Aerosil dispersed in a liquid crystal: magnetic order and random silica disorder

Dispersions of silica spheres (aerosil) in octylcyanobiphenyl (8CB) liquid crystal were investigated with deuteron NMR. For the lowest silica density dispersions, there is a field-induced liquid crystal alignment as the field anneals most elastic strains. Increasing the silica density, the molecular alignment is stabilized by the spheres and is retained after sample rotation in the field; in the process, a few silica strand links are broken by the field, which realigns some molecules. At higher densities, the aerosil dispersions are aerogel like and disordering effects are apparent.