Synthesis and Characterization of Poly [2,2-( m-phenylene) -5,5-bibenzimidazole] in 1-butyl-3-methylimidazolium Chloride

Poly[ 2, 2-（m.phenylene） -5, 5-bibenzimidazole] （mPBI） were synthesized by mixing 3, 3＇, 4, 4＇-tetraaminobiphenyl and isophthallc acid in 1 -butyl-3 -methyUmidazolinm chloride （ E BMIM] CI）. Intrinsic viscosity of mPBI polymers was 0.67 dL/g which was measured in 96% sulfuric acid. The polymer was characterized by Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance （ 1H-NMR ）, and thermogravimetric analysis （TGA）. The effects of polymerization conditions on the intrinsic viscosity of mPBI were investigated. It showed that the molecular weight of polymer mainly depended on pre-reaction time and reaction temperature. Comparison of structure and properties of mPBI synthesized in ionic liquids（ILs） and polyphosphoric acid was also reported. It indicates that the ionic liquids are a kind of good solvents in synthesis process of m_PBI and ionic liquids mainly affect molecular weight of mPBL