An ordered polyurethane with a head-to-head (H-H) or tail-to-tail (T-T) content over 95% was prepared by polyaddition reaction of a nonsymmetric monomer, p-isocyanatobenzyl isocyanate (1) with a symmetric monomer, ethylene glycol (2). The model reactions were studied in detail to demonstrate the feasibility of polymer formation. The polymerization was conducted in THF in the presence of triethylamine (TEA) at 0 degrees C by slow addition of a half amount of 2 to 1, followed by removing THF and then adding the rest of 2 in DMF at once at 30 degrees C in the presence of dibutyltin dilaurate (DBTL). The microstructure of the polymer obtained was investigated by C-13 NMR spectroscopy, and it was found that the polymer had the expected structural regularity. The constitutional regularity of polymers influenced their thermal properties.