| Popis: |
Radical polymerization of methylmethacrylate in an aqueous emulsion was carried out using the complex oxide RbTe 1.5 W 0.5 O 6 as a photoinitiator under visible light irradiation with λ= 400-700 nm. Studies of the process and reaction products using modern methods of physical and chemical analysis (GPC, IR, NMR, etc.) have shown that several directions of monomer transformations occur simultaneously in the reaction mixture. Polymethylmethacrylate, produced in the organic phase and characterized by Mn ~ 140-145 kDa, is a result of polymerization initiation by a hydroxyl radical formed due to complex transformations of electron-hole pairs during irradiation of the photocatalyst. Moreover, the interaction of the hydroxyl radical with OH groups on the complex oxide RbTe 1.5 W 0.5 O 6 surface and the subsequent formation of oxygen-centered radicals lead to grafting polymer macromolecules onto the photocatalyst surface. In addition, methylmethacrylate is able to oxidize to a cyclic dimer with terminal double bonds and then form a polymer with cyclic dimer links due to coordination by double bonds on the complex oxide RbTe 1.5 W 0.5 O 6 surface. The high activity of the hydroxyl radical made it possible to obtain the graft copolymer PMMA-pectin by grafting the polymer product onto the surface of the natural polymer-pectin. Comparison of the sponge morphology of the graft copolymer PMMA-pectin and the initial pectin samples using the scanning electron microscopy method showed a noticeable difference in their structural and topological organization. This fact is especially interesting in terms of studying the properties of the graft copolymer as a material for the scaffolds. |
