Synthesis of mesoporous silica core-shell particles and using as a stationary phase in column HPLC

In recent years the application of spherical mesoporous silica core-shell particles has been a research hotspot to high performance chromatographic studies thanks to the fast separation, low back-pressure, high resolution and convenient instrumental utilization advantages. Formerly the size-minimization of the packing particles was exploited to elevate the separation efficiency. Half-Sized particles doubled the separation efficiency level quadruplicating the apparatus pressure nevertheless. The efficiency of 3 µm core-shell particles corresponds to that of 1.7 µm fully porous particles in the same apparatus pressure condition for 3 µm fully porous particles[1]. In this work we synthesized the core of the particles through the Stober method and by some modifications[2] .The particles were raised to 2 µm. Then through multiple methods using urea/formaldehyde, polyvinyl alcohol binders and cetyl trimethylammonium bromide(CTAB) surfactant the porous shells with several thicknesses ranging from 100 nm to 1 µm were coated over the core particles and by calcination of the binders and the surfactant were driven out. BET surface area, pore volume and pore diameter are 280 m2/g, 0.6691 ml/g and ~9 nm, respectively. The prepared particles were functionalized by octadecyltrichlorosilane and used as a general column for HPLC. This column was examined over a number of Aromatic hydrocarbon mixtures and showed efficient separations[3].