Vinyl Functionalized Porous Silica Nanospheres Prepared by Poly(1-vinyl-2-pyrrolidone) Grafted Surface-Protected Selective Etching Strategy.

A new effective surface poly(1-vinyl-2-pyrrolidone) (PVP) grafted layer protected selective etching strategy has been used for preparing vinyl functionalized porous silica nanospheres (V-PSNSs). The main reaction mechanism was relied on the vinyl groups distributed on the surface of outer vinyl silica nanospheres (V-SiO2) which can be polymerized with another vinyl monomer, such as 1-vinyl-2-pyrrolidone (VP), in the presence of initiator. It was observed from the research results that only grafting PVP on the surface of outer vinyl silica nanospheres (V-SiO2) can V-PSNSs be obtained, because grafting PVP was able to protect outer V-SiO2 from being etched prior to inner pure silica (sSiO2). In addition, effect of the amounts of sSiO2@V-SiO2 as another monomer substrate on the formation of PVP grafted sSiO2@V-SiO2 (sSiO2@V-SiO2/PVP) was discussed. The results showed that the less of the sSiO2@V-SiO2 amounts, the thinner of the PVP grafted layer on the surface of sSiO2@V-SiO2, the poorer protection ability of the surface. In the present study, V-PSNSs with 29 m2g-1 of BET surface areas and 0.1 cm3g-1 pore volumes were successfully synthesized by grafting 0.3 g of VP on the surface of 0.3 g of sSiO2@V-SiO2 and subsequent etching.