Organic-inorganic hybrid hollow nanospheres with microwindows on the shell

We demonstrate, for the first time, that organic-inorganic hybrid hollow nanospheres with controllable size (12-20 nm) and shell thickness (4-7 nm) can be successfully synthesized through the condensation of 1,2-bis(trimethoxysilyl)ethane (BTME) around an inorganic-electrolyte-stabilized F127 micelle under a mild buffer condition (NaH2PO4-Na2HPO4, pH similar to 7.0). The hollow spheres feature microwindows with pore size about 0.5-1.2 nm on the shell, which allow the guest molecules to diffuse into the hollow cavities. It was found that the concentration of the buffer solution in the synthesis was crucial to the formation of hollow nanosphere. At a low buffer concentration (20-100 mM), the surfactant exists as individual micelle. A core/shell nanocomposite was formed by the deposition of BTME at the corona of individual micelle, which leads to the formation of organic-inorganic hybrid nanoparticles with hollow interior after the extraction of the surfactant. The aggregation of individual micelles was observed at higher buffer concentration (>200 mM), which favors the formation of irregularly shaped particles with ordered mesostructure. This work presents a novel and facile strategy to fabricate hollow nanospheres with microwindows, which provides a versatile platform for practical applications of organic-inorganic hybrid materials in a broad range of fields such as catalysis, encapsulation, and drug delivery, etc.