Abstract: Abstract:Micro sized silica gel particles were first surface modified with coupling agent γ-mercaptopro pyltrimethoxysilane (MPMS), obtaining the modified particles MPMS-SiO2, on which thiol groups were chemically attached. Subsequently, a surface initiating system was constituted with the thiol groups on the surfaces of MPMS-SiO2 particles and 2,2′-azobis(2-methylpropionitrile) (AIBN) in the organic solvent, namely the thiol AIBN initiating system was formed. The “surface initiated graft polymerization” of glycidyl methacrylate (GMA) was carried out, preparing the grafted particles PGMA-SiO2 with a high grafting degree of 23 g/100 g. The effects of the main factors on the graft polymerization of GMA were examined, and the mechanism of the surface initiated graft polymerization was explored.The functional modification of the grafted particles was conducted using sodium 4 aminobenzenesulfonate as reagent via the ring opening reaction of the epoxy groups of the grafted PGMA, obtaining the functional particles BSNa-PGMA-SiO2 on which sodium benzenesulfonate (BSNa) groups were bonded, and their functionality was preliminarily investigated. Results show that by inducing the decomposition reaction of AIBN, the thiol groups on the surfaces of the particles MPMS SiO2 will produce a hydrogen atom transfer process from thiol groups to the free radicals that were the product of the decomposition reaction of AIBN. As a result, a great deal of sulfur free radicals will produce on the surfaces of silica gel particles, and they will effectively initiate the monomer GMA to be graft polymerized onto silica gel particles. For the graft polymerization system, 55 ℃ should be selected as a suitable reaction temperature, and an amount of AIBN with 0.8% of the monomer mass should be selected as an appropriate used amount of AIBN in the solution. The functional particles BSNa-PGMA-SiO2 carry negative charge with a high density because of the presence of anionic polyelectrolyte on their surfaces. By right of strong electrostatic interaction, the functional particles BSNa-PGMA-SiO2 possess strong adsorption ability towards alkaloids such as for matrine and cytisine.