbon nanotubes

“…Since we have analyzed the frequency dependence of the permittivity  and conductivity σ of nano-PDLC with MN in detail in the work [5], let us consider in detail the similar properties of nano-PDLC with SWNT and nano-PDLC with SWNT and MN together. Fig.…”