Study On Block Copolymerization Initiated With Potassium Diperiodatonickelate (â…£)

This paper has invested the application of potassium diperiodatonickelate(IV) (Ni(IV)) in the block/graft copolymerization of poly(ethylene glycol)(PEG),poly(1,2-propylene glycol adipate)(PPA),polyacrylamide(PAAM) and will be divided in three section. In the first chapter, the development and the present research situation of Ni(IV) and block copolymer were elaborated; The application of Ni(IV) to initiating block copolymerization of acrylate monomers,acrylonitrile onto Poly(ethylene glycol)(PEG) ,Poly(1,2-propylene glycol adipate)(PPA) respectively was also cited, which has great theoretical and current significant. Moreover, it was set forth that the graft copolymerization of PAAM and its research purpose. In the secondly, Ni(IV)-PEG,Ni(IV)-PPA redox system was employed to initiate the block copolymerization of methyl acrylate(MA) onto PEG ,PPA in aqueous alkaline medium. The blocking parameters have been determined as a function of concentrations of monomer and initiator, temperature as well as time. The structure and thermal stability of the block copolymers were confirmed by Flourier transfer infrared spectroscopy(IR), thermogravimetric analysis (TGA), 1H nuclear magnetic resonance(1HNMR) and scanning electron microscope (SEM). The two separate single-electron transfer mechanism is proposed to explain the formation of the radical and the initiation. In the last chapter, the graft copolymerization of methyl methacrylate(MMA) onto polyacrylamide(PAAM) by -Ni(IV)-PAAM in aqueous alkaline medium was investigated. The graft copolymer was characterized by Flourier transfer infrared spectroscopy(FTIR), thermogravimetric analysis(TGA) and X-ray diffraction, scanning electron microscope (SEM). Thermogravimetric analysis validated that the graft copolymer was more resistant to moisture absorption, and had higher heat-stability than polyacrylamide.