Synthesis and characterization of ordered polyurethanes from nonsymmetric diisocyanate and ethylene glycol

An ordered polyurethane with a head-to-head (H-H) or tail-to-tail (T-T) con tent over 95% was prepared by polyaddition reaction of a nonsymmetric monom er, p-isocyanatobenzyl isocyanate (1) with a symmetric monomer, ethylene gl ycol (2). The model reactions were studied in detail to demonstrate the fea sibility of polymer formation. The polymerization was conducted in THF in t he presence of triethylamine (TEA) at 0 degrees C by slow addition of a hal f 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 (DBT L). The microstructure of the polymer obtained was investigated by C-13 NMR spectroscopy, and it was found that the polymer had the expected structura l regularity. The constitutional regularity of polymers influenced their th ermal properties. (C) 2000 John Wiley & Sons, Inc.