Graft polymerization of vinyl monomers initiated by peroxycarbonate groups introduced onto silica surface by Michael addition

The introduction of peroxycarbonate groups onto a silica surface and the graft polymerization of vinyl monomers initiated by peroxycarbonate groups introduced onto a silica surface were investigated. The introduction of peroxycarbonate groups onto a silica surface was achieved by Michael addition of amino groups introduced onto the silica surface to t-butylperoxy-2-methacryloyloxyethylcarbonate (HEPO). The amount of peroxycarbonate groups was determined to be 0.17 mmol/g. The graft polymerization of various vinyl monomers such as styrene (St), N-vinyl-2-pyrrolidinone (NVPD), and 2-hydroxyethyl methacrylate (HEMA) was initiated by peroxycarbonate groups introduced onto the silica surface to give the corresponding polymer-grafted silicas. The percentage of poly(St)-grafting reached about 120% after 5 h. This means that 1.20 g of poly(St) is grafted onto 1.0 g of silica. The surface of poly(St)-grafted silica shows a hydrophobic nature, but the surfaces of poly(NVPD) and poly(HEMA)-grafted silica show a hydrophilic nature. Furthermore, the poly(St)-grafted silica was found to give a stable colloidal dispersion in a good solvent for the grafted polymer.