A unique example of macromolecular self-assembly, where a mono-component homopolyimide bearing carboxy end-groups spontaneously forms nanopartilces with novel dimple-like morphology in a single good solvent, is presented. The self-assembly process is dramatically affected by the solution concentration and the temperature. It is proposed that such an unexpected self-assembly behavior is a synergistic result of the self-complementary hydrogen bonding between carboxy end-groups and the propensity to parallel packing of polyimide chains through aromatic interactions.