Mesoporous silica helical ribbon and nanotube-within-a-nanotube synthesized by sol-gel self-assembly

Using N-miristoyk-L-alanine sodium salt (C(14)-L-AlaS) and 3-aminopropyltriethoxysilane (APES) as structure and co-structure-directing agents (CSDA), mesoporous silicas with the morphologies of helical ribbon and nanotube-within-a-nanotube have been fabricated just by increasing the APES/C(14)-L-AlaS molar ratio from 1.0 to 1.15 and 1.25. The microstructures of the mesoporous silicas have been studied by electron microscopy and it was found that: 1) The mesostructure of the helical-ribbon silica materials was double-layer and the mesopores in the wall were disordered; 2) The nanotube-within-a-nanotube silica was multilayer and the mesopores in the wall were also disordered; 3) The silica materials obtained by increasing the APES/C14-L-AlaS molar ratio to 1.25 maintained the nanotube-within-a-nanotube morphology, but with the existence of larger mesopores in the wall. (C) 2010 Elsevier B.V. All rights reserved.