Phosphorylated silica nanotubes: preparation and characterization

Recently, the strategy of doping inorganic particles into polymer membranes to modify them has been studied intensively. However, these inorganic particles have a disadvantage without being in good compatibility with the polymers. To enhance the compatibility between inorganic particles and polymers, phosphorylated silica nanotubes (PSNTs) with specific high ratios of length to diameter are prepared. Silica nanotubes (SNTs) are prepared through the hydrolysis of tetraethyl orthosilicate in a mixture of aqueous ammonia and dl-tartaric acid, then PSNTs are obtained by silylation and phosphorylation modifications. The optimum synthesis conditions of PSNTs are explored; in addition, the as-prepared PSNTs are characterized by Fourier transform infrared, transmission electron microscope, BET, x-ray photoelectron spectroscopy analysis and thermogravimetric analysis. The results indicate that the ratio of length to diameter of the PSNTs is approximately 20, the thickness of the tube wall is 20 nm, the specific surface area of the PSNTs is 460.2 m(2) g(-1), the inner diameter of the PSNTs is 76 nm, many mesopores are distributed in the tube walls of the PSNTs, and the PSNTs have numerous hydroxyl active sites along their length direction. Therefore, PSNTs are desirable as suitable fillers of polymer membranes.