Preparation, characterization, and morphology control of micron-sized monodisperse thiol-containing hollow organosilica microspheres

Hollow organosilica microspheres (HOMs) possess distinctive properties and are promising in various fields. However, research on micron-sized uniform functional HOMs is limited. Herein, micron-sized monodisperse thiol-functionalized HOMs (HOMs-SH) were fabricated via a dual-templating strategy. The hard and soft templates used in the preparation of HOMs-SH were micron-sized SiO 2 microspheres prepared through a modified Stöber method and hexadecyltrimethylammonium bromide (CTAB), respectively. The precursors were 1,2-bis(triethoxysilyl)ethane (BTEE) and (3-mercaptopropyl)trimethoxysilane (MPTMS), and the etchant was Na 2 CO 3 . This strategy was simple, controllable, mild, and eco-friendly. The morphology, chemical composition, pore structure, thermal stability, and mechanical properties were characterized by TEM, SEM, FTIR, Raman, solid-state 29 Si NMR, XPS, BET, XRD, TGA, and AFM. Results revealed that the micron-sized monodisperse HOMs-SH exhibited hollow structures with a core cavity and thin shell with micropores (1.95 nm) and mesopores (2.95 nm). They had the merits of easy separation and thiol groups concentrated on the surface. BET specific surface area reached 342 m 2 /g, enhancing the availability of thiol sites. The formation of shells and morphology of HOMs-SH were influenced by formula and process conditions in the step of coating organosilica onto the templates, including the size of templates, temperature, dosages of CTAB and precursors, and MPTMS/BTEE ratio. The shell thickness (43–140 nm) and diameter (1149–3205 nm) of HOMs-SH were controllable. This article provides new insights into the design of micron-sized functional hollow microspheres with expected structures and properties for diverse applications, and contributes to the understanding and optimization of coating organosilica shells onto other micron-sized templates.