Advanced Functional Materials, Vol.18, No.4, 541-550, 2008
Synthesis and characterization of silica nanotubes with radially oriented mesopores
Hierarchical silica nanotubes with radially oriented mesoporous channels perpendicular to the central axis of the tube were synthesized by using self-assembled chiral anionic surfactant, co-structure directing agent (CSDA) and silica precursor. The average inner diameter and the wall thickness were similar to 94, similar to 62, and similar to 62 nm and to similar to 27, similar to 33, and similar to 45 nm, respectively, by manipulating the synthesis gel composition, while the diameter of the wall mesopofes was kept constant at similar to 4 nm. These materials with such a unique structure were produced only with chiral surfactant and achiral or racemic surfactant did not give rise to mesoporous silica nanotubes. The existence of helicity in the lipid bilayer template was confirmed by means of circular dichroism spectroscopy. The mesoporous penetrating from outside to inside of silica nanotubes are thought to originate from the initial formation of self-assembled lipid tubes with helical bilayers, which in turn re-assemble to form the mesopores in the wall of the nanotubes upon addition of co-structure directing agent and silica source.