Macroinitiator Induced Controlled/Living Radical Polymerization Of Polyacrylamide With Ultra High Molecular Weight In Aqueous Phase

This paper mainly studies the synthesis of two kinds of macroinitiator and controlled/living radical polymerization of polyacrylamide with ultra high molecular weight in the water phase through the reversible coupling fracture mechanism of the initiators. Firstly,9,9'-bis isopropyl thia anthracene-9,9'-diol(BITX) and 9,9'-bis xanthenes-9,9'-diol(BIXAN) are synthesized with isopropyl thioxanthone and xanthones as raw material. These two small molecules initiator are used to initiate the polymerization of acrylamide in DMF solvent in order to obtained a certain molecular weight macroinitiator. Structure and composition of macroinitiator are characterized by ultraviolet and infrared. The effects of several conditions like solvent, reaction time, reaction temperature on the properties of macroinitiator are also studied. We obtain the best reaction conditions for the synthesis of macroinitiator with high initiation activities.The synthesized macroinitiator PAM-ITX initiate controlled/living radical polymerization of acrylamide in the visible light or heat conditions. During the reaction process, the changes of monomer conversion rates and polymer molecular weight are studied, in addition to the influences of monomer concentration, initiator concentration, reaction temperature and light intensity to reaction kinetics. The PAM-ITX can initiate the controlled/living radical polymerization of acrylamide in aqueous phase, and the molecular weight of the obtained polymer reaches as high as nineteen millions.The synthesized macroinitiator PAM-XAN initiate the polymerization of water-soluble acrylamide monomers in the UV light or heat conditions. Monomers including acrylamide, acrylic acid, sodium acrylate, mixture of acrylamide and sodium acrylate are polymerized with PAM-XAN as initiator in aqueous phase. The obtained polymer also possess ultra high molecular weight. The influences of monomer, monomer concentration, initiator concentration, reaction temperature and light intensity to reaction kinetics are discussed. The results indicate that PAM-XAN can also initiate the controlled/living radical polymerization of acrylamide in aqueous phase. Furthermore, PAM-XAN is more stable than PAM-ITX, leading to better initiation activities.