Synthesis and characterization of ordered poly(urethane-urea)s from p-isocyanatobenzyl isocyanate and 4-aminophenylethyl alcohol

The ordered (-abcd-) poly(urethane-urea) was prepared by the polyaddition reaction of two nonsymmetric monomers, p-isocyanatobenzyl isocyanate (XabX) (1) with 4-aminophenylethyl alcohol (YcdY) (2) in the presence of dibutyltin dilaurate as a catalyst. The polymerization was conducted in N,N-dimethylformamide (DMF) at 0 degreesC by mixing both monomers all at once, producing the ordered poly(urethane-urea) with a number-averaged molecular weight of 49 000. Authentic ordered and random poly(urethane-urea)s were prepared to verify the structure of the ordered polymer. The microstructure of polymer obtained was investigated by H-1 and C-13 NMR spectroscopy, and the expected (-abcd-) ordered structure was confirmed. The constitutional regularity influenced the solubility, crystallinity, and thermal and mechanical properties of polymers. Furthermore, the model reactions were studied in detail to demonstrate the feasibility of polymer formation.