Effect of Solvent on the γ-Aminopropyltriethoxysilane Modified Titanium-Pillared Montmorillonite

Titanium pillared montmorillonite was prepared by the sol-gel method with the precursor of isopropyl titanate. Subsequently, the Ti-pillared montmorillonite was modified by gamma-aminopropyltriethoxysilane (APTES) in three solvents with different polarities. Combining with X-ray diffraction pattern, Fourier transform infrared spectroscopy, thermal analysis, scanning electron microscopy, and nitrogen adsorption-desorption, the structure, morphology, specific surface area, and pore-size distribution of the product were discussed. The distance of (001) lattice planes achieved 11.46 nm after titanium pillaring, accompanied with the increased specific surface area and pore size. The hydrolysis of APTES was easy to conduct in the presence of anhydrous ethanol and methanol. Since the water molecules on the surface of titanium oxide can be replaced by alcohol, the hydrolysis of APTES was promoted and the samples have high silane loading amounts in ethanol and methanol systems. However, due to the molecular repulsion, the water molecules tend to enter the interlayer channel of titanium pillared montmorillonite in cyclohexane system. This inhibited the bonding between silanes and interlayer titanium oxides, resulting in a lower grafted amount. Therefore, by choosing different solvents, the grafting amount of silane on the Ti-pillared surface could be adjusted.