A novel diamine monomer 3,5-diaminobenzoic-4’-(o-hydroxy) aniline acylamide has been synthesized, and a new polyimide (PI) containing pendent benzoxazoline group was synthesized from this diamine, 3,3’,4,4’-oxydiphthalic dianhydride (ODPA) and bis(4-aminophenyl)ether (ODA) by a one-step high- temperature polycondensation with a certain catalyzer in 1-methyl-2-pyrrolidinone (NMP). This PI is soluble in NMP. At the same time, mechanical and thermally stable properties of the PI film were investigated. The excellent mechanical properties of general polyimide films are reasonably maintained, and the polyimide film with pendent groups showes higher tensile strength (158 MPa) and modulus (2.4 GPa). TGA study showes a typical two-step weight loss behavior corresponding to the pyrolysis of pendent groups and main chains of the PI with (o-hydroxy)-anilide, respectively. Moreover, the PI with benzoxazoline side groups has one-step weight loss behavior, and an initial decomposition temperature near 597 ℃ was obtained.

Key words: polyimide, benzoxazoline side group, mechanical property