N-alkylammonium intercalated 2-d hydrous titanates and their thermotropic phase transition

The long chain alkylammonium (CnH2n+1NH3, n = 8∼18) titanates have been prepared by reacting the 2-dimensional layered hydrous titanate (H2Ti4O9 · 1.2H2O) with the corresponding alkylammonium salt in an aqueous solutions and their thermotropic phase transition was also observed. The intercalation reaction could be carried out successfully by the exchange reaction between guest molecules, where the layered titanantes were intercalated in advance with a smaller butylammonium guest before reacting with a larger and longer alkylammonium one in order to reduce the steric hindrance during the intercalation reaction. The interlayer distances of the alkylammonium derivatives increase almost linearly with the number of carbon atom (Δd/Δn = 1.19Å) and the interlayer alkylammonium ions form bilayer with average tilting angle (θ) of ≈ 70°. Thermotropic phase transition of the intercalated compounds were also investigated with DSC and high temperature XRD.