Preparation of Grafted Particles of PHEMA-SiO₂ in Non-aqueous Media by Surface-Initiated Graft Polymerization Method and Their Adsorption Property for Quercetin

The mercapto groups (-SH) of coupling agent γ-mercaptopropyl trimethoxysilane (MPMS) were first bonded on the surface of silica gel particles in the micron level, and the modified particles MPMS-SiO₂ were prepared. In the non-aqueous solvent, N, N-dimethylformamide (DMF), a redox surface-initiating system was made up by the benzoyl peroxide (BPO) in the solution and the mercapto groups on the surface of modified particles MPMS-SiO₂. The graft-polymerization of 2-hydroethyl methylacrylate (HEMA) on the surface of silica gel particles in the non-aqueous medium was achieved. The grafted particles PHEMA-SiO₂ were successfully prepared of which the grafting degree was up to 28 g/100 g. The particles PHEMA-SiO₂ were characterized by FT-IR, TG and SEM, and the effects of the main factors on the graft-polymerization were examined. On this basis, the adsorption action of the particles PHEMA-SiO₂ based on hydrogen bond for quercetin was investigated. Results show that the -SH/BPO initiating system can make the graft-polymerization of HEMA be carried out smoothly in the non-aqueous solvent. The suitable temperature is 65℃, and the appropriate used amount of the initiator BPO mass fraction is 1.0% of the monomer. The common hydrogen bond with multi-site and π-type hydrogen bond will produce between the particles PHEMA-SiO₂ and quercetin molecule, which leads to the strong adsorption ability of PHEMA-SiO₂ particles for quercetin. The solvent competitive adsorption and raising the temperature will decrease the adsorption capacity of quercetin.