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 (C₁₆TMAB-SDS-EO₂₀PO ₇₀EO₂₀) 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 C_nTMAX-SDS-EO_nPO _mEO_n ternary-surfactant mixtures.