Synthesis of Hollow Silica Spheres with Mesostructured Shell Using Cationic−Anionic-Neutral Block Copolymer Ternary Surfactants

Abstract

Hollow silica spheres with mesostructured shells (HSSMS) were prepared with a vesicle template of cetyltrimethylammonium bromide-sodium dodecyl sulfate-Pluronic P123 (C16TMAB−SDS-EO20PO70EO20) at a SDS/C16TMAB ratio of 0.6−0.8 following a fast silicification in dilute silicate solution at pH ≈ 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/C16TMAB ratios. A bi-template model, in which the C16TMA+-DS- form the stable bilayer vesicle structure and the P123 copolymers anchored on C16TMA+-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 CnTMAX-SDS-EOnPOmEOn ternary-surfactant mixtures.