Study On Free Radical Polymerization Initiated By Potassium Ditelluratoargentate (Ⅲ)

This paper is mainly about the application of potasium ditellruatoargentate(III) (DTA) in free radical polymerization and will be discussed in four sections.Chapter I: The development and the present research situation of DTA as well as the present study on graft copolymerization of cellulose and sodium alginate were reviewed systematically. In addition, the theoretical and practical significance of DTA's application in homopolymerization and in graft copolymerization of vinyl monomers onto natural macromolecules were pointed out.Chapter II: It is the first time that DTA was employed in radical polymerization. A two-step single-electron-transfer process of DTA reductions is proposed to explain the production of free radicals and the initiation. The kinetic and mechanistic features of DTA initiated aqueous polymerization of acrylamide (AM) have been investigated in an alkaline medium. The results indicated that the equation of the rate of polymerization (Rp) is: Rp = k[AM]1.68 [DTA]0.67 and that the overall activation energy of AM polymerization is 33.6kJ/mol. Based on the FTIR and 'H NMR spectra analyses, a tentative initiation mechanism is proposed.Chapter III: DTA, paired with hydroxyl-characteristic groups with reducibility on the macromolecules' backbones was used to initiate the graft copolymerization of acrylate monomers onto cellulose and sodium alginate. High grafting parameters were obtained. The dependence of grafting parameters on such reaction conditions as temperature, reaction time, initiator concentration and the amount of monomer were also investigated. The resultant graft copolymers were characterized through FTIR, SEM, X-ray diffraction, and TGA. Furthermore, a tentative mechanism involving a two-step single-electron- transfer process in DTA reduction is proposed to explain the generation of radicals and the initiationChapter IV: Potassiumdiperiodatonickelate(IV) wasemployed to initiate the;grafting of MAonto terpolyamide(nylon 6/nylon 66/nylon 1010); High graftingefficiency (>90%) were obtained, which indicated that Ni (IV)-terpolyamide system is an efficient redox initiator for this grafting. Maximum grafting efficiency and percentage of grafting were obtained at [Ni(IV)] = 8 X 10-4mol/L, MA/nylon(weight)= 4.5, t = 35癈. FTIR, SEM and X-ray diffraction were employed to characterize the graft copolymers. A mechanism based on the two separate single-electron-transfer process of Ni (IV) to Ni (II) is proposed to explain the formation of radicals and the initiation. In addition, the copolymers were used as compatibilizer in blends of terpolyamide and poly(methyl methacrylate). The SEM photographs illustrate that the addition of graft copolymer efficiently improved the miscibility of the blends.