Graft Polymerization of Acrylonitrile Initiated by Cerium Salt on Surface of Silica Gel Particles

Coupling agent, 3-glycidoxypropyltrimethoxysilane (EPPS) was bound on the surfaces of silica gel particles. The ringopening reaction of the epoxy groups of the bound EPPS was performed with acidic catalyst, leading to the modified particles with hydroxy groups HXYGSiO2 (HXYG). Graft polymerization of acrylonitrile (AN) was conducted on the particles HXYG-SO2 with the redox initiating system, cerium salt and the hydroxyl groups, to form the grafted particles PAN-SiO2. The effects of factors on the graft polymerization were examined. The experimental results show that the grafted particles PAN-SiO2 have high grafting degree （0.19 g/g） and there is a high graft efficiency of monomer as the initiating species are located on the surfaces of silica gel particles. The concentration of the initiator and cerium salt affects the graft degree of PAN. The excessive cerium salt will accelerate the oxidation termination process, leading to lower graft degree. The cerium salt concentration of choice is around 5.93×10-3 mol/L. The graft degree of PAN first increases and then decreases with the increasing of sulfonic acid concentration, and it reflects the microscopic mechanism of graft polymerization initiated by cerium salt. As H+ concentration is 0.38 mol/L, the graft degree of PAN on PANSiO2 microspheres has a maximum value.