Langmuir, Vol.22, No.1, 6-9, 2006
Synthesis of hollow silica spheres with mesostructured shell using cationic-anionic-neutral block copolymer ternary surfactants
Hollow silica spheres with mesostructured shells (HSSMS) were prepared with a vesicle template of cetyltrimethylammonium bromide-sodium dodecyl sulfate-Pluronic P123 (C(16)TMAB-SDS-EO20PO70EO20) at a SDS/C(16)TMAB ratio of 0.6-0.8 following a fast silicification in dilute silicate solution at pH approximate to 5.0. The mesostructure of the shell is disordered, and the mesopore size is about 5.5-7.5 nm. Moreover, the direction and length of the nanochannels of the shell change with the SDS/C(16)TMAB ratios. A bi-template model, in which the C(16)TMA(+)-DS- form the stable bilayer vesicle structure and the P123 copolymers anchored on C(16)TMA(+)-DS- vesicle act as the template for the mesoporous silica, was proposed to explain the formation of the HSSMS. This bi-template model can be applied extensively to prepare the HSSMS with different diameters and pore sizes by using other C(n)TMAX-SDS-EOnPOmEOn ternary-surfactant mixtures.