In this work, we for the first time prepared a series of novel highly branched block copoly (urethane-imide)s (CoPUIs) successfully by the condensation polymerization of star-like prepolymers and dianhydrides, (including pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 4,4'-oxydiphthalic anhydride) and the star-like prepolymers were synthesized from pentaerythritol (PAT) and toluene-2,4-diisocyanate (TDI) or isophorone diisocyanate. Our results revealed that it took about 40 min to complete the prepolymerization of PAT and TDI at 40 C. In addition, the imidization of the prepolymer and PMDA was successfully carried out at 120 C for 2 h. The X-ray diffractometer patterns exhibited that the resulting CoPUIs presented heterogenous structure with the d-spacing around 0.40 nm. Differential scanning calorimeter curves showed that the T of these CoPUIs ranged from 214 to 229 C in N-2 atmosphere. Thermogravimetric analyzer curves indicated that these synthesized CoPUIs had obviously two steps of weight loss in N2 atmosphere due to the used monomers which decomposed at 230-235 C and 602-644 C, respectively. The solubility testing results showed that the highly branched block CoPUIs had desirable solubility in several strong polar aprotic solvents and exhibited a strong resistance to dilute acid corrosion. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 99-104, 20