Large-pore mesoporous silica spheres: Synthesis and application in HPLC

Large-pore mesoporous silica microspheres with tailored pore sizes were prepared via a two-step synthesis process by using a triblock copolymer EO ₂₀PO₇₀EO₂₀ as template in combination with a cosurfactant cetyltrimethylammonium bromide (CTAB) and a cosolvent ethanol. The obtained mesoporous silica spheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and N₂ sorption. The pore size of the silica spheres was increased up to 9.8nm with increasing the hydrothermal treatment temperature in the second step to 130°C. The presence of the cosolvent ethanol was found to be essential to the formation of mesoporous silica with a perfectly spherical morphology. Spherical mesoporous silica was successfully functionalized by dimethyloctadecylchlorosilane (C₁₈), leading to the formation of a C₁₈-modified spherical mesoporous silica. It has been shown that the C₁₈-modified mesoporous silica microspheres can be used as a good packing in high performance liquid chromatography (HPLC) to separate both small aromatic molecules and large biomolecules such as proteins.