Synthesis and characterization of novel optically active poly(urethane urea)s: Effect of left/right rotation conformation

Helical R / S ‐poly(urethane urea)s ( R / S ‐HPUUs) were synthesized successfully with R / S ‐1,1′‐binaphthyl‐2′,2‐diol, toluene 2,4‐diisocyanate, and 1,4‐diaminobenzene by a simple hydrogen‐transfer addition reaction. The structure and optical properties of R / S ‐HPUUs were investigated systematically with Fourier transform infrared spectroscopy, 1 H‐NMR spectra, absorption and circular dichroism, thermogravimetry, differential scanning calorimetry, and X‐ray diffraction measurements. Fourier transform infrared spectra showed that all the NH and carbonyl groups in R / S ‐HPUUs were hydrogen‐bonded. R ‐HPUU and S ‐HPUU were two enantiomorphs with wonderful mirror‐image symmetry according to circular dichroism spectroscopy analysis. R / S ‐HPUUs exhibited optical activity, and the optical rotations were +54.7 and −60.7°, respectively. R / S ‐HPUUs showed excellent thermal stability because of the plane‐bifurcated interchain hydrogen bonds and helical stereostructures according to thermogravimetry, differential scanning calorimetry, and X‐ray diffraction analysis. Moreover, the left‐handed rotation was more stimulative for the construction of hydrogen bonds than the right‐handed rotation, so S ‐HPUU showed higher thermal stability and better crystallizability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009