Preparation and evaluation of crosslinked polystyrene-divinylbenzene stationary phase on porous silica by atom transfer radical polymerization for high performance liquid chromatography

A crosslinked polystyrene-divinylbenzene (PS-DVB) stationary phase was prepared onto silica gel with the pore size of 100 Å and 300 Å (SiL-PSD-10, SiL-PSD-30) by surface-initiated atom transfer radical polymerization (ATRP) for high performance liquid chromatography (HPLC) separation of alkylbenzenes, fullerites, and proteins, respectively. The SiL-PSD coating and the pore size distribution were characterized by FT-IR, TGA, and nitrogen adsorption-desorption isotherms. The crosslinking degree within stationary phase was determined in good consistency with the feeding ratio, as confirmed by RP-HPLC. It was found the SiL-PSD-10 particles could resist the harsh etching of 0.1 M NaOH for at least 6 h, while bare silica was totally dissolved and commercial C18 silica was partially dissolved under the same conditions. Under alkaline conditions (pH 11), the column bleeding rates of SiL-PSD-10 were reduced by 83 % and 96.0 % respectively compared to commercial C18 column and bare silica. Under accelerated aging conditions, SiL-PSD-10 maintained over 94 % of its initial column efficiency after exposure to 16,000 column volume of mobile phase. On SiL-PSD columns, alkylbenzenes could be separated in reversed-phase mode, and fullerite (C₆₀/C₇₀) could be baseline resolved within 2 min with benzene as the mobile phase. During the continuous monitoring for 70 h, RSDs of the retention times of proteins were between 0.49 % and 1.19 %. Generally, SiL-PSD had been demonstrated to combine the excellent mechanical strength and uniform porosity of silica gel with the outstanding chemical resistance of PS-DVB, and could be used for HPLC separation across a wider pH.