Electrorheological Properties of Liquid Crystalline Gold Nanoparticles in a Nematic Solvent

The electrorheological (ER) properties of a composite material consisting of a nematic liquid crystal (LC) and gold nanoparticles covered with mesogenic groups are studied. The gold nanoparticles are covered by normal alkyl chains and LC compounds. The miscibility of the gold nanoparticles with the nematic LC is investigated by polarizing optical microscopy (POM). In order to improve the ER effect of the composite, a simple strategy is investigated from the viewpoint of a material design in surface-modified gold nanoparticles by a lateral substitution of the mesogenic groups. The presence of the gold nanoparticles in the nematic LC leads to the slight enhanced ER effect compared to that observed for 5CB. This study demonstrates the potential of a hybrid system consisting of LCs and gold nanoparticles to yield a larger ER effect.