Three different ionic liquids were prepared and examined as solvents for polyimide synthesis. The solubility of 4, 4′-oxydianiline and pyromellitic dianhydride as starting materials in ionic liquids was first evaluated, and then their polycondensation was carried out. Although these starting materials were hardly soluble in 1-benzyl-3-methylimidazolium bis (trifluoromethane sulfonyl) imide (3), addition of imidazolium type zwitterion, 1-(1-butyl- ...