High-performance and flexible poly(pyrrolone imide)s (PPyIs) were firstly prepared by the reaction of dianhydrides with an unsymmetric phosphinated triamine, 1-(3,4-diaminophenyl)-1-(4-aminophenyl)-1-(6-oxido-6H -dibenz < c,e > < 1,2 > oxaphosphorin-6-yl)ethane (1), which was prepared by a facile, one-pot procedure from the reaction DOPO, 4-aminoacetophenone in excess o-phenylenediamine in the presence of p-toluenesulfonic acid. Thermal properties of the resulting PPyIs were evaluated and compared with those of phosphinated polyimides with a similar structure. All of the prepared PPyIs films are tough and creasable. They display higher Tg (374412 degrees C), lower coefficient of thermal expansion (3446 ppm/degrees C), and better thermal stability (Td 5 wt %: 456477 degrees C, 800 degrees C char yield: 5963%) than analogous phosphinated polyimides. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 27092715