專利摘要：
A solvent-free, catalyst-free and contamination-free method of synthesis of polyimides is disclosed. The method includes polymerizing a diamine with 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) at a pressure of 0.1-760 mm Hg, preferably a reduced pressure at about 36 mm Hg, and a temperature of 90-400° C., preferably 10-240° C.