Preparation And Characterization Of TiO₂ Nanomaterial By Lyotropic Liquid Crystal As Template

Nanometer materials have been one of hot-spot study fields for the last few years. The morphology, pore structure as well as surface state have been defined as very important factors for materials performance. Lyotropic liquid crystal phases, which were formed by different surfactant system, were used as soft template to synthesize nanomaterials with desired morphologies and structures. The relationship between the structure of the lyotropic liquid crystal phases and the formed samples were studied in order to control the performance of the products.In this paper, antase TiO₂ nanoparticles were prepared using TiOSO4 as inorganic titanium source, CO(NH₂)₂ or NH₃·H₂O as precipitator by homogeneous precipitation method or direct precipitation method combined with lyotropic liquid crystal as soft template, which was formed by SDS/CTAB/C₅H₁₁OH/H₂O quaternary system, TritonX-100/C₁₀H₂₁OH/H₂O termary system or TritonX-100/H₂O binary system. Polarized optical microscopy (POM), Low angle X-ray Diffraction (Low-angle XRD) and Fourier Transform Infrared Spectra (FT-IR) were applied to investigate the effects of different composition and aqueous concentration on the templete structure of lyotropic liquid crystal. It was found that lyotropic liquid crystal would transform from hexagonal to lamellar as the increase of surfactant concentration. Changing aqueous concentration within a certain range affected the order of lamellar liquid crystal but didn't change the structure. Surfactant, alcohol and water in system associated by some method and hydrophobic interaction leads to the system phase transition from disorder to order. The prepared samples were characterized by different method such as Fourier Transform Infrared Spectra (FT-IR), Thermogravimetry-Differential Thermal Analysis (TG-DTA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results showed that washing alone could not completely remove organics. when calcined at 450°C, the organic could be removed completely and the sample could transform from amorphous into anatase. TiO₂ sample had cast the structure of the LLC phases. TiO₂ with nanohole structure such as hexagonal-shaped, cubic-shaped and lamellar nano-TiO₂ had been synthesized by lyotropic liquid crystal as soft template.