Synthesis of higher molecular weight PAN polymers in DMSO/H_2O

High molecular weight polyacrylonitrile(PAN) was obtained by the free radical suspension copolymerization of itaconic acid(IA) and acrylonitrile(AN), which was carried out in DMSO/H 2O using azodiisobutyronitrile(AIBN) as initiator. The effects of polymerization parameters, such as IA monomer concentration, DMSO/H 2O ratio, the conversion of polymerization and viscosity average molecular weight were specially described. The copolymerization reaction rate and the viscosity average molecular weight of copolymer decrease with the result of high chain transfer constant of DMSO. For copolymerization of AN and IA, with the inclusion of suitable solvent DMSO, the solution degree of AN in DMSO/H 2O is higher than that in water. As a result, the resulting copolymer pellets becomes from soft bulk to solid grain. The morphology structure PAN copolymers was also studied by the use of SEM. For the same solid content in the PAN solution, high molecular weight polymers have the higher viscosity which will decrease as temperature increases.