Synthesis and properties of new optically active and organosoluble poly(ester-imide)s containing L-valine moieties in the main chain by direct polycondensation reaction

摘要

New optically active poly(ester-imide)s (PEIs) containingbicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic diimide in the mainchain were prepared by the reaction of N,N'-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetra carboxylic)-bis-L-valine 4 as a diacid monomer withvarious aromatic diols 5a-g in a system of tosyl chloride (TsCl),pyridine (Py), and N,N-dimethylformamide (DMF). The reactions withTsCl were significantly promoted by controlling alcoholysis withdiols, in the presence of catalytic amounts of DMF, to give a seriesof optically active poly(ester-imide)s. The resulting new polymerswere obtained in good yields and inherent viscosities, ranging between0.36 and 0.62 dL g^{-1}, and were characterized with FT-IR and ^1H-NMRspectroscopy, including specific rotation. All of these polymers werehighly organosoluble at room temperature in solvents likeN,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF),dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and sulfuricacid. The thermal stability of the resulting PEIs was evaluated withthermogravimetric analysis (TGA) and differential scanning calorimetry(DSC) techniques under a nitrogen atmosphere, which indicated that theresidual weight percent of the polymers at 600 °C was 43.69%-60.5%and showed that they are moderately thermally stable.