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 EO20PO70EO20 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 9.8 nm 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.