Synthesis of Porous Hollow Organosilica Particles with Tunable Shell Thickness

Abstract

Porous hollow silica particles possess promising applications in many fields, ranging from drug delivery to catalysis. From the synthesis perspective, the most challenging parameters are the monodispersity of the size distribution and the thickness and porosity of the shell of the particles. This paper demonstrates a facile two-pot approach to prepare monodisperse porous-hollow silica particles with uniform spherical shape and well-tuned shell thickness. In this method, a series of porous-hollow inorganic and organic-inorganic core-shell silica particles were synthesized via hydrolysis and condensation of 1,2-bis(triethoxysilyl) ethane (BTEE) and tetraethyl orthosilicate (TEOS) in the presence of hexadecyltrimethylammonium bromide (CTAB) as a structure-directing agent on solid silica spheres as core templates. Finally, the core templates were removed via hydrothermal treatment under alkaline conditions. Transmission electron microscopy (TEM) was used to characterize the particles′ morphology and size distribution, while the changes in the chemical composition during synthesis were followed by Fourier-transform infrared spectroscopy. Single-particle inductively coupled plasma mass spectrometry (spICP-MS) was applied to assess the monodispersity of the hollow particles prepared with different reaction parameters. We found that the presence of BTEE is key to obtaining a well-defined shell structure, and the increase in the concentration of the precursor and the surfactant increases the thickness of the shell. TEM and spICP-MS measurements revealed that fused particles are also formed under suboptimal reaction parameters, causing the broadening of the size distribution, which can be preceded by using appropriate concentrations of BTEE, CTAB, and ammonia.

Traceable characterization of hollow organosilica beads as potential reference materials for extracellular vesicle measurements with optical techniques

“…HOB samples were prepared using a hard template method combined with a basic amino acid catalysis route, as described previously [ 26 ]. , and nominal diameter silica core particles from Alpha Nanotech (Vancouver, Canada) were used for the preparation of 02-HOB-AN200, as shown in Fig.…”

Quantitative Elasticity Mapping of Submicron Silica Hollow Particles by PeakForce QNM AFM Mode

“…It should be noted that the inherent nature of the synthesis results in micro- or mesoporous structures of the silica materials fabricated by a sol–gel method. Moreover, the porosity, pore size distribution and pore structure can be tailored by varying the synthesis method or reaction conditions, e.g., pH of the reaction mixture, the characteristics of the surfactants used, as well as the concentrations and sources of silica [ 38 , 39 , 40 ]. On the other hand, the mechanical properties of porous silica materials strongly depend on their microstructure and overall degree of porosity.…”