Agglomeration of silica nanoparticles in filled nematic liquid crystals

The large memory effect of about 95 per cent was achieved in nematic liquid crystal filled with big hydrophilic silica nanoparticles (d=40 nm) and low surface area 50+/-15 m(2)/g. We have measured the temperature dependence of transmittance and heat flow of this system. We have found a small but clearly positive shift of the nematic liquid crystal-isotropic liquid transition temperature with the increase of concentration of nanoparticles. The main origin of the large memory effect is the orientational influence of surface of the silica nanoparticle agglomerates. Agglomeration of nanoparticles is induced by orientational elastic forces of liquid crystal. This effect can be used to form regular or complex microstructures from silica nanoparticles. Applications of such a mixture also include 2-dimensional pressure imaging.