Microstructure and electrical conductivity of hybrid liquid crystalline composites including 5CB, carbon nanotubes and clay platelets

Abstract

The microstructure and electrical conductivity of 4-pentyl-4′-cyanobiphenyl (5CB) liquid crystal (LC) filled with multiwalled carbon nanotubes (NTs), organophilic montmorillonite (OM) clay platelets or their hybrid mixture OMNT were studied in the temperature range 290–350 K. The OMs were prepared by organic modification of montmorillonites obtained from different mineral deposits. In general, the samples 5CB+OMNT containing OM demonstrated more homogeneous distribution of filler particles than the samples 5CB+NT with the same amount of nanotubes. For the OM based on montmorillonite from Pyzhevsk deposit (Ukraine) we obtained that change of OMNT filler concentration from 1 to 4.5 wt% resulted in transition from the well developed nanoparticle network to the structure of isolated agglomerates. This was accompanied by an increase (1% of OMNT filler) and a decrease (4.5% of OMNT filler) of electrical conductivity in more than one order of magnitude as compared with the 5CB+NT composite with the same amount of nanotubes. The microstructure and electrical conductivity of the composites were also dependent on the geological origin of the clay minerals.