Dispersion control and nematic ordering of Ni/Al layered double hydroxide suspensions

In this paper, we report the preparation of aqueous suspensions of Ni/Al layered double hydroxide (LDH) nanoparticles by a non-steady co-precipitation followed by peptization. By choosing suitable peptization temperature and time, well-dispersed suspensions were obtained. Meanwhile, the particle size, shape and size polydispersity can be efficiently controlled. Nematic ordering is observed in colloidal Ni/Al LDH suspensions and confirmed by birefringence observations and SAXS measurements. Furthermore, we showed that the sol–gel transition takes place after a liquid crystalline phase transition in concentrated Ni/Al LDH suspensions. The absence of isotropic–nematic phase separation can be attributed to the fact that the nematic phase droplets are too small to settle to the bottom of the cuvette.