One-step synthesis of structure controlled vinyl functionalized hollow mesoporous silica nanospheres

In the present study, vinyl functionalized hollow mesoporous silica nanospheres (V-HMSNSs) with tailored mesostructure have been successfully synthesized via a one-step synthetic strategy using the cation surfactant cetyltrimethylammonium bromide (CTAB) as a single micelle template, vinyltriethoxysilane (VTES) as a precursor. It was demonstrated, for the first time, that V-HMSNSs with controllable mesostructure can be easily obtained by adjusting the concentration of CTAB in aqueous solution at low amounts of ammonia. Only solid spheres including vinyl functional groups were generated below the critical micelle concentration value (CMC, 0.0009 M) of CTAB. However, the nanospheres or nanorods with hollow mesostructure were obtained at this value or above it (0.005 M). Whereas no particles were obtained at a higher concentration of CTAB (0.008 M or more than it). It was suggested that the formation of CTAB micelles was closely related to the formation of V-HMSNSs. In addition, the V-HMSNSs with well-defined mesostructure could be obtained when the volume ratio of alcohol to water was about 25:25. More importantly, from these investigations, it appeared that the synthetic method should be highly flexible and enable uniform distribution of functional groups within mesoporous silica frameworks.