Micron-sized silica gel particles were chemically surface-modified with coupling agent KH-590

mercapto groups were introduce onto the surfaces of silica gel particles

and a redox initiation system of mercapto group-cerium (Ⅳ) salt was constructed.On this basis

the highly effective graft-polymerization of acrylonitrile on surfaces of silica gel particles was explored successfully

and the grafted particles SiO2-MPMS-g-PAN with a high grafting degree of 30 g/100g were obtained.The grafted particles SiO2-MPMS-g-PAN were characterized by FTIR

TGA and SEM methods.The effects of the main factors on the graft polymerization of AN were examined.The experimental results show that mercapto group-cerium (Ⅳ) salt system is similar to hydroxyl group-cerium (Ⅳ) salt system

and it can effectively initiate the vinyl monomers to be graft-polymerized on the surfaces of solid particles.As compared with the method of grafting through

the graft polymerization initiated by cerium (Ⅳ) salt has the character of high graft efficiency because the active sites lie on the surface of the support

and it is a highly effective method of surface-initiated grafting.In order to prepare the grafted particles SiO2-MPMS-g-PAN with high grafting degree in this system

the suitable H+ concentration should be 0.25 mol/L

and the appropriate cerium (Ⅳ) salt concentration should be 5.010-3 mol/L.At the same time

the graft polymerization should be allowed to carry out at 50℃.