A new synthesis route for elastic polyurethane-imides (EPUIs) has been established by a method involving the use of urea. Various EPUIs were synthesized from polyurethane-urea, which was prepared from 4,4'-diphenylmethane diisocyanate (MDI), polyoxytetramethylene glycol (PTMG) and 4,4'-diphenylmethanediamine (MDA), and pyromellitic dianhydride in N-methyl-2-pyrrolidone (NMP). Flexible films were cast from these solutions that had different inherent viscosities. Imidization of the EPUI films was completed at 200 degrees C for 4 h in vacuo. The EPUIs were determined by FTIR, H-1 NMR, and C-13 NMR spectra. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115:242-248, 2010