Abstract
A simple method of forming ultra-thin chrysotile nanotubes was developed. A solution of MgCl2 and NaOH was treated hydrothermally in the presence of silica or silicate glasses. The thinnest tubular particles, containing pores with an inner diameter of 8–10 nm, an outer diameter of ca. 15 nm and length ca. 150 nm, were formed in the Mg-rich systems. As the NaOH content in the system was increased, the wall thickness increased while the outer diameter was unchanged, i.e. the inner pore size decreased. Newly formed chrysotile decomposed at ca. 500°C, i.e. between the corresponding temperatures for Mg(OH)2 (350°C) and natural chrysotile (600°C). The mesoporosity of the nanotubes was confirmed by the appearance of hysteresis loops in both nitrogen adsorption and water vapour adsorption measurements. Heat treatment led to a narrowing of the pore edges and brought about the sealing of the tube ends. Nitrogen and water adsorption measurements were also performed to analyze the effect of heat treatment on the porous structure and the condensed phases in the pores.