Amine―Quinone Polyimides for Protecting Iron against Corrosion

摘要

Two dianiline monomers, 2,5-bis (4,4'-methylenedianiline)-1,4-benzoquinone (AQMDA) and 2,5-bis (4,4'-oxydianiline)-1,4-benzoquinone (AQODA), were prepared by condensing 1,4-benzoquinone and 4,4'-methylenedianiline and by 1,4-benzoquinone and 4,4'-oxydianiline, respectively, via Michael addition. The monomers were condensed with 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA) or 3,3', 4,4'-hexafluoroisopropylidene tetracarboxylic dianhydride (6FDA) to give polyamic acids. The polyamic acids were soluble in NMP and films were cast onto glass or iron squares. The films were thermally imidized at 290℃ to give the corresponding polyimides. The amine-quinone polyimides had thermal decomposition temperatures greater than 440℃ and glass transitions in the range 279 to 310℃. The tensile strength for the amine-quinone polyimides was in the range 92 to 166 MPa and the modulus was in the range 0.9 to 1.5 GPa. The amine-quinone polyimide made from AQMDA and BTDA protected iron against corrosion by aqueous sodium chloride electrolyte.